Organic pigments are pigments made of organic compounds whose color comes from the conjugated system or aromatic ring structure in the molecular structure. According to their different molecular structures, organic pigments can be divided into three categories: azo pigments, phthalocyanine pigments and aromatic pigments.
1. Azo
Pigment Azo pigment is one of the common organic pigments, which contains azo group (-N=N-) in its molecular structure. The color of azo pigment depends on the position of azo group, the type and number of substituents and other factors. The common azo pigments are yellow No.4 for orange color, red No.3 for red color, blue No.1 for blue color and so on.
2. Phthalocyanine pigment
Phthalocyanine pigment is a kind of organic pigment containing phthalocyanine structure, which contains four pyrrole rings and one benzene ring in its molecular structure. The color of phthalocyanine pigment depends on the substituent group on the benzene ring and the type of metal ion on the pyrrole ring. Common phthalocyanine pigments include green copper phthalocyanine, blue cobalt phthalocyanine and so on.
3. Aromatic pigments
Aromatic pigment is a kind of organic pigment which contains aromatic ring structure, and its molecular structure contains benzene ring, naphthalene ring, anthracene ring and so on. The color of aromatic pigment depends on the type and number of substituents on the aromatic ring. Common aromatic pigments include yellow aniline yellow, red red F3RK and so on.
In conclusion, the structural classification of organic pigments mainly includes three categories: azo pigments, phthalocyanine pigments and aromatic pigments. Different organic pigments have differences in molecular structure, so their colors are different. Organic pigments have the advantages of bright color, light resistance, heat resistance, acid and alkali resistance, etc. They are widely used in ink, paint, plastic, rubber, textile and other fields.
