New trends in garment dyeing

Abstract

The garment industry today plays a vital role in meeting the quick challenging demands on the fashion market. The production of short run repeat orders relatively low skill input , low reject rates ,Many complex design, unique wash, value addition etc.,The most garment dyeing enable to be carried out using simple relatively inexpensive equipment with modest space requirement with out effluent production.

However, we are exploring new garment finishing system that can be used in conjunction with garment dyeing. A wide variety of dyes may be used to create unique look on garment. Garments are dyed with direct, reactive, sulphur, pigments.Sulphur and pigments are mainly used for getting ‘worn out looks’. Smart colorants are those which respond to different in environmental condition. This paper focuses on garment dyeing ,washing produces special effects like flat look denim, quick wash denim, tinted denim, grainy look denim, sand blasting. New development like laser technology, toneless stone wash effect, ion wash, mud wash, ozone fading, water jet fading etc., which are all the topics discussed in this paper

Introduction

As the fashion trends keep on changing, no one can predict quite in advance what sort of colors will run as far as garment sale is concerned. In order to be able to sense the market trend and to cut down the delivery time, the general trend is to defer the finishing after the garment is made. In such a situation, it is possible that the color in demand can be used for garment dyeing and subsequently the garments could be finished to have required resistance to wrinkles and dimensional stability. The dyeing of cotton in garment form is increasing in importance.

Smart colorants for garments:

Smart colorants are those, which respond to differences temperature or light and environmental conditions. They are called smart because they sense conditions in their environment and respond to those conditions. Initially, smart colorants were developed for specialized applications but now have become available for application on textiles / Garments. Smart colorants can be classified into three categories.

Photo chromic color:

Fabric color changes when exposed to sunlight or other source of UV radiation.

Thermo chromic color:

Fabric color changes with temperature

Glow – in – the dark color:

Fabric color glows in dark.

Uses

• On garment to create novel products and promotional items like T-Shirts
• On fabric/garment to print company logo/brand name to prevent duplication
• On garment for party wear, night clubs etc.
• Thermometers and temperature indicators.
• Security printing. • Food industry to indicate temperature of packaged food.

Photo chromic color:

Photo chromic color changes from clear when indoors to color when taken out-doors. The phenomenon produced in Photo chromic materials is called photochromism, where the change in color is due to incident light. Specifically, they exhibit color in response to exposure to sunlight or other source of UV radiation. UV light changes the chemical structure of the photo chromic material and makes it absorb color like a dye. It then reverts to a clear state when the UV source is removed.
However, to date, photochromism is most important for optical switching data and imaging systems, rather than in textile applications.

Application of photo chromic colors on garment:

Americos photo chromic colors are plastisol based ready to use off-white liquid. When exposed to UV radiation, color appears. These colors are available various hues. Photo chromic colors can be applied on garment by three methods:

• Spray
• Brush
• Screen Print

In all the above methods, photo chromic colors are directly applied on garment and cured at 1500C for 30-90 seconds.

Thermochromic colors:

Color changing inks were introduced during the 1970s with novelty items such as cups that change color when not liquids such as coffee or tea are poured in to them. Color changes of thermo chromic pigments are induced by a temperature change. When temperature rises to a specific temperature, the color changes. The color starts fading back to the original color as the pigment is cooled down.

Application of thermo chromic color on garment:

There are fifteen thermo chromic colors like Americos Red, Magenta, Vermilion, Orange, Yellow, Yellow Green, Charm Green, Sky Blue, Turq Blue, Dark Blue, Violet, and Black.

The temperature interval available from 0OC to 70OC. Specific demand can be set up for different temperature intervals from 2OC to 10OC. By using the above colors another color can be obtained but use different colors of thermo chromic pigments with the same temperature range to create more colors. Regular pigments can also be mixed with thermo chromic pigment so that the color can be changed from one to another. At lower temperature, the color reveals matched shade. When the temperature is increased, the thermo chromic pigments start fading to colorless. It only shows color of the regular pigments. By mixing the thermo chromic pigments with different temperature ranges, the color can be varied for more than two colors like temperature ranges for 3 – color variation.

