Textile Dyeing Auxiliaries: From Molecular Design to Sustainable Dyeing and Finishing System Solutions

I. Introduction and Industry Background

1.1 Definition of Dyeing Auxiliaries and Their Position in the Industry Chain

Textile dyeing auxiliaries are indispensable fine chemicals in the wet processing of textiles, playing a critical role as a "process bridge" between fibers and dyes. From an industry chain perspective, the textile value chain encompasses five core stages: "fiber → spinning → weaving → dyeing and printing → garment manufacturing." Although dyeing auxiliaries typically account for only 5% to 15% of total production costs, they exert a decisive influence on the final textile's color quality (shade accuracy, dyeing uniformity), handle and style (softness, fullness, drape), and functional properties (water repellency, antistatic performance, antimicrobial activity, etc.).

Unlike dyes, which determine "what color the textile will display," auxiliaries determine "whether the color can be perfectly realized" and "whether the dyeing process can operate efficiently, stably, and economically." By regulating the physicochemical environment of the dye bath (such as pH, surface tension, ionic strength), modifying fiber surface and interfacial properties (wettability, zeta potential, degree of swelling), and intervening in the kinetics of dye uptake (dyeing rate, diffusion behavior, fixation efficiency), auxiliaries enable the process upgrade from "being dyeable" to "being dyed with excellence."

Typical dyeing auxiliary product lines cover the entire workflow from pretreatment to finishing:

• Pretreatment auxiliaries: Including penetrants, scouring agents, peroxide bleach stabilizers, and chelating dispersants, responsible for removing natural impurities and synthetic sizes, providing a clean, high-whiteness, high-capillarity fiber substrate for subsequent dyeing.
• Dyeing auxiliaries: Including leveling agents, dispersing agents, exhausting agents, retarding agents, and fixing agents, directly participating in the regulation of the dyeing process to ensure uniform and sufficient dye uptake and fixation on the fibers.
• Printing auxiliaries: Including thickeners, binders, crosslinking agents, and resist agents, used for rheology control of printing pastes and ensuring sharpness of printed patterns.
• Finishing auxiliaries: Including softening agents, water/oil repellents, antistatic agents, antimicrobial agents, and flame retardants, imparting additional value-added and differentiated functionalities to textiles.

1.2 Global Market Drivers (2026 Perspective)

As of 2026, the global textile dyeing auxiliary market has stabilized at a scale of tens of billions of US dollars, with a compound annual growth rate maintained between 4% and 6%. However, the structure of market growth is undergoing profound changes. The traditional logic of "volume growth" has been replaced by "quality upgrade." The following three major drivers are reshaping the industry landscape:

(1) Consumer Side: Paradigm Shift from Fast Fashion to High-Quality and Sustainable Fashion

The fast fashion model that dominated the market over the past decade is gradually receding. Consumer demands for textiles are shifting from "cheap and disposable" to "durable and comfortable." Specific manifestations include:

• High color fastness requirements: Especially light fastness and combined perspiration-light fastness, imposing higher demands on auxiliaries' UV absorption capacity and antioxidant performance.
• Low water and energy consumption: Water-saving dyeing processes (such as low-liquor-ratio dyeing and cold pad-batch dyeing) require auxiliaries to maintain excellent dispersion and penetration performance under extreme conditions (high electrolyte concentrations, low temperature, or room temperature conditions).
• Skin-friendliness and health safety: Zero-tolerance of formaldehyde content, extractable heavy metals, and allergenic disperse dyes in infant clothing and underwear forces auxiliary manufacturers to develop purer and milder formulations.

(2) Regulatory Side: Continued Tightening of Global Chemical Control Frameworks

Dyeing auxiliaries are one of the primary sources of chemical residues in textiles. The global regulatory system has formed a multi-level, multi-dimensional constraint network:

• ZDHC (Zero Discharge of Hazardous Chemicals) Program: Its MRSL (Manufacturing Restricted Substances List) has been updated through multiple versions, explicitly specifying chemicals that are prohibited from intentional use during textile manufacturing processes, covering APEOs (alkylphenol ethoxylates) in surfactants, PFOA (perfluorooctanoic acid) and related substances in repellents, etc.
• OEKO-TEX Standard 100 and EU Ecolabel: Set extremely stringent limit values for residues in finished products; for example, formaldehyde content in the baby product category must not exceed 16 ppm.
• REACH Regulation (SVHC Candidate List): Continuously adds new chemical substances to the Candidate List of Substances of Very High Concern, requiring auxiliary manufacturers to continually adjust formulations and screen for substitutes.

