Dyes and Colour Index

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Questions and Answers

What is the purpose of a Colour Index Generic Name for a dye?

To specify the textile usage of a dye

To classify dyes according to their fastness properties

To indicate the chemical constitution of a dye

To provide a unique identifier for a dye based on its application and hue (correct)

What type of dye is CI Reactive Blue 4?

A direct dye

A basic dye

An acid dye

A reactive dye (correct)

Which of the following is NOT a classification of dyes according to chemical constitution?

Azo dyes

Anthraquinone dyes

Reactive dyes (correct)

Indigoid dyes

What type of information is tabulated for each dye listed?

Dyeing methods and fastness properties Signup and view all the answers

What is the difference between CI Acid Red 1 and Orange II?

CI Acid Red 1 and Orange II have similar dyeing properties Signup and view all the answers

What is the term for a subgroup of dyes that includes a number of different subgroups containing heterocyclic systems?

Heterocyclic dyes Signup and view all the answers

How are dyes classified according to textile usage?

By their dyeing methods Signup and view all the answers

What is the purpose of classifying dyes according to chemical constitution?

To understand their chemical properties Signup and view all the answers

What is the result of precipitation of a dye inside the fibre or its chemical reaction with the fibre?

Better fastness to washing Signup and view all the answers

What form must dyes be in to diffuse into a fibre?

Individual molecules Signup and view all the answers

What is the term for a dye's attraction to a fibre during the dyeing process?

Substantivity Signup and view all the answers

What is the primary purpose of the Colour Index?

To catalogue dyes and pigments Signup and view all the answers

How many subgroups of dyes are classified according to usage in the Colour Index?

19 Signup and view all the answers

What is the characteristic of dyes that allows them to maintain their colour during washing?

Reasonable fastness properties Signup and view all the answers

What type of dye is Congo Red?

Anionic dye Signup and view all the answers

What is the term for the process of a dye becoming depleted in solution during the dyeing process?

Exhaustion Signup and view all the answers

What is the CI Constitution Number of the direct dye Congo Red?

22120 Signup and view all the answers

Which type of dye is used mainly for dyeing cotton?

Reactive dye Signup and view all the answers

What is the purpose of Volume 5 of the Colour Index?

Documenting commercial names used by dye manufacturers Signup and view all the answers

What is the common characteristic of dyes with the same manufacturer's brand name?

Same dyeing class Signup and view all the answers

What is the CI Constitution Number of Indigo, CI Vat Blue 1?

73000 Signup and view all the answers

What is the characteristic of Remazol dyes marketed by DyStar?

They are reactive dyes with vinyl sulphone reactive groups Signup and view all the answers

Which of the following is NOT a characteristic of the Colour Index?

It provides a list of all possible dyeing methods Signup and view all the answers

What is the format of the 4th edition of the Colour Index?

Online with registration fees Signup and view all the answers

Study Notes

Dye Classification and Nomenclature

Dyes have a Colour Index Generic Name based on application and hue
Dyes are classified according to chemical constitution and usage
The Colour Index is a major catalogue of dyes and pigments, first published in 1924
The Colour Index classifies dyes into 30 subgroups by chemical constitution and 19 subgroups by usage

Characteristics of Dyes

Dyes have four major characteristics:
Intense colour
Solubility in water at some point during the dyeing cycle
Substantivity for the fibre being dyed
Reasonable fastness properties of the dyeing produced

Dyeing Methods

Dyeing methods include:
Direct absorption
Precipitation of dye inside the fibre
Chemical reaction with the fibre
These methods result in better fastness to washing, as they are essentially irreversible processes

Colour Index Constitution Number

Dyes of known molecular structure are given a 5-digit CI Constitution Number
Examples:
CI Direct Red 28 has CI Constitution Number 22120
CI Vat Blue 1 has CI Constitution Number 73000
CI Reactive Red 1 has CI Constitution Number 18158
CI Disperse Blue 14 has CI Constitution Number 61500

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Description

This quiz covers the classification and properties of dyes, including their Colour Index Generic Names and applications.