A method for buffer system to control the viscosity of iron oxide yellow

Abstract

The invention relates to a new method for the production of low-viscosity iron oxide yellow in a buffer system, which uses crystal seeds to oxidize in the buffer system, and stabilizes the pH condition without violent pH changes due to the impact of ferrous sulfate and liquid caustic soda. Let the seed crystals grow under certain conditions. On the one hand, it can make the iron yellow particles grow more uniformly. On the other hand, the iron yellow particles grown in a relatively stable pH environment are not easy to produce bifurcations, the surface of the particles is smoother, the aspect ratio is reduced, and its viscosity As low as 36Ku.

Description

technical field [0001] The invention relates to a low-viscosity iron oxide yellow pigment, in particular to preparing low-viscosity iron oxide yellow in a buffer system by controlling the reaction. Background technique [0002] Iron oxide yellow, also known as iron oxyhydroxide, its molecular formula is FeOOH or Fe2O3·H2O, it is yellow powder, its particle shape is needle-like, it has high coloring power, hiding power, and it is non-toxic and harmless, and is environmentally friendly Type inorganic pigment, its light fastness reaches 6-7 level. Iron oxide yellow pigments are widely used in building materials, coatings, paints, plastics, rubber, electronics, industrial catalysts, tobacco, cosmetics and other industries. [0003] Due to the difference in surface charge distribution and particle shape, ordinary iron oxide yellow has high viscosity and has many limitations in the application field of coatings. Compared with other axial crystal systems such as iron oxide red is...

AI Technical Summary

Problems solved by technology

At present, high solid content and low VOC is an important development target of the coating industry, and the viscosity of the pigment determines the size of the solid content. Excessively high pigment viscosity leads to high flow resistance of the coating, which is extremely unfavorable to production.

[0006] At present, relevant literature reports at home and abroad show that the viscosity of iron oxide yellow can be improved by changing the surface charge of iron oxide yellow particles or reducing the aspect ratio of iron oxide yellow particles. In China, there is a patent with application number 201410767118.7 published by Zhejiang United Pigment "A low-viscosity iron oxide yellow pigment", the principle is to destroy the shape of some iron oxide yellow pigment particles by grinding with steel balls, but not reduce the aspect ratio of all iron oxide yellow particles as a whole. Although this method reduces the particle size to a certain extent The viscosity of the pigment is reduced, but the effect is not obvious enough and the hue of the pigment will change; Nantong Baoju Pigment Co., Ltd. published the patent No. ZL201310277999. The charge on the surface of yellow particles is used to improve the viscosity of iron oxide yellow, the effect is ideal, but there is still room for improvement; Zhejiang Huayuan Pigment's published application number ZL201610596145.1 patent "a low-viscosity iron oxide yellow" through high-pressure reaction and Controlling the temperature of the system to reduce the viscosity of iron oxide yellow has a certain effect, but the high-pressure reaction is dangerous and consumes a lot of energy

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