The impact of these regulations has extended from export-oriented enterprises to the entire supply chain. Environmental compliance is no longer a "bonus point" but a "ticket to entry."

(3) Technology Side: Digital and Intelligent Dyeing Poses New Requirements for Auxiliaries

The wave of Industry 4.0 is profoundly transforming dyeing workshops:

• Digital color matching and recipe management: Computer color matching systems demand an unprecedented level of batch-to-batch stability from auxiliaries; any minor fluctuation in active content may cause the color difference value ΔE to exceed the tolerance range.
• Automated titration and online monitoring: Real-time monitoring of dye bath pH, conductivity, and oxidation-reduction potential requires auxiliaries not to generate interfering signals, precipitation, or scaling under these sensor environments.
• Small-batch, multi-variety production mode: Frequent switching between dyeing processes requires auxiliaries to have wider process adaptability—maintaining stable performance output across different temperatures, times, and liquor ratios.

1.3 Value Proposition of This Article: The Role Upgrade of Auxiliaries

The core argument of this article is: in contemporary dyeing and finishing engineering systems, dyeing auxiliaries are no longer subsidiary "auxiliary chemicals," but have been upgraded to become the "intelligent process regulators" of dyeing and finishing operations. This role upgrade manifests in three dimensions:

• From passive adaptation to active regulation: Traditional auxiliaries only passively adapt to dyeing conditions, while modern auxiliaries actively intervene in the dyeing process through molecular design strategies (such as block copolymers, responsive polymers) to achieve synergistic optimization of leveling, fixation, and softening functions.
• From single-function to system integration: Multi-functional composite auxiliaries (such as one-bath auxiliaries combining scouring and bleaching, and composite silicones combining softening and hydrophilic finishing) are reducing the number of process steps and lowering overall water and energy consumption.
• From experience-driven to data-driven: Evaluation of auxiliary performance is transitioning from traditional "handle assessment" and "shade card comparison" to quantitative metrics (such as contact angle measurement, zeta potential analysis, and dynamic surface tension curves), laying the foundation for process digitalization.

The following chapters will systematically analyze the complete technical landscape of dyeing auxiliaries from five dimensions: scientific classification and mechanisms of action, application strategies by fiber substrate, technological innovation frontiers, environmental compliance pathways, and market selection guidelines, aiming to provide dyeing engineers, procurement decision-makers, and industry researchers with technical references that possess both theoretical depth and practical value.

II. Scientific Classification and Mechanisms of Action of Dyeing Auxiliaries (Core Technology Layer)

Dyeing auxiliaries come in a wide variety. Based on the stage at which they are introduced into the dyeing and finishing process, they can be systematically classified into three major categories: pretreatment auxiliaries, dyeing auxiliaries, and finishing auxiliaries. The functionality of each category is built upon its unique molecular structure and interfacial action mechanisms. Understanding these underlying scientific principles is a prerequisite for precise selection and process optimization.

2.1 Pretreatment Auxiliaries (Scouring and Bleaching Engineering)

Pretreatment is the "foundation engineering" of dyeing and finishing. Its objective is to provide a clean, uniform fiber substrate with appropriate reactivity for subsequent dyeing and printing. The core functions of pretreatment auxiliaries are to assist in completing desizing, scouring, bleaching, and mercerizing processes.

(1) Penetrants/Wetting Agents

The core function of penetrants is to reduce the surface tension of aqueous solutions and the interfacial tension at fiber/water interfaces, promoting rapid and uniform penetration of working solutions into the fiber interior and yarn interstices. Their mechanism of action is based on the hydrophilic-lipophilic balance (HLB) characteristics of surfactants:

• For hydrophilic fibers (cotton, linen, viscose): Natural cellulosic fibers have abundant hydroxyl groups and inherently possess some wettability. However, during desizing and scouring, sizes and natural impurities (waxes, pectins) form hydrophobic barriers. Penetrants remove these barriers through emulsification and dispersion, exposing the hydrophilic fiber surface again.
• For hydrophobic fibers (polyester, polyamide): Synthetic fiber surfaces lack reactive groups and have poor wettability. Penetrants need to introduce long-chain alkyl and polyoxyethylene ether segments in their molecular structure to provide both hydrophobic anchoring points for adsorption onto fiber surfaces and hydrophilic segments to reduce contact angles.

