Optical Brightener ER Liquid: High-Performance Whitening Solution for Polyester (C.I. 199)

Optical Brightener ER Liquid Product Overview:

When exposed to ultraviolet light in the range of 350–364 nm, the molecule absorbs energy and re-emits a blue-violet fluorescence reddish-blue hue. This fluorescent light optically neutralizes the intrinsic yellowish cast of polyester fibers, delivering a brilliant, clean white appearance. One of its key technical advantages is its outstanding dispersion stability and fluorescence retention under melt-spinning conditions, making it an ideal choice for polyesters that require high-temperature processing.

Technical Specifications

Parameter ValueAppearance： Pale yellow paste / liquid dispersion Chemical class： Stilbene derivative Ionic character： Non-ionic Active content ：2% – 30% Shade： Reddish-blue / blue-violet fluorescence Maximum absorption wavelength： 364 nm UV absorption range： 350 ± 10 nm Specific gravity ：1.05 ± 0.01 pH 10 g/L solution： 6.0 – 8.0 Particle fineness ≤2 μm： ≥ 90% The liquid is supplied as an aqueous dispersion, readily soluble in most organic solvents. It shows good stability toward cationic softeners and can be applied in the same bath with sodium hypochlorite, hydrogen peroxide, and reducing bleaching agents. With at least 90% of particles below 2 μm, it guarantees uniform dispersion in high-temperature dyeing baths, preventing uneven whiteness or spots on fabrics.

Key Performance Features

1. High Fluorescence Efficiency and Exceptional Whiteness Optical Brightener ER Liquid delivers outstanding whitening results even at very low dosages. Recommended amounts: Exhaust dyeing 0.2–0.6% on weight of fabric o.w.f. Continuous pad-thermosol 1–6 g/L Melt-spinning polyester chips only 100–300 ppm 0.01–0.03% Compared to conventional brighteners like DT, ER liquid offers significantly higher brightening power and a purer, more vivid shade. The unique reddish-blue cast gives treated polyester fabrics a natural bright-white finish rather than a harsh, dead white. 2. Outstanding Thermal Stability and High-Temperature Resistance ER liquid is designed to withstand elevated processing temperatures: High-temperature exhaust dyeing up to 130 °C Pad-thermosol heat setting 180–190 °C Melt-spinning as pure powder stable up to 330 °C without decomposition This thermal robustness makes it perfectly suited for polyester fibers and rPET recycled PET applications where high-temperature melt processing is required. 3. Excellent Lightfastness and Wash Fastness The brightener exhibits good lightfastness rated S and excellent wash fastness. It also has high sublimation fastness, meaning it does not migrate or lose efficiency during heat-setting processes, ensuring consistent whiteness after finishing. 4. Broad Chemical Compatibility The non-ionic nature of ER liquid provides stability across a wide pH range and in hard water. It performs reliably in acidic, alkaline, and peroxide-containing baths. It is also stable toward reducing agents, oxidizers, and hypochlorite compounds, allowing one-bath processing with many bleaching auxiliaries. Importantly, it contains no 24 prohibited aromatic amines, no formaldehyde, and no APEO, making it non-toxic and non-carcinogenic. 5. Superior Sublimation Fastness and Anti-Yellowing Performance Polyester fabrics are often heat-set at 180–200 °C, where many standard brighteners sublime, causing yellowing or loss of whiteness. ER liquid maintains its fluorescent efficiency after heat-setting, delivering a pure white shade. This property is especially valuable for polyester filament, staple fibers, and blended fabrics that undergo high-temperature finishing.

Application Areas：

Textile & Dyeing Industry：

ER liquid is specially formulated for whitening and brightening polyester PET fibers and their blends, including: Polyester staple and filament Polyester/cotton, polyester/linen, polyester/wool blends Triacetate CTA and polyamide nylon fibers Processing methods: High-temperature exhaust dyeing suitable for yarn, cheese, and fabric Continuous pad-thermosol for large-volume, high-speed production Low-temperature adsorption 95–100 °C for blends that cannot tolerate 130 °C, followed by high-temperature curing to develop whitenessPlastics & Synthetic Fibers：

When used in powder form or high-purity liquid concentrate, ER is widely applied in: Melt-spinning of virgin and recycled polyester rPET chips Thermoplastics such as PE, PP, PVC, PC, and ABS Injection-molded and extruded plastic products For food-contact packaging applications, this brightener functions similarly to premium anti-yellowing agents such as ANTI YELLOW REMAP 00185 by lowering the b-value yellowness index of recycled PET, bringing its appearance close to that of virgin polyester. Other Industrial Uses：

Coatings used as FWA ER-I in water-based paints and latex coatings to improve whiteness Clear resin systems eliminates processing-induced yellowing in epoxy, acrylic, and polycarbonate resins, improving transparency Inks & paper enhances whiteness in printing inks and paper coating.

