Analyze the performance requirements of nylon colorants

1, heat and light fastness

Many organic pigments, inorganic pigments and solvent dyes have been used for the coloring of most thermoplastic engineering plastics.

Resin processing temperature and requirements for colorants:

As can be seen from the table, the processing temperature of the polyamide is very high, and the coloring agent used needs to have high heat resistance. In addition to the thermal stability of the organic pigment for plastics, it is necessary to have Better light fastness. Many organic pigments have a significant negative effect on the properties of the polyamide melt, so there are certain restrictions on the organic pigments used for polyamide coloring.

2, chemical stability

Both the colorant and the resin should not undergo a chemical reaction and should not promote decomposition of the resin. For a highly reactive resin such as a polyamide resin (PA), its molten state exhibits a reducibility, and it is easy to change the color of the colorant, and therefore, only a few colorants are available.

3, migration resistance

There are three main types of colorant migration:

Solvent extraction, ie bleeding in water and organic solvents;

Contact migration, causing contamination of adjacent objects;

The surface is frosted. When heated, the colorant has a greater solubility in the polymer, while at room temperature, the colorant has less solubility.

In general, the dispersion of inorganic pigments in polymers is heterogeneous and does not cause blooming; while organic pigments have different degrees of dissolution in polymers and other organic materials, and migration is more likely.

4, tinting strength

The amount of tinting force determines the amount of colorant used to achieve the target color. In general, the coloring power increases as the particle size of the colorant decreases. The coloring power of the organic pigment is higher than that of the inorganic pigment, and when the color pigment is used in combination with the white pigment, the coloring power can be remarkably improved.

5, dispersion

The colorant is uniformly dispersed in the polymer only in a minute particle state in order to have a good coloring effect. Pigments contain many aggregated particles, which must be broken by high shear forces to form small aggregates to meet the requirements.