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The Fixing Agent for Improving Wet Rubbing Fastness is a high-performance textile auxiliary developed by Zhejiang Kefeng Silicone Co., Ltd. (KFSilicone), specifically engineered to address one of the most persistent challenges in textile dyeing and finishing: the poor wet rubbing fastness of reactive dyeings, particularly in deep and extra-deep shades.
Founded in 2002 with a registered capital of 60 million RMB, Zhejiang Kefeng Silicone Co., Ltd. has established itself as a leading manufacturer of textile printing and dyeing auxiliaries in China. The company operates three major manufacturing bases—two located east and north of Hangzhou, and one in the Quzhou Green Gathering Area, a national chemical industrial park. Recognized as one of the “Top 20 Enterprises with Comprehensive Strength of Textile Printing and Dyeing Auxiliaries in China,” Kefeng has built its reputation on technological innovation, product stability, and a commitment to sustainable chemistry .
This Fixing Agent represents the culmination of Kefeng's deep expertise in reactive dye chemistry and polymer science. It is designed to significantly elevate the wet rubbing fastness of cellulosic fabrics—cotton, linen, viscose, modal, and their blends—after reactive dyeing, ensuring that colored textiles meet the most stringent international quality standards.
Reactive dyes are the preferred choice for dyeing cellulosic fibers due to their vibrant shades, excellent color yield, and the formation of covalent bonds with fiber hydroxyl groups. However, achieving satisfactory wet rubbing fastness—especially in dark shades—remains a significant technical hurdle for the textile industry .
The root cause lies in the dyeing process itself. During reactive dyeing, a portion of the dye molecules undergo hydrolysis instead of reacting with the fiber. These hydrolyzed dye molecules, along with unfixed dye that remains loosely adsorbed on the fiber surface, constitute what is known as “floating color.” When a wet fabric is subjected to rubbing—whether during domestic laundering, perspiration, or industrial processing—these unfixed dye molecules are easily transferred to adjacent materials, causing staining, color bleeding, and customer complaints .
The challenge is particularly acute for dark and extra-deep shades, where a higher concentration of dye is required, resulting in proportionally more unfixed dye on the fiber surface. Traditional soaping processes can remove some of this floating color, but they are often insufficient on their own to achieve the desired fastness levels, especially for demanding applications such as denim, workwear, and dark-colored home textiles .
Kefeng's Fixing Agent for Improving Wet Rubbing Fastness operates through a sophisticated dual-action mechanism that addresses both the chemical and physical aspects of dye fixation .
Chemical Fixation through Ionic Bonding
The fixing agent is formulated as a high-molecular-weight cationic polymer with multiple reactive functional groups. When applied to dyed fabric in a slightly acidic bath (typically pH 4–5), the cationic groups of the fixing agent form strong ionic bonds with the anionic sulfonic acid groups present in reactive dye molecules—both the fixed dye covalently bonded to the fiber and the unfixed hydrolyzed dye . This electrostatic interaction effectively “locks” the dye molecules in place, preventing them from migrating or dissolving during subsequent wet processing.
Physical Film Formation and Surface Sealing
Beyond ionic bonding, the fixing agent molecules deposit on the fiber surface, forming a dense, crosslinked network film. This film serves multiple protective functions: it seals the pores of the cellulose fiber, reducing the accessibility of water to the dye molecules; it encapsulates any residual floating dye, preventing it from being released during rubbing; and it creates a smooth, lubricated surface that reduces the coefficient of friction between the fabric and the rubbing medium .
Synergistic Enhancement of Fastness Properties
The combination of chemical bonding and physical film formation produces a synergistic effect that dramatically improves wet rubbing fastness. The fixing agent not only prevents dye transfer during rubbing but also enhances wash fastness, perspiration fastness, and water fastness, ensuring comprehensive color durability throughout the garment's lifecycle .
The primary function of this fixing agent is to elevate the wet rubbing fastness of reactive dyeings by 1 to 2 grades or more, depending on the dye type, shade depth, and fabric substrate. For many deep-shade applications that would otherwise fail to meet commercial standards, treatment with Kefeng's fixing agent brings performance into compliance with international requirements such as ISO 105-X12 and AATCC 8. Research on fixing processes for dark shades has demonstrated that optimized fixing agent application can improve wet rubbing fastness by 1–2 grades without significantly compromising color depth (K/S value) .
Kefeng's Fixing Agent is formulated as a non-formaldehyde product, free from APEO, NPEO, and other restricted substances. This aligns with the company's commitment to green chemistry and enables textile manufacturers to meet the stringent requirements of eco-labels such as OEKO-TEX® Standard 100 and ECO PASSPORT. The product is suitable for processing textiles intended for sensitive applications, including children's wear, underwear, and close-to-skin garments .
