Why is nylon resistant to boiling water? How to color the boiled nylon?

First, the analysis of the reasons for the boiling of nylon parts:

1. Our commonly used nylon is nylon 6 (PA6), nylon 66 (PA66), which is a crystalline thermoplastic material;

2. The nylon material is easy to absorb water and contains a hydrophilic group (acylamino group).

For crystalline polymers, very rapid cooling during injection molding prevents the material from crystallizing naturally, resulting in strong internal stresses within the material. Nylon materials that have not been subjected to "tempering" treatment, because the macromolecules tend to move toward natural orientation and crystallization after being shaped, which causes the internal stress of the material to further increase. Therefore, the nylon member which has not been subjected to the boiling process is very brittle and easily collapses or breaks when subjected to an external force.

Second, how to make the natural macromolecules that have been formed naturally oriented and crystallized, and try to eliminate the internal stress? How to color it?

In fact, it is the boiled water that we are talking about. The boiling process is actually the same as the setting of our metal “tempering” treatment process. That is to let the nylon parts soak at a certain water temperature, so that the internal macromolecules tend to be naturally oriented as much as possible and reach the balance of internal crystallization and decrystallization, thereby eliminating internal stress. The performance is outside: the toughness of the nylon parts is greatly enhanced, and the brittleness is basically eliminated.

1) So why do you want to boil it?

That is because nylon contains a hydrophilic group, an amide group, which causes the nylon to absorb water easily, but the nylon absorbs a certain amount of water, which contributes to the orientation and crystallization of the macromolecule inside.

Optimum temperature and time for boiling nylon parts: 90-100 ° C, 2-3 hours

Below 90 degrees, the effect is not good, more than 3 hours, there will be no better results. In terms of cost performance, the above process conditions are the best.

2) How to color the resistant nylon?

General nylon needs to be cooked after coloring, so the pigment used for nylon also needs to be cooked without fading. In the past, cadmium pigments and dyes were commonly used, but cadmium pigments are now subject to many restrictions due to heavy metal problems, and most of the colors are unstable and discolored after the dyes are boiled. Therefore, the resistant nylon is more suitable for the use of inorganic pigments, solvent dyes or organic pigments (azo pigments, anthraquinone pigments, fused cyclic ketones (reduced), pigment phthalocyanine pigments, novel metal complex pigments).