Direct transfer technology of aqueous pigment paste

In order to obtain excellent dispersibility, high color strength, bright color, suitable for the printing ink coloring of organic pigments in new formulations, in addition to the addition of an effective dispersant, such as rosin acid or other additives, during the synthesis process or post-treatment process. To improve the polarity of the product's particle surface and to prepare a powdered product suitable for oil-based offset printing inks; a more efficient preparation process is through conventional Pushing Prncess, the aqueous cake and the resin In the presence of a specific surfactant, the binder (the varnish) transfers the pigment from the aqueous phase to the human phase, separates the water, dehydrates it to form the base ink product, and ultimately is used to produce the printing ink.

BASF company in the United States patent US4300954 (1981) has described the use of water-based pigment slurry squeezing water transfer technology for the benzidine pigments, red lake C, and copper enamel and other varieties; its principle is based on the synthesis of water-based pigments Slurry (at least 2% solids, or 50% of high solids in the filter bowl, using a special squeeze water phase inversion equipment to complete the process of pigment inversion, the color paste continuous squeeze water transfer equipment schematic diagram as follows Show:

The water-based paint is filled from the feed port (1), and is mixed into the pump body via the meter (3) and the conduit ((5)), and at the same time the feed material (inner ink) is discharged from the population (11) through the meter. Adding, mixing in the mixer, due to the shear force applied by the twin-screw kneader (27, 29) and completing the phase inversion process, the moisture is removed under vacuum conditions, and a color paste meeting the requirements is continuously prepared.

Thus, the continuous phase transfer technology recommended in the patent has the characteristics of time saving, energy consumption reduction, and simplified operation, but it must have a special special water-sweeping phase conversion reaction equipment.

The phase transfer technology of this article aims to simplify the process without the above-mentioned special equipment, and has better practical features; this technology is based on the synthesis of aqueous pigment paste, adding resin binder to the reaction mixture, and directly under stirring. The phase transformation process of the pigment is carried out using CI Pigment Red 53:I (gold light red C) as an example. The diazotization of CLT acid is coupled with octacophenol, and the yttrium salt lake is formed. Then the phase transformation is carried out. The process is as follows: Show:

The process for preparing the base ink: The synthesized GI Pigment Red 53:1 aqueous lake pigment suspension material is added to the stirred reactor ((5 tons)) while it is being stirred at a high temperature and at a specific temperature. In the case of varnish, the pigment particles are transferred to the organic phase (diverted oil) to form fine (about 1 mm) colored ink particles, and the water is quickly separated; after the phase is completed, the stirring is stopped and the colored ink particles are put. In the filter tank, most of the mother liquor is filtered out, the ink particles are transferred to a squeezed water machine, and water is added to stir, and the water-soluble salt wax therein is washed to assist in heating to remove a small amount of residual water, and the red lake C is obtained. Base ink, the amount of its disposable processing equivalent to 100 kg of dry powder pigments.

It should be pointed out that the content of the added resin oil must be strictly controlled during the phase inversion. When the amount is insufficient, the pigments in the aqueous medium cannot be completely transferred to the oil phase, and the water separation is not complete; when it is too large, the ointment may be easily agglomerated and not easily formed. material.

The test results and mass production show that the process of squeezing and converting water from the synthesized pigment slurry directly has many advantages, such as simplifying the production process, omitting the pressure filtration and drying equipment, shortening the production cycle, improving the working conditions, and not requiring high temperatures. Dust and other physical labor; saving manpower; reducing energy consumption, etc., and can improve the product's intrinsic quality and increase the competitiveness of this type of organic pigments.


Information source "Dyes and dyes"

(Author/Liu Linduan Tianjin Ink Factory)