Pigment is a psychophysical quantity, which is not only related to human visual characteristics, but also to the observed objective radiation. Color is an important indicator for evaluating the quality of pigment products.
The expression of pigments can generally be divided into two categories, one is represented by three basic attributes of pigments, such as the Munsell pigment system that classifies and calibrates the surface colors of various objects, in which H represents hue and V represents Brightness, C stands for chroma, written as HV / C; the other is based on two sets of basic visual data, a set of pigment representation, measurement and calculation method is the CIE standard colorimetry system.
The inspection of pigments is divided into two categories, one is the pigment comparison method, which gives the result by visual comparison with the reference sample or instrument test; the other is the direct color measurement method, which uses the instrument or visual to directly give the amount of pigment Value or sample number.
nature
1. The color of the pigment: it is the result of the selective absorption of the white light component by the pigment. The physical properties of pigments, such as dispersion, affect the color within certain limits, because the degree of dispersion affects the reflection conditions of the pigment. Generally, the smaller the particle size, the darker the hue and the greater the brightness.
2. Covering power: The pigment in the paint film can cover the surface that bears the paint film, which is its ability to be exposed through the paint film.
3. Coloring power: the ability of a certain color to be mixed with another color to form the color strength, strong coloring power, less dosage.
4. Oil absorption: The size of the pigment oil absorption material is related to the degree of dispersion, but it is not determined by the degree of dispersion alone.
5. Particle size: not only determines the characteristics of the pigment, but also determines the quality of the coating film.
6. Light resistance: The color of the pigment changes with varying degrees under the action of light.
7. Pulverization: After a certain period of exposure after the coating film is made, the film-forming material in the coating film is destroyed, and the pigment on the surface cannot continue to be firmly in the coating film, but falls off from the coating film to form a powder The layer can be wiped off or rinsed off with water. This phenomenon is called pulverization.
8. Organization
9. Moisture: The moisture of the pigment is too high, which often causes many problems for the paint.
10. Heat resistance
11. Solvent resistance
12. Acid and alkali resistance
13. Relative density and specific volume