Description

Direct Red 31 is a synthetic, water-soluble azo dye belonging to the direct dye class, known for its affinity for cellulosic fibers. Its primary value lies in providing a strong, vibrant red color with good wash fastness properties on cotton, viscose, and other natural materials. This product is essential for manufacturers in the textile dyeing and paper coloring industries seeking reliable and consistent colorants for their processes. Direct Red 31 CAS NO 5001-72-9 is also utilized in the leather industry and for the staining of biological specimens.

Application

• Textile Dyeing: Primary application for dyeing cotton, rayon, linen, and other cellulosic fibers to achieve a bright red shade.
• Paper Coloring: Used in the production of colored paper, tissues, and packaging materials.
• Leather Finishing: Imparts color to leather goods, including footwear, bags, and upholstery.
• Biological Staining: Employed as a histological stain in laboratory settings for microscopic analysis.
• Ink Formulation: A colorant component in the manufacture of certain inks and toners.
• Wood Staining: Used to color wood and wood-based products for decorative purposes.

Basic Information

Product Name	Direct Red 31
CAS No.	5001-72-9
Molecular Formula	C29H19N5Na2O8S2
Molecular Weight	675.60 g/mol
Synonyms	Direct Red 31; C.I. Direct Red 31; C.I. 29100; Direct Fast Red 3B; Direct Red 3B; Pontamine Fast Red 3B; Sirius Red 3B; Aizen Direct Fast Red 3BH; Atul Direct Fast Red 3B
EINECS	225-658-8

Quality Control

Our Direct Red 31 is manufactured under a stringent quality management system to ensure batch-to-batch consistency and performance. Each lot is tested against key parameters including color strength, shade, solubility, and impurity profile to meet industry specifications. A comprehensive Certificate of Analysis (COA) detailing purity, physical properties, and conformance is provided with every shipment.

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 incompatible materials and sources of ignition. For long-term storage, ensure the original packaging remains sealed to prevent moisture absorption and contamination.

Specification

Item	Specification
Appearance	Reddish-brown powder
Identification (IR)	Conforms to standard
Color Strength	≥ 98% (vs. Standard)
Moisture Content	≤ 5.0%
Water Insoluble Matter	≤ 1.0%
Ash Content	≤ 1.0%
pH (1% Solution)	6.0 - 8.0

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