Dyeing polyester fabric
Experiment title: Dyeing on Polyester material with Disperse dyes.
Dyes tend to be coloured, unsaturated organic compounds effective at giving color to a substrate (a textile), in other words. colouring or dyeing it.
The term “disperse dye” were applied to the organic colouring substances that are free of ionizing groups, are of low-water solubility and are usually ideal for dyeing hydrophobic fibres. Disperse dyes have substantivity for one or higher hydrophobic fibres e.g. cellulose acetate, plastic, polyester, acrylic also artificial fibres.
The bad charge on top of hydrophobic fibres like polyester can not be decreased by any means, so non-ionic dyes like disperse dyes are utilized that are not impacted by that surface fee.
Reputation for Disperse dyes:
In 1922, Green and Saunders made one type of colored azo compound, for which a solubilizing group (for instance- methyl sulphate, -CH2-SO3H) is mounted on amino group. In dye shower, these are generally slowly hydrolyzed and produce azo compound and formaldehyde bi sulphate. This no-cost azo chemical had been effective at dyeing cellulose acetate fibres. This dye ended up being named “ionamine”. But this ion amine couldn't give satisfactory result in dyeing.
Later on in 1924, Baddiley and Ellis produced sulpho ricinoleic acid (SRA) for dyeing acetate fibres. This SRA was utilized as dispersing representative. Later it was seen that SRA ended up being effective at dyeing Nylon, polyester, acrylic etc. In 1953 this dye had been named as “Disperse Dye”.
Characteristics of Disperse Dyes:
- Disperse dyes are nonionic dyes. So that they are clear of ionizing team.
- They have been ready made dyes and so are insoluble in water or have very low water solubility.
- They truly are organic colouring substances which are suitable for dyeing hydrophobic fibres.
- Disperse dyes can be used for dyeing man-made cellulose ester and synthetic fibres especially acetate and polyester fibres and often nylon and acrylic fibres.
- Carrier or dispersing representatives are required for dyeing with disperse dyes.
- Disperse dyes have actually reasonable to good light fastness with score about 4-5.
Classification of Disperse Dyes:
Based on Chemical Construction:
- Nitro Dyes
- Amino Ketone dyes
- Anthraquinonoid dyes
- Mono azo dyes
- Di- azo dyes
Application Ways Of Disperse Dyes:
- Process N: Regular dyeing method. Dyeing temperature is 80-100°C.
- Regular NC method: approach to dyeing at normal temperature with providers. Dyeing temperature 80-100°C.
- Process HT: warm dyeing technique. Dyeing heat 105-140°C.
- Process T: Thermasol dyeing method. Dyeing temperature 180-220°C, constant approach to dyeing.
- Pad roll technique: semi-continuous dyeing technique.
- Pad vapor method: Continuous dyeing method.
Dyeing System of Disperse Dye:
The dyeing of hydrophobic fibres like polyester fibres with disperse dyes may be considered as an activity of dye transfer from liquid solvent (liquid) to a good natural solvent (fibre).Disperse dyes tend to be included with liquid with a surface active representative to make an aqueous dispersion. The insolubility of disperse dyes makes it possible for all of them to go out of the dye alcohol because they are much more substantive toward organic fibre than to the inorganic dye liquor. The use of heat into dye liquor increases the power of dye particles and accelerates the dyeing of textile fibres.
Heating of dye liquor swells the fibre somewhat and helps the dye to enter the fibre polymer system. Thus the dye molecule got its devote the amorphous regions of the fiber. As soon as occurring within the fibre polymer system, the dye particles are held by hydrogen bonds and Van Der Waals’ force.
The dyeing is considered to take place when you look at the following simultaneous actions:
Diffusion of dye in solid stage into water by splitting up into specific particles. This diffusion depends on dispersibility and solubility of dyestuff and is aided by the presence of dispersing representatives and increasing temperature.
Adsorption regarding the mixed dye from solution onto the fibre surface. This dyestuff adsorption by fibre area is impacted by the solubility for the dye in the dye bath hence into the fibre.
Diffusion of this adsorbed dye through the fibre area to the interior of the fibre material towards center. In typical condition, the adsorption rate is often higher than the diffusion rate. And this could be the governing step of dyeing.
Whenever equilibrium dyeing is reached, the following equilibria may also be founded:
- Dye dispersed when you look at the bathtub
- Dye dissolved when you look at the bath
- Dye adsorbed from the fiber
- Dye diffused into the fiber
Effectation of Numerous Problems on Disperse Dyeing:
Effect of Temperature:
In case there is dyeing with disperse dye, temperature plays an important role. For swelling of fibre, heat above 100°C is required if temperature dyeing technique is applied. Again in case of provider dyeing strategy, this swelling does occur at 85-90°C. In case it is kept for more time, then dye sublimation and loss of textile strength may possibly occur.
Effectation of pH:
For disperse dyeing the dye bath must certanly be acidic and pH should really be in-between 4.5-5.5. For maintaining this pH, generally speaking acetic acid is usedAt this pH dye exhaustion is satisfactory. During color development, correct pH must be maintained usually fastness may be substandard and color should be volatile.
Carrier Dyeing Process:
- In the beginning, a paste of dye and dispersing broker is ready after which liquid is included with it.
- Dye shower is kept at 60°C temperature and all sorts of the chemical compounds together with the material are included with it. Then the bath is held for 15 min without raising the temperature.
- pH of bath is managed by acetic acid at 4-5.5.
- Today temperature of dye bathtub is raised to 90°C and at that temperature the shower is held for 60 min.
- After that heat is lowered to 60°C and resist and decrease cleansing is done if needed. Reduction cleaning is completed simply to increase the clean fastness.
- Material is again rinsed really after reduction cleansing after which dried.
High Temperature Dyeing Process:
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