Thermo chromic colors can be applied on garment by three methods.

• Spray
• Brush
• Screen Printing.

In all the above methods, thermo chromic color are mixed with suitable binder As desired viscosity needed for application. After application, garment is dried and cured at 1500C for 5 minutes.

Glow –in – the dark color:

Glow in dark is basically phosphorescence, which can be defined as the emission of light by a luminescent pigment after excitation has ceased. Americos glow in dark colors hold it’s after – glow for up to two hours. The after glow effect is dependent on pigment concentration, surface area and the amount of radiant energy absorbed

Application of glow – in – the dark color on garment:

Americos Glow – in – the dark color can be applied on garment by three methods

• Spray
• Brush
• Screen Printing.

In all the above methods, Glow-in-the dark color is directly applied on garment And cured at 1500C for 5 minutes.
Dyeing with Different Dyes:

The growth of garment – dyeing has given rise to demands for increased productivity and efficiency. The machinery manufacturers have responded by developing new machines based on the rotary-drum principle

Exclusive Features:

High temp. Up to 140° C. Working pressure - 4 Kg./cm² Capacity - 200 kg. / 400 kg. Main Vessel & Basket - SS 316 L Motor - 10 HP., With A.C. Drive Planetary Gear Box Also can druming without bags / with bags.


Following are there dyes used for cotton garment dyeing:

a) Direct dyes.

(for low colour fastness) –for ‘fashion’ merchandise for boutique outlets. Which carries a ‘hand wash separately’ care label.

b) Reactive dyes-

(for low colour fastness) – best suitable for cotton garment dyeing. Due to good level dyeing properties and high migration, diffusion properties, both cold brand and hot brand HE and HEXL dyes can be used.

c) Vat dyes –

limited use in garment dyeing. Economical for jade green shades.

d) Sulphur dyes –

used for navies and blacks.

e) Pigment dyeing –

In conventional exhaust pigment dyeing mainly there are three steps i.e., cationisation of the garment, pigmentation and treatment with binder. The above conventional process requires plenty of water and it is also time consuming which indirectly affects production. To counter this, Zytex India Ltd, Mumbai has developed a new system in pigment dyeing called OBOS one bath one step). Following are the advantages of this system.

1) Complete dyeing is carried out in single bath.

2) Intervals between addition of chemicals is only 5 minutes.

3) Water saving, equivalent to 3 drains.

4) Dyeing time is only 80 minutes.

5) 40% time is saved.

Excellent fastness and good reproductively. The process is as follows.

a) Desizing, / Scouring

b) Hot wash

c) Cationic pre-processing.

d) Garment pH should be neutral and good absorbency.

e) Then add the following chemicals: anticreasing agent, dispersing cum leveling agent, polymeric cationising agent for cotton (Zycat PD) – runfor 20-30 mins. At 60-70 deg c.

f) Then add a range of pigment colors specially developed for exhaust pigment dyeing.(ZYpigment). Run for 30 mins. At 70 deg c to 100 deg c.

g) Add polymer based binding cum fixing agent for pigments. (Zyfix PF) then run for 30-40 mins at 30 deg c to 60 deg c.

h) Rinse, unload

i) Drying / curing for binder fixation at 90 deg c to 130 deg c for 10 mins. One advantage of garment dyeing cotton is that there will be no problem with shrinkage for the customer.

Al the above process is conveniently carried out in the new generation of rotary – dyeing machines. They are of two types.

a) Divided b) Open-drum

Accordingly the type of mechanical agitation can be selected, and fitted with a microprocessor controller and a dosing pump; they can be programmed to run through the full dyeing procedure automatically.
Among the most important chemicals for the garment dyeing sector are lubricants for preventing marking by creases formed during running or lying, bleaching and scouring streaks and chafe marks, which are some of the most common quality impairing problems of garment dyers and jean washers.

Different Color Depth Fabric:

To cut processing time, effluent load, and minimum damage to fabric and; minimum use of chemical, there are different depth of indigo in denim. For example, in case of ice wash where we remove more than half the dye during washing. One can use lighter shade fabric which will help to cut the process time, chemical consumption, effluent load, it will help garment processor to process garment processor to process garment more economically and with minimum faults

Flat look denim:

Different chemicals and processes are used to get flatter look on the denim garments. To meet this requirement special denim fabric has been developed which offers flat look after washing.

