Shanto-Mariam University of Creative Technology                                       ASSIGNMENT ON

Topic: Prerequisite process of dyeing

Module Title: Dyeing, Washing, Finishing-Knit-Woven

MODULE CODE: TEX-303/353

Submitted to:

Nasrin Ferdous

Lecturer, SMUCT

                                                                               Submitted By:

Asraful islam 142051001

                                     Group: B

                                        Batch: 23

                                          Semester: 5

Date of Submission:

Introduction of Dyeing

Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. Dyeing is normally done in a special solution containing dyes and particular chemical material. After dyeing, dye molecules have uncut Chemical bond with fiber molecules. The temperature and time controlling are two key factors in dyeing. There are mainly two classes of dye, natural and man-made.For most of the thousands of years in which dyeing has been used by humans to decorate clothing, or fabrics for other uses, the primary source of dye has been nature, with the dyes being extracted from animals or plants. In the last 150 years, humans have produced artificial dyes to achieve a broader range of colors, and to render the dyes more stable to resist washing and general use. Different classes of dyes are used for different types of fiber and at different stages of the textile production process, from loose fibers through yarn and cloth to completed garments.Acrylic fibers are dyed with basic dyes, Nylon and protein fibers such as wool and silk are dyed with acid dyes, polyester yarn is dyed with disperse dyes. Cotton is dyed with a range of dye types, including vat dyes, and modern synthetic reactive and direct dyes.

Garment Dyeing

Garment dyeing is the process of dyeing fully fashioned garments (such as pants, pullovers, t-shirts, jeans, sweaters, dresses, bathrobes, casual jackets, shirts, skirts, hosieries) subsequent to manufacturing, as opposed to the conventional method of manufacturing garments from pre-dyed fabrics. Most garments are made of cotton knit goods and/or cotton woven fabrics.

Although several other fabrics can be found in the whole or in part such as wool, nylon, silk, acrylic, polyester and others. Due to cost savings and fashion trends, garment dyeing has been gaining importance and popularity in the past years and will continue to do so in the future.

Why Garment Dyeing?

Traditionally, garments are constructed from fabrics that are pre-dyed (piece dyed) before the actual cutting and sewing. The advantage of this process is the cost effectiveness of mass producing identical garments of particular colors. A major drawback with this approach is the risk associated with carrying a large inventory of a particular style or color in today's dynamic market.

Feature of DyeingDyeing are cationic soluble salts of colored bases. Basic dyes are applied to substrate with anionic character where electrostatic attractions are formed. Basic dyes are not used on cotton as the structures are neither planar nor large enough for sufficient substantively or affinity. Dyeing are called cationic dyes because the chromospheres in basic dye molecules contains a positive charge. The basic dyes react on the basic side of the is electric points. Basic dyes are salts, usually chlorides, in which the dyestuff is the basic or positive radical. Basic dyes are powerful coloring agents. It’s applied to wool, silk, cotton and modified acrylic fibers. Usually acetic acid is added to the dye bath to help the take up of the dye onto the fiber. Basic dyes are also used in the coloration of paper.

Ionic nature:-The ionic nature of these dyes is cationic.

Shade range:-These dyes exhibit an unlimited shade range with high tinctorial strength, brightness and many colors are having fluorescent properties.

Solubility:-The solubility of these dyes is very good in water ,in the presence of glacial acetic acid.

Leveling properties:- These dyes have a very high strike rate , therefore leveling is poor.

Exhaustion:   cationic dyes exhaust at a variable rates, K values are used to define the exhaustion characteristics of the cationic dyes. K=1 means the fastest exhaustion , while K=5 means the slowest exhaustion. So while making the combination shades the dyes of similar K values must be used.

Affinity:- These dyes shows a very affinity towards wool , silk and cationic dye able acrylic, but have no affinity towards cellulosic’s. To dye cellulosic’s with basic dyes the material must be treated with suitable mordanting agents.

Pretreatment of Dyeing

Bleaching

Bleaching is chemical treatment employed for the removal of natural coloring matter from the substrate. The source of natural color is organic compounds with conjugated double bonds , by doing chemical bleaching the discoloration takes place by the breaking the chromophore , most likely destroying the one or more double bonds with in this conjugated system. The material appears whiter after the bleaching.

Objective:

1. It removes natural color from textile materials.2. It brings the textile materials permanent white.3. Improve the absorbency of the textile materials.4. Produce the textile materials for the next process.5. Some fabrics are sold as bleached goods.

Working Principle

NaOH                               17ml/kg

SOAP (DTC)                    2ml/kg 

STABILIZER                    5ml/kg 

 H2O2                               30ml/kg 

Reaction time                     25min. 

       speed                                50-70m/min

Singeing

The verb ‘singe’ literally means ‘to burn superficially’. Technically, singeing refers to the burning-off of. Loose fibers not firmly bound into the yarn and/or fabric structure. Singeing is an important part of pretreatment. This is the burning off of protruding fiber ends from the surface of the fabric. If not done properly, unclear print patterns, mottled fabric surfaces, and pilling results.