The fixing agent exhibits excellent stability across a range of processing conditions. It is resistant to hard water, acids, and electrolytes, and maintains its effectiveness in the presence of residual leveling agents or other auxiliaries. The working bath remains clear and stable, without precipitation or aggregation, effectively preventing the formation of fixing spots—a common defect associated with inferior fixing agents . This stability ensures consistent, reproducible results in industrial production.
Traditional fixing agents often impart a stiff or harsh hand feel due to excessive film formation on the fiber surface. Kefeng's advanced formulation is designed to provide effective fixation while preserving the soft, natural hand feel of the fabric. The polymer film is flexible and does not interfere with the fiber's inherent tactile properties, making it suitable for finishing soft-to-touch textiles such as knitwear, towels, and bedding .
By effectively fixing the unfixed dye molecules, the fixing agent maximizes the utilization of the applied dye. This can result in a perceived increase in color depth and brilliance, allowing dyes to achieve target shades with potentially reduced dye consumption—a significant economic advantage in competitive textile production .
Parameter | Specification |
|---|---|
Appearance | Liquid (typically clear to slightly colored) |
Ionic Type | Cationic |
pH (1% solution) | 4.0–5.0 (as supplied or recommended working range) |
Solubility | Easily soluble in cold and warm water |
Stability | Resistant to hard water, acids, electrolytes |
Formaldehyde Content | None |
APEO/NPEO | None |
(Specific technical data should be confirmed with Kefeng's technical team for the exact product grade selected.)
Kefeng's Fixing Agent is suitable for both exhaustion and pad-dry-cure processes, providing flexibility for different production setups .
Exhaustion Method (Recommended for most applications)
Parameter | Recommendation |
|---|---|
Dosage | 1.0%–5.0% o.w.f. (depending on shade depth; higher for extra-deep shades) |
Liquor Ratio | 1:10 – 1:15 |
pH | Adjust to 4.0–5.0 with acetic acid |
Temperature | 40°C–60°C |
Time | 20–30 minutes |
Process | Add fixing agent to bath at specified temperature, run for designated time, then drain and proceed to drying |
Pad-Dry-Cure Method (for continuous processing)
Parameter | Recommendation |
|---|---|
Dosage | 20–50 g/L |
Pick-up | 70%–80% |
Drying | 100°C–120°C |
Curing (optional) | 150°C × 2–3 minutes (if required for maximum durability) |
Pre-treatment: Ensure fabric is thoroughly soaped and rinsed to remove as much floating color as possible before applying the fixing agent. Residual soaping agents can interfere with fixation if not properly rinsed.
Bath Preparation: Add the fixing agent to the bath at the recommended temperature and pH. Ensure thorough mixing before introducing the fabric.
Compatibility: The fixing agent is compatible with most non-ionic and weakly cationic auxiliaries. Avoid direct mixing with strongly anionic products, which may cause precipitation.
Post-Treatment: After fixation, fabrics can be dried using standard procedures. The fixing effect is permanent and does not require re-application after subsequent washing.
Kefeng's Fixing Agent for Improving Wet Rubbing Fastness is suitable for a wide range of cellulosic fabrics and their blends, including:
Cotton woven and knit fabrics: especially dark shades (black, navy, deep red, dark green) for apparel and home textiles
Denim and denim blends: improving wet rubbing fastness of indigo-dyed fabrics, a well-known industry challenge
Linen and hemp blends: enhancing fastness of reactive dyeings on these increasingly popular natural fibers
Viscose, modal, and lyocell: ensuring color durability for these regenerated cellulose fibers
Cotton/polyester blends: providing fixation for the cellulosic component of blended fabrics
Selecting this product means choosing a solution backed by more than two decades of textile chemical expertise:
Industry-Leading Manufacturer: Kefeng is recognized as one of China's top 20 textile printing and dyeing auxiliaries enterprises, with a reputation for product stability and technical innovation .
Proven Performance: The fixing agent is formulated to deliver consistent, reproducible improvements in wet rubbing fastness across a wide range of dyes, shades, and fabric types.
Environmental Compliance: Non-formaldehyde, APEO-free formulations meet the most demanding international eco-textile standards, supporting sustainable textile production.
Technical Support: Kefeng provides comprehensive technical support, including process optimization, troubleshooting, and customized solutions tailored to specific customer requirements .
Supply Reliability: With three manufacturing bases and a monthly production capacity of 1,000 tons of crude block silicone oil, Kefeng ensures stable supply and timely delivery for customers worldwide .
For textile manufacturers seeking to achieve superior wet rubbing fastness on reactive-dyed cellulosic fabrics—especially in challenging dark shades—Kefeng's Fixing Agent represents a reliable, high-performance, and eco-conscious solution. It is more than an auxiliary; it is a key to unlocking premium quality and meeting the colorfastness demands of today's global textile market.
