What is the migration resistance and weatherability of functional masterbatch?
1、 resistance to migration
Migrations that occur in plastic products usually appear as blooming and smoke. Blooming refers to the migration of colorants from the plastic to the surface of the article, while smoke refers to the migration of colorants into adjacent plastic products or solvents.
Organic pigments, which are generally soluble in oils and plasticizers, are prone to migration. The colorant migration phenomenon occurs because the binding force of the colorant molecules is different, so that the colorant molecules have the ability to arbitrarily move within the matrix resin. Therefore, the rigidity and intermolecular tightness of the plastic molecular chain and the colorant can be considered. Related to the migration. Resins with good rigidity and close intermolecular connections are not conducive to peristalsis of the colorant molecules. When the amount of plasticizer is increased, the molecular structure in the resin becomes loose, thereby reducing the interaction between polymer molecular chains. , increase the chance of migration.
The molecular structure of the pigment also has an effect on the migration of the colorant. Pigments with short molecular chains and low relative molecular mass are generally prone to migration, especially when plasticizers are used in large quantities in plastics, such as soft polyvinyl chloride, pigments with low molecular weight should be avoided. Macromolecular organic pigments, due to their large molecular size, make them less soluble, so migration can be avoided. Inorganic pigments generally do not migrate.
2、 weather resistance
Plastic products need to have a certain time of use, so that they have use value, especially products used outdoors and products used under special circumstances require good weather resistance.
For example, the impact of the environment on pigments mainly considers the following factors: light, rain, and acid-alkali contaminants in the atmosphere. Some pigments will have different color changes under light irradiation. Most of these inorganic pigments have good lightfastness, and only a few varieties of inorganic pigments are darkened by changes in their crystalline or chemical composition after exposure to light. Organic pigments and dyes generally have poorer lightfastness than inorganic pigments, but organic pigments such as phthalocyanines have good lightfastness.
The discoloration, darkening, or change in color of a colorant is generally caused by reactive groups in the pigment. These reactive groups can interact with atmospheric moisture and chemical agents, particularly acid, alkali and smoke contaminants in industrial areas. For example, cadmium yellow discolors under the combined effects of moisture and sunlight. Litholol is a monoazo pigment and is a precipitate of metal salts. Therefore, the alkali and acid in the air will discolor it.