Disperse Print

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    Experiment name: Printing on Polyester fabric with Disperse dyes.

    Introduction:

    Dyes are coloured, unsaturated organic chemical compounds capable of giving colour to

    a substrate (a textile), i.e. colouring or dyeing it.

    The term disperse dye have been applied to the organic colouring substances which

    are free from ionizing groups, are of low water solubility and are suitable for dyeing

    hydrophobic fibres. Disperse dyes have substantivity for one or more hydrophobic fibres

    e.g. cellulose acetate, nylon, polyester, acrylic and other synthetic fibres.

    The negative charge on the surface of hydrophobic fibres like polyester can not be

    reduced by any means, so non-ionic dyes like disperse dyes are used which are not

    influenced by that surface charge.

    History:

    In 1922, Green and Saunders made one type of coloured azo compound, in which a

    solubilizing group (for example- methyl sulphate, -CH2-SO3H) is attached to amino

    group. In dye bath, they are slowly hydrolyzed and produce azo compound and

    formaldehyde bi sulphate. This free azo compound was capable of dyeing cellulose

    acetate fibres. This dye was named ionamine. But this ion amine did not give

    satisfactory result in dyeing.

    Later in 1924, Baddiley and Ellis produced sulpho ricinoleic acid (SRA) for dyeing acetatefibres. This SRA was used as dispersing agent. Later it was seen that SRA was capable of

    dyeing Nylon, polyester, acrylic etc. In 1953 this dye was named as Disperse Dye.

    Properties of Disperse Dyes:

    Disperse dyes are nonionic dyes. So they are free from ionizing group.

    They are ready made dyes and are insoluble in water or have very low water

    solubility.

    They are organic colouring substances which are suitable for dyeing hydrophobic

    fibres.

    Disperse dyes are used for dyeing man made cellulose ester and synthetic fibres

    specially acetate and polyester fibres and sometimes nylon and acrylic fibres.

    Carrier or dispersing agents are required for dyeing with disperse dyes.

    Disperse dyes have fair to good light fastness with rating about 4-5.

    Classification of Disperse Dyes:

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    According to Chemical Structure:

    1.Nitro Dyes

    2.Amino Ketone dyes

    3.Anthraquinonoid dyes

    4.Mono azo dyes

    5.Di- azo dyes

    Recipe:

    Disperse Dyes 4 parts

    Dispersing agent 2 parts

    Water As required

    Thickener 83 parts

    (NH4)2SO4 0.7 gm

    NaClO3 0.2 gm

    Print paste preparation:

    1. Thickener paste preparation (70 gm sodium alginate + 13 C.C H2O stirr with heat)

    2. 4 gm dyes + 2 gm dispersing agent

    3. 0.7 gm (NH4)2SO4 + 0.2 gm NaClO3

    4. (1 + 2 + 3) Stirr uniformly

    After treatment:

    The printed fabric is steamed in the steamer 10 min at 105 110 0C to penetrate the

    dye in the fabric and fix it.

    Comments:

    Disperse dyes have low molecular weight (200 400 gm per mole) and are non ionic

    which is necessary for preparing stable dispersions. The fact that disperse dye stuffs

    must be able to prepare in free divided states is important. To achieve level dyeing the

    particle size also must be maintained below 4 microns and preferably 0.5 3 microns.

    Naturally the particle size also must be as uniform as possible. Since disperse dye stuffs

    are crystalline in the pure state it is frequently difficult to grind them to meet the above

    requirements. Dye particles of over 4 microns produce specky coloration.

    Some of the disadvantages of disperse dyes included limited wash fastness, gas fading,

    the resistance of multi step fibre pretreatment, the problem of flocculation of the dye

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    stuff, the addition cost of the required additives and the environmental concern over

    many of the aromatic solvent dye carries employed. Barre effects do occur but can be

    controlled by standing the dyeing cycle and slightly increasing the dye bath

    temperature.

    From this experiment we can get a clear idea about Disperse dyes. From others dye this

    type of dye is different. During this experiment we have to face some problems that are

    to be considerable. Overall, the knowledge of this dye helps us to dye Man made fibre

    especially Polyester properly and helps us in our practical life.

    Read more:http://textilelearner.blogspot.com/2012/01/printing-on-polyester-fabric-

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