Development overview and related applications of t

2022-08-24
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Overview of the development of iron oxide series pigments and related applications (III)

through special treatment, the heat resistance of iron black can be improved, so that iron black can be used in some coatings, plastics and other occasions that need to be processed and used at higher temperatures

the most famous heat-resistant iron black is Bayer 303t, with a temperature resistance of 220 ℃. To produce heat-resistant iron black, iron black with relatively large particle size and relatively stable thermal performance must be selected. First, it should be coated with a layer of aluminum and silicon coating of "made in China 2025", which has become a national strategy. Then, an organic substance with good heat-resistant performance should be used to form a second layer of coating, and its service performance should be improved at the same time

2. Transparent iron oxide pigment

the original particle size of transparent iron oxide is only dozens of nanometers. When it is fully dispersed in the transparent medium to form a continuous film, light will bypass the pigment particles and diffract, so that the film has good transparency. The chemical structure of transparent iron oxide determines that it has good light resistance, weather resistance, acid resistance, alkali resistance and solvent resistance. It also has strong UV absorption capacity due to its very fine original particle size. Its light resistance is even better. The transparent iron yellow, transparent iron orange and transparent iron red produced by BASF company contain 1.7, 1.3 and 0.9 grams per square meter of paint film respectively, which can absorb 99.5% of UV light. Transparent iron oxide can be used in high-end car flash paint, hammer paint, wood coating colorant, mahogany like paint, tank head bottle inner wall paint, interior and exterior wall paint for construction, as well as ink and plastic coloring. Transparent iron oxide, which strictly controls arsenic and heavy metals, can replace the gradually banned azo pigments, dyes and other synthetic pigments and be used as colorants for food, drugs and cosmetics

the service life of products in developed countries will also be extended. Since the late 1970s, transparent iron oxide pigments have been used in many countries. The main manufacturers are bath company of Germany, Bayer company, Hilton davisco of the United States Blythecolorsltd And chappelleco With years of development, its application field has expanded from the initial high-end car flash paint to various fields

at present, there are three main process routes for the production of transparent iron oxide, namely, air oxidation method, carbonyl iron combustion method and sodium chlorate oxidation conversion method 9 Wood moisture content tester: detect the moisture content of materials. The product particles produced by air oxidation method are needle shaped, and the ratio of long and short axes is 5~8; Carbonyl iron combustion method is the unique technology of BASF company. The product particles are amorphous, and the particle size is only a few nanometers; Sodium chlorate oxidation conversion method is mainly used in China. The product particles are spindle shaped, and the ratio of long axis to short axis is 3~5. We can solve it for you only after there is a problem. After all, the things that happen are different, and the length of short axis is 10~20 nm

2.1. Transparent iron yellow

I once published the paper "preparation of transparent iron oxide yellow", which described in detail the preparation principle and method of transparent iron yellow. Here is a brief introduction of sodium chlorate oxidation conversion method. Oxidize ferrous sulfate with sodium chlorate to form ferric sulfate, neutralize ferric sulfate with alkali to form colloidal ferric hydroxide, and in the presence of iron sheet, convert amorphous ferric hydroxide colloid into -feooh, wash with water, surface treatment, filtration, drying and crushing to obtain transparent iron yellow pigment

the chemical reaction formula is as follows:

oxidation: 6feso4+naclo3+3h2so4=3fe2 (SO4) 3+nacl+3h2o

precipitation: Fe2 (SO4) 3+6naoh=2fe (OH) 3 +3na2so4

Transformation: Fe (OH) 3= -feooh+h2o

2.2 Transparent iron red

transparent iron yellow FeOOH is goethite, which has poor thermal stability. If the temperature is higher than 177 ℃, it will gradually lose crystal water, resulting in phase changes, and turn into -fe2o3 hematite

transparent iron red is obtained by calcining and dehydrating transparent iron yellow at 300~350 ℃

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