What Is Dyes or Dye/Classicification Of Dyes or Dye

DYES: Substances that add color to textiles. They are incorporated into the fiber by chemical reaction, absorption, or dispersion. Dyes differ in their resistance to sunlight, perspiration,washing, gas, alkalies, and other agents; their affinity for different fibers; their reaction to cleaning agents and methods; and their solubility and method of application.

Types Of Dye or Dyes:
Acid Dyes: A class of dyes used on wool, other animal fibers, and some manufactured fibers.Acid dyes are seldom used on cotton or linen since this process requires a mordant. Acid dyes are widely used on nylon when high washfastness is required. In some cases,even higher washfastness can be obtained by aftertreatment with fixatives.

Aniline Dyes: Dyes derived chemically from aniline or other coal tar derivatives. Anthraquinone Dyes: Dyes that have anthraquinone as their base and the carbonyl group
(>C=O) as the chromophore. Anthraquinone-based dyes are found in most of the synthetic dye classes.

Azo Dyes: Dyes characterized by the presence of an azo group (-N=N-) as the chromophore.Azo dyes are found in many of the synthetic dye classes.

Azoic Dyes: See DYES, Naphthol Dyes.

Basic Dyes: A class of positive-ion-carrying dyes known for their brilliant hues.Basic dyes are composed of large-molecule, water-soluble salts that have a direct affinity for wool and silk and can be applied to cotton with a mordant. The fastness of basic dyes on these fibers is very poor.Basic dyes are also used on basic-dyeable acrylics, modacrylics, nylons, and polyesters, on which they exhibit reasonably good fastness.

Cationic Dyes: See DYES, Basic Dyes.

Developed Dyes: Dyes that are formed by the use of a developer. The substrate is first dyed in a neutral solution with a dye base, usually colorless. The dye is then diazotized with sodium nitrate and an acid and afterwards treated with a solution of B-naphthol, or a similar substance, which is the developer. Direct dyes are developed to produce a different shade or to improve washfastness or lightfastness.

Direct Dyes: A class of dyestuffs that are applied directly to the substrate in a neutral or alkaline bath. They produce full shades on cotton and linen without mordanting and can also be applied to rayon, silk, and wool. Direct dyes give bright shades but exhibit poor washfastness. Various aftertreatments are used to improve the washfastness of direct dyes, and such dyes are referred to as “aftertreated direct colors.”

Disperse Dyes: A class of slightly water-soluble dyes originally introduced for dyeing acetate and usually applied from fine aqueous suspensions. Disperse dyes are widely used for dyeing most of the manufactured fibers.

Fiber-Reactive Dyes: A type of water-soluble anionic dye having affinity for cellulose fibers. In the presence of alkali, they react with hydroxyl groups in the cellulose and thus are liked with the fiber. Fiber-reactive dyes are relatively new dyes and are used extensively on cellulose when bright shades are desired.

Gel Dyeing: Passing a wet-spun fiber that is in the gel state (not yet at full crystallinity or orientation) through a dyebath containing dye with affinity for the fiber. This process provides good accessibility of the dye sites.

Macromolecular Dyes: A group of inherently colored polymers. They are useful both as polymers and as dyes with high color yield. The chromophores fit the recognized CI classes, i.e., azo, anthraquinone, etc., although not all CI classes are represented. Used for mass dyeing, hair dyes, writing inks, etc.

Metallized Dyes: A class of dyes that have metals in their molecular structure.They are applied from an acid bath.

Naphthol Dyes: A type of azo compound formed on the fiber by first treating the fiber with a phenolic compound. The fiber is then immersed in a second solution containing a diazonuim salt that reacts with the phenilic compound to produce a colored azo compound.Since the phenolic compound is dissolved in caustic solution, these dyes are mainly used for cellulose fiber, although other fibers can be dyed by modifying the process. (Also see DYES, Developed Dyes.)

Premetallized Dyes: Acid dyes that are treated with coordinating metals such as chromium. This type of dye has much better wetfastness than regular acid dye. Premetallized dyes are used on nylon, silk, and wool.

Sulfur Dyes: A class of water-insoluble dyes that are applied in a soluble, reduced form from a sodium sulfide solution and are then reoxidized to the insoluble form on the fiber. Sulfur dyes are mainly used on cotton for economical dark shades of moderate to good fastness to washing and light. They generally give very poor fastness to chlorine.

Vat Dyes: A class of water-insoluble dyes which are applied to the fiber in a reduced, soluble form (leuco compound) and then reoxidized to the original insoluble form. Vat dyes are among the most resistant dyes to both washing and sunlight. They are widely used on cotton, linen rayon, and other cellulosic fibers.

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