What should you pay attention to when dyeing elastic fabrics?

The functionality and fashionability of elastic fabrics are becoming more and more important in the textile market, but elastic fabrics have very particular requirements for dyeing processes. The properties of elastic fibers and their fabrics affect various processes from pretreatment to fabric finishing. The textile editor of this article summarizes the key factors that should be paid attention to in the dyeing and finishing of elastic fabrics, the selection of relevant products and the recommendations of process parameters, and specially shares them with friends.

Elastic fabrics and raw materials are not suitable for long-term storage. When spinning and winding, use a large amount of silicone oil and other lubricants to improve spinnability; when weaving and knitting, use more oils and additives to ensure good processing performance. During long-term storage, degradation of these products causes the fabric to yellow until elasticity decreases. “Ambient hardening” is a potential problem that can cause lasting creases. If the fabric is stored for more than 3 months, it should be sealed in an airtight and light-tight plastic film. Elastic yarn is always woven into the fabric under a certain tension, and heat setting avoids streaks and wrinkles during dyeing and ensures good dimensional stability. Usually heat set at 180-190℃ for 30-45 seconds. Higher temperatures cause elastic fibers to turn yellow and lose elasticity. Because silicone oil and lubricants will destroy the levelness of the dye and reduce the color fastness, they should be removed as much as possible before dyeing elastic fabrics. The oil residue on elastic fiber blended gray fabrics is usually invisible before dyeing, but metal complex dyes are lipophilic, that is, the oil spots on the gray fabrics are affinity with them at the beginning of the dyeing process. When the dyeing temperature rises, the oil is emulsified, but the dye remains, causing irremovable stains. Do not use cold water for rinsing after washing, because this will cause the emulsified oil to precipitate again, causing spots on the textiles. An effective method is to use hot water for thorough overflow rinsing and cold water for final rinsing.

During the dyeing process of elastic fabrics, high temperature and mechanical stress can cause elastic loss. In order to preserve its elasticity, elastic fabrics with an elastic fiber content of more than 10% should be dyed on a slow-flow jet machine. Fabrics with an elastic fiber content of less than 10% can be dyed on an air jet machine. The wet fastness grade of polyamide and elastic fiber blended fabrics is lower than that of pure polyamide fibers. Experience shows that dyeing with alkaline pH value is a practical method to reduce the dyeing speed of lanaset dye and improve the level dyeing. Polyester is increasingly used in elastic fabrics. This is a challenge for dyeing: on the one hand, disperse dyes require high temperatures, on the other hand, the elasticity of elastic fibers is greatly reduced when the temperature exceeds 225°C. Another obstacle to processing such blended fabrics is the heavy staining of the elastane fibers by disperse dyes and their low wet fastness. The new dispersion accelerator cibapb allows the use of terasilw dyes at different temperatures without loss of elasticity. The recommended pb dosage depends on the required color concentration. Polyester and elastic fiber blended fabrics need to be thoroughly restored and cleaned after dyeing. Usually used at a temperature of 70°CInsurance powder, caustic soda and os complete the reduction and cleaning of polyester fiber. In order to remove disperse dyes from elastic fibers, the temperature needs to be between 80°C and 90°C. Ordinary insurance powder reacts too quickly and is therefore ineffective. If disperse dyes are to be removed from spandex, then os is the only effective product for reduction cleaning. Proper temperature, stable dispersant and good dispersant will determine the appropriate reduction cleaning.

In elastic fabrics blended with cellulose and elastic fibers, the higher the elastic fiber content, the greater the risk. Careful selection of reactive dyes that ensure easy migration before fixation of cellulose fibers is the only way to obtain good results. Compared with other reactive dyes, the use of cibacronls dyes can significantly reduce the amount of salt used; because these dyes are less sensitive to changes in liquor ratio, they are ideal for dyeing cellulose and elastic fiber blended fabrics. Especially for regenerated cellulose fiber, it is recommended to use the process of adding salt in batches during dyeing. Dyeing regenerated cellulose fiber only requires 70% of the recommended salt amount for ordinary cotton dyeing. Wool-like elastic fabrics gain additional functionality and good performance due to the increased elastic fiber content. Elastane blended with wool improves its dimensional stability and wrinkle resistance. In the dyeing process, piece dyeing is usually recommended. Good surface level dyeing requires dyes with good migration properties. Cibane-olan dye is very suitable. It can be used when the pH value is 3.5. Even in traditional dark colors, satisfactory color fastness can be obtained. Even trickier are fabrics where polyester and wool are blended with elastane. Due to the sensitivity of wool to strongly alkaline conditions, enhanced reduction cleaning is difficult to remove disperse dyes from elastic fibers. Especially dyeing black and navy blue are more restricted. The use of disperse dye accelerator can ensure good reproducibility and reduce staining of blended wool and elastic fiber disperse dyes. Under weakly alkaline conditions (ammonia adjusts the pH value to 8.5), use stable insurance powder to moderately reduce and post-process at 45-50°C for 20 minutes to ensure the improvement of wet fastness characteristics.

Pre-treatment, dyeing and finishing of blended elastic fabrics. Wet and dry pre-treatments such as shrinking, heat setting and washing depend on the fabric structure and its sensitivity to mechanical stress. The right machine is critical to maintaining high elasticity, good levelness and reproducibility. Understanding all parameters, correct product selection and careful process adjustments will help achieve optimal performance of elastic textiles. I hope the textile editor’s sharing can provide some help to my friends.