ENERGY CONSERVATION IN WET PROCESSING

(a)    ENERGY CONSERVATION IN SIZING

Foam sizing : in this method foam is used for sizing. Hence considerably less water is required as compared to the conventional sizing. This results is saving in energy and time for evaporation of size.

High pressure squeezing during sizing : this saves the energy as well as the water. after sizing material is squeezed at high pressure to remove maximum water from it. Because of this energy required for drying the material is saved.

Simultaneous dyeing and sizing: for denim warp yarns by using rapiodogen dyes and stabilizer with sizing formulation sizing and dyeing can be carried out simultaneously. This saves energy and water.

B) ENERGY CONSERVATION IN BLEACHING

Fast bleaching with VAPORLOC machine

Mather and platt developed this machine. In this machine, bleaching can be carried out in 90 to 120 seconds at a temperature of 135 degree C. and pressure 30-psi. for this process hydrogen peroxide, stabilizers and suitable alkali is used. 50% energy can be saved with this process.

Novel method : this is a combined desizing scouring and bleaching of polyster/cotton blend. This is carried out is which using material to liquors ratio1:25. the liquor consists of hydrogen peroxide(35%w/v) magnesium sulphate heptahydrate (1.6gpl) sodium hydroxide(4gpl) wetting agent (0.5gpl) EDTA(2gpl) and gluconic acide (2gpl) at 95 degree C for one hour. The washing is giving at 95 degree C.

Potassium permanganate method : cotton goods can be bleached with potassium permanganate. This saves energy and water. It also gives eco-friendly effluent.

Cold pad-batch method : in this method peroxide bisulfate used as a bleaching agent. The bath also contains some compounds which accelerate the bleaching reaction like urea glucose sodium citrate methyl carbonate tetra acetyl ethylene diamine etc.

DSB process: in this process desizing scouring and bleaching takes place in a single stage. The bath contains hydrogen peroxide peroxygen booster sodium silicate peroxide sulphates etc. to this some compounds like urea glucose which accelerate the peroxide reaction are added. This process saves energy water and labor.

C) ENERGY CONSERVATION IN MERCERISATION

It is the process in which the material is treated with concentrated sodium hydroxide solution indeally at at 15 to 20 degree C. this gives luster to the material and the absorptivity of the material is increased considerably.

In mercerization process saving in energy can be done if the process is carried out on wet-on-wet basis I e the in between drying process is eliminated which saves the energy.

Hot mercerization can be done so that scouring is eliminated at 70*c so without doing separate scouring process yarn or fabric is directly subjected to hot mercerization.

Caustic recovery : for the caustic recovery maximum washing is given to the fabric. Temperature of the washing water is maintained at 90*c and suction is provided. All this results in 80 to 85%  of the caustic recovery.

D) ENERGY CONSERVATION IN DYEING

Cost savings and quality improvement in dye house can be dine by some process modifications and suitable replacement of processing machines.

Some of these processes are given bellow.

Energy saving by padding mangle

Cost savings and quality improvement in dye house can be done by some process modifications and suitable replacement of processing machines.

Some of these processes are given bellow.

Energy saving by padding mangle

Padding mangle mainly used for two purposes 1) to impregnate any processing solution in fabric 2) to remove excess amount of processing liquor from the fabric by squeezing. Kusters mangle is a modified from which has uniform expression percentage with low wet pick-up. Expression percentage can be changed by changing speed and pressure. On this machine uniform and accurate results are obtained with the saving in energy.

Pad-jig method

This method can be used for dyeing with vat reactive azoic dyes with this method. Dyeing quality is improved with respect to levelness and solidity of shades. Dye penetration is also good. In this power & steam required is less.

Colour

Colour attributes

Each colour has its own distinct appearance, based on three elements: hue, chroma and value (lightness). By describing a colour using these three attributes, you can accurately identify a particular colour and distinguish it from any other.

Hue : Hue indicates a particular colour sensation which is dependent simply on the relevant wavelength; the inherent colour of a thing; the purest or brightest form of a colour having no white or black mixed with it. Quite simply, hue is how we perceive an object’s colour — red, orange, green, blue, etc. Each hue has an intrinsic tonal value on the chromatic scale.

Chroma: Chroma is the extent of a colour’s brightness or saturation; the purity of a colour, in other words, how close the colour is to either gray or the pure hue. For example, think of the appearance of a tomato and a radish. The red of the tomato is vivid, while the radish appears duller.

Lightness: Lightness is the luminous intensity of a colour. It is that attribute of a colour which indicates the extent of the light which it reflects. Colours can be classified as light or dark when comparing their value.

Spandex

Spandex, Lycra or elastane is a synthetic fibre known for its exceptional elasticity. It is made up of a long chain polymer called polyurethane, which is produced by reacting a polyester with a diisocyanate. Spandex gained interest quickly due to it’s superiority to the strength in durability of rubber. Spandex also has a better resistance to dry heat & oil, in comparison to rubber. The level of comfort and wicking ability found in Spandex are unparalleled, and do not exist in such high amount with any other fabric. Spandex is being used in a continually widening array of clothing articles, including woven and knits, and synthetics and natural fibers.

PHYSICAL PROPERTIES:-

1. Cross section- spandex filaments are extruded usually from circular orifices, but the evaporation of solvent or the effects of drying may produce non-circular cross-sectional shapes. This may take various forms. In the multi-filament yarns, individual filaments are often fused together in places. The number of filaments in a yarn may be as few as 12 or as many as 50;the linear density of filaments ranges from 0.1 to 3 tex (g/km).

2. Density: The density of spandex filaments ranges from 1.15 to 1.32 g/cc, the fibres lower density being based on polyesters.

3. Moisture regain: The moisture of fibres from which the surface finish has been removed lies between 0.8 & 1.2%

4.Length:It can be of any length. May be used as filament or staple fibre

5.Colour: It has white or nearly white colour.

6. Luster :-It has usually dull luster.

7.Strength: Low strength compared to most other synthetic fiber.

8.Elasticity: Elastic properties are excellent. This is the outstanding characteristic of the fibre.

9.Heat: The heat resistance varies considerably amongst the different degrades over 300 F.

10:Flammability:It Burn slowly.

11:Electrical conductivity: It has Low electrical conductivity.

12. Breaking tenacity: 0.6 to 0.9grams/denier.

CHEMICAL PROPERTIES.

1. Acid: Good resistance to most of acids unless exposure is over 24 hours.

2.Alkalies: Good resistance to most of the alkalies, but some types of alkalies may damage the fibre.

3.Organic solvents: offer resistance to dry cleaning solvents.

4.Bleaches: can be degreaded by sodium hypochloride. chlorine bleach should not be used.

5.Dyeing: A full range of coloures is available. Some types are more difficult to dye than others.