Core evaluation metrics for penetration performance include:

• Wetting time (sinking test): According to ISO 8022 standard, measuring the time required for a cotton canvas disc to completely sink from the moment it contacts the liquid surface, typically required to be within 5 to 30 seconds.
• Contact angle: Using an optical contact angle goniometer to measure the dynamic contact angle of the working solution on fiber bundles or film surfaces; lower values indicate better wettability.
• Penetration depth: Assessing the uniformity of working solution penetration into yarn bundles through dye tracing methods or capillary rise methods.

(2) Scouring Agents

Scouring agents are responsible for removing naturally occurring concomitants from cotton fibers, including pectins (approximately 0.8% to 1.2%), waxes (approximately 0.4% to 1.0%), nitrogenous substances (approximately 0.3% to 0.6%), and cotton seed husk fragments. The mechanism of action involves the synergistic effects of multiple surfactants and auxiliary builders:

• Emulsification: Non-ionic surfactants (such as fatty alcohol polyoxyethylene ethers) emulsify and disperse hydrophobic impurities like waxes in the scouring liquor, preventing their re-deposition onto fiber surfaces.
• Saponification and hydrolysis: Under alkaline conditions (pH 10 to 12), anionic surfactants assist in saponifying the ester bonds in pectins, converting them from high molecular polymers into water-soluble low-molecular fragments that dissolve out.
• Dispersion and chelation: Chelating dispersants (such as sodium gluconate, polyacrylates) chelate calcium and magnesium hardness ions in water, preventing the formation and deposition of insoluble soap scum on fibers.

Quantitative evaluation system for scouring effectiveness:

• Capillary effect (wicking height): Suspending the scoured cotton fabric strip vertically in water, measuring the height to which water rises along the strip within 30 minutes. High-quality scouring should achieve 10 to 15 centimeters or more.
• Residual pectin content (ruthenium red dyeing method): Using ruthenium red dye to stain the scoured fabric and quantitatively characterizing pectin removal rate through color depth value K/S. High-quality scouring requires pectin removal rate ≥ 85%.
• Residual wax content (Soxhlet extraction method): Extracting with organic solvent followed by gravimetric determination; residual wax should be below 0.2%.

(3) Peroxide Bleach Stabilizers

Hydrogen peroxide (H₂O₂) is the most commonly used oxidizing agent for bleaching cotton and its blended fabrics. Its bleaching activity originates from the decomposition to produce hydroxyl radicals (·OH) and hydroperoxide anions (HO₂⁻). However, if hydrogen peroxide decomposes too rapidly or uncontrollably, the following problems arise:

• Oxidative degradation of cellulose, causing significant loss of fabric strength (embrittlement).
• Ineffective decomposition producing oxygen gas bubbles within the fabric, leading to uneven bleaching (pinhole risk).
• Unstable decomposition rate of hydrogen peroxide, resulting in batch-to-batch fluctuations in whiteness and absorbency.

The core function of peroxide bleach stabilizers is "deceleration and targeting": by chelating transition metal ions (especially Fe³⁺, Cu²⁺, Mn²⁺) to inhibit their catalytic decomposition of hydrogen peroxide, while keeping the decomposition rate within a mild and controllable range. Peroxide bleach stabilizers are mainly divided into two categories:

• Silicate-type stabilizers: Such as sodium silicate (water glass), which forms colloidal magnesium/calcium silicate precipitates to adsorb metal ions. They are low-cost and effective but are prone to forming silicate scale (silica deposits) on equipment surfaces and have poor resistance to high alkali and high temperature.
• Organic phosphonate/polymer-type stabilizers: Such as aminotri(methylenephosphonic acid) (ATMP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP), sodium polyacrylate, etc. They possess excellent chelating and dispersing capabilities, are free from silica scaling risks, and have good alkali resistance, making them the current mainstream choice.

Performance Comparison of Main Pretreatment Auxiliaries

2.2 Dyeing Process Auxiliaries (Dye-Fiber Interaction Regulation)

Dyeing process auxiliaries directly intervene in the kinetics and thermodynamics of dye uptake and are the key technical factors determining dyeing quality. Different dye classes (reactive dyes, disperse dyes, acid dyes, etc.) and different fiber substrates correspond to distinctly different auxiliary action mechanisms.

