What is the dyeing performance of polylactic acid fiber-Suzhou Kingcharm New Materials Corp.

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What is the dyeing performance of polylactic acid fiber

source：www.kingcharmgroup.com | Release time：2026-09-01

PLA belongs to aliphatic polyester fibers, with a structure similar to polyester (PET), but with ester bonds in the molecular chain, lower crystallinity, and glass transition temperature Tg, and can only be dyed with dispersed dyes; The dyeing temperature window is narrow, and it is sensitive to alkali and high temperature. The dyeing and color fastness of dark colors are weaker than that of ordinary polyester, making it a variety of biodegradable fibers with prominent dyeing difficulties.
1. Dye selection
Applicable: E-type and SE type dispersed dyes with low molecular weight, suitable for low-temperature dyeing;
Not applicable: Reactive dyes, direct dyes, acid dyes, almost never dye;
Not suitable for high-temperature S-type macromolecular dispersed dyes: requires a high temperature of 130 ℃ or above, at which point PLA will soften and shrink, and its strength will decrease.
Raw material coloring PLA has good color fastness, but poor color flexibility and higher cost.
2. Dyeing temperature (core control point)
Dyeing temperature: 95-110 ℃
Risks above 120 ℃: Fiber softening, rapid increase in thermal shrinkage, molecular hydrolysis degradation, decreased strength, yellowing of fabric surface;
Below 90 ℃: The dye has a low dye uptake rate and produces light colors, making it difficult to achieve deep and dark colors.
Compared to polyester: polyester is dyed under high temperature and high pressure at 130 ℃, while PLA cannot be directly copied from polyester technology.
3. The impact of pH value is crucial
PLA molecular ester bonds undergo alkaline hydrolysis.
Dyeing pH: 5.0-6.0, weakly acidic environment, adjust pH with acetic acid;
Alkaline conditions with pH>7: Even at low temperatures, hydrolysis occurs, resulting in loss of fiber strength and fabric brittleness;
Alkaline staining is prohibited, alkaline reduction cannot be done, and silk finishing cannot be performed.
4. Dyeing characteristics
1. The heating rate should be gentle, as heating too quickly can lead to color distortion and color difference;
2. There is thermal migration phenomenon in some dispersed dyes: during high-temperature drying and shaping, the dye migrates to the fiber surface, reducing the friction fastness;
3. Difficulty in making dark colors: PLA can achieve medium to light colors, but when made in deep shades of blue and black, the color depth is not as good as polyester; To achieve deep colors, it is necessary to screen for specialized dispersed dyes and increase the amount of dye used, but the color fastness will be under pressure.
5. Color fastness performance
Washing fastness: Good for medium and light colors; The fastness to dark washing has decreased and requires thorough restoration cleaning;
Alkaline reducing solution cannot be used for restoration cleaning! PLA is not alkali resistant and requires an acidic reduction cleaning system, which is completely different from polyester reduction cleaning.
Friction fastness: acceptable under dry friction; Dark colored wet friction is generally weak;
Sun fastness: Different dyes have significant differences, and some dispersed dyes have poorer sun fastness on PLA than PET. Therefore, it is necessary to choose a sun resistant grade;
Sublimation fastness: The setting temperature should not be too high, as high temperatures can cause dye sublimation and decrease fastness.
6. The influence of post dyeing heat setting on dyeing
The shaping temperature is strictly controlled at 110-130 ℃, and the over feeding process is employed
Excessive temperature: fabric shrinkage, discoloration, dye sublimation, fiber brittleness;
Low temperature: The fabric undergoes significant thermal shrinkage and the washing size is unstable.
7. Difficulties in Blended Dyeing
1. PLA/cotton/viscose blend
Cotton requires alkali pretreatment, but PLA is not alkali resistant. Pre treatment can only use mild and weak alkaline processes; The two fiber dye systems are different: PLA uses dispersed dyes and cotton uses reactive dyes. The process pH and temperature need to be controlled to ensure that PLA does not hydrolyze while cotton is colored.
2. PLA/polyester blend
The two have conflicting dyeing temperature requirements: polyester requires 130 ℃, which PLA cannot withstand; Only low-temperature dyeable polyester dispersion dyes can be used, which limits the depth of color.

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