Project onTextile Finishing

By Adnan Mukhtar

and Qaiser Razzaq

Introduction to Textiles

A Textile is a flexible material comprised of a network of natural or artificial fibres often referred to as thread or yarn.

Textile refers to any material made of interlacing fibres

Textiles are made in various strengths and degrees of durability, from the finest gossamer to the sturdiest canvas

There can be Animal Textiles, Plant Textiles, Mineral Textiles, Synthetic Textiles

Departments Of Textiles

Textiles are divided in 3 major categories

» Spinning

» Weaving

» Wet-Processing

Spinning

The process of converting the fibres in the form yarn is called Spinning

A flexible material comprised of a network of natural or artificial fibres often referred to as thread or yarn

Yarn is produced by spinning raw wool fibres, linen, cotton, or other material on a spinning wheel to produce long strands known as yarn

Synthetic yarns are made by spinneret

Weaving & Knitting

The process of converting yarn in the form of fabric is called Weaving

Fabric formed by the interlacement of warp and weft yarn is called weaving

Fabric formed by the interlooping of yarns is called Knitting

Wet-Processing

This is the another entirely different stage of textile sector. It involves various stages, and can be divided as suchPretreatments

» singe» desize» scour» bleach» mercerize

Dyeing/Printing Finishing

Pretreatments

The term “pretreatments” include all operations of preparing the textile material, such as fibres yarn and woven, knit and non-woven fabrics and garments for the subsequent processes for dyeing printing and finishing.For all practical purposes the pretreatments are carried out along with dyeing and printing and their equipments is part of the wet-processing plant

Dyeing and Printing

The process of application of dyes on to the substrate (fabric, yarn or fibres ) in the solution form is called Dyeing.The process of application of dyes on the substrate (fabric) in the paste form is called PrintingDyes can of various classes as mentioned

– Direct dyes– Reactive dyes– Vat dyes– Sulphur dyes– Azoic dyes– Disperse dyes– Acid or Anionic dyes, pre-mettalised or mordant

dyes– Basic or cationic dyes

Finishing Textile finishing is a term commonly applied to different processes that the textile materials undergo after pretreatments, dyeing or printing for final embellishments to enhance their attractiveness and sale appeals well as for comfort and usefulness. The term has been used in the past for all the treatments that the fabric may undergo after weaving and knitting but this significance is now conveyed with the phrase “Wet Processing”.Finishing treatments are basically meant to give the textile material certain desirable properties like

» Softness» Lusture» Pleasant handle» Drape» Dimensional stability» Crease recovery » Antistatic » Non-slip» Soil release

However these also include finishes that have to meet certain specific end uses such as

» water repellency

» Flame retardency

» Mildew proofing

Chemical and Mechanical finishing

The finishing processes are applied in various forms and various types of finishes effect can be obtained such as discussed belowA finish that is classified as durable is one that will endure through successive wet or dry cleaningA non-durable, or soluble finish, is one that will be removed through successive washing or dry cleaningsTextile finishes applied after the coloring process generally fall into one of two general categories according to purpose or end result. These categories are

» wet or chemical finishes » decorative or mechanical finishes

Standard Chemical or Wet finishes

Standard, chemical or wet finishes augment the textile's durability or ability to perform in a given way. These finishes include antibacterial or antiseptic Anti-static Easy CareFlame retardant Insulative Lamination or BondingMothproof Soil repellent Water repellentWater absorbency finishes

Decorative or Mechanical Finishes

Decorative finishes achieve a decorative result or an enhanced aesthetic handle or appearance. Some of them areBrightening finishes Calendering finishes Ciré (chintz) finishes Delustering finishes Durable press calendering Embossed finishes

Etch printing or burn-out finishes Friction calendering French wax finishes Moiré finishes Napped finishes Panné finishes Plisse finishes Resin finishes Schreiner calendering

Flock Finishes

Flocked finishes are the adherence of tiny fibers or fine particles to create a pile effect on a fabric through one of two methods:

1. Adhesive is applied to the surface of the fabric, which may be in a design or pattern. The fibers are added with the excess flocked fibers vacuumed off. The adhesive is cured and the fabric brushed and cleaned.

2. Electrostatic flocking uses adhesive on the ground cloth, which is then passed through a high-voltage field that charges the fibers causing them to be attracted to the adhesive.

