Oil-based inks for inkjet printers - Patents

Oil-based inks for inkjet printers

Patent Agent: C. Irvin Mcclelland Oblon, Spivak, Mcclelland, Maier & Neustadt, P.C. - Alexandria, VA, US
Patent Inventors: Yukio Sugita, Mitsuyoshi Tamura
Applicaton #: 20070000409
Class: 106031860 (USPTO)
Related Patents: Compositions: Coating Or Plastic, Miscellaneous, Marking, Inks, Pigment Containing, Specified Vehicle, Solvent, Or Dispersing Medium Containing, Organic Oxygen Compound Containing
01/04/07
wherein X3 and X4 each independently represents a hydrogen atom or a C1-7 alkyl or alkenyl group, and m stands for an integer of from 1 to 3. wherein X1 represents an alkyl group, X2 represents a hydrogen atom or an alkyl group, and n stands for an integer of from 1 to 4. The amount of the cyclic ester is from 1 to 60 parts by weight per 100 parts by weight of the compound represented by the formula (1). Preferably, the cyclic ester is a compound represented by the following formula (2): An oil-based ink for piezoelectric inkjet printers contains a binder resin, a pigment and a solvent. The solvent contains a cyclic ester and a compound represented by the following formula (1):

SUMMARY OF THE INVENTION
[0006] Therefore, an object of the present invention is to provide an oil-based ink of the pigment type for piezoelectric inkjet printers, which are free from ink clogging at printhead nozzles during printing, are excellent in ejectability and ejection recoverability, and are also superb in fixing properties and drying properties on recording media.
[0007] The above-described object can be achieved by the present invention to be described hereinafter. Described specifically, the present invention provides an oil-based ink for piezoelectric inkjet printers, said ink comprising a fixing (binder) resin, a pigment and a solvent, wherein said solvent comprises a cyclic ester and a compound (hereinafter called "the compound A") represented by the following formula (1): wherein X.sub.1 represents an alkyl group, X.sub.2 represents a hydrogen atom or an alkyl group, and n stands for an integer of from 1 to 4; and an amount of said cyclic ester is from 1 to 60 parts by weight per 100 parts by weight of said compound represented by the formula (1).
[0008] The present inventors have proceeded with an extensive investigation to resolve the above-described problems. As a result, it has been found that, especially when employed in piezoelectric inkjet printers, the above-described ink, compared with oil-based pigment inks making use of conventional solvents, is free from ink clogging at printhead nozzles which would otherwise take place at the edge of the printhead nozzles during printing by the deposition of solid components from the ink, is excellent in ink ejection recoverability even when printing is resumed subsequent to a temporary discontinuation, is free from a reduction in ink ejectability which would otherwise take place by a viscosity increase of the ink within the nozzles as a result of a concentration of the ink, and is superb in fixing properties and drying properties on recording media.
[0009] According to the present invention, the use of a specific mixed solvent in place of a solvent in an oil-based ink of the pigment type has made it possible to provide an ink which, especially when employed in a piezoelectric inkjet printer, is free from the deposition of solid components from the ink at the edge of printhead nozzles, is free from a viscosity increase of the ink within the nozzles as a result of a concentration of the ink, and excellent in the ejectability and ejection recoverability from the printhead nozzles and also in the fixing properties and drying properties on recording media.
[0010] As the ink according to the present invention is free from ink clogging at printhead nozzles even when used in continued printing and also retains good ink ejection recoverability even when the printheads are left over between printing operations, it is excellent in ejectability, fixing properties and drying properties and therefore, is effectively usable as an ink for piezoelectric inkjet printers.
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