GARMENTS DYEING

The process of dying garments after manufacturing from grey fabric is called garments dyeing. Colored garments are not used for garments dyeing but the garments which are manufactured from grey fabric are used to dye only in solid color form.Checks, stripes or multi- colored fabrics are not used for garments dyeing.In Bangladesh cotton garments manufactured from grey fabric is used to dye in solid color form.

Garments dyed polo shirt

Advantages of Garments Dyeing

1. Comparatively lower cost of production for any solid color dyed garments.
2. Comparatively less time is required to produce and supply solid color garments.
3. No possibility of shade variation within the garments.
4. Different color
5. could be carried out at low liquor ratios, hence consumption of steam, garments of lower quality could be produced and comparatively lower cost.
6. Old garments could be re-dyed.
7. All the pretreatment, dyeing and finishing could be done in the same machine.
8. Comparatively lower capital investment cost to setup garments dyeing project.
9. In some cases garments dying chemicals, dyes etc are required less. So reduce dyeing cost.

Disadvantage of Garments Dyeing:

No possibility of multi color dyeing. The garments made from grey fabric used to dye only in solid color form.

Precaution to Be Taken Before Garments Dyeing:

Garments made from grey fabric need some precaution before dyeing are describing as follows:

-        Garments design should be made from the engineering point of view.

-        If garment is made after desizing, scouring and bleaching, after garments dyeing problem may be reduced.

-        If possible grey fabric should be collected from single batch and single source.

-        If elastic is used in garments (in cuff, waist band etc.), the seam in those part should not be too loose or too tight, which may cause irregular dyeing in those part.

-        If knitted and woven types of fabrics are used in same garments then the fabric should be preshrunk otherwise seam pucker may develop after garments dyeing.

-        If garment is made from mixed fibers (cotton and viscose), dye should be selected carefully otherwise after dyeing shade variation may occur.

-        If any metal component used in the garments as an accessories, may be damage by the action of alkali, dyes and other chemicals. So in that case metal component should be made from Nickel or its alloy.

-        Sewing thread used for making the garments should be made from same fiber as the garment fabric otherwise after dyeing shade variation may occur in thread and garments fabric.

-        Button used in the garments should be selected carefully.

-        Button makes on cellulose and nylon may be damaged during garments dyeing.

-        If elastic is used in the garments and elastic contain natural rubber or polyurethane fiber (Lycra) there may be a problem after garments dyeing.

-        Interlining used in the garments which is to be dyed, should be selected very carefully.

-        The garments made from compactly woven fabric should be dyed with hot brand reactive dyes.

-        Crease may develop in the cotton garments dyeing. To avoid such problem special chemical may be used to remove those creases.

Name of Garments Dyed Items:

-          Active Wear -          Dresses -          Leisure Wear -          Pullover -          Pantyhose -          Terry Items -          T-shirts -          Skirts

-          Shirts -          Socks -          Slacks -          Jeans -          Denim -          Tie -          Tight -          Roves

Features of Garments Dyeing Machine:

a.    A large- size central door, which enables us to offer both atmospheric and pressurized versions of the machine.

b.      Lighter construction, with no problems of balancing at high pressure.

c.       Simple single A.C drive with an A.C converter to give variable speed between 5 and 35 r/min.

d.      Two dye- additional tanks with the basic machine.

e.       Possibility to have extra tanks for shrinkage- resist treatments, salt additions etc.

f.       If indirect heating and additional circulation is required than separate circulating- pump heater and filter is used.

g.      Fully piped, wired and tested on one frame, ready for connection to customer’s service.

Self Cleaning Fabric: Now a reality

Self-Cleaning Clothes

These self-cleaning fabrics have a nanofilm coating of titanium dioxide nanoparticles, which can break down dirt molecules, pollutants, and microorganisms when exposed to visible and UV light. Clothes made this way could be cleaned by simply exposing them to sunlight. Daoud and Xin have developed a method for applying the thin film of titanium dioxide to cotton easily and inexpensively. With their method, self-cleaning fabrics could be produced commercially and for public use. The scientists note that self-cleaning fabrics could be especially useful for people who don't have the time or means for washing their clothes, such as military personnel or hikers.

