Exam 3 Coloration Study Guide - Disperse/Acid/Basic & Dyeing Blends

Disperse Dyes

Nonionic, Water soluble, commonly used for PET (AQ, Azo, and Nitrodiphenylamine)

Disperse dyes fixing to Polyester

1. Disperse dye particles are dispersed in the dyebath.

2. Small dye particles dissolve into individual dye molecules.

3. Dye molecules move onto the fiber surface.

4. Dye molecules diffuse INTO the polyester fiber.

5. The molecules reaggregate inside the fiber.

Fibers that have affinity for disperse dyes

• PET (polyester)

• Cationic dyeable PET

• Cellulose acetate

• Nylon

• Acrylic (slight coloration)

• Aramid fibers (slight coloration)

Application methods of Disperse

Atmospheric batch - Around 100C and uses carriers

High Temperature/Pressure batch - Around 130C, no carrier needed

Thermosol continuous - Pad, Dry Heat; dye sublimes and enters PET

Carriers

Chemicals that:

• Penetrate Polyester

• Cause the fiber to swell

• Increase Polymer chain mobility

• Help Dye molecules diffuse more easily

• Allowing dyeing at lower temperatures

Reduction Clearing

Removes excess surface dye after dyeing

Acid Dyes

• Have one or more sulfonate groups

• Carry a negative charge

• Are generally water-soluble

• Commonly smaller and more compact than direct dyes

• Have affinity for wool, nylon, and silk

• Common Chromophores (Azo, AQ)

Leveling Agents

Help control how quickly dye enters the fiber and improve uniformity

Anionic Leveling Agents

• Control available dye sites

• Displaced by dye during later stages

• Glauber’s salt

Cationic Leveling Agents

• Control the amount of available dye in the bath

• Gradually release dye through controlled hearing

Syntans (Synthetic tanning agents)

• Attach to unused dye sites

• Block additional dye adsorption

• Improve wash-fastness

Blocking unused dye sites so additional dye cannot attach later

Basic Dyes

• Cationic (positively charged)

• Are water and alcohol soluble

• Excellent brightness and color strength

• Can produce a full range of color

• Common chromophores (Azo, Anthraquinone, Xanthene)

Strike Rate

Basic dyes have a very high strike rate, meaning they attach to the fiber very quickly, meaning the dye may attach unevenly, creating unlevel dyeing.

• control temperature or use cationic or anionic retarders

Basic - Dyeing Bath Components

Acetic Acid - Controls pH

Leveling Agent/Retarder - Controls strike rate

Wetting Agent - Helps wet the fabric

Electrolyet - Slows exhaustion

Union Dyeing

Both fibers are dyed to the same shade

Tone-on-Tone Dyeing

Two fibers are dyed, but to different shade depths

Cross-dye Shade

Each fibers is dyed to a contrasting color

Resist/Reserve Shade

One fiber is dyed, while the other is left undyed

Staining Issues

Occurs when a dye intended for one fiber also slightly colors the other fiber.