1. Hiding power
When an object is coated with a certain kind of paint, the pigment in the paint can cover the background color of the surface of the painted object, so that the background color can no longer be revealed through the paint.
Hiding power = pigment mass (g) / surface area of the object to be coated (CM2)
2. Heat resistance
It means that at a certain processing temperature, the pigment does not undergo obvious changes in shade and tinting strength. It refers to the resistance of the pigment to the change of tinting strength caused by the processing temperature.
Noteworthy:
① While considering the high temperature resistance of the pigment, it is also necessary to consider its heating time.
② What needs to be considered is the thermal stability of the colored resin itself.
3. Light fastness
It refers to the color change of the pigment under the irradiation of light. The light fastness rating is the best with the eighth grade and the worst with the first grade.
4. Weather resistance
It refers to the change of pigments in various forms of climatic conditions, including visible light and ultraviolet light, moisture and temperature, and product color. After the organic pigment is irradiated by light, it will cause changes in the molecular configuration of the pigment, which will affect the decrease in saturation, and even fade into gray or white. The weather resistance of the pigment is rated as 5 grades, and 5 grades are the best.
5. Migration resistance
It means that the pigment migrates from the inside of the plastic to the surface of the product or to the adjacent plastic product and solvent when it migrates. In the evaluation, grade 5 means no migration, and grade 1 means severe migration.
The specific performance is as follows:
① Blooming: During storage at room temperature, pigment particles migrate from the plastic/pigment system to the surface.
② Solvent exudation: Pigment components enter the adjacent solvent, dyes and some organic pigments show this phenomenon.
③ Plastic/plastic contact migration.
6. Oil absorption
Refers to the amount of refined linseed oil absorbed by a pigment sample under specified conditions, which can be expressed by volume/mass or mass/mass. The amount of oil absorption has a certain influence on the leveling and gloss of the coating.
7. Solvent resistance
It means that after the pigment is in contact with the solvent, some pigments will dissolve in the solvent, which will cause the solvent to be stained. The solvent resistance of the pigment refers to the performance of the pigment to resist the dissolution of the solvent and cause the solvent staining.
8. Softening point
The temperature at which a thermoplastic resin changes from a solid state to a viscous state is called the softening point. If the softening point is too low, the product is easy to agglomerate; if the softening point is too high, the injection temperature must be increased, otherwise the pigment is difficult to melt and disperse.
9. Decomposition point
The temperature at which the resin is destroyed and decomposed at high temperature is called the decomposition point. The decomposition point can reflect the thermal stability of the resin.
10. Particle size
Particle size is an important index reflecting the particle size of fluorescent pigments, and the unit is um. The finer the particle size, the easier the product is to disperse and melt into downstream products.
