Application of Acid Dyes in Nylon Fiber Dyeing

Nylon (polyamide fiber) is widely used in textile, automotive interior and industrial materials fields due to its excellent strength, abrasion resistance and resilience. As a synthetic fiber, nylon has significant differences in dyeing properties from traditional natural fibers (such as wool and silk). Acid dyes have become one of the main choices for nylon dyeing due to their chemical affinity with nylon fibers.

The following are four key process parameters

PH control

Acid dye dyeing needs to be carried out under weak acidic conditions (pH 3-6). Low pH can promote the protonation of amino groups in nylon fibers and enhance the binding with dyes; but too low pH (<3) will cause excessive swelling of the fibers and even damage.

Commonly used acid agents include formic acid, acetic acid or ammonium sulfate, and the amount of acid agent needs to be adjusted according to the type of dye and fiber specifications.

Temperature and time

The glass transition temperature (Tg) of nylon is about 50-60℃. Dyeing usually starts from low temperature (40℃), gradually increases to 95-100℃, and keeps warm for 30-60 minutes to ensure full penetration of the dye.

High temperature can open the amorphous region of the fiber and promote the diffusion of dye molecules, but it is necessary to avoid fiber degradation caused by long-term high temperature.

The role of electrolytes

Adding neutral salts (such as sodium sulfate) can reduce the repulsion between the dye and the fiber through the "salt effect" and increase the dyeing rate. However, the number of amino groups in nylon is limited, and the amount of electrolytes needs to be precisely controlled. Excessive use may cause dye aggregation.

Application of leveling agents

Nylon fibers are prone to uneven dyeing due to uneven distribution of amino groups. Anionic or non-ionic leveling agents (such as fatty alcohol polyoxyethylene ethers) need to be added to reduce the initial dyeing rate through competitive adsorption and improve leveling.

n the Chinese dye market, Tiankun's acid dyes stand out

Skyacido® Acid Dyes are specially designed for nylon (polyamide) fiber dyeing, offering excellent dyeing stability, color fastness, and environmental performance. Key features include:

✅ Excellent Dye Uptake – Skyacido® acid dyes have a strong affinity for nylon fibers, allowing for quick and uniform dyeing under weak acidic conditions (pH 3-6), ensuring high-efficiency coloration.

✅ Superior Color Fastness – These dyes exhibit outstanding fastness to washing, perspiration, rubbing, and light, maintaining vibrant colors throughout the product's lifespan.

✅ High-Temperature Resistance – Suitable for high-temperature and high-pressure dyeing, providing exceptional stability during the dyeing process while minimizing shade variations and migration issues.

✅ Outstanding Leveling Properties – Skyacido® dyes are easy to formulate and work well with leveling agents, preventing dye streaks and improving overall color consistency.

✅ Eco-Friendly & Sustainable – Compliant with international environmental standards, free from APEO, formaldehyde, and heavy metals, meeting OEKO-TEX®, ZDHC, and other sustainability requirements, making them ideal for eco-friendly textile production.

Skyacido® acid dyes are widely used in nylon fabrics, swimwear, lingerie, sportswear, and carpets, providing customers with high-quality dyeing solutions tailored to their specific color needs!

If you want to get the color card ,please contact us :info@tiankunchemical.com our visit our website :www.tiankunchemical.com