Description

Reactive Red 21 is a high-purity, reactive azo dye belonging to the vinyl sulfone class, known for its excellent color fastness and brilliant red hue. Its primary value lies in its ability to form a strong covalent bond with cellulose fibers, ensuring vibrant, wash-fast coloration in demanding textile applications. This product is essential for manufacturers in the textile dyeing and printing industries, particularly for cotton, viscose, and other cellulosic materials, where consistent shade and durability are critical.

Application

• Exhaust Dyeing of Cellulosic Fibers: Primary application for dyeing cotton, rayon, linen, and hemp in batch processes.
• Continuous Dyeing: Used in pad-batch and pad-steam processes for uniform, large-scale fabric coloration.
• Textile Printing: Formulated into printing pastes for creating sharp, durable patterns on fabrics.
• Leather Coloring: Employed in the dyeing of leather goods to achieve rich, stable red shades.
• Paper Staining: Used for coloring specialty papers where high color value is required.
• Research & Development: Serves as a reference standard or intermediate in chemical synthesis and dye research.

Basic Information

Product Name	Reactive Red 21
CAS No.	11099-79-9
Molecular Formula	C26H21N5Na4O19S6
Molecular Weight	1083.84 g/mol
Synonyms	Reactive Red VS-R; C.I. Reactive Red 21; Remazol Red RB; Levafix Red E-2B; Procion Red H-E3B; Sumifix Red 3BF; Vinylsulfone Reactive Dye Red 21; 2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3-[[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-6-(phenylamino)-, tetrasodium salt
EINECS	234-328-9

Quality Control

Every batch of Reactive Red 21 is manufactured and tested under a strict quality management system. We ensure compliance with industry standards for reactive dyes, including color strength, solubility, and fixation rate. A comprehensive Certificate of Analysis (COA) detailing purity, shade, and physical-chemical parameters is provided with each shipment to guarantee batch-to-batch consistency and performance reliability.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). Keep away from strong oxidizing agents and excessive heat. The product is hygroscopic (moisture-sensitive); ensure the original packaging is sealed after use to prevent moisture absorption and caking.

Specification

Item	Specification
Appearance	Reddish-brown powder
Identification (IR)	Conforms to standard
Color Strength	100 ± 3% (vs. Standard)
Moisture Content	≤ 5.0%
Water Solubility (at 50°C)	≥ 100 g/L
pH (1% Solution)	5.5 - 7.5
Fixation Rate (on Cotton)	≥ 70%
Dusting Grade	Low dusting

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