What is dyeing? | How to dyeing of 100% cotton fabric with direct dye by exhaust method.

Dyeing of 100% cotton fabric with direct dye by exhaust method.


Dyeing

Experiment

Title:

To study dyeing of 100% cotton fabric with direct dye by exhaust method.

Abstract:

In this experiment dying of 100% bleached cotton fabric by direct dye (Indosol Red BA). Exhaust method was used for this purpose. It was performed with the liquor ratio of 1:50 and dye 1%, 2%, 3% owf (on the weight of fabric) in 45 minutes at 90 ^oC in the presence of auxiliaries like wetting agent (Na₂CO₃) and salt (NaCl). Experiment was performed under control conditions of temperature, pH 10-11 and time. After the experiment a colour fabric was achieved.

Introduction:

Direct dye, also called Substantive Dye, any of a class of colored, water-soluble compounds that have an affinity for fibre and are taken up directly, such as the benzidine derivatives. Direct dyes are usually cheap and easily applied, and they can yield bright colours. Wash fastness is poor but may be improved by after treatment. Most packaged dyes sold for home use are direct dyes. Properties of direct dyes Direct dyes have some characteristics. Followings are the main properties of direct dyes. Direct dyes are water soluble dyes. It is anionic in nature. It needs electrolyte for exhaustion. Dyeing process is carried out in alkaline condition. Generally applied for cellulosic as well as protein fibers. Fastness properties are improved by after treatment. It is not widely used as compared with reactive dyes. Comparatively cheap in price. Direct dyes are used for cheap goods for local market. Direct dyes are used to dye the fabric directly without any specific arrangement. Salts are added and increase the heat to increase the rate of absorption of dye molecules into the fibers. Why wash fastness of direct dye is poor than reactive dye? Light and wash fastness properties of direct died fabrics are poor. The reason is that Direct dyes anions are attached to the cellulose polymers by hydrogen bonds and van der Waals forces both of which are weak and auxochromes of direct dyes are polar. And direct dye is bleed when we wash the fabric. And reactive dye has strong hydrogen bond with fabric and don’t bleed when we wash the fabric.

According to SDC (society of dyeing and colorant) there are three classes of direct dye.

dyes that are not self-levelling and which are highly sensitive to salt. It has big molecule and substantivity more and sulphonic group less and solubility less and wash fastness good due to big molecule. The exhaustion of these dyes cannot adequately be controlled by addition of salt alone and they require additional control by temperature; they are described as temperature-controllable.

The aim of this experiment was to study dyeing of 100% cotton fabric with direct dye by exhaust method. Direct dyes are used to dye the fabric directly without any specific arrangement. In this experiment salt (NaCl) was added to increase the attraction of dye to fabric and high temperature was given to enhance the energy of dye molecules and to swell the fabric. This process was performed to achieve a dye fabric.

Material and recipe:

Material:

· Cotton fabric samples.

· Oven

· Dye (Indosol red BA)

· Measuring beaker.

· Hot water bath

· Wetting agent

· Salt

Recipe:

Dye = 1%, 2%, 3% owf (on the weight of fabric).

Liquor ration = 1:50.

NaCl = 30g/l.

Na₂CO₃= 10g/l.

Required recipe:

Sr#	Sample	weight	Liquor ratio	Dye	NaCl	Na₂CO₃
1	A	3.48	3.48: 174	1/100 ×3.48 = 0.0348	30/1000 ×174 = 5.22	10/1000 × 174 = 1.74
2	B	3.67	3.67: 183.5	2/100 × 3.67 = 0.0734	30/1000 ×183.5 = 5.55	10/1000 × 183.5 = 1.835
3	C	3.57	3.57 : 178.5	3/100 × 3.57 = o.171	30/1000 ×178.5 = 5.355	10/1000 × 178.5= 1.785

Procedure:

First of all, three sample of fabric was weighted through weight balance that was 3.48, 3.67and 3.57g. after that 1% 2% and 3% solution of direct dye (Indosol Red BA) was prepared respectively. and added these solutions in the 174.5ml water for sample A, 183.5 for sample B and 178.5 for sample C which were taken in the beaker. Then 1.74g wetting agent for sample A, 1.835g wetting agent for sample B and 1.785g wetting agent for sample C was added in the solution. After that, given fabric was dipped into the solution and beaker was put into a hot water bath at temperature 90^oC for 45minutes. After that fabric was hot and then cooled washed. Fabric was dried through oven.

Result and Discussion:

After the experiment a dyed fabric was achieved. Fabric showed a light red color. Fabric weight increased after dying.

Discussions:

As before the experiment fabric was not dye but after the experiment a color fabric was achived. Color shades were different according to the different % of dyes.. Also weight of fabric was increased in small limit. During the experiment all instructions were considered.

Conclusions

100% bleached cotton fabric was dyed by indosol red BA direct dye. The color shade of fabric depended upon the die percentage used in solution.

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