Tag Archives: Scouring

Process Flow Chart of Dyeing Textile Materials | Basic Structure of Wet Processing Technology

Wet processing technology and its uses are huge in textile sector. Dyeing process for different textile materials could be different but its basic idea is same for all. For all types of dyeing pre-treatment is must for removing unwanted materials from textile materials. Pre-treatment style differs for the shade of dyed materials. Shade may be light or deep. Also these pre-treatment depends on buyer’s requirement. After pre-treatment textile materials are ready for dyeing. After dyeing after-treatment is necessary for get the final finished products. At last, that’s product becomes ready to use. This sequence can be expressed by a flow chart.

Basic Flow chart of dyeing textile materials is like the followings:

Grey Textile Materials (Fiber, Yarn or fabric)

Singeing

Desizing

Scouring

Bleaching

Mercerizing

DYEING/PRINTING

Finishing

Marketing

Now I like to discuss shortly about the different terms of the flow chat. Here, grey textile materials are fiber, yarn or fabric which is also consider as the raw materials for dyeing.

Singeing is the first steps of pre-treatment. The process by which loose, hairy and projecting fibers are removed is called Singeing.

Desizing is the second steps of pre-treatment. By this process gummy materials are removed. Also size materials removed by this process.

Scouring is the third steps of pre-treatment. This process is performed for removing impurities of the textile materials.

Bleaching is another important step which is used to reduce natural color of the raw materials. Dyeing performance depends on it much more.

Mercerizing is the special types of treatment. It performs if buyer wants. It is an additional treatment. It increases the strength and luster of the materials.

Dyeing is the main process where a white material becomes decorated by different colors. We have to know about the depth of shade of the materials.

Printing is called as localized dyeing. Different types of printing are done for giving special appearance on colored or white fabric.

Finishing is the last treatment of wet processing. Different types of properties can be added to the materials by different finishing effects.

Marketing is our main goal. Say, if we done everything but there have no buyer then everything is waste. So we should have a strong marketing department.

So, all of this is about flow chart of Dyeing.

 

Mercerizing of cotton fabric || Methods of Mercerizing Process

Mercerizing is done after bleaching operation. Bleaching is enough for prepared the fabrics for dyeing and printing but mercerizing is done for adding some advantage to the fabric. Luster and strength of the fabric increases for mercerizing process. Cotton mercerizing is the most popular operation.

Mercerizing of cotton is done in three basic stages of materials. They are as:

  • Yarn stage
  1. Hank form
  2. Package form
  3. Beam form
  • Fabric stage
  1. White fabric
  2. Woven fabric
  3. Knitted fabric
  • Dyed fabric stage

Methods of application: Yarn or fabric can be mercerized by J-Box. Mercerizing is a continuous process. At first fabric is hanked by the roller in a J-Box. Fabric is passed through a solution which contains 23% NaOH at room temperature. Fabric is passed for 4-5 minutes. Then fabric is squeezed by the squeezed roller and washing is done in a bath at 85 degree Celsius. Then it also immersed in an acid solution bath which contain 5% CH3COOH. After that is washed in another bath at 85 degree Celsius. By this way we can get a mercerized fabric.

For white finished goods, mercerizing is done by the following sequence:

Fabric after scouring and bleaching process

Padding in alkaline liquor

Washing

Neutralization in acid solution

Washing

Drying

A marketable fabric can be produced by different way. But day by day man wants to wear that’s type of fabric which has all possible facilities. Mercerizing is done in different types of machine. Generally mercerizing is done in dyeing machine. Yarn and Fabric Mercerizing is near similar.

Different well known buyer wants to get mercerized products. They strictly follow the qualities of product. After mercerizing fabrics become more suitable for dyeing or printing or for white goods it ready for delivery to buyer.

Scouring || Definition-Objectives-Effects and Methods of Scouring

Scouring is the pretreatment process of wet processing technology. Scouring is the first stage of pretreatment. Before dyeing or printing of textile materials natural fibers must pass scouring process. Scouring process bears an impotency in wet processing.

Scouring is the process by which natural (oil, wax, gum, fat etc) as well as added (during fabrication process) impurities are removed completely as possible. Especially hydrophobic character which is present in the fiber of fabric is removed by this process.

Objectives of Scouring: Scouring process has some important objectives. The objectives of scouring process are given bellow:

  1. The main purpose of the scouring is to remove impurities from the textile materials.
  2. The textile materials are leave in a highly absorptive condition without undergoing any chemical or physical damage significantly.
  3. After scouring process materials become suitable for next bleaching process.

Effects of Scouring: Followings changes occurred during scouring process:

  1. Saponifiable oils and free fatty acids are converted into soaps.
  2. Pectose and pectin are changed into soluble salts of pectic acid.
  3. Proteins are hydrolysed into soluble degradation products.
  4. Mineral matters are dissolved in the water.
  5. Unsaponifiable oils and waxes are emulsified by the soaps formed from saponification.
  6. Dust particles are removed and held in suspension.

In above I have written about Saponification. So, the reaction by which the insoluble and water immiscible materials are converted into water soluble products is called saponification. The reaction is as follows:

Oil + Caustic soda + Water = Soap + glycerin

Methods of Scouring: Scouring process is done by the following two ways. They are:

  • Continuous process: In this process scouring of the fabric is done continuously in a J-Box.  In this machine pretreatment and dyeing process are done continuously. This type of application is very limited.
  • Discontinuous process: This type of process also called batch process. Here scouring is done discontinuously in Kier Boiler, Jigger or Winch dyeing machine. Before dyeing different batch or lot is created.

In the dyeing machine different controlling parameters are controlled strictly. I like to give a sample recipe of scoring process of cotton in kier boiler.

Caustic Soda                        = 0.5 to 3% on the weight of fabric (owf)

Sodium-bi-Carbonate             = 0.5 to 1% owf

Wetting Agent                      = 0.5 to 1% owf

Materials: Liquor                    = 1: 6/8/10/12 (as required)

Temperature                         = 100 to 140 degree Celsius

Pressure                               = 10 to 30 PSI

Time                                    = 60 to 90 minutes

Material forms                       = Rope or Open width

Scouring is generally done for natural fiber. Better dyeing or printing performance depends on better scouring of the materials. Otherwise different types of dyeing or printing faults are appearing on the face of the fabric. So, it needs to take care on scouring process. It also depends on the shade of the fabric. Generally it is important for light shade dyeing.

So, Scouring agent is supplied by different textile chemical manufacturing companies. Before use the scouring agent one should ensure the properties of scouring agent.