Application of acid dyes in leather dyeing

As a natural protein material, leather is widely used in shoes, bags, clothing and furniture due to its unique texture, breathability and durability. Acid dyes have become an important choice for leather dyeing due to their excellent color brightness, high permeability and affinity with leather collagen.

The following are four key process parameters

PH value regulation

Acid dye dyeing needs to be carried out in a weakly acidic to moderately acidic environment (pH 2.5-4.5). Too low pH (<2.5) may cause excessive acid swelling of the leather and destroy the fiber structure; too high pH reduces the degree of amino protonation and reduces dye adsorption.

Commonly used acids include formic acid, acetic acid or lactic acid, and the acid concentration needs to be adjusted according to the tanning type (chrome tanning/vegetable tanning).

Temperature and time control

The dyeing temperature is usually 40-60℃, and high temperature (>60℃) can easily cause leather shrinkage or surface roughness. Chrome tanned leather has good heat resistance, so the temperature can be appropriately increased to 55-60℃; vegetable tanned leather needs to be controlled at 40-50℃.

The dyeing time is generally 30-90 minutes, which needs to be adjusted in combination with the leather thickness and the target color depth.

Penetration and leveling auxiliaries

Adding anionic or nonionic penetrants (such as alkyl sulfonates) can reduce the surface tension of the dye solution and promote the diffusion of dyes into the deep layers of the leather.

Leveling agents (such as fatty alcohol polyoxyethylene ethers) reduce the color problems caused by uneven fiber structure by delaying the adsorption rate of dyes.

The influence of electrolytes

Neutral salts (such as sodium sulfate) reduce the affinity of dyes and water through the "salting out effect" and increase the dyeing rate. However, the amino density of leather fibers is lower than that of nylon. Excessive salt may cause dye aggregation, so the dosage needs to be carefully controlled (usually 1-5%).

Choose high-quality acid dyes to improve leather dyeing quality

Choosing a high-quality acid dye is the key to ensure bright, uniform and long-lasting leather color. Skyacido® leather series acid dyes are specially developed for leather dyeing process, with high color fastness, excellent penetration and excellent leveling performance. Whether it is shoes, bags, clothing or furniture leather, Skyacido® can provide stable dyeing effect to meet different dyeing depth and color requirements. like yellow MR, Orange EG,Orange GS ,Scartlet 3G ...In addition, this series of dyes is compatible with various tanning processes (chrome tanning, vegetable tanning), ensuring stable and controllable dyeing process and improving production efficiency.

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