Description

C.I.Direct Black 51 is a high-performance, substantive direct dye belonging to the chemical class of benzidine derivatives. This product is engineered to deliver deep, consistent black shades with excellent build-up properties and good overall fastness on cellulosic fibers. It is a critical component for textile manufacturers, leather tanneries, and paper producers seeking reliable and cost-effective coloring solutions for their industrial processes.

Application

• Textile Dyeing: Primary application for dyeing cotton, viscose, rayon, and other cellulosic fibers to achieve deep black shades.
• Leather Processing: Used in the dyeing of leather goods, providing uniform and penetrating color.
• Paper Coloring: Employed in the manufacture of colored papers, including specialty packaging and decorative papers.
• Ink Formulation: A potential colorant for certain types of industrial inks where its substantivity is beneficial.
• Batch Dyeing Processes: Well-suited for exhaust dyeing methods in jiggers, winches, and becks due to its good solubility and migration properties.
• Blend Fabrics: Can be used in union dyeing of cotton-polyester blends when combined with appropriate disperse dyes.

Basic Information

Product Name	C.I. Direct Black 51
CAS No.	72207-95-5
Molecular Formula	C34H25N9Na2O7S2
Molecular Weight	781.72 g/mol
Synonyms	Direct Black 51; C.I. 27720; Direct Deep Black EW; Direct Black EW; Pontamine Black EW; Benzidine Black EW; Atul Direct Black D; Amanil Black B; Dinamine Black EW; Solar Black B
EINECS	Contact for details

Quality Control

Our production of C.I. Direct Black 51 adheres to stringent quality management protocols to ensure batch-to-batch consistency and performance reliability. Every lot is tested against key parameters including color strength, shade, solubility, and fastness properties. A comprehensive Certificate of Analysis (COA) detailing purity, physical properties, and performance metrics is provided with each shipment to guarantee it meets your specific application requirements.

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. The product is hygroscopic (moisture-sensitive); ensure containers are sealed after each use to prevent moisture absorption and caking.

Specification

Item	Specification
Appearance	Black to bluish-black powder
Identification (IR)	Conforms to standard
Color Strength	100 ± 3% (vs. Standard)
Shade	Conforms to standard
Moisture Content	≤ 5.0%
Water Insoluble Matter	≤ 1.0%
Solubility in Water	Conforms (at 80-90°C)
pH (1% Solution)	6.0 - 8.0
Fastness Properties	Typical data available on request

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