Textile Auxiliaries for Polyamide Dyeing

Polyamides are thermoplastic synthetics composed of organic macromolecules. The monomer units of polymers are bonded through polycondensation or polymerization reactions. Amide groups are characteristic of polyamides. Amide Group

Polyamides are classified into various groups. These are:

Aliphatic Polyamides Polyamide Type AA-BB: Unbranched diamines and dicarboxylic acids (for example PA 6.6) Polyamide Type AB: X-amino acids or their lactams (for example PA 6) Aromatic Polyamides The structure of monomers is more complex. Their common characteristic is that they contain a benzene ring. Poly-m-phenylene isophthalamide AR (for example: Nomex®, Conex ®) Poly-p-phenylene terephthalamide AR (for example: Kevlar®, Twaron ®)

Applications of Polyamides

• Apparel, • Outerwear, • Hosiery, • Underwear, • Swimwear, • Sportswear, • Home textiles (automotive sector), • Backing for upholstery, • Carpets, • Technical textile products, • Umbrella and raincoat fabrics, • Belts and ropes, • Parachute fabrics, • Zippers, • Support materials for coatings/laminates.

Heat Setting

Heat setting of raw polyamide products is very important and provides dimensional stabilization. Through heat setting, problems such as curling and dimensional changes in polyamide knitted fabrics containing elastane are reduced in subsequent processes. The following problems occurring during dyeing are prevented. • Crease marks, • Moiree effect in piece dyeing, • Yellowing tendency.

Application Example

Heat Setting with Tuboset Dap

Low foaming tendency, application of surface-active antioxidant—Tuboset Dap protects fiber from yellowing and oxidative damage. Heat protection also ensures good dyeing of polyamide fibers. Additionally, Tuboset Dap has very high detergent effect and, if the material is washed after heat setting, removes general finishes and silicone-containing finishes. Heat setting should be carried out according to the supplier's recommendations. For fiber blends containing elastane, the heat setting temperature should not exceed 195°C.

Recipe Recommendation: Application on raw PA or PA/EL blends:

Impregnation with 10–30 g/l TUBOSET DAP Pick up: 50–70% Impregnation temperature: 20–30°C After drying and heat setting of polyamide and polyamide blends, continuous or batch washing is carried out, followed by one cold rinse.

Heat Setting of Raw Polyamide Knitted Fabric

Leveling Agents

Today's market expects high quality from textile products made from polyamide. CHT largely meets these expectations with the help of leveling agents. Sarabid Ipd and Sarabid Ipf are leveling agents for dyeing fiber products containing amino groups with acid and metal complex dyes. Sarabid Ipd and Sarabid Ipf are applied in polyamide dyeing. They can also be applied in wool and silk dyeing. Both products are reliable leveling agents with general use for all dyeing procedures in polyamide dyeing. Sarabid Ipd and Sarabid Ipf are like team players and provide optimal surface uniformity. Sarabid Ipd is a highly effective, low-foaming leveling agent with dye affinity that supports uniform dye uptake throughout all stages of dyeing and even dye distribution during the migration phase. The combinability of dyes is improved and therefore repeatability is enhanced. It does not adversely affect wet fastness and light fastness. Dyeing time and/or dyeing temperatures may vary due to the product's high leveling property and uniform dye uptake characteristic. The product contributes greatly to energy efficiency. Sarabid Ipf is solely a leveling agent with affinity for fiber and is used for dyeing polyamides that may develop streaking problems, excellently masking affinity differences in materials. Sarabid Ipf ensures homogeneous dye uptake during heating and increases uniformity. This product also excellently reserves polyamide during dyeing of polyamide-wool blends. Sarabid Ipm is a multifunctional leveling agent with low foaming property for polyamide dyeing. The product has affinity for both polyamide fiber and dye. It completely controls dye distribution during dyeing and shows high leveling property even in products that could be dyed in stripes. Sarabid Ipm is suitable for applications in job dyeing or in frequently changing PA qualities due to its product-specific properties.

Sarabid Ipd – Has Dye Affinity

Improving Surface Uniformity with Sarabid Ipd Migration Test Example: Best leveling results are obtained with Sarabid Ipd. Dyed and undyed material (fiber type 3). Treated at 1:1 ratio at 98°C, pH 5 for 30 minutes. The dye migration force in dyed and undyed fiber is evaluated visually. Affinity difference example: Sarabid Ipd has very good leveling effect and has a positive effect on the combinability of acid and metal complex dyes. In combined dyeing, Sarabid Ipd balances the uptake property of individual dye components.

