Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Patent
1997-08-27
1999-03-16
Bell, Mark L.
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
106 3172, 106 3173, 106 3175, 106 3179, 106 318, 106 3181, 106496, 106500, C09B 6300
Patent
active
058823948
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an aqueous paste of a monoazo lake pigment useful for an offset printing ink, a process for the production thereof, and an offset ink containing the same. More specifically, it relates to an aqueous paste of a monoazo lake pigment improved in flushing suitability, fluidity, clearness, gloss and freedom from bronze, a process for the production thereof, and an offset ink containing it.
TECHNICAL BACKGROUND
A monoazo lake pigment obtained by coupling an aromatic amine having a soluble group as a diazo component and .beta.-hydroxynaphthoic acid or .beta.-naphthol as a coupler component is widely used in the fields of printing inks, coating compositions and coloring of plastics. The monoazo lake pigment has been treated with a rosin for obtaining transparency and clearness in color tone and improving the dispersibility thereof. The rosin treatment is generally carried out by adding an alkali salt solution of a rosin (so-called "rosin soap") to a coupler component or a dye, and then adding a metal salt for a lake such as calcium chloride to precipitate the rosin on the surface of each pigment particle in the form of a rosin lake metal salt.
The above rosin treatment controls the pigment particles so as to have a fine particle size and improves the transparency and clearness of the pigment. Moreover, the rosin treatment has excellent effects that it as a coating prevents the coagulation of the pigment and that it improves the dispersibility of the pigment. However, it cannot be said that any conventional rosin treatment exhibits its full effects. In a pigment for an offset ink in particular, the amount of a rosin for improving the dispersibility is large. The use of the rosin in a large amount causes many problems such as a decrease in fluidity or a decrease in printing suitability caused by poor water resistance. Further, when the amount of the rosin is decreased, there are caused such problems as a decrease in transparency and clearness, an increase in bronze and a decrease in flushing compatibility.
It has been therefore desired to develop a surface treatment technique for effectively coating the pigment and to develop a monoazo lake pigment improved in flushing suitability, fluidity, clearness, gloss and freedom from bronze.
It is therefore an object of the present invention to provide an aqueous paste of a monoazo lake pigment, which can decrease the amount of the rosin so that the flushing time length can be decreased and that an exhausted water is less colored, and which is excellent in fluidity, clearness, gloss and freedom from bronze and also excellent in the suitability for offset printing, a process for the production thereof, and an offset ink.
DISCLOSURE OF THE INVENTION
The present invention provides a aqueous pigment paste for an offset ink, which contains a lake pigment of an azo dye obtained by coupling a diazonium salt of an aromatic amine having a soluble group and a coupler component, 3 to 15% by weight, based on the azo dye, of a rosin, 1 to 20% by weight, based on the azo dye, of a vehicle for an offset ink and 60 to 90% by weight, based on an entire composition, of water.
Further, the present invention provides a process for the production of a aqueous pigment paste for an offset ink, which comprises the steps of coupling a diazonium salt of an aromatic amine having a soluble group and a coupler component to obtain an azo dye, lake-forming the obtained azo dye in the presence of a rosin to obtain a slurry of a monoazo lake pigment, adding a vehicle for an offset ink to the obtained slurry of a monoazo lake pigment, and concentrating the slurry of a monoazo lake pigment obtained in the preceding step to produce the aqueous pigment paste for an offset ink.
Further, the present invention provides an offset ink obtained by flushing the above-obtained aqueous pigment paste for an offset ink with a vehicle for an offset ink, and a process for the production of the above offset ink.
PREFERRED EMBODIMENTS FOR WORKING THE INVENTION
In the
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Aida Seiji
Nishina Hiroki
Sugamo Hitoshi
Bell Mark L.
Hertzog Scott L.
Toyo Ink Manufacturing Co. Ltd.
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