Color and Wet Fastness of PA Fabrics
The two synthetic polyamides (PA) which are most commonly used in textile applications are called PA 6,6 (Nylon) and PA 6 (Perlon). These polyamide textiles can be dyed or printed with a variety of dye classes such as acid, 1:1 or 1:2 metal complex, reactive or direct dyes. They are usually dyed in aqueous liquors at the boil. At the end of the dyeing cycle, the unfixed dyestuff is flushed out of the fabric through a wash process. In printing, the dyestuffs are fixed by steaming. Excess printing pastes and dyestuffs are eliminated in a final washing process. Despite thorough washing, the required standards for wet and color fastness are often difficult to meet. By implementing an additional aftertreatment with tannin products, the fastness properties of textile fabrics made of polyamide fibers can be significantly improved.
The Mechanism of Tannins
Tannins are vegetable tanning agents. In chemical terms, they are water-soluble polyhydroxyphenols. With their numerous hydroxy groups, they build crosslinks between macromolecules, for example connecting fiber and dyestuff molecules. This mechanism can be used in textile aftertreatment processes in order to fix dyestuffs to polyamide fibers. Due to the molecular linkage, the dyestuff molecules are strongly fixed to the fibers and are more difficult to remove. Furthermore, the dyestuffs are less sensitive to oxidizing agents such as chlorine which breaks down the chromophoric groups. Oxidizing agents with bleaching effects are used to disinfect water in swimming pools. In textile finishing, these agents can also be used in washing liquors with chlorine-containing washing auxiliaries and detergents. As a result, the aftertreatment with tannins significantly improves the wet fastness as well as color fastness to chlorinated water.
Sustainable Aftertreatment with Tannins
Tannins are natural substances which are found, for example, in grapes and woods, as well as in the bark of trees such as oaks and chestnuts. Tannin products come from sustainable, renewable plant sources and are completely biodegradable. Cationic products such as quaternary ammonium compounds (quats) are also used in the aftertreatment of dyed and printed textiles. In comparison to tannin derivatives, quats are poorly biodegradable and cannot be sufficiently removed from the effluent in sewage treatment plants. For this reason, quats can potentially enter the environment via surface water, and have detrimental effects on aquatic organisms.
PERFIXAN TAL contains only sustainably produced substances, which are harmless for the environment and health. All ingredients are in accordance with the criteria of the Manufacturing Restricted Substances List (MRSL) of Zero Discharge of the Hazardous Chemicals (ZDHC) program. You can find further information online in our ZDHC brochure. PERFIXAN TAL is also compatible with the OEKO-TEX STANDARD 100®. It does not contain any free phenol and no free formaldehyde.
Our Product Recommendations for Fastness Improvement
PERFIXAN TAL is a tannin-based anionic aftertreatment agent. It is used to improve color fastness to chlorinated water and wet fastness of polyamide dyeings and prints. The product is suitable for the aftertreatment of fashionable items such as swimwear, lingerie, underwear and sportswear. Aftertreatment with PERFIXAN TAL significantly improves fastness to chlorinated water as well as further washing and contact fastness. The treatment with PERFIXAN TAL has no negative impact on the handle. The product shows good levelling properties and a high exhaustion level. This way you can achieve maximum effectiveness and at the same time, excellent reproducibility.
Our Laboratory Service Offers Fastness Testing
For our customers, we offer application-technical consulting as well as reliable laboratory services. We are happy to elaborate on different procedures with the goal of creating recipes with improved fastness of dyeings and prints on your textile fabrics.
In our laboratories we can carry out color fastness testing of textiles against various aqueous solutions, for example:
- DIN EN ISO 105-E01: Textiles – Color fastness to water
- DIN EN ISO 105-E02: Textiles – Color fastness to sea water
- DIN EN ISO 105-E03: Textiles – Color fastness to chlorinated water (swimming pool water)
In our technical application laboratories we are also equipped to carry out a variety tests which are necessary for conformity to international standards, such as for washing, perspiration and rub fastness.
Please Contact Us.
Do you have questions on dyeing, fastnesses and fastness improvement? Our specialists will be happy to answer your inquiries.
- Ulrike Beurer
- Application technology
- +49 7121 9589-35
- ulrike.beurer@drpetry.de