Sarabid Ipd Improves Uniform Dyeing Property

Dye uptake test example: Sarabid Ipd, in combined dyeing, balances the uptake property of individual components, controls the absorption power of dyes during heating and ensures equal distribution of dyes in the migration phase. In this test, dyeings are carried out at different temperatures up to the fixation temperature (98°C) for 10 minutes. The fabrics are removed. Fresh white fabrics are added to the remaining liquor and treated at 98°C for 30 minutes.

Sarabid Ipf Against Streaking

Before dyeing, anionic leveling agents bind to polyamide fiber. The reason Sarabid Ipf is the first choice is that it does not create streaks. Sarabid Ipf very well covers structural differences inherent to the material, thus achieving dyeings with good surface uniformity.   Especially in cases where polyamide is dyed with 1:2 metal complex dyes due to fastness requirements, application of Sarabid Ipf is recommended. Dyes reveal most of the structural differences due to the material and thus cause streaked dyeings. With Sarabid Ipf application, these differences are largely prevented and uniform surface dyeings are obtained.

Anti-Crease Agents

Anti-crease agents help achieve more uniform dyeing depending on the dyeing machine and fabric type. Crease formation can result from the following causes: • Swelling differences in the material, • Heating the dye liquor at high speed, • Cooling the dye liquor at high speed, • Low initial temperature, • Hot discharge and filling with cold water, • Excessive mechanical action, • Overloading of machines, • Insufficient heat setting. In most cases, Biavin Bpa or Biavin Pcv is applied in polyamide dyeing. Biavin Pcv additionally has dispersing property. The product is also suitable for heat setting on yarns.

Acid Donors

Acid donor ensures proper conditions for dyeing in polyamide dyeing and assists in leveling.

Meropan Ef 200

The classic conventional acid donor Meropan Ef 200 slowly penetrates the liquor during the heating and boiling phase of the dyeing process. The acid released into the liquor increases the pH value towards acidity and dye uptake by the fiber gradually increases. This pH control provides the best conditions for obtaining uniform dyeing results. For more uniform dyeing, use of an appropriate leveling agent (for example, Sarabid Ipd, Sarabid Ipm, Sarabid Ipf) in the polyamide dye bath is recommended.

Meropan Ls

Meropan Ls is a problem solver for very critical PA qualities. The most important advantage of Meropan Ls is slow decomposition and acid release at high temperatures. Thus, Meropan Ls can be added at high temperatures (HT dosage at 98–106°C). Using this method, critical polyamide qualities are started initially at a higher pH value. Through Meropan Ls application during heating, pH is continuously reduced.

Improving Polyamide Fastness Through Aftertreatment

In most cases, aftertreatment should be applied in dyeing of polyamide and polyamide/elastane fiber blends and for increasing wet fastness. Dyes are fixed through ionic interaction with anionic fixing agents (Rewin Kf, Rewin Knr, Pafix No1, ...). Wet fastness properties of polyamide fibers and their blends with acid and metal complex dyes can be improved through appropriate aftertreatment. Anionic aftertreatment agents are generally applied at 70–80°C in a fresh bath and within 20–30 minutes at pH 4–4.5 through the drawing procedure after dyeing. There is no single agent for aftertreatment of polyamide fibers and blends. The most suitable fixative should be selected based on demand and fiber blend.

Pafix No1

Maximum Performance for Bright Polyamide Dyeings Pafix No1 is a high-quality product and an environmentally friendly innovative aftertreatment agent. Good fastness values are obtained with Pafix No1 even in bright fluorescent colors. Pafix No1 is particularly suitable for frequently washed sportswear and functional garments. • Maximum process safety. • Versatile fixative for fluorescent bright PA dyeings as well as standard shades. • Can be dosed in all dosing units. • Suitable for drawing and continuous processes. (Narrow band PA dyeings) • Superior fastness level: Improves wash, sweat, water and seawater fastness. • Does not affect light fastness. • Does not change fabric handle. • Shows no yellowing tendency on color tone. Therefore ideal for pastel shades and bright colors. • Thermostable: No effect on heat setting or steaming processes. • Environment compatible. • Phenol free and formaldehyde free. • Bluesign® approved. • Meets ZDHC MRSL requirements. Ersel Yılmaz / Group Director Yarn and Dyeing / CHT Tekstil Kimya