Direct Dye


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Related to Direct Dye: Mordant Dye, Reactive dye, disperse dye

direct dye

[də¦rekt ′dī]
(materials)
A group of coal tar dyes that act without mordants, for example, benzidine dyes. Also known as substantive dye.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Direct Dye

 

(also substantive dye, commercial dye), a synthetic dye that does not require mordanting before application, because the dye has an affinity to cellulosic fibers. It is believed that direct dyes are retained in the fibers owing to the presence of hydrogen bonds and dispersed van der Waals forces. Hydrogen bonds may form hydroxyl groups of cellulose and OH groups, NH2 groups, and CONH groups of dyes.

Most direct dyes are classified as azo dyes by chemical structure, but some are placed in the dioxazine and phthalocyanine groups. Direct dyes usually contain sulfo groups and are readily soluble in water. A typical example of a direct dye is direct light blue:

Direct dyes are available in all colors. They are inferior to reactive dyes in brightness, and many have low photosensitivity. To increase stability to water, perspiration, and the mechanical effects of laundering, fabrics colored with direct dyes are treated with fixatives. These agents are special substances that form high-molecular protective films on fiber or interact with the dyes to produce water-insoluble salts, which are retained in the pores of the fiber.

Direct dyes are used for cotton fibers, viscose, leather, and paper; to a lesser degree, they are used for natural silk, wool, and polyamide fibers. Their widespread use is the result of their low cost and easy application.

REFERENCES

Chekalin, M. A., B. V. Passet and B. A. loffe. Teknologiia organicheskikh krasitelei i promezhutochnykh produktov. Leningrad, 1972.
Emel’ianov, A. G. Priamye krasiteli i ikh primenenie v tekstil’noi promyshlennost’. Moscow, 1963.

M. A. CHEKALIN

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Szabadai, "Investigation of the aggregation of three disazo direct dyes by UV-vis spectroscopy and mathematical analysis," CHEMISTRY MAGAZINE, vol.
Removal of acidic and direct dyes using polyamide-6/chitosan nanofibrous filter media has been investigated with response surface methodology based on CCD.
A dyeability test can be used in the case of woven cotton fabric, since it can be easily dyed with direct dyes. This test is not suitable for PP material, since it cannot be dyed from an aqueous bath because of its hydrophobicity and nonpolar chemical structure.
Cellulose fibres interact strongly with direct dyes and will therefore be dyed red in the double and triple dye experiments.
This dye, which only later became known as Congo red, was the first of many so-called direct dyes. Unfortunately for the Friedrich Bayer Company, Bbb tiger's supervisors showed little interest in the young chemist's project.
I work in what is called the direct dye method, also known as resist dye painting.
(2007).Adsorption of direct dye on palm ash: Kinetic and equilibrium modeling.
Increasing export of organic & inorganic chemicals, rise in the production of dyes & dye intermediates such as reactive acid & direct dyes and the growing demand for the polymer from various end-use sectors such as automotive, construction, healthcare, etc., is anticipated to drive the demand for acid chlorides through the forecast period.
With a newly even-toned base, the Silver Conditioner then deposits custom direct dyes onto the fiber for a beautiful, brightening silver pay off.
Similar to direct dyes, acid dyes are also water-soluble anionic dyes with a general formula RSO3Na.
The term direct dyes arose from the fact that such dyes possess direct substantivity for cellulosic fibres.
Presence of sulpho-groups in acid dyes reduce the possibility of adsorption process, whereas these groups do not influence the adsorption in case of reactive and direct dyes [7], which show responses to this method.