latest development in wetprocessing

LATEST DEVELOPMENTs IN WETPROCESSING

LATEST DEVELOPMENTS

APPLICATION OF PLASMA TECHNOLOGY

APPLICATION OF ULTRA SONIC WAVES

APPLICATION OF CRITICAL FLUID CO2

APPLICATION OF MICROENCAPSULATION

FOAM DYEING BIOTECHNOLOGY IN WETPROCESSING

PLASMA TECHNOLOGY

Plasma is called fourth state of matter other than solid,liquid,gas.

The gas become plasma when the heat is added.When the heat is added the atoms in the gas

release some of electrons.Reamaining part of atoms left the positive

charge .So the the gas is electrically charged called

ionized When enough atoms are ionized significantly

affect the electrical charecteristics of gas it is a plasma.

Contd..

When a textile to be placed in a reaction chamber with any gas then plasma is ignited.

The generated particles interact with the surface of the textile.

In this way the surface of textile to be strctured or chemically functionalised or even coated with nm-thin film depending on the type of gas used and control of the process.

Reaction of plasma on cotton fabricsReaction of plasma on cotton fabricsReaction of plasma on cotton fabrics

The siloxan plasma treatment can lower the moisture content and decreases surface resistivity.

Then the surface of the fabric become smooth and the contact angle of water with the fabric increased to 130*.

So the fabric become hydrophobic.

Reaction of plasma on polyester fabric

The oxygen plasma used for removing the contaminates,finishing, from the fabric.

Desizing of the polyester fabric that used polyvinyl alcohol as the sizing agents can be removed by plasma treatment.

The wetability of the polyester fabric to be increased by introduction of polar groups.

Plasma induced surface modification of micro denier polyester produces cationic dyeable polyester fibre.

PRINCIPLE OF PLASMA

ADVANTAGES OF PLASMA DYEINGPLASMA dyeing technology reduces

detrimental impacts on the environment.substantially less water and chemicals discharged.

maximum color durability Soil-resistant, flame-retardant, Plasma treatment modifies the fibre surface rather than its interior

ULTRA SONIC WAVES

Ultra sound energy is sound waves with frequencies above 20000oscillations per second,which is above the upper limit of human hearing.

Use of ultra sonic waves in dyeing

Ultrasound energy of 20KHz frequencies is suitable for inducing cavitation.

It is used for collapse the microbubble is most effective for better dye uptake.

It will increase the swelling of fibre in water.

Reducing the glass transition (Tg)temperature of the fibre.

Reduce the size of the dye particles so the transport of the dye to fibre is easy.

WHAT IS CRITICAL FLUID

Any gas that is above its critical

temperature is able to retain the free

mobility of gaseous state but if pressure

is increased its density will tend to

increase towards liquid. Such highly

compressed gases are supercritical fluids

and that is the reason they are able to

combine properties of both liquid and

gas.

CO2 QUALIFICATIONS Carbon dioxide is also considered the best supercritical fluid

for the dyeing process. It is naturally occurring, chemically inert, physiologically compatible, relatively inexpensive and readily available. Other attributes of carbon dioxide are:

It is an inexhaustible resource. Its use does not release volatile organic compounds

(VOCs). It is biodegradable as a nutrient for plants. There are no disposal issues. It can be recovered and

reused from the dyeing process. It is non-flammable and non-corrosive. It is non-toxic and low cost. The critical point of the carbon dioxide is well within the

manageable range (31C and 73 bar).

DYING PROCESS

Roll of fabric is inserted into the cylindrical dyeing chamber on a retractable carriage. In dyeing, CO2 is heated to 120°C and pressurized to 250 bar.

CO2 penetrates synthetic fibres, thereby acting as swelling agent and enhances diffusion of dye into the fibres. In other words, glass transition temperature of fibre is lowered by the penetration of CO2 molecules into polymer. This accelerates the process for polyester by a factor of two. Finally, the CO2 is able to transport the necessary heat from a heat exchanger to the fibre.

CONTD…

CO2 loaded with dyestuff penetrates deep into the pore and capillary structure of fibres. This deep penetration provides effective coloration of these materials which are intrinsically hydrophobic. The process of dyeing and the act of removing excess dye can be carried out in the same plant.

During the dyeing, the CO2 is circulated through a heat exchanger, through a vessel where the dye is delivered to the textile. After the dyeing cycle the CO2 is gasified, so that the dye precipitates and the clean CO2 can be recycled by pumping it back to the dyeing vessel.

AUXILARIES FREE DYEING

Current disperse dyes contains 40% detergents and salts to enable the solubilisation of hydrophobic dyes in the water. When applying carbon dioxide, none of these additives are required and pure dyestuff can be used.

advantage, specifically for polyester, is that undeAnother r supercritical conditions the CO2 molecules penetrate and swell the polymer. This plasticises the fibres and increases diffusion coefficient of dyes inside the polyester by one order of magnitude, relative to aqueous dyeing.