(1) Leveling Agents

Leveling agents are among the most technologically sophisticated and diverse categories of dyeing auxiliaries. Uneven dyeing (i.e., "shade spotting") is one of the most common quality defects encountered in dyehouses. The task of leveling agents is to prevent spotting from occurring at its source or to repair it through "migration" once it has occurred.

Based on their action pathways, leveling agents can be divided into two major types:

• Fiber-affinity leveling agents (substrate-affinity type): These leveling agents contain groups with high affinity for fibers (such as cationic groups having affinity for amino groups in polyamide). They pre-occupy dye sites on the fibers. As the dyeing temperature rises, the leveling agents gradually desorb from the fibers, progressively releasing dye sites to dye molecules, thereby reducing the initial dye uptake rate and achieving a "retarding" effect. Typical representatives are anionic leveling agents (such as naphthalenesulfonic acid formaldehyde condensates) used in polyamide/acid dye systems.
• Dye-affinity leveling agents (dye-affinity type): These leveling agents form reversible associations with dye molecules, "encapsulating" the dyes in the dye bath and slowing their diffusion to fiber surfaces. As temperature rises, the associations gradually dissociate, releasing the dyes and achieving both retarding and leveling effects. Typical representatives are non-ionic leveling agents (such as fatty amine polyoxyethylene ethers) used in polyester/disperse dye systems.

In high-temperature, high-pressure dyeing (polyester/disperse dyes, 130°C, 2.5 to 3 atm), leveling agents also need another critical capability—migration power: when dyes are unevenly distributed on the fibers, the leveling agent can promote the desorption of already-fixed dyes from deeper-shade areas and their re-uptake onto lighter-shade areas through diffusion. The performance of migration is typically quantitatively evaluated by the "migration index"—the percentage of dye transferred from pre-dyed fibers to undyed fibers under specific conditions. High-quality leveling agents should achieve a migration index of 70% or higher.

(2) Dispersing Agents

Dispersing agents play an irreplaceable role in disperse dye dyeing. Disperse dyes themselves are non-ionic hydrophobic dyes with extremely low water solubility (typically < 1 mg/L), existing in the dye bath as fine crystalline particles (usually 0.5 to 2 micrometers in diameter). Under high temperature (130°C) and high pressure, these particles have a strong tendency to agglomerate. Once agglomeration occurs, it leads to:

• Dye precipitating at the bottom of the dyeing machine or on fabric surfaces, forming difficult-to-remove "dye stains" and "tarry deposits."
• Significant reduction in dye utilization efficiency and insufficient dyeing depth.
• Clogging of filters and circulation pumps, increasing equipment maintenance costs.

The molecular design principle of dispersing agents is: on a hydrophobic aromatic ring/long-chain backbone (anchoring group), multiple hydrophilic polyoxyethylene ether chains or sulfonic acid groups (solvating chains) are introduced, enabling firm adsorption onto the surfaces of dye particles and preventing particle agglomeration through electrostatic repulsion and steric hindrance effects. High-quality dispersing agents must also possess comprehensive heat resistance, salt resistance, and pH tolerance, maintaining efficient dispersing performance at 130°C and under acidic conditions (pH 4.5 to 5.5).

(3) Exhausting Agents and Retarding Agents

Reactive dyes are the main dye class for cellulose fiber dyeing, with the dyeing process consisting of three stages: "dye uptake → diffusion → fixation." Since cellulose fibers carry a negative charge in water (fiber surface zeta potential approximately -30 to -50 mV), and reactive dyes are also anionic, there is electrostatic repulsion between the two, hindering dye molecules from approaching the fiber surface.

• Exhausting Agents: The most commonly used exhausting agents are electrolytes, such as Glauber's salt (sodium sulfate, Na₂SO₄) and common salt (sodium chloride, NaCl). They neutralize the negative charge on fiber surfaces, compress the electrical double layer, and reduce electrostatic repulsion between dyes and fibers, thereby increasing dye uptake (exhaustion rate). In deep shades, Glauber's salt usage can be as high as 60 to 100 g/L. However, the discharge of high-concentration electrolytes causes significant environmental burden (total dissolved solids TDS exceeding limits). Therefore, the development of salt-free/low-salt dyeing auxiliaries is an important research direction for the industry.
• Retarding Agents: At the initial stage of reactive dye dyeing, an excessively fast dye uptake rate can easily cause uneven dyeing both internally and externally. Retarding agents typically slow the initial uptake rate by competitively occupying dye sites on the fibers or forming temporary associations with dyes. However, due to the strong reactivity of reactive dyes, the operational window for retarding agents is relatively narrow and difficult to control industrially. In practice, the retarding effect is more commonly achieved through temperature gradient control and staged salt addition.

