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Why are reactive dyes more popular than direct dyes for cotton dyeing?
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Mary Helsaple
Why are reactive dyes more popular than direct dyes for cotton dyeing?
Reactive dyes containing reactive groups can react with the -OH groups in cotton, wool and other fibers in a basic aqueous solution to form a covalent bond, it formed by matrix, links and active group ,so it can form strong covalent with fibre when use, hence the term reactive, and with incomparable characteristics than other cellulose fibers dyes which developed and established key position of a cellulose fiber dyes.
But direct dye can work on cellulose fiber in neutral or weak alkaline medium directly, generally do not need a mordant, only need to add salt or sodium sulphate and boiling, it is usually formed with the aid of cellulose and dye on the combination of weak hydrogen bonding and van der Waals force.
Reactive dyes can stimulate the splitting of dyes into dyes that can bond with cotton fibers under basic conditions, while direct dyes can greatly improve the directness of dyes to dye fibers under acidic conditions.
Reactive dyes can dye much brighter, more intense and deeper colors than direct dyes with much better color fastness.
Reactive dyes containing reactive groups can react with the -OH groups in cotton, wool and other fibers in a basic aqueous solution to form a covalent bond, it formed by matrix, links and active group ,so it can form strong covalent with fibre when use, hence the term reactive, and with incomparable characteristics than other cellulose fibers dyes which developed and established key position of a cellulose fiber dyes.
But direct dye can work on cellulose fiber in neutral or weak alkaline medium directly, generally do not need a mordant, only need to add salt or sodium sulphate and boiling, it is usually formed with the aid of cellulose and dye on the combination of weak hydrogen bonding and van der Waals force.
Reactive dyes can stimulate the splitting of dyes into dyes that can bond with cotton fibers under basic conditions, while direct dyes can greatly improve the directness of dyes to dye fibers under acidic conditions.
Reactive dyes can dye much brighter, more intense and deeper colors than direct dyes with much better color fastness.
Direct dyes and reactive dyes have the potential to provide the full gamut of colours. The main difference and the advantage for reactive dyes is that they give much higher fastness than direct dyes. The reactive dye bonds covalently, double bond, with the end groups on the cotton. Providing a strong bond, which in washing running tests etc would easily show grade 4 or 5. The direct dye would not be able to achieve these levels of performance, addition of binders etc would improve the fastness but not to the reactive level and would have detrimental effect on the handle of the fibre.
Direct dyes and reactive dyes have the potential to provide the full gamut of colours. The main difference and the advantage for reactive dyes is that they give much higher fastness than direct dyes. The reactive dye bonds covalently, double bond, with the end groups on the cotton. Providing a strong bond, which in washing running tests etc would easily show grade 4 or 5. The direct dye would not be able to achieve these levels of performance, addition of binders etc would improve the fastness but not to the reactive level and would have detrimental effect on the handle of the fibre.
Reactive dyes containing reactive groups can react with the -OH groups in cotton, wool and other fibers in a basic aqueous solution to form a covalent bond, it formed by matrix, links and active group ,so it can form strong covalent with fibre when use, hence the term reactive, and with incomparable characteristics than other cellulose fibers dyes which developed and established key position of a cellulose fiber dyes.
But direct dye can work on cellulose fiber in neutral or weak alkaline medium directly, generally do not need a mordant, only need to add salt or sodium sulphate and boiling, it is usually formed with the aid of cellulose and dye on the combination of weak hydrogen bonding and van der Waals force.
Reactive dyes can stimulate the splitting of dyes into dyes that can bond with cotton fibers under basic conditions, while direct dyes can greatly improve the directness of dyes to dye fibers under acidic conditions.
Reactive dyes can dye much brighter, more intense and deeper colors than direct dyes with much better color fastness.
Reactive dyes containing reactive groups can react with the -OH groups in cotton, wool and other fibers in a basic aqueous solution to form a covalent bond, it formed by matrix, links and active group ,so it can form strong covalent with fibre when use, hence the term reactive, and with incomparable characteristics than other cellulose fibers dyes which developed and established key position of a cellulose fiber dyes.
But direct dye can work on cellulose fiber in neutral or weak alkaline medium directly, generally do not need a mordant, only need to add salt or sodium sulphate and boiling, it is usually formed with the aid of cellulose and dye on the combination of weak hydrogen bonding and van der Waals force.
Reactive dyes can stimulate the splitting of dyes into dyes that can bond with cotton fibers under basic conditions, while direct dyes can greatly improve the directness of dyes to dye fibers under acidic conditions.
Reactive dyes can dye much brighter, more intense and deeper colors than direct dyes with much better color fastness.
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Direct dyes and reactive dyes have the potential to provide the full gamut of colours. The main difference and the advantage for reactive dyes is that they give much higher fastness than direct dyes. The reactive dye bonds covalently, double bond, with the end groups on the cotton. Providing a strong bond, which in washing running tests etc would easily show grade 4 or 5. The direct dye would not be able to achieve these levels of performance, addition of binders etc would improve the fastness but not to the reactive level and would have detrimental effect on the handle of the fibre.
Direct dyes and reactive dyes have the potential to provide the full gamut of colours. The main difference and the advantage for reactive dyes is that they give much higher fastness than direct dyes. The reactive dye bonds covalently, double bond, with the end groups on the cotton. Providing a strong bond, which in washing running tests etc would easily show grade 4 or 5. The direct dye would not be able to achieve these levels of performance, addition of binders etc would improve the fastness but not to the reactive level and would have detrimental effect on the handle of the fibre.
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