Additives for Crosslinking Finishes

Additives, when added to a chemical finishing liquor, bring about changes in physical or chemical properties of the treated fabrics Additives are also used to enhance the stability and smooth running properties of the finishing liquors. Wetting, dispersing and antifoam agents These auxiliaries are usually added in small quantities (I-5 g/l) to finishing liquors Dispersing agents ensure stability and compatibility of the various components of a chemical finishing bath for prolonged periods (6-8 h) Antifoam agents prevent foaming of the liquor in the pad trough or at the nip formed by the padding rollers. They act by modifying surface tension and many different products are available, several of them silicones.

Softners

Softeners are used to improve the handle and smoothness of treated fabrics. Resilience (i.e. the ability to resist and recover from stretching, deformation and creasing) can also be improved. Softening agents are classified according to their ionic properties.Anionic agents are based on:

» (a) Sulphated oils or fatty acid esters» (b) Alkyl sulphates» (c) Fatty acid condensation products.

Nonionic agents are based on:» (a) Polyglycol ethers and esters» (b) Ethoxylated phenols» (c) Silicone products.

Cationic agents are based on:» (a) Quaternary ammonium or pyridinium derivatives» (b) Aminoesters and amides.

Needle Lubricants (SOFTNERS)

Needle lubricants improve the sewing properties of easycare cellulosic fabrics. help to reduce losses in tear strength and abrasion resistance. In general three types of products are employed,

» (a) Primary and secondary dispersions of polyethylene

» (b) Silicic acid ester dispersions » (c) Silicone dispersions

Handle Modifiers

They enable the handle of fabrics to be varied from soft to firm according to demand.Secondly they restore bulk and firmness to fabrics that have become limp during preparation and dyeing processes. Thirdly they enable fabrics to be stiffened if necessary to facilitate making-up procedures. Finally a stiffening finish is required for end uses such as interlinings, work wear, table linen, bed linen, mattress covers, tapes and ribbons.

Hydrophilic Finishes

Synthetic fabrics have low regain values. Nylon takes up 5% moisture at equilibrium, polyester only 0.5%. To improve comfort in wear, particularly for underwear in contact with the skin, it is desirable to impart a hydrophilic finish. Fatty acid adducts and modified polyamide dispersions are widely used.

Hydrophobic Finishes

Makes the fabric less hydrophilic or water absorbing to protect them against moisture damage.

Can be durable or non-durable.

Used for tarpaulins and canvasses

Based on different chemical sources

Teflon Finish

The name have been given by the chemical manufacturing company Dupont, by the 3M’s the name is Scotch GuardIt is an oil, soil and sometimes also water repellentThey are based on fluorinated hydrocarbons fluorinated acrylate esters, chromium complexes of perfluorocarboxylic acids and others

Anti Slip Finishes

Slippage of warp and weft yarns is a well known defect of loosely woven filament fabrics arising from the smoothness of synthetic yarns. The problem can be overcome by reducing fibre surface smoothness, thereby increasing interfibre friction, by applying silicic acid esters, sometimes in combination with polyacrylates. The most popular blends are those of polyester with cellulosic fibres, either cotton or viscose, combining the excellent easy-care and hard-wearing properties of polyester with the comfort and freedom from static or soiling of cellulosic fibres.

Durable Press

Durable press is a generic term for a finishing process in which chemical or physical stabilizations of a fabric takes place after making-up in garment form. By delaying the final finishing step until making-up is completed, it is possible to stabilizes the shape of a garment in its final saleable form. In durable press finishing a distinction is normally made between precure and postcure methods.

Precure

This method is applicable only if the polyester content is at least 60% of the total fabric weight. Before making-up, the cellulosic component is chemically finished in fabric form, in the usual way. The polyester component is heat set after making-up, thereby imparting the desired shape to last the life of the garment.

Postcure

In this method blend fabrics are carefully impregnated with crosslinking reactant, catalyst and additives, but reaction between cellulosic fibres and crosslinking agent is prevented by appropriate selection of chemicals and close attention to working conditions. The chemically sensitised fabric is subsequently made up into garments, the required final shape of which is obtained by prolonged curing in an oven.

Flame-retardant Finishes

Flame-retardant finishing of cotton and blends, to impart self-extinguishing behaviour in normal wear and after repeated launderings, creates problems far more complex than those encountered in any other finishing process.they function by decomposing into chemical species that alter the thermal degradation reactions of the substrate, decreasing the concentration of combustible products and increasing the amount of char produced

Conclusion

Textile chemistry is a deep science in itself.

It keeps us bound, to explore more and more.

We have only touched a minor part of this beneficial science

SPECIAL THANKS TO

SIR KASHIF MUNIR (OUR TEACHER)SIR KALEEM(BEBE JAN MILLS)SIR ANWAR(NISHAT MILLS)SIR KASHIF(KOHINOOR MILLS)