Riso Kagaku Corporation

Koichi Okusawa

Takanori Hasegawa

A water-in-oil (w/o) emulsion ink for stencil printing, which contains carbon black having a pH of 5 or lower, preferably 3.5 or lower as a colorant added to the oil phase, in an amount of 2-10 % by weight based on the total weight of the ink, is provided. The emulsion ink is improved in phase separation in course of time and stabilized while printability is kept well.

Emulsion ink for stencil printing

Provided is a device which can form favorable perforated images corresponding to the resolution of the thermal head, reproduce faithful printed images for all kinds of original picture images, avoid ink transfer, and adapt itself to different environmental conditions, and is suitable for use with different thermal recording materials such as thermal recording paper, OHP TP sheets, and thermal stencil master plates. In the device of the present invention, a thermal head 4 consisting of a plurality of heat emitting elements 5 arranged in a single row in the primary scanning direction is directly contacted to the recording surface of a thermal recording material such as thermal recording paper, and the thermal recording material 1 is moved relative to the thermal head 4 in the secondary scanning direction which is perpendicular to the direction of the row of the heat emitting elements so that picture images may be formed with a dot matrix by selectively heating the thermal heat emitting elements at an appropriate timing in relation to the movement of the thermal recording material in the secondary scanning direction, the ratios of the length of each heat emitting element 5 in the primary and secondary scanning directions to the pitches of the primary and secondary scanning are set 30 to 70% and 60 to 95%, respectively.

Device and method for dot-matrix thermal recording

In the thermal stencil master plate and the method for processing the stencil master plate according to the present invention, since swelled and solidified unprocessed regions formed by film lumps or a part thereof produced from the melted film are provided continuously, the merging and excessive expansion of the perforations can be avoided so that clear printed picture images may be formed even in the regions of solid picture images. Further, the ink passing through each of the perforated dots is reliably separated from the ink passing through adjacent perforation dots before it is deposited onto the printing paper so that excessive deposition of the ink is avoided and the time required for drying the printing ink is reduced so that offsetting may be avoided.

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Tokyo-to, Japan

Koichi Okusawa