US 5,406,314 AGranted

Electrothermal printing ink with monodispersed synthetic pigment particles and method and apparatus for electronic printing therewith

OwnerManfred R. Kuehnleinventor

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Abstract

A printing ink comprises a clear, transparent, polymeric carrier material and uniform, colloidal size charged color particles evenly dispersed therein. The carrier and the particles are adhesively bonded to one another so as to form a matrix which can collectively respond to an externally imposed electrostatic field to promote co-movement of a "bite" of ink to an imaging medium without change of the bulk particle/carrier ratio. During the printing process, the ink is melted and exposed to electrostatically charged latent image areas on a heated image cylinder, resulting in the transfer of the ink thereto in proportion to the electrostatic field strength. The ink exhibits a relatively sharp liquid-to-solid transition, thereby enabling rapid ink solidification and complete transfer from the imaging medium to the relatively cool printing substrate. Also disclosed is a printing method and apparatus that facilitate continuous, variable and on-demand color printing in conjunction with the ink. Use of essentially monodispersed, color-coated, colloidal size, spherical particles in the ink results in excellent color purity and chromaticity range.

Claims29

Dependent claims

A process of printing on a substrate, comprising the steps of:

a. establishing an imagewise electrostatic dot-like charge pattern on the surface of an image member;
b. heating the image member to a predetermined temperature;
c. providing an ink comprising:
1) a colorless carrier material comprising an electrostatically polarizable polymeric substance which is molten at the predetermined temperature and which, in its liquid phase, is responsive to an externally imposed electrostatic field and attracted to the source of the field;
and
2) colored, non-melting, evenly dispersed fine particles of composite structure and of colloidal dimensions, whose size, shape, and compositional chemistry are substantially identical and conform to predetermined values, the particles being adhesively integrated in the carrier material to form an interactive matrix therewith;
d. bringing molten ink into contact with the heated, imagewise-charged surface of the image member, thereby effecting electrostatically the transfer of both the carrier material and the particles of the ink as an interactive fixed-ratio matrix onto the image member, in thicknesses proportional to the field strengths emanating from each charged image-member region;
and
e. bringing the ink-bearing image member momentarily into contact with printing substrate having a temperature less than the predetermined temperature, thereby effecting the rapid solidification and transfer of the ink onto the substrate to form an image on the printing substrate.

6 more elements

An apparatus for printing on a substrate comprising:

a. an image member having a hard, dielectric surface;
b. means for establishing an imagewise electrostatic charge pattern on the surface of the image member;
c. means for heating the image member to a predetermined temperature;
d. a source of ink that comprises:
1) a colorless carrier material comprising an electrostatically polarizable polymeric substance which is molten at the predetermined temperature and which, in its liquid phase, is responsive to an externally imposed electrostatic field and attracted to the source of the field;
and
2) colored, non-melting, evenly dispersed fine particles of composite structure and of colloidal dimensions, whose size, shape, and compositional chemistry are substantially identical and conform to predetermined values, the particles being adhesively integrated in the carrier material to form an interactive matrix therewith;
e. means for bringing molten ink into contact with the heated, imagewise-charged surface of the image member, thereby effecting electrostatically the transfer of both the carrier material and the particles of the ink as an interactive fixed-ratio matrix onto the image member, in thicknesses proportional to the field strengths emanating from each charged image-member region;
and
f. means for bringing the ink-bearing image member momentarily into contact with printing substrate having a temperature less than the predetermined temperature, thereby effecting the rapid solidification and transfer of the ink onto the substrate to form an image on the printing substrate.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/166,098Filed 13 Dec 1993 · division
Priority: 15 Nov 1991
Granted: 11 Apr 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G03G 9/08728
Polymers of unsaturated acids or derivatives thereof: polymers of esters
B41C 1/105
For lithographic printing; Master sheets for transferring a lithographic image to the forme: by electrocoagulation, by electro-adhesion or by…
B41J 2/415
For electrostatic printing: by passing charged particles through a hole or a slit
C09D 11/02
Inks: printing inks