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Introduction to Textile processing

Textile Processing

2Flow Chart of Textile Processing

3 Categories of Fabric w.r.t Treatment

4SingeingThe verb ‘singe’ literally means ‘to burn superficially’. Technically, singeing refers to the burning-off of. Loose fibres not firmly bound into the yarn and/or fabric structure. Singeing is an important part of pretreatment. This is the burning off of protruding fiber ends from the surface of the fabric. If not done properly, unclear print patterns, mottled fabric surfaces, and pilling results. Singeing of fabric is done in order to achieve the following

objectives. To improve pilling rating of fabric To give a uniform luster to the surface Removal of projection fiber

5 Singeing Types1.Plate singeing machine   In this type of singeing machine, the cloth passes over and in

contact with one or two heated curved copper plates. The thickness of the plates ranges from 1 to 2 inches. The heating of the plates is done by a suitable burning arrangement of gas mixed with air. The plates are heated to bright redness and the cloth passes over and in contact with these plates at a speed ranging from 150 to 250 yards per minute.

 

Brass is a metal alloy made of copper and zinc (melting point 900-1025°C)

6 Singeing Types

2. Roller Singeing Machine In this type of singeing machine, the cloth passes over and in

contact with a heated rotary cylinder made of copper or cast iron. The rotary cylinder has internal firing and revolves slowly so that constantly a fresh surface of the roller comes in contact with the cloth. The direction of rotation of the cylinder is opposite to the direction of the fabric so that the protruding fibres or nap of the fabric is raised.

3. Gas Singeing MachineIn this type of singeing machine, the fabric passes over a burning gas flame at such a speed that only the protruding fibres burn and the main body of the fabric is not damaged by the flame. This is the most common type of machine used for singeing fabrics as well yarns

7 DESIZING

The removal of sizing material is called desizing. It is done in desizng chamber. In this way the sizing material is removed.

METHODS OF DESIZING Following methods are used for desizing.

• Water Desizing• Acid Desizing• Enzymatic Desizing

8 Types of Desizing1-Water De-Sizing  It is the oldest method for desizing. For this purpose we use hot

water. If our sizing material is soluble in water then it becomes soluble in water and is removed in this way.

2-Acid Desizing For acid desizing we use very dilute HCL or H2SO4 for 4---8 hours.

It is done at room temperature. 3-Enzymatic Desizing  In this method certain enzymes are used for biodegradation of

sizing material (starch) such as amylase (C6H10O5) n amylase n(CO2) + n(H2O) +energy

9 ScouringThe term ‘scouring’ applies to the removal of impurities such as oils, waxes, gums, soluble impurities and sold dirt commonly found in textile material and produce a hydrophilic and clean cloth.Objective of Scouring :Scouring removes all the waxes, pectins and makes the textile material hydrophilic or water absorbent.

10 BLEACHING

Bleaching means the removal of the all color impurities. Woven and knitwear fabric that made of wool, cotton and silk are not white owing to their natural color or contamination in the preceding process, for fabric that have to dyed in pure white or any color, the has to bleached.

Bleaching is done by different methods such as

Hydrogen peroxide(H2O2)

Sodium hypochlorite (NaClO)

Sodium Chlorite(NaClO2)

11 MercerizingThe luster , Dye affinity and tensile strength of the cotton can be increased by mercerizing. This gives knitwear a smoother feel and higher dimensional stability. Mercerizing is specially applied on cotton products such as bed-linen table cloth and fabric for dresses. The material is treated with concentrated caustic soda solution .the fiber surface become smoother so that the light reflecting ability and thus gloss is increased.

Knitted fabric mercerizing machine

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Dyeing

Dyeing is the process of coloring textile materials by immersing the in an aqueous solution of dye called dye liquor. Generally the dye liquor consists of dye, water and other such materials which increase the effect of dyeing. Heat is usually applied to the liquor.

13 Some specific dyeing materials are mentioned for some fiber materials.

Different dyeing materials are used for different fiber materials. Various dyeing materials exits, as the fiber posses different reactive groups due to their chemical structure

Cellulose:• Direct Dyes• Vat Dyes• Reactive Dyes• Sulfur dyesWool:• Acid Dyes• Chrome Developed dyesPolyester:• Disperse dyes

14 PrintingPrinting is actually a type of dyeing. The main difference between printing and dyeing is that in dyeing the fabric is given one color only by dipping in the solution of dye, whereas in printing different colors are applied according to the requirement of design.

15 PRINTING MACHINE

For printing usually four types of machines are used.• ROLLER PRINTING MACHINE• MULTI ROLLER PRINTING MACHINE • FLAT BELT PRINTING MACHINE • ROTARY PRINTING MACHINE

16 FINISHING DEPARTMENTIn finishing department final process is done. The fabric is brought to finishing department after bleaching, dyeing or printing. Many qualities are produced in fabric during finishing like  The Finishing process is divided into two major portion1. Mechanical Finishing

This is surface treatment of textile by means of special mechanical processing machine. This process is used to developed the special fabric characteristics e.g. Shearing, Gigging, Calendaring.

2. Thermal FinishingThermal Finishing includes finishing process that requires warmth, coating of chemical finishes and drying processes are belong to this group.

17 STANTER MACHINESTANTER MACHINE

It is very important machine which is used to finish and dry the fabric. Its main purposes are:   Adjustment of fabric width Coating(chemical finishes)

The main parts of Stanter machine are:

Chemical bath Stretching frame Drying chamber Cooling chamber