Pigment red, yellow light fastness refers to the use of organic pigment red or pigment yellow coloring ink or paint, in daylight, in a specific period of time to maintain its own color performance. This is especially important for outdoor prints, especially advertising boards and signboards. Except for a few inorganic pigments. Most inorganic pigments and organic pigments in the light of more or less discoloration occurs. Light fastness of organic pigments and inks is influenced by the properties of the organic pigments themselves (including their chemical structure and physical form) on the one hand. On the other hand by the application of other components of the system (such as resins, additives, etc.) the nature of the impact. How to improve the fastness of pigment red and pigment yellow it, the color Swiss Xiaobian believe that the following two aspects can improve the fastness of pigment red and pigment yellow.

  First, the molecular structure of pigment hydrogen bond formation and performance of the relationship     

  In azo pigments, the diazo component in the amino ortho, para nitro, sulfonic acid, carboxylic acid, chlorine and other electron-withdrawing substituents, the coupling component of amido phenyl ring ortho, para a Group, ethyl, methoxy, ethoxy and other electron-donating substituents, there is a tendency to strengthen the formation of hydrogen bonds and make the pigment have better fastness. Such as Pigment Yellow - Fast Yellow G, Pigment Red - Permanent Red FGR and so can form intramolecular hydrogen bonding structure, so have a good light fastness. Benzimidazolone azo pigments, can form hydrogen bonds between molecules, so light, heat, solvent resistance, migration resistance is more excellent. 

  Second, increase the relationship between pigment relative molecular mass and performance    

  Increasing the relative molecular mass of a pigment can improve various properties, for example, benzidine yellow is better than lightfast yellow on the properties of heat resistance, solvent resistance and migration resistance. Generally only a single azo pigment molecular weight of only 300 to 500, while the condensed azo pigment relative molecular mass between 800 to 1100, so light, heat, solvent, migration resistance has greatly improved.