In plastic color matching, we must know some characteristics of masterbatch products in order to better carry out plastic color matching, in order to avoid unnecessary accidents.
In today's article, we will explain the resistance to migration and weather resistance of color masterbatch products when they are used in color matching.
First, resistance to migration
Migration occurring in plastics is usually characterized by frosting and smoke coloration.
Frosting refers to the migration of the colorant from the plastic body to the surface of the product, while smoke refers to the migration of the colorant to the adjacent plastic product or solvent.
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Generally, organic pigments soluble in oils and plasticizers are prone to migration.
The phenomenon of colorant migration occurs because the binding force of colorant molecules is not large, which makes the colorant molecules have the ability to swim freely in the matrix resin. Therefore, it can be considered that the rigidity of the plastic molecular chain and the tightness between molecules are related to the migration of colorant.
Rigidity, close connection between the molecules of the resin, is not conducive to the peristalsis of the dye molecules, when the amount of plasticizer is increased, the molecular structure of the resin will become loose, thus reducing the interaction between the polymer molecular chains, so that the opportunity of migration increases.
The molecular structure of pigments also has an effect on the migration of colorants.
Pigments with short molecular chains and low relative molecular weight are generally more likely to migrate, especially when a large number of plasticizers are used in plastics, such as soft polyvinyl chloride. Pigments with low relative molecular weight should be avoided as far as possible.
Macromolecular organic pigments are less soluble because of their large molecular size, so they can avoid migration.
Inorganic pigments generally do not migrate.
Second, weather resistance
Plastic products need to have a certain use time, so that they have use value, especially in the outdoor use of products and products used in special environment, the requirements of the colorant has a good weather resistance.
The influence of the environment on the pigment mainly considers the following factors: illumination, rain and pollutants such as acid and alkali in the atmosphere.
Certain pigments show different colors when exposed to light.
Most of the inorganic pigments have good light resistance, and only a few kinds of inorganic pigments darkened because of changes in their crystal or chemical composition after being irradiated by light.
The light resistance of organic pigments and dyes is generally worse than that of inorganic pigments, but organic pigments such as phthalocyanines have good light resistance.
The fading, darkening, or tonal change of a colorant, usually caused by reactive groups in pigments.
These reactive groups can interact with water and chemicals in the atmosphere, especially acid, alkali and smoke pollutants in industrial areas.
Cadmium yellow, for example, is discolored by a combination of water and sunlight, while Risol red is a monoazo pigment that is a precipitate of metal salts, and is thus discolored by both alkali and acid in the air.