Quick wash denim:

Quick wash denim fabric is dyed with modified technique of dyeing. So that during wash cycle, indigo dye can be removed quickly. Giving washed look at shorter washing cycle. This results in more economical washes i.e. low water consumption, less usage of chemicals, less time and retaining fabric strength.

Tinted denim:

With increase in demand of tinted/ over dyed look on garment, garment processor is using an additional process of tinting/over dyeing, which is time consuming. It consumes large quantity of water and chemicals. It is also associated with the risk of patches and unevenness on garments. Now the denim fabric is also available in tinted form which saves processors time and risk.

Grainy look denim:

Different chemicals and processes are used to get grain look on the denim garments. To meet this requirement special denim fabric has been developed which gives grainy look after processing of denim garment Soft feel denim: To meet such requirement, different varieties of denim fabric are available, which are having inherent softness. These fabrics require minimum application of softener at the garment stage.

Recent Developments in Garment Processing:

It was considered impossible to obtain wrinkle free finish on white garments in wet processing. It was rather difficult to achieve wrinkle free performance with minimal yellowing and strength loss, and good handle. Achieving any of these attributes implied compromising on the other two. Now, thanks to recent product developments, it is possible to strike a good balance between these features, with the help of a wrinkle-free system containing an inbuilt catalyst and softener.

Also, microencapsulated fragrance finishes are becoming important value-adds in garment processing. When these finishes are applied on to the garments, in the same way as perfumes, the active ingredients get gradually released on to the skin.

Laser-based processing is another emerging versatile technology in denim finishing, which permits application of laser-based photographic effects, abrasion effects and new laser-based stone washes.
Recent developments have also made it possible to use antimicrobial finishes, water and oil-repellent finishes, flame-retardant finishes, antiozonate finishes, UV absorber finishes and coatings individually, and in combinations of two or three.

Avoiding the Environmental Hazards of Garment Processing:

Textile processing uses vast amounts of water, chemicals and energy, and therefore, has considerable effects on the environment in the textile manufacturing regions. The effluents from wet processing of garments cause similar environmental hazards as fabric processing. Moreover, the garment processing sector is highly unorganized; effluents are released in to municipal drains causing environmental problems.

Apart from investing heavily in effluent treatment, pollution loads can also be reduced by 30-50%, by using pollution prevention techniques. Here’s list of wheat can be done.

1) Reduce wastewater volume by:

• Good housekeeping

• Counter flow processing

• Re-using process water,

• Automating machinery,

• Processing alternatives

i.e., green cleaning over conventional dry cleaning where perchloroethylene is replaced by CO2 in liquid state, or by organic hydrocarbons, ozonated water and ultrasonic cleaning.

2) Reduce the amount of dyes and chemicals used by:

• Good housekeeping

• Process optimization,

• Recovery and re-use of process chemicals,

• Automation of machinery,

• Replacement of conventional chemicals with eco-friendly chemicals.

The dyestuffs, pigments and chemical products ‘saved’ by these methods mean less effluent in the system. Textile processors have begun focusing on pollution reduction, on a process-by-process basis. But we need to think about his holistically, so that, at each step of the processing cycle, we make decisions that impact down stream process, beginning with product design and ultimately involving the consumer.

Global needs cannot be met by concentrating only on the product design and products effects on downstream processing. We should also examine the manufacturing process, in terms of containers, machine parts, drums, mix tanks, etc, to reduce solvent loss and quality. Such thinking should extend even to the consumer’s use of products, in terms of after-market treatments, cleaning solvents, use conditions, installation and maintenance and so on.

onclusion

Garment dyeing brings with it a plethora of possibilities, which can help the textile industry earn immense benefits. However, lack of vision and a few temporary hurdles are preventing it from playing its rightful role in textile processing. We need to take proactive measures and adopt a holistic approach to tackle the shortcomings, after which garment-dyeing will be all set to contribute a lion’s share to the success of the Pakistan textile Industry.