Loose yarns not firmly bound into the fabric structure;

Protruding fiber ends sticking out of the textile yarns and/or fabrics.

Objectives & Advantages of   Singeing

Singeing of a fabric is done in order to obtain a clean fabric surface which allows the structure of the fabric to be clearly seen.

Fabrics, which have been singed, soil less easily than un-singed fabrics. The risk of pilling, especially with synthetics and their blends, is reduced in case of

singed fabrics. Singed fabrics allow printing of fine intricate patterns with high clarity and detail. The risk of skitter dyeing with singed articles dyed in dark shades is considerably

reduced, as randomly protruding fibers are removed in singeing which could cause diffused reflection of light.

Working Principle

To produce a smooth surface finish on fabrics made from staple fibers first the fabric surfaces are brushed lightly to raise the unwanted fiber ends.

Then the fabric is singed with or passed over heated copper plates or open gas flames. The fiber ends burn off.

The fabric is moved very rapidly, and only the fiber ends are destroyed. As soon as the fabric leaves the singeing area, it enters a water bath or desiring bath. This

stops any singeing afterglow or sparks that might damage the cloth.

Desizing

Desizing is done in order to remove the size from the warp yarns of the woven fabrics. Warp yarns are coated with sizing agents prior to weaving in order to reduce their frictional properties, decrease yarn breakages on the loom and improve weaving productivity by increasing weft insertion speeds. The sizing material present on the warp yarns can act as a resist towards dyes and chemicals in textile wet processing. It must, therefore, be removed before any subsequent wet processing of the fabric.

Objects of Desizing:

1. To remove the starch material from the fabric.2. To increase the absorbency power of the fabric.3. To increase the affinity of the fabric to the dry chemicals.4. To make the fabric suitable for the next process.5. To increase the luster of the fabric increase of dyeing and printing. 

Desizing Process:

The major desizing processes are:

1. Enzymatic desizing of starches on cotton fabrics2. Oxidative desizing3. Acid desizing4. Removal of water soluble sizes

Scouring

The term ‘scouring’ applies to the removal of impurities such as oils, was, gums, soluble impurities and sold dirt commonly found in textile material and produce a hydrophilic and clean cloth. 

Objectives of Scouring:

1. To remove natural as well as added impurities of essentially hydrophobic character as completely as possible

2. To increase absorbency of textile material3. To leave the fabric in a highly hydrophilic condition without undergoing chemical or

physical damage significantly.

Working Principle

Kier boiling (discontinuous) scouring. Scouring in J or L box (continuous). Exhaust method

2. Special scouring process:

Solvent scouring process. Vapor lock scouring process.

Clean water wantedNovozymes' enzymes have proved to save 70,000 liters of water per ton of knitted fabric produced in a textile mill. With an annual production of approximately 9 million tons of knitwear globally, we would have an additional 630 billion liters of fresh water every year if all knitwear were produced using enzymes. That corresponds to the annual water consumption of about 10 million Europeans.

Enzymes, once they have done their job in the textile dye house or garment laundry, are broken down into harmless pieces of protein that do not harm the surrounding environment. That makes for clean waste water and cleaner, healthier rivers and streams.

Bioscouring

Bioscouring is enzymatic removal of pectin and other impurities from raw cotton and is a gentle preparation for the subsequent wet processing stages. Bioscouring replaces the conventional high temperature alkaline scouring and either eliminates or reduces the need for adding softeners.

The weight loss is lowered with 1-2% due to the elimination of cotton damage and the cotton retains its structure which means higher fabric strength for longer-lasting cottons. 

Textile mills can create knits with a superior hand feel and lasting softness. Furthermore, enzymatic scouring will require less water, as fewer rinses are needed, and there are significant reductions in COD, BOD and salt (acid and alkali) in the wastewater. Bioscouring will primarily work on medium to dark shades and can be combined with desizing and biopolishing.

Fiber dyeing

Stock dyeing, top dyeing, and tow dyeing are used to dye fibers at various stages of the manufacturing process prior to the fibers being spun into yarns. The names refer to the stage at which the fiber is when it is dyed. All three are included under the broad category of fiber dyeing.

Stock dyeing is dyeing raw fibers, also called stock, before they are aligned, blended, and spun into yarns.

Top dyeing is dyeing worsted wool fibers after they have been combed to straighten and remove the short fibers. The wool fiber at this stage is known as top. Top dyeing is preferred for worsted wools as the dye does not have to be wasted on the short fibers that are removed during the combing process.

Tow dyeing is dyeing filament fibers before they are cut into short staple fibers. The filament fibers at this