Pigment inspection

Pigment is a highly dispersed substance that is insoluble in water and film-forming substances (oil, hot oil, etc.), and is characterized by a generally large refractive index.

According to the classification method proposed by Belinki and HB, Riskin, all pigments can be divided into two types: achromatic and chromatic. These two types of pigments can be further divided into subcategories according to their colors: white, black, gray, yellow, orange, red, green, blue, purple and other colors. Each type of pigment is different in chromophore, the so-called chromophore is those atoms or atomic groups that produce the color of the pigment. For example, chromic acid pigments (lead chrome yellow, lead chrome orange, lead chrome red, zinc chrome yellow, etc.) containing CrO4 chromophores are included in the branches of yellow, yellow and red pigments; Iron oxide pigments (yellow, red, brown and black iron oxide) and so on. Among the pigments of green, blue, purple and other colors, there are chromium pigments (chromium oxide, chrome emerald green) containing Cr chromophore; iron blue (Fe(CN)6==chromophore) and so on.

In addition, there are some special organic pigment categories (pigment dyes, alizarin lakes, sedimentation lakes) and special-purpose pigment categories (used in heat-sensitive paints, luminescent paints, and ship bottom anti-corrosion paints). pigments in paint).

The use of pigments is very diverse, but its important use is to be used in color paints to prevent metal corrosion and atmospheric action, and to decorate the color of the painted utensils. As we all know, most of the varnish film (that is, the paint film without pigment) formed by widely coating the film-forming material on the surface of the utensil can be penetrated by moisture and other components contained in the atmosphere, so it is almost impossible to use Protects various materials from atmospheric effects. In order to enhance the protective performance of the paint film, pigments must be added to the film-forming substance. The suspension of pigments in film-forming substances is called paint. Paint is also the main material to prevent corrosion of the painted surface.

Some pigments with special properties can be used in special color paints (such as ship bottom antifouling paints), thermal sensitive paints (thermal sensitive pigments), signal color paints (luminescent pigments) and so on.

In addition, pigments can also be used in various special purposes, such as rubber fillers, manufacturing batteries and so on.

When describing the performance and testing methods of pigments, the main focus is on their use in the manufacture of color paints.