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| Application of dispersants in the textile industry |
| Hits：280 AddTime：2026/8/24 16:50:56 |
| #Application of dispersants in the textile industry Dispersant is a key auxiliary agent for printing and dyeing. It relies on two mechanisms: electrostatic repulsion and steric hindrance, to stably suspend dyes, impurities, and oligomers in small particles, prevent agglomeration and sedimentation, and run through the entire process of dye preparation, pretreatment, dyeing, printing, and soap washing and finishing. Mainstream types of textiles: naphthalene based (NNO, MF), lignosulfonates, polymer chelating dispersants, anionic non composite dispersants. ##1、 Commercialized production of dyes (dye factories) Dispersed dyes and reducing dyes are almost insoluble in water. Synthetic filter cakes require grinding, and dispersants must be added to sand and grind the dye particles to a size of * * 0.1-2 μ m * * to produce commercial powder/liquid dyes. 1. Naphthalene dispersant NNO/MF: Good grinding and high-temperature stability, suitable for dispersing dyes and reducing dyes; 2. Lignosulfonate: Low cost, mostly used for reducing dyes, some of which may affect color light; > >Function: To prevent the growth of dye crystals, prevent storage clumping, and ensure the stability of subsequent dyeing baths. ##2、 Practical application of dyeing and finishing processes ###1. Dyeing process (maximum usage) ####(1) Polyester dispersed dye high temperature and high pressure dyeing (130 ℃) Pain point: Under high temperature conditions, dyes are prone to aggregation and coking, resulting in color spots and spots; At the same time, polyester will precipitate oligomers (white powder), which will adhere to the fabric surface and cause defects. -Anionic dispersant (NNO/MF): resistant to high temperatures of 130 ℃, prevents dye agglomeration and coking, and has certain leveling and transfer effects; The dosage is * * 1-2g/L * *, with light colors being higher and dark colors being lower. -Polymer dispersant: Simultaneously dispersing dyes and polyester oligomers, reducing color difference and white powder problems in the inner and outer layers of tube yarn, suitable for dyeing tube yarn and twisted yarn. > >Risk: Insufficient dispersant → dye agglomeration color spots; Excessive → the color becomes lighter and the foam rises. ####(2) Dyeing with vat dyes (cotton) Reductive dyes are insoluble in water, and the dye bath relies on dispersants to keep particles suspended; Prevent dye particles from depositing on the fabric surface and avoid color spots; The continuous pad dyeing process is particularly important. ####(3) Nylon acid dye, acrylic cationic dyeing Compound dispersant improves dye solubility, inhibits dye aggregation, enhances uniformity, and reduces color spots. ###2. Printing process 1. Paint printing paste: disperses pigment particles, prevents pigment agglomeration, ensures fine paste, clear printing contours, and avoids clogging; 2. Dispersed/reduced dye printing: Dispersants are added to the color paste to prevent dye aggregation during steaming and improve color uniformity; 3. Digital printing dispersed ink: Dispersant is the core component of ink, which stabilizes dye particles and prevents nozzle clogging. ###3. Pre treatment: desizing, boiling, bleaching (mainly using chelating dispersants) 1. Complex Ca ² ⁺, Mg ² ⁺, and Fe ³ ⁺ in water to eliminate the effects of hard water and prevent the deposition of calcium magnesium soap and rust on fabrics to form yellow spots; 2. Block iron ions in the bleaching bath to prevent catalytic decomposition of hydrogen peroxide and prevent fabric holes; 3. Disperse the decomposition products of the slurry, oil and wax impurities, prevent dirt from sticking back, and improve the whiteness and uniformity of the fabric; > >Phosphate free polycarboxylate chelating dispersant is currently the mainstream environmentally friendly product. ###4. Soap wash and clean wash afterwards (to prevent backflow) After dyeing and printing, soap is boiled, and dispersants suspend the detached floating colors, hydrolyzed dyes, and impurities in the bath solution to prevent them from re adsorbing back onto the fabric (white stains), significantly improving washing fastness and rubbing fastness. -Reactive dye printed white fabric: soap washing with dispersing anti staining agent to prevent the base dye from contaminating the white area; -Cowboy washing: Disperse indigo dye to prevent it from sticking back to the white fabric area. ###5. Color correction and stripping In the color repair and stripping bath, the dispersant suspends the stripped dye to prevent it from being re dyed and improve the success rate of color repair. ##3、 Comparison of main dispersant types Table |Type | Representative Product | Advantages | Shortcomings | Typical Scenarios| | --- | --- | --- | --- | --- | |Naphthalene anions | NNO, MF | High temperature resistance, strong dispersibility, high cost-effectiveness | Some bubbles are high, some affect color | Polyester high-temperature dyeing, dye sanding processing| |Lignosulfonates | Wood sodium, wood calcium | Low cost | Can reduce discoloration, affecting bright colors | Reductive dyes, commercialization of dyes| |Polymer chelating dispersant | Polycarboxylate liquid | Combining chelation and dispersion, alkali resistance, oligomer prevention, environmentally friendly and phosphate free | High unit price | Pre treatment, soap washing, polyester dyeing anti white powder| |Yin non compound dispersing and leveling agent | Various dyeing polyester fabrics | Dispersion+leveling+transfer dyeing, low foaming, low oligomer inhibition | High cost | Tube yarn, high demand polyester dyeing| ##4、 Common pitfalls on site 1. High temperature dyeing only pursues dispersion and ignores temperature resistance: Ordinary non-ionic low-temperature dispersants fail to desorb at 130 ℃, and the dye remains burnt; High temperature resistant anions or specialized polymer dispersants are preferred for polyester high-temperature dyeing. 2. * * Blind addition of dispersant * *: excessive amount will reduce dye uptake, make the color lighter, and increase the foam, which will increase the pressure of sewage treatment. 3. * * Hard water conditions without chelating dispersants * *: Calcium and magnesium ions will neutralize the charge of the dispersant, causing the dispersion system to fail directly and resulting in color spots. 4. * * Soap washing relies solely on soap detergent, lacking dispersing components * *: If the floating color falls off and re sticks to the fabric surface, the fastness cannot be improved. 5. Environmental restrictions: Traditional naphthalene based compounds are limited in some scenarios, and phosphorus free polymers are gradually replacing them. ##5、 Typical process reference dosage 1. High temperature dyeing of polyester: dispersant * * 0.5-2 g/L * *; 2. Pre treatment boiling and bleaching: chelating dispersant * * 0.2-1 g/L * *; 3. Soap washing after printing: anti stick dispersant * * 1-3 g/L * *; 4. Dye grinding: Dispersants account for 10-25% of the dye mass. |
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