(4) Fixing Agents

Fixing agents are core auxiliaries in the aftertreatment of reactive dye dyeing. Reactive dyes achieve fixation on cellulosic fibers by forming covalent bonds with hydroxyl groups. However, not all dyes that have been taken up can successfully form these bonds:

• Some dyes hydrolyze under alkaline fixation conditions, generating "hydrolyzed dyes" that have lost their reactivity.
• The fixation reaction itself is in equilibrium; some dyes remain only physically adsorbed on fiber surfaces ("surface dye").

These unfixed dyes are easily dislodged during washing and domestic laundering, causing serious degradation of color fastness (especially wet rubbing fastness and wash fastness). The action of fixing agents involves three main mechanisms:

• Cationic capping: Cationic fixing agents (such as quaternary ammonium salt polymers, poly(diallyldimethylammonium chloride)) form sparingly soluble ionic complexes with the sulfonate groups in dye molecules, blocking water-soluble groups and reducing dye solubility.
• Resin crosslinking film formation: Resin-type fixing agents (such as reactive polyurethanes, epoxy resin derivatives) form continuous or discontinuous films on fiber surfaces, physically encapsulating dyes and hindering their dissolution.
• Reactive crosslinking: Some fixing agent molecules contain reactive groups (such as hydroxymethyl, epoxy groups) that can simultaneously undergo crosslinking reactions with both hydroxyl groups on fibers and reactive sites on dyes, forming three-dimensional network structures that significantly improve the durability of the fixation effect.

The negative impacts of fixing agent treatment are mainly reflected in: stiffening of fabric handle (especially with resin-type fixing agents), and slight alteration of shade (typically causing dulling of color). Therefore, when selecting fixing agents, a balance must be struck between the degree of fastness improvement and handle loss.

Functional Comparison of Main Dyeing Process Auxiliaries

2.3 Finishing Auxiliaries (Style and Function Impartation)

Finishing is the "finishing touch" step in dyeing and finishing—the primary source of product differentiation and added value. Unlike dyeing auxiliaries, which focus primarily on color quality, finishing auxiliaries impart hand feel, tactile perception, visual style, and special functionalities to textiles, directly determining the consumer's "first impression" and long-term user experience.

(1) Softening Agents

Softening agents are the most widely used and most diverse category of finishing auxiliaries in terms of product variety. Their core function is to reduce the coefficient of friction between fibers, making fabrics more supple, smooth, and pliable when bent, compressed, or subjected to surface sliding. The mechanism of action of softening agents can be summarized as: forming a lubricating molecular film on the fiber surface that modifies the tribological properties of the fiber surface.

Based on chemical structure and mode of action, softening agents can be classified into the following categories:

• Amino-modified silicones: Currently the most comprehensively performing class of softening agents. Amino silicones are polydimethylsiloxanes carrying amino functional groups (—NH₂ or —NH—) in side chains or at terminals. The introduction of amino groups imparts excellent affinity to fibers (especially hydroxyl-containing fibers like cotton and viscose) and self-crosslinking film-forming capability. Fabrics treated with amino silicones achieve a comprehensive handle characterized by smoothness, bulkiness, and fullness, with excellent elastic recovery and wash durability. However, excessively high amino content can lead to yellowing (especially during high-temperature heat-setting) and excessive hydrophobicity (affecting moisture absorption and wicking).
• Polyether-modified silicones: Introduction of polyoxyethylene ether (EO) or polyoxypropylene ether (PO) segments into the silicone backbone significantly enhances the hydrophilicity and self-emulsifying properties of the silicone. This type of softener is suitable for fabrics with moisture absorption requirements, such as sportswear and underwear, but the degree of smoothness in handle is generally inferior to that of amino silicones.
• Non-silicone softeners: Including softeners based on fatty acid amides (softening flakes), quaternary ammonium salts (ester quats), paraffin wax emulsions, etc. They are lower in cost, tend to impart a "soft" rather than "smooth" handle, and have inferior wash durability compared to silicone types. However, they are free from silicone spot risks and are suitable for deep-shade fabrics sensitive to silicone or for fabrics that will subsequently undergo coating processing.

