Two Methods of Scouring Process!!

Scouring is the process to remove natural and foreign impurities from the fabric and preparing the fabrics for the next subsequent process. This process makes the fabric hydrophilic so that it can absorb the chemicals and dyes properly. In this article, we will discuss the methods of the scouring process.

The non-continuous scouring process consists essentially of circulating hot alkali liquor through the cloth in a vessel called kier.

The continuous scouring and bleaching in the J-Box have been established after 1960s. The continuous process is based on the impregnation of the fabric in an alkali solution followed by the steam aging stage, the fabric being either in rope form or open width form.

Kiers have given way to J-Boxes and J-Boxes are discarded in favor of open width scouring which requires only 2-15 min having very high production. In comparison, kiers take 6-12 h depending upon the number of impurities.

Two Methods of Scouring Process

There are two methods of scouring processes are available. They are described below:

Continuous process: J-box machine
Dis-continuous process: Kier boiler, Winch or Jigger machine

Batch Type or Discontinuous Process in Brief

Batch type or discontinuous scouring process in (rope form) are carried out in:

Low pressure kier
High pressure kier
Jafferson-Walker’s kier
Gebauer kier

Batch Type Scouring Machine (Open Width Form) is carried out in:

Mather and Platt’s horizontal kier
Jackson kier
Jig process

Among all of these the most used process is high pressure kier boiler. In this article, we will cover this type of kier boiling method.

Machine Profile for Batch Process

The prototype of a modern high pressure kier that has multi-tubular heater is often referred to as Walsh’s kier and considered to be the best.
This machine is about 9 inch high and 6.5 inch in diameter with a 2 tons capacity.
This machine is mounted on R.C.C columns.
The maximum working pressure for this machine is 40 lb/in² (2.812 kg/cm 2) at 141°C and is composed of mild steel plates with countersunk rivet heads inside to give a smooth surface.
Various mountings and accessories like pressure gauge, safety valve, blow-off valves for air and steam, steam traps, liquor level indicators, and draincock are provided with this machine.

Recipe for Batch Process Scouring

Chemicals

Amount needed

· Caustic soda

· Soda ash

· Wetting agent

· Sequestering agent

· Temperature

· M:L

· 0.5-2.4 g/L

· 0.5-1.0 g/L

· 120-130°C

· 1:100

Image Source: Basic Principle of Textile Coloration

Process Description

On perforated false bottom the substrate needs to be plaited. No matter, it can be done either manually or mechanically.
An alkaline solution is prepared that contains caustic soda (2 to 3%), sodium silicate (0.75 to 1%), sodium carbonate (0.5 to 1%) and wetting agent (0.1%) and the substrate is saturated in this solution at the time of piling.
From the underside of kier, enough scouring liquor is introduced. Thus entrapped air is swept out to prohibit the oxy-cellulose formation.
Then the lid is closed but the air valve is kept open.
Turning on the steam, the liquor is circulated with the help of centrifugal pump.
High pressure kier operates at about 130°C (2.109 kg/cm 2) for about 8 to 10 hours with a liquor ratio 5:1 to 6:1.
After scouring the draincock is opened at reduced pressure (5 to 6 lb/in 2) and equivalent amount of hot water is admitted from the top.
Once the cold water circulation on the goods is done, they are removed and transfer to the rope machine for washing.
From the bottom of kier, the withdrawal of the liquor is carried out that is forced through the heater. A distributor is then used to spread over the substrate.

Fabric that is to sell at white state is given two boils whereas the fabrics intended for printing are given a single boil.

Advantages & Dis-Advantages of Batch Process

Advantages

Dis-advantages

· Suitable for small orders

· Fabric can be scoured in both open width and rope form.

· Not economical for large orders

· Time requirement is more than continuous process

Continuous Process in Brief

The continuous scouring process can be carried out by the following machines. A continuous process is rarely followed in the industry. But among all of these J-box machine is used mostly. So, we will cover j-box machine here.

Saturator- J-Box-rope washer
Open width roller steamer
Vaporloc system
High pressure Klienewefer roller steamer
Conveyer storage steamer system
Roller bed steamer with pre-swelling zone

Saturator- J-Box- rope washer

This procedure can be divided into 4 stages:

Saturator
Pre-heater
J-box
Washing unit

Recipe for Continuous Process

Chemicals

Amount needed

· Caustic soda

· Wetting agent

· Sequestering agent

· Impregnation temperature

· Storing time in J-box

· J-box temperature

· 5 g/L

· 1-4.5 g/L

· 1-5 g/L

· 70-80°C

· 8-10 min (open width form)

40-60 min (rope form)

· 100-105°C

Process Description of Continuous Process

Saturator: If you are thinking about continuous machine, a series of j-box can be used for scouring or desizing. The desized and washed cloth is first saturated with scouring solution at about 70-80°C in a saturator.
Pre-heater: The cloth before entering J-Box is rapidly pre-heated by means of steam in a U-shaped heating tube. Where the temperature range is 110-120°C. In case of Becco system, there is no pre-heater and the cloth is directly heated in the J-Box which is used as a steamer
J-box:

Once the padding is completed, the substarte passes through the pre-heater. Then it enters into Du Pont type J-Box and kept for 40-60 min in plaited form at 100°C.
No friction occurs on the moving substrate. This is so because the internal area of the j-box is very smooth.
In-stead of rope form a multi-stage J-Box in open width form can also be used with a dwell time of 8-10 min in J-Box.

Washing unit: The scoured fabric is washed outside heaving a counter current arrangement at the temperature of about 70-80°C.

Image Source: Basic Principle of Textile Coloration

Advantages & Dis-Advantages of Continuous Process

Advantages

Disadvantages

· Fabric is scoured in both open width and rope form.

· Suitable for large orders

· Less time required

· Not economical for large orders

Wrapping It Up!

Scouring is a must procedure that should be carried out in the case of natural fibers. Otherwise, proper dyeing can’t be possible. Without scouring, no wax or foreign materials won’t come off from natural fibers and that will lead to patchy dyeing.

You can also check: What is scouring? A comprehensive look!

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