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FGF PRESENTATION ON

SHAPE RETENTION FINISHING

OF FABRICS

PRESENTED BY :MANISHA UTTAMPUNAM KUMARISHWETA YADAVSONAKSHI KOCHHAR

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What is shape retention finishes?

Fabrics that lack the ability to retain their shape- they wrinkle andcrush easily. To make them competitive with other fibres, a variety ofshape-retentive finishes are given. This process is known as shaperetention finishing.

The initial process was for the purpose of making spun rayon fabricswrinkle-resistant. This was followed by similar treatment for cotton andlinen. With further development, chemical finishes were added tocotton fabrics for what became known as wash and wear cottons. Afurther extension of this is the development of permanent press, whichis used on cotton-blend fabrics as well as wool and wool blends.

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These finishes are all based on resins or reactants that will combinechemically with the fiber through a process called cross-linking,whereby adjacent molecular chains of cellulose in the fiber are linked ortied together to provide greater molecular rigidity and to preventintermolecular slippage.

Earlier used chemical finished was urea-formaldehyde.

The most widely used agent is di-methyloldihydroxydimethylethyleneurea (DMDHEU)

All of these finishes reduce by 30 to 50 percent the tensile and tearstrength of the fabrics to which they are applied, as well as reducing theabrasion resistance.

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WRINKLE RESISTANT FINISHES

These finishes are also sometimes called crease-resistant finishes.

The purpose is to keep the fabric flat and smooth as compared withcreases or pleats that are deliberately placed in the fabric.

Durable wrinkle-resistant finishes have been developed for cotton andlinen and, to a lesser extent, for rayon.

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WASH AND WEAR FABRICS

These are also known as drip-dry finishes. They are of same type asthe wrinkle-resistant finishes. Garments made of fabrics with wash andwear finishes will dry smooth and need little or no ironing after washing,depending upon the quality of the finish and the construction.

The fabrics have a good soft hand and a neat appearance. Wash andwear finishes have been used primarily on broadcloth and oxfordshirting but are also applicable to other types of cotton fabrics.

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SUBTRATES

WOOLSILKTHERMOPLASTIC FIBERS

COTTONLINENRAYON

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FINISHING PROCESS

DURAPRESS

o Durable press finishes can be defined as those chemicals or methodused to improve the properties and performance of washable fabrics.

o Permanent Press fabrics resist wrinkling and also help to maintaincreases and pleats throughout wearing and cleaning.

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DURAPRESS BY UTILIZING FIBRE PROPERTIES

Heat setting of synthetic fibres can provide durability for creases andpleats.

Further more, synthetic fibres that are quite resilient may not requireironing after laundering.

These fabrics are not given chemical finishes.

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DURA PRESS USING RESINS

In this the resin used have at least two functional groups that react withadjacent cellulose molecules.

The most commonly used resin treatment isdimethyloldihydroxyethyleneurea (DMDHEU).

It has two- OH (hydroxyl) groups and two-NH2OH (methylol) groupsthat can react with cellulose.

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When blends consisting of cellulosic fibres and synthetic fibres aretreated , the resin reacts only with the cellulosic fibres in the blend.

After the resin treatment, the fabric is dried and then it is cured at hightemperature.

It is in this step where the chemical reaction takes place.

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DURABLE PRESS WOOL FINISHES

Wool has its own natural memory. It is elastic, resilient and tends toreturn to its original shape after tension or compression is exerted.

PROCESS :The process requires that the crease area of the garment be sprayedwith a chemical reducing agent such as mono ethanolamine sulphitewhich temporarily inhibits the wools resilience. When the garment ispressed, the heat resets the wools memory with this crease so that thefabric always tends to return to the new creased condition. Moisture

increases this reaction and when wet (worn in the rain for instance) thecrease tends to become sharper.

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PROBLEMS WITH DURA PRESS

Manufacturing- the production of durable press items raises the costof manufacturing.

The additional step required and the cost of special equipment forfinishing both contribute to this increase in price that is passed alongto the consumer.

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Use and care-durable press fabrics, like their forerunners the crease-resistant and wash- and-wear fabrics, exhibit some loss in strength andparticularly a decrease in abrasion resistance.

Frosting also takes place due to breakage and loss of fibres because ofabrasion.

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Another problem was that the quantities of resin needed to producesatisfactory durable press made some of these fabrics rather stiff. Theydid not drape as well and were less comfortable to wear in warmweather than untreated fabrics.

If fabrics were not given an adequate after rinse, they had a fishy odour.

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Safety- formaldehyde is an important component of easy-care anddurable press finishes. Under hot, humid conditions, the reactionforming the finish can reverse, releasing formaldehyde.

One approach has been to alter the methylol groups in DMDHEU thatare the source of formaldehyde. Finishes based on this approach showminimal formaldehyde release but are not as cheap or effective as thetraditional commercial finish.

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Current research focussed on polycarboxylic acids, compounds withmultiple acid groups that can react with cellulose molecules formingester bonds. Fabric finished with this have good durable press featureswith better strength retention and abrasion resistance but are eitherexpensive or cause yellowing of the fabric.

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MODIFICATIONS OF DURA PRESS FINISHES

Modified and new approaches are being developed to reduce andeliminate problems of strength loss, abrasion rsistance and colordegradation. Among these are methods which would alter themolecular structure the molecular fiber so as to increase the strength.

The fiber construction can be oriented by swelling with sodiumhydroxide without tension and allowing the cotton to shrink, thenstretching the yarn while it remains in the caustic soda. This techniquehas been found to increase the strength of the permanent press cotton

so that it is equal to that of untreated cotton after 20 launderings.

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Pretreatment of cotton and cotton polyester fabrics with liquid ammoniahas been found to improve luster, tensile strength, wrinkle resistance,flex life and hand of goods that are subsequently cross linked.

A steam cure followed by a dry cure of cross linked cotton is alsoeffective and importantly, to provide about 300% greater abrasionresistance than the convention method.

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THANK YOU