Direct Red 28

TRADE NAME:: Congo Red; Direct red 4B; Direct Scarlet 4B; Direct Scarlet 4BE

CAS NO: 573-58-0

CI.NO: 22120

Molecular Formula: C32H22N6Na2O6S2
Molecular Weight: 696.67
Shade:yellow light red powder, tan powder.

COLOR TEMPLATE

Direct Red 28 Physical and Chemical properties

sun exposure	standard depth	—
sun exposure	1/12 depth	—
soaping	original color change	4
soaping	white fiber stained	2
flooding	original color change	4
flooding	white fiber stained	3~4
perspiration	original color change	3
perspiration	white fiber stained	4~5
rubbing	wet	3
rubbing	dry	4~5
ironing		4~5
acid and alkali resistant	vitriol	1~2
	acetate	1
	soda ash	4~5

Colour Fastness Test

Sun exposure

Soaping

Flooding

Perspiration

rubbing

ironing

Acid and alkali resistant

standard depth

1/12

depth

original color change

white fiber stained

original color change

white fiber stained

original color change

white fiber stained

dry

wet

vitriol

acetate

soda ash

—

3~4

4~5

1~2

4~5

Direct Red 28 (Direct red 4B) alias direct red, direct red 4BE, direct red, Congo red. Appearance is generally brown powder. Dissolved in water is yellow red, sensitive to hard water. Dissolved in alcohol is orange, very slightly soluble in acetone. It is blue in sulfuric acid, turns blue light after dilution, has a blue precipitate; it is olive brown to blue-grey precipitate in concentrated nitric acid. The aqueous solution is concentrated with red hydrochloric acid and has a red-blue precipitate. Yellow light, yellowish red in concentrated ammonia water. When the copper ion color is yellow and dark, the iron ion color is slightly yellow.

Direct Red 28 Application:

Direct Red 28 has been widely used in the dyeing of cotton and viscose fiber.

Use condition:

1. Direct Red 28 (Direct red 4B) has been used to dye cotton or viscose fiber to get bright yellow red, good dyeing rate, poor transferability, slow temperature rise during dyeing and salt addition to control dyeing, can get uniform color. After dyeing The stage dyeing solution should be naturally cooled to 80 ° C, which is beneficial to the dye exhaustion. The dye bath should be slightly alkaline to maintain a bright color.

2. It has also been used for dyeing silk and wool, and should be dyed with neutral bath. When cotton, viscose fiber and other fibers are dyed in the same bath, silk and wool are lighter than cotton or viscose fiber yellow, and nylon is heavily stained. Color, the second vinegar fiber is slightly stained, polyester, acrylic fiber does not stain.

3. It is not used for direct printing on cotton or viscose fabrics.

4.It is very sensitive to acid, dyed fabrics are exposed to the air for a long time or stored for a long time, and can also absorb carbon dioxide from the air to change the color. It is blue-dark and can be treated with a dilute soda solution to restore its original color.