Designex Presentation

8/3/2019 Designex Presentation

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DYEING, PRINTING & FINISHING OF FABRIC S

MAC FERGUSSONRMIT UNIVERSITY


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CLASSIFICATIONMAJOR FIBRE TYPES USED FOR FURNISHINGS

1. NATURAL FIBRES, COTTON, LINEN, WOOL2. REGENERATED FIBRES, VISCOSE, ACETATE

3. SYNTHETIC OR MAN MADE FIBRES

POLYESTER, ACRYLIC, NYLON

4. BLENDS OF NATURAL WITH SYNTHETIC ORBLENDS OF DIFFERENT SYNTHETIC WITH THEREGENERATED FIBRES.


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REGENERATED FIBRES Fibres obtained from plant material (wood or

stems) after chemical processing of the originalmaterial.

Viscose rayon - from wood pulp

Cuprammonium rayon

wood pulp

Lyocell (TencelTM) environmentally friendlymanufacturing process.

Bamboo fibre - from the stem of the bambooplant (type of viscose rayon). Cellulose acetate wood pulp


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SYNTHETIC FIBRES

Polyamide

Nylon 6 & Nylon 66, differingproperties in terms of dyeing and melting point.

Polyester two types available normal dyeable &

cationic or basic dyeable. Both polyester and nylon available as micro fibres.

Acrylic fibre.

Polypropylene fibre dyeable type available.

Special flame retardant polyester fibres such asTrevira CS TM are available.


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DYES AND PIGMENTS There is no Universal dye that will dye all fibres.

Different fibre types require different dyes.

Dyes that dye fibres based on cellulose, do not dyewool to give good properties.

Dyes for polyester will dye acetate and acrylic and thenew types of polypropylene.

To achieve the best possible performance on Acrylicfibres special dyes are used


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Dye Fibre Classification

Cellulosic

fibres

Protein

fibres

CelluloseAcetate

Polyamide

Nylon 6 &66

Acrylic Polyester

Reactive Acidincluding

metal

Complex

Disperse Acid Basic Disperse

Direct Mordant

(chrome)

Disperse Disperse

Vat Reactive Mordant(chrome)

Sulphur

Azoic


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PIGMENTS

Pigments are different to dyes.

Pigments have no chemical attraction for textile fibres

Pigments are held onto the fibre by means of a resin

binder, similar in all respects to a paint. The quality of the binder influences the properties of the

pigment particularly performance to dry cleaning.

Rubbing fastness is a function of binder adhesion and

pigment particle size.. Light fastness and dry cleaning fastness are related to the

chemistry of the pigment.

Pigments are often used for printed fabrics.


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DYES

Dyes that give the best performance on cotton fabrics interms of light stability, washing and dry cleaning areusually the most expensive to apply.

Very high quality furnishings in cotton and linen wouldbe either dyed or printed with Vat dyes. Azoic dyesmay also be used in some cases.

Reactive dyes are also being used but some have theirlimitations in terms of performance.


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DYEING PROCESSES

Textile fibres can be dyed at various stages on themanufacturing chain.

These include Loose Fibre, where large volumes of one colour are

required e.g. carpet manufacture

Sliver in the case of wool & synthetic fibres

Yarn

particularly for jacquard designs Piece for solid colours or where the design is made

from yarns of different fibres sources.


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DYEING PROCESSES

Different fibres require different dyeing conditions.Wool and nylon are normally dyed at 98 - 100C

Acrylic fibres are also dyed at 98 - 100C

Polyester on the other hand is dyed at higher

temperatures 125

130C.

Polyester wool blends are dyed at lower temperatures107C 120C special chemicals being added to protectthe wool fibre from damage.

Cotton can be dyed at temperatures from 60C to 98Cdepending on the dye class chosen.

Special chemicals are included to promote evenness of

colour.


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DYEING MACHINERY Loose fibre, sliver and yarn dyeing machines are all of

the liquor circulation type. The dye liquor is pumpedthrough the material.


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PIECE OR FABRIC DYEING

Several methods are available.

Today the most common method used is the jet dyeing

machine. This machine uses less water, energy, dyes and

chemicals.

The machines are fully automated so labour content is

lower. Continuous dyeing is usually restricted to solid

colours.


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H.T. JET DYEING MACHINE


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TEXTILE PRINTING

A number of printing techniques are available,

Hand table

Flat screen

Engraved copper roller. Rotary screen

Heat transfer, sublimation printing

Digital ink-jet


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PRINTING (contd)

Rotary Screen printing is probably the most popular.

The system can give good definition

Suited to long runs. More economical than flat screen machines because of

higher production speeds.

Screen costs tend to be higher

Suitable for both pigment prints and dye prints.


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PIGMENT vs DYE PRINTS

Basic pigment process consists of printing and curingto cross link the binder to maximum fastnessproperties, no wet processing is required.

Dye printing is a multi stage process.

Printing

Fixation usually steaming

Washing

off to remove unfixed dyes and auxiliaries Drying and finishing


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ROTARY SCREEN PRINTING

video courtesy of cotton council of America


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DIGITAL INK JET PRINTING


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Digital vs ROTARY

DIGITAL ROTARY

Very high definition, photographicquality.

No screen costs, no limits onrepeat size

Instant colourway changes

Printing is slow approx. 200 m2per hour.

Restriction on fabric width

Printing of blends can be aproblem.

Printing with pigments has been a

problem in the past.

High rates of production,depending on the design.

Design limitations, repeat sizedepends on screen diameter.

Depending on the machinefabric width up to

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