Study of Cotton:
Cotton is the most common natural fiber. It the most popular fiber all over the world. Cotton is the cellulose fiber. Because of its wear comfortability, it becomes famous all over the world. So that study on dyeing of cotton fabric with reactive dye is famous for every lerner.
properties of cotton:
- Color: Creamy white, yellowish-white.
- Tensile strength: Normally strong fiber. Tenacity- 3-5 gm/den
- Elongation at break: 5-10%
- Elastic recovery: It is inelastic fiber. At 2% elongation ER=74% and at 5% it will 45%
- Specific gravity: 1.54
- Moisture regain%= 8-8.5
- Sunlight effect: It loses strength on sunlight and turn into yellow.
- Effect of alkali: It is not damaged on alkali.
- Dissolving: It is dissolved in copper complexes and concentrated (70%) sulphuric acid.
- Water absorbency: 1gram fiber can absorb 24gm of water.
Study of Reactive dyes:
Reactive dyes are the most usable and popular dyes stuff all over the world because of their good fastness property. it makes the covalent bond to the cellulose.
Properties of reactive dyes:
- Reactive dyes is water soluble dye.
- This dyes is anionic in nature.
- They have good water and light fastness property.
- Substantively is better.
- It can make strong covalent bond to the cellulose fiber.
- Need alkaline condition to dye
- Small amount of dyes are hydrolyzed during application.
Considering factor dyeing of cotton fabric with reactive dye:
Some influencing factors are essential for study on dyeing of cotton fabric with reactive dye. are given below-
- PH: Reactive dyeing needs in alkaline medium. It should be 11.5-11.
- Temperature: Normally at 60’C. But it depends on the brand of reactive dyes.
- Concentration of electrolyte: Depends on the shade%.
- Time: Normally 60min to 90min.
- Liquor ratio: Depends of the fabric property, dyes behavior and Dyeing machine performance.
General structure of Reactive dyes:
C–B–R= reactive group.
C= Chromophore (Azo group, Anthraquinone, Phthalocyanine group, Complex group of metal)
B= Bridging Group (Imino, Ethyl & Methyl, Oxide, and Sulphide group)
R= Reactive Group (-Cl, -Br, -SH, -OCH etc.)
Mechanism for the study on dyeing of cotton fabric with reactive dye:
Cellulose+ Reactive dyes= Cellulose–Hydrogen bond–Reactive dyes
There are three basic techniques to consider for the reative dyeing process. This dyeing mechanism occurs only in the dyeing portion of the dyeing process flow chart. which are given below:
- The attachment of the dye molecule to the surface of the fiber.
- The penetration of dye molecules to the core of the fiber.
- The fixation of dye molecule to the molecular structure of the fiber.
There are three basic part of the reactive dyeing process which are giving below:
- Pretreatment: The process for preparing the fiber to dye. Scouring, Bleaching, and enzyme process make the fiber prepared for dyeing.
- Dyeing: Colorant material is use hare to dye the fiber molecule.
- Aftertreatment: loose dyes removes here. Dye fixing chemicals are uses here to fix up the dye material. The fiber is also softening here.
100% practical usable dyeing process of reactive dye on cotton are given below:
Scouring and bleaching
Enzyme if need
Levelling 40’c 5 minute
Runtime 5 minute
Temperature raise to 80’c
Color dosing 80’c 30 minute
Runtime 15 minute
salt dosing 10 minute
Runtime a10 minute
Tempeture up to 90’c runtime 20 minute
cooling at 60’c (Fabric Check)
soda dosing 10% at 15 minute
Soda dosing 90% at 25 minute
Runtime 10 minute
Rise temperature at 80’C
Runtime 10 min
If ok then BD(Batch drop)
Normal hot 80’c
For better understanding a complete dyeing with photograph are
Conclusion study on dyeing of cotton fabric with reactive dye:
Cotton is the most popular using fiber as well as reactive dyes is also most popular dye to use. So that study on dyeing of cotton fabric with reactive dye is so important topic.
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