Pigments And Dyes For Coloring Nylon
Nylon is a hydrophobic fiber containing amino and carboxyl groups on the fibers, which can be dyed with disperse dyes, acid dyes, especially weak acid dyes, says pb29 pigment manufacturer. The commonly used nylons are nylon 6 (PA6) and nylon 66 (PA66), which are crystalline thermoplastic materials that readily absorb water and contain hydrophilic groups. For crystalline polymers, very rapid cooling during the injection molding process prevents the material from crystallizing naturally, resulting in strong internal stresses within the material. Nylon materials that have not undergone the “tempering” process, its internal because after the stereotypes, the macromolecules will still tend to natural orientation, crystallization of the movement, which will lead to a further increase in the internal stress of the material. As a result, the nylon parts that have not been boiled are very fragile and can easily fall apart or break when subjected to external forces.
So, how to eliminate the internal stresses if the already molded nylon macromolecules are allowed to orient and crystallize naturally? That is what we call boiling, boiling process is actually similar to our metal “tempering” treatment process. That is to let the nylon in a certain water temperature for immersion, so that its internal macromolecules as much as possible tend to the natural orientation and to achieve the balance of internal crystallization and decrystallization, so as to eliminate its internal stress. The performance of the outside is: the toughness of the nylon parts to strengthen the brittleness of the basic elimination.
How to color boil-resistant nylon
General nylon coloring still need to boil, so the pigment used for nylon also need to boil after not fade, the past commonly used cadmium pigments and dyes, but cadmium pigments due to the heavy metal problem has been a lot of limitations, and dyes after boiling most of the color is not stable discoloration.
Inorganic pigments for nylon
Inorganic pigments which can be used in nylon include: C.I pigment yellow 184, pigment blue 29, pigment blue 28, pigment green 50, titanium dioxide, carbon black and so on.
Organic pigments applicable to nylon
● Azo pigment: Because nylon resin shows strong reducibility when melting, it will fade and darken in the process of nylon melting and is not suitable for coloring of nylon.
● Perylene pigment: Perylene pigment is one of the ideal colorants used for coloring plastics, due to its good heat-resistant stability, but they are not suitable for coloring nylon because of their reversible reduction reaction in nylon melt.
● Thickness ring ketone pigment: in plastic, thick ring ketone organic pigment has excellent light fastness, good solvent resistance, migration resistance, heat stability, some of the red and yellow pigment varieties are suitable for nylon coloring, and there are also quinacridones and so on.
● Phthalocyanine pigment: Due to the planarity and symmetry of phthalocyanine molecular structure, it has good stability and excellent heat resistance, light, migration, acid and alkali properties. Copper phthalocyanine is a kind of relatively economic pigment because of its low cost of raw materials despite its complicated structure. Its blue and green pigment varieties are suitable for PA coloring.
● New metal complex pigment: In recent years, the development of nickel complex pigment containing benzimidazole group or isoindoline group has the same excellent performance, and it is suitable for coloring almost all plastics, such as PA, PESPC, and so on.