Direct Blue 151

Direct Blue 151 is a water-soluble direct (azo) dye primarily used to color cellulose fibers such as cotton, linen and viscose; it appears as a bluish-black to reddish-blue powder and is sold under names like Direct Copper Blue 2R (C.I. 24175).

Direct Blue 151 is Blue-black powder. Soluble in water for blue purple or purple solution, and adequate soluble in ethanol for red light purple.‍

TRADE NAME:Direct Copper Blue 2B,Direct Blue Light Fast R,Copper Blue 2R

Main features

• Type: Direct (di-azo) dye suitable for exhaust dyeing of cellulose fibers.

• Solubility: Readily soluble in water (gives blue-purple solution); limited solubility variations in alcohol and concentrated acids.

• Fastness: Moderate to good washing and rubbing fastness; light fastness typically moderate (varies by substrate and shade).
• Dyeing behavior: Strong affinity for cellulose with highest uptake around high temperature (reports indicate peak affinity near 100 °C for exhaust processes).
• Post-treatments: Fastness can be improved by metal salt (e.g., copper sulfate) or crosslinking/after-fixation (formaldehyde-based or other fixing agents) depending on process and regulation.
• Typical applications: Exhaust dyeing of cotton/linen/viscose, rayon/brocade fabrics, paper pulp and leather coloration in industrial processes.

Application:

Direct Blue 151 Mainly used for cotton, linen, rayon and other cellulose fibers, rayon / brocade fabric dyeing, leather and paper pulp can also be used for coloring.

Technical Specifications

• ‍CAS NO: 110735-25-6
• CI.NO: 24175
• Molecular Formula:C34H25N5Na2O10S2
• Molecular Weight: 773.7
• Shade: Red light blue.

FAQ

Will Direct Blue 151 cause significant staining or migration during finishing?

It is described as having relatively high staining strength and good rub fastness when properly fixed; however, wet rubbing and poor fixation can still cause migration. Use recommended after-fixation and thorough washing to minimize staining in mixed-fiber goods. 

What safety, storage and handling notes should my technical sheet include?

Store in a cool, dry place in original sealed packs; avoid inhalation of dust — use appropriate PPE. Dispose of dye waste per local regulations; do not release concentrated dye solutions to drains. For SDS/Safety details cite supplier MSDS and follow local wastewater treatment rules. (Provide SDS link from your supplier.) 

Can Direct Blue 151 be used in printing pastes or reactive printing?

It is primarily an exhaust direct dye and is not a reactive dye; printing is possible but requires careful formulation (fixatives, binders and after-fixation) and will not give the same washfastness as reactive systems on cellulose. For durable reactive printing on cotton, consider reactive dyes instead.