OTHER APPLICATION OF CO2 In the case of cotton dyeing, fixation of

99-100% is achieved by CO2.Developed reactive dyes can also be

used on synthetic polymers by CO2 dyeing process, enabling dye houses to dye bends such as cotton-polyester with a single dyestuff in a single run- reducing process time by factor five and achieving tremendous savings on energy and water

Key Advantages of Supercritical Dyeing

I. Elimination of water consumption II. Elimination of wastewater discharges III. Wastewater treatment process

eliminated IV. Elimination of drying and dryer

effluent V. Reduction in energy consumption VI. Approximately 95% of CO2 can be

recycled VII.Dyeing time significantly reduced

MICROENCAPSULATIONIt is the process by which individual particles or droplets of solid or liquid or gas material (the core) are surrounded or coated with a continuous film of polymeric material (the shell) to produce capsules in the micrometre to millimetre range, known as microcapsules.

The wall material may be an organic polymer, hydrocolloid, sugar, wax, fat, metal or inorganic oxide

The objectives of microencapsulation is to Protect the active core material from

external environment till required To affect the controlled release of the

active core material till the right stimulus is encountered.

To increase the durability of the finish

OBJECTIVES:

Preparation of microcapsulesPMs contained Diphenylmethane-

4,4′diisocyanate(MDI)(wall material) and disperse dye (core material) and were prepared at an adequate ratio with GPE2040 (2% w/w) as the emulsifier and PVA (1% w/w) as the stabiliser.

The reaction being carried out at 50°C for 180 min.

After reaching room temperature microcapsules were seperated by decantation.

After washing with 10% w/w ethanol to remove unreacted isocyanate, the microencapsulated material was dried in a vacuum oven at 25 °C for 24 h.

Dyeing of polyester using microencapsulated disperse dyes in the absence of auxiliaries Dyeing of polyester requires water and certain chemical

auxiliaries such as dispersing agents, penetrating agents and levelling agents, in the dyebath. Unfortunately, residual auxiliaries and dyestuff may be present in the effluent and may cause pollution.

Polyester fabric was dyed with microencapsulated CI Disperse Blue 56 using a high temperature dyeing process without dispersing agents, penetrating agents, levelling agents or other auxiliaries. The quality of the polyester fabric dyed in this manner without reduction clearing was at least as good as that dyed traditionally after washing and reduction clearing. After separating off the polyurea microcapsules, the dyebath was virtually colourless and was shown to be suitable for reuse.

DYEING BEHAVIOUR

The dyeing behavior of the dyes in PM form was compared with fabric dyed traditionally.

The results show that the levelness and fastness to soaping and rubbing of PET samples dyed with 1 in PM form, without auxiliaries or reduction clearing, were at least as good as those obtained by traditional disperse dyeing after washing and reduction clearing.

The excellent wash-off properties of the PET fabric dyed with the PM disperse dyes may be attributed to reduced staining of the surface of the fibre, making the need for washing much less important.

FOAM DYEINGI. A fIn case of foam dyeing, the main

dyeing element is foam. For that’s this dyeing is called foam dyeing.

II. fabric is padded with a foam formed from an aqueous solution of a dyestuff, a foaming agent and a carrier for the dyestuff and the padded fabric is maintained at elevated temperatures to fix the dye

ADVANTAGES OF FOAM DYEING

Reduction of amount of water required to 30%-95%.

Dryieng can be carried out in in low temperature.

Lower consumption of dye and chemicals.

High fixation of dyes.Energy cost is less.

ENZYME IN PROCESSING

Enzymes come from a Greek word “Enzymos” which means „in the cell‟ or „from the cell‟.

Enzymes are proteins, composed of amino acids, which are produced by all living organisms. These are responsible for number of reactions and biological activities.

Enzymes not only work efficiently and rapidly also biodegradable.

USES OF ENZYME

IN DESIZING The amylase enzyme is used for convert

the starch into soluble substances.

In SCOURINGThe pectinase,lippase,protease are used

to convert the insoluble oil,wax, protein,pectin into soluble substances.

Contd..

IN BLEACHINGAfter bleaching with hydrogen peroxide

catalase enzyme is used in decompsing the hydrogen peroxide into water and oxygen.

IN BIOPOLISHINGCellulase enzyme is used in the

biopolishing of cotton.it removes loose fibre protrouding from the fabric surfaces.

ADVANTAGES OF ENZYME

It is easily biodegradable.It is ecofriendly in nature.it is ecofriendly in nature.The water consumption is less.The time consumption is less.The energy consumption is less.

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