Direct Red 31(TDS)

Application and parameters of Direct Red 31

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Direct Red 31

Direct Pink 12B
Direct peach red 12B
Direct Red 12B
Direct Fast Pink
Direct Pink 5B

CAS NO: 5001-72-9

CI.NO: 29100

Molecular Formula: C32H21N5Na2O8S2
Molecular Weight: 713.65
Shade: colourful red blue light. Red brown powder

Direct Red 31 Physical and Chemical properties

Dyeing depth % 2
Insolubles % 0.15
Light Fastness 2
Washing Fatness 3
Rubbing fastness(dry) 4-5
Rubbing fastness(wet) 2

Colour Fastness Test

sun exposure






acid and alkali resistant

standard depth



original color change

white fiber stained

original color change

white fiber stained

original color change

white fiber stained






soda ash













Direct Red 31 (Direct peach red 12B) alias direct pink, direct pink 5B. Appearance is generally reddish brown uniform powder. Dissolved in water is magenta, slightly soluble in alcohol is red orange, soluble in cellosolve, insoluble in other organic solvents. In the sulfuric acid, the orange turns reddish brown, and after dilution, there is a dark blue red precipitate; in the concentrated nitric acid, it is brown and precipitates. The aqueous solution is added with concentrated sodium hydroxide to turn orange brown, and the concentrated hydrochloric acid has a red precipitate, in concentrated ammonia. It is reddish in the middle.

Direct Red 31 Application:

Mainly used in viscose, such as cotton, silk, polyamide fiber cellulose fiber and viscose/silk blended fabric dyeing, can be used for pulp shading.

Use condition:

1. Direct Red 31(Direct pink 12B) dyed cotton or viscose fiber has bright blue red color, good dyeing rate and transferability.

Naturally cooling to 40 ~ 60 ° C, is conducive to dye exhaustion.

2. It can be used for dyeing of rich fiber, the dyeing rate is very good, the color light is better than cotton yellow. It is also used for dyeing silk. It should be dyed with neutral bath. The color light on silk is yellower than viscose fiber. When dyeing vinylon, The dyeing rate is worse than that of cotton, and the color light is better than cotton yellow. When cotton, viscose fiber and other fibers are dyed in the same bath, the silk color is sometimes lighter than cotton or viscose fiber, wool and nylon can be dyed, and the second vinegar fiber is stained. Polyester and acrylic are slightly stained.

3. It can be used for direct printing of cotton or viscose fabric. Urea is needed to dissolve the color paste, especially printing.

When the pattern is deep.

4. It is one of the main red direct dyes, widely used in the dyeing and printing of cotton and viscose fibers. Sometimes used for the color discharge of viscose fabrics. In addition, in cotton knits, carpets, There are also a small number of applications in fleece and blended fabrics such as nylon and viscose.


Direct Red 31 is not a banned dye, but it should be noted that after the aniline is diazotized, a small amount of 4-aminobiphenyl is produced.


20 or 25kg/compound bag, carton box, iron drum, fiber durm for powder dye and 1000kg/tank for liquid dye

Direct Red 31 Material Safety Data Sheet (MSDS)

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