Scope of use of self cleaning fabrics:

In addition to suits, the self cleaning fabric could be applied to hospital garments, sportswear, military uniforms and rain coats. Other possible applications include awning material for outdoor campers, fabrics for lawn furniture and convertible tops for cars.

How Self-Cleaning Fabric Works

The self-cleaning fabrics works using the photocatalytic properties of titanium dioxide, a compound used in many new nanotechnologies solar cell applications. The fabric is coated with a thin layer of titanium dioxide particles that measures only 20 nanometers in diameter. When this semi-conductive layer is exposed to light, photons with energy equal to or greater than the band gap of the titanium dioxide excite electrons up to the conduction band. The excited electrons within the crystal structure react with oxygen atoms in the air, creating free-radical oxygen. These oxygen atoms are powerful oxidizing agents, which can break down most carbon-based compounds through oxidation-reduction reactions. In these reactions, the organic compounds (i.e. dirt, pollutants, and micro organisms) are broken down into substances such as carbon dioxide and water. Since the titanium dioxide only acts as a catalyst to the reactions, it is never used up. This allows the coating to continue breaking down stains over and over. Titanium dioxide can also destroy pathogens such as bacteria in the presence of sunlight by breaking down the cell walls of the microorganisms making self-cleaning fabrics especially useful in hospitals and other medical settings.

Figure. Above is an illustration of how self-cleaning fabric cleans itself. When photons of light hit the layer of titanium dioxide, electrons excited up to the conduction band react with oxygen molecules in the air. The double bond of the oxygen molecule is broken

No More Washing Machines?

Breakthroughs in nanotechnology have made self-cleaning fabrics both practical and economical. With commercial production making the technology readily available to the masses, will washing machines and laundry detergent become obsolete?

There are several factors limiting how quickly current self-cleaning fabrics would be able to break down organic compounds. Sunlight is the best source of light for activating the self-cleaning process. A ketchup-stained shirt would have to be left outside in the sun for at least a day in order to remove the stain. However, for military persons or hikers, who are outside in the sun for long periods of time without the time or means to clean their clothes, self-cleaning fabric would be ideal. It's also important to note that the newly developed method for producing self-cleaning fabric has only been developed for cotton. Further research would be required to test ways of applying titanium dioxide nanofilms to other textiles.

Self-Cleaning Fabric Problems

The main reasons that self-cleaning fabrics require a lot of time to break down stains is because titanium dioxide is very inefficient at using energy from sunlight. The titanium dioxide serves as a catalyst for the break down of dirt molecules by providing electrons that oxidize oxygen molecules in the surrounding air. The electrons are freed from the titanium dioxide via the photoelectric effect. But because of titanium dioxide's high band gap energy, only high energy blue and UV light photons have enough energy to excite electrons to the conduction band. High energy blue and UV light only make up 3% of the solar spectrum, so titanium dioxide can only use a very small portion of the sun's energy to break down stains.

Excitation of electrons to the conduction band is only the beginning of the cleaning process. These electrons must then react with oxygen atoms, which then react with the dirt particles. All of these reactions are limited by access to and the amount of freed electrons in the titanium dioxide. So for a large stain, a lot of light energy is needed before the fabric can fully break it down.

Figure. Above is an illustration of the inefficiency of self-cleaning fabric. The titanium dioxide's catalytic powers can only be activated by a small portion of blue light and UV light, which is only 3% of the solar spectrum. All the rest of the light energy is wasted

Conclusion:

Self-cleaning property will become a standard feature of future textile and other commonly used materials to maintain hygiene and prevent the spreading of pathogenic infection. It can also help in reducing the consumption of chemicals, such as detergents and dry-cleaning solvents, water, and energy. But more extensive research is required to make it economically feasible to consumers.