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Performance requirements for nylon with colorants
- Aug 04, 2018 -


(1) heat resistance and sun resistance

So far, many organic pigments, inorganic pigments and solvent dyes can be used for coloring most of thermoplastic engineering plastics.

The processing temperature of the resin and the requirements for the coloring agent:


It can be seen from the table that the processing temperature of polyamides is very high, and the coloring agent needs to have high heat resistance. In addition to the thermal stability of the plastic, it needs better fastness. Many organic pigments have obvious negative effects on the properties of polyamide melts, so there are some limitations in the use of organic pigments for polyamide coloring.

(2) chemical stability

The chemical reaction between coloring agent and resin should not occur, and the decomposition of resin should not be promoted. For highly active resins, such as polyamide resin (PA), the melting state of the resin shows reducibility and makes the colorant change color easily, so only a few coloring agents can be selected.

(3) resistance to mobility

There are three main types of migration of colorants:

Solvent extraction, that is, in water and organic solvents;

Contact migration, causing pollution of adjacent objects;

When the surface is sprayed, the solubility of the colorant in the polymer is larger when heated, while the solubility of the colorant is smaller at normal temperature.

In general, the dispersion of inorganic pigments in polymers is heterogeneous and does not produce frosting; organic pigments are dissolving in varying degrees in polymers and other organic compounds, which are easier to migrate.

(4) coloring force

The coloring power determines the amount of colorant to achieve the target color. Generally speaking, the coloring power increases with the decrease of colorant size. The dyeing power of organic pigments is higher than that of inorganic pigments. When the color pigments are used with white pigments, the dyeing power can be significantly improved.

(5) dispersivity

The coloring agent can only be dispersed in a small particle state even in polymer, so as to achieve good coloring effect. The pigment contains a lot of aggregated particles, and it is necessary to break the aggregate with high shear force and form a small polymer so as to meet the requirements.