The selection of softening agents requires comprehensive trade-offs among handle style, yellowing tendency, hydrophilicity, stability (shear resistance, salt resistance, pH resistance), and cost. Modern dyehouses typically adopt blending strategies, mixing different types of softeners in specific proportions to achieve a desired handle "fingerprint profile."

(2) Water and Oil Repellents

Water and oil repellent finishing imparts textiles with the ability to resist wetting and penetration by aqueous and oily liquids, and is widely used in outdoor apparel, home textiles, and technical textiles. The chemical principle is: forming a film with extremely low surface energy on the fiber surface, causing liquid droplets to bead up and roll off rather than spread (the "lotus effect").

The historical iteration of water and oil repellents clearly reflects the driving force of environmental regulations:

• C8 fluorocarbons (first generation): Polymers based on perfluorooctanesulfonyl (PFOS) and perfluorooctanoic acid (PFOA) offer the most excellent water and oil repellency (oil contact angles up to 120° or more), but due to the persistent organic pollutant (POPs) characteristics of PFOA/PFOS, they have been gradually phased out globally.
• C6 fluorocarbons (second generation): Short-chain fluorocarbons based on six-carbon fluoroalkyl chains. Their degradation products do not contain PFOA/PFOS, and the environmental risks are significantly reduced. However, the water and oil repellency (especially oil repellency grade) is about 1 to 2 levels lower than that of C8 products (from AATCC grade 8 down to grades 6 to 7).
• Fluorine-free (C0) repellents (third generation): Non-fluorine systems based on silicones, waxes, dendritic polymers, hyperbranched polymers, etc., completely eliminating the environmental concerns of fluorocarbons. However, current repellency performance (especially durability) still lags behind fluorocarbon systems. Contact angles of fluorine-free repellents are typically ≤ 140°, whereas C6 systems can achieve 150° or more. Fluorine-free systems are the clear direction for the future, but continued performance improvement requires substantial R&D investment.

Durability (i.e., wash resistance) of water and oil repellent finishing is another critical technical indicator, typically enhanced by incorporating crosslinkers (such as melamine resins, blocked isocyanates) to improve the bonding strength between the finishing agent and the fiber.

(3) Antistatic Agents, Antimicrobial/Anti-mite Agents, and Flame Retardants

• Antistatic agents: Synthetic fibers (especially polyester and polyamide) are prone to electrostatic charge accumulation in dry conditions due to their low moisture absorption, causing garment cling, dust attraction, and unpleasant electric shocks. Antistatic agents typically employ hydrophilic surfactants (such as polyoxyethylene alkylamines, phosphate esters) to accelerate charge dissipation by increasing the moisture-absorbing layer on fiber surfaces. Durable antistatic agents achieve long-lasting antistatic effects through chemical grafting of hydrophilic segments onto fiber surfaces.
• Antimicrobial and anti-mite agents: Including silver ions/nanosilver, quaternary ammonium silane salts, halogenated diphenyl ethers (such as triclosan), and natural extracts (chitosan, tea polyphenols). The mechanisms of action involve disrupting bacterial cell walls, interfering with microbial metabolic enzyme activities, or inhibiting the growth and reproduction of mites. The durability and safety of antimicrobial finishing are core concerns, particularly requiring testing for skin sensitization and cytotoxicity.
• Flame retardants: Including halogenated types (brominated flame retardants, with significant environmental controversy), phosphorus-nitrogen types (intumescent flame-retardant systems), and inorganic types (aluminum hydroxide, borates). The mechanisms of flame retardants are divided into gas-phase (free radical scavenging) and condensed-phase (char-forming thermal insulation) modes. Textile flame retardancy typically requires passing vertical flame tests (such as GB/T 5455) or achieving a limiting oxygen index (LOI) value of 28% or higher, which is generally considered to indicate self-extinguishing behavior.

Functional and Property Comparison of Main Finishing Auxiliaries

The selection of finishing auxiliaries is a classic "multi-objective optimization" problem: the five dimensions of Performance, Handle, Durability, Compliance, and Cost form a decision matrix. Different end-use applications (such as sportswear, underwear, outerwear, home textiles, technical textiles) assign completely different weights to each dimension, requiring close collaboration between dyeing engineers and auxiliary suppliers for targeted laboratory simulations and bulk-scale validation.