Usage Guidelines

High-Temperature Exhaust DyeingParameter Recommendation Dosage o.w.f. 0.1 – 0.6% Dispersing agent 0.5 – 1 g/L Liquor ratio 1:10 – 1:20 pH adjusted with acetic acid 5.0 – 6.0 Temperature / time 120–130 °C for 30–60 min After-treatment Hot wash → Dewater → Heat setContinuous Pad-ThermosolParameter Recommendation Dosage 1 – 6 g/L Pick-up approx. 70% Process Pad one dip-one nip or two dips-two nips → Pre-dry at 100 °C → Thermosol at 180–190 °C for 40–50 sLow-Temperature Adsorption for sensitive blendsParameter Recommendation Dosage o.w.f. 0.5 – 1.0% Dyeing temperature 95–100 °C After-treatment Wash → High-temperature curing to develop whiteness Melt-Spinning Polyester Chips / rPETParameter Recommendation Dosage 100 – 300 ppm 0.01 – 0.03% Processing Dry-blend with chips → direct spinning or injection moldingPlastics Extrusion / Injection MoldingParameter Recommendation Dosage on total compound weight 0.01 – 0.05% Processing temperature 180–300 °C for PET: 270–290 °CImportant notes:Stir ER liquid thoroughly before use it is an aqueous dispersion. Remove residual alkali from fabrics prior to treatment for optimal whitening results. Do not exceed the recommended dosage over-use may cause yellowing yellowing point occurs at approx. 5 g/L. Store at 0–40 °C, avoid freezing and direct sunlight. Shelf life 6 months if stored longer, stir well before use. Adding a small amount of blue-violet fluorescent brightener together with ER liquid can further improve whiteness and brilliance

Competitive Advantages

1. Cost-Effective Performance Compared to some high-end brighteners like OB-1 C.I. 393, ER liquid offers a much more favorable cost-to-performance ratio. The low active dosage directly translates into significant raw material savings for users. 2. Internationally Compliant & Environmentally Safe ER liquid is non-toxic, odorless, and free from the 24 restricted aromatic amines, formaldehyde, and APEO. It has passed relevant safety certifications and meets the environmental standards required for export to European and North American markets. Using purified water as the dispersion medium results in very low VOCs, making it an eco-friendly alternative to traditional solvent-based brighteners. 3. Reliable Supply Chain & Optimized Total Cost Mature domestic production of ER liquid ensures ample capacity and short delivery lead times. Compared to imported equivalents, locally produced ER liquid offers clear advantages in both price stability and supply reliability. 4. Versatile Processing Compatibility ER liquid works seamlessly with three mainstream application methods exhaust dyeing, pad-thermosol, and low-temperature adsorption. This flexibility is especially beneficial for manufacturers handling diverse product mixes and smaller batch sizes.

Packaging, Storage & Transport

Item Specification Standard packaging 25 kg PE drum Custom packaging Available upon request Storage conditions Keep in a cool, dry, well-ventilated place, protected from light temperature 0–40 °C Shelf life 6 months if stored beyond 6 months, mix thoroughly before use Transport Ship as ordinary chemical avoid inversion and violent impacts

Market Outlook & Trends:

Demand for high-performance, environmentally friendly fluorescent brighteners continues to grow, driven by the global textile industry and the increasing use of polyester. ER liquid remains a leading product for polyester whitening, and its market is expected to expand steadily in the coming years.

Key growth drivers include:

Circular economy & rPET upgrading Recycled PET often requires brightening / anti-yellowing treatment for use in apparel, packaging, and other high-value applications. ER liquid is a proven solution to restore whiteness in rPET. Premiumization of synthetic fibers Differentiated, high-quality polyester fibers demand superior whiteness ER liquid’s high efficiency at low dosages perfectly meets this need. Tightening environmental regulations With strict limits on APEO, formaldehyde, and other restricted substances in major export markets, ER liquid APEO-free, formaldehyde-free is an ideal choice for compliant formulations. Expansion beyond textiles From plastics modification to coatings and inks, ER liquid is finding new applications across multiple industries, unlocking further market potential. Disclaimer: The technical information provided in this document is based on publicly available data and is intended for reference only. Actual performance may vary depending on specific formulations and processing conditions. Users are advised to conduct preliminary trials to validate suitability for their own applications. Product specifications are subject to change without notice.