Description

Fluorescent Brightener 251 is a high-performance stilbene-based optical brightening agent (OBA) with the CAS registry number 16324-27-9. This compound is engineered to absorb ultraviolet light and re-emit it as visible blue light, effectively compensating for yellowing and enhancing the perceived whiteness and brightness of materials. It is an essential additive for manufacturers in the plastics, synthetic fibers, coatings, and detergent industries seeking to improve the aesthetic appeal and market value of their finished products.

Application

• Primary whitening and brightening agent for a wide range of thermoplastics, including polypropylene (PP), polyethylene (PE), ABS, and PVC.
• Critical component in the production of brightened synthetic fibers such as polyester, nylon, and polyacrylonitrile.
• Formulation additive for paints, coatings, and inks to achieve high-visibility, brilliant white finishes.
• Key ingredient in laundry detergents and fabric softeners for superior whitening effects on textiles.
• Used in the manufacturing of paper and paperboard to achieve high-grade brightness standards.
• Application in adhesives and sealants to improve visual clarity and product quality.

Basic Information

Product Name	Fluorescent Brightener 251
CAS No.	16324-27-9
Molecular Formula	C₄₀H₄₂N₁₂O₆S₂
Molecular Weight	843.0 g/mol
Synonyms	2,2'-(1,2-Ethenediyl)bis[5-[4-[bis(2-hydroxyethyl)amino]-6-(phenylamino)-1,3,5-triazin-2-yl]amino]benzenesulfonic acid; FB 251; Optical Brightener 251; Fluorescent Whitening Agent 251; Tinopal UNPA-GX; Blankophor P 167%; 4,4'-Bis[(4-anilino-6-bis(2-hydroxyethyl)amino-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic acid; Stilbene Brightener 251
EINECS	Contact for details

Quality Control

Our Fluorescent Brightener 251 is produced under a stringent quality management system. Every batch is subjected to comprehensive analytical testing, including HPLC for purity, spectrophotometry for strength, and checks for solubility and hue. We provide full traceability and Certificates of Analysis (COA) are available upon request to ensure compliance with your specific application requirements.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at a controlled room temperature (15-25°C). Keep away from heat sources and incompatible materials. The product is light-sensitive (store away from light).

Specification

Item	Specification
Appearance	Light yellow to yellow-green powder
Identification (IR)	Conforms to standard
Assay (HPLC)	≥ 98.0%
Strength (Spectrophotometry)	100 ± 3%
Moisture Content	≤ 1.0%
Ash Content	≤ 0.5%
Solubility (in water)	Clear, faint yellow solution
pH (1% aqueous solution)	7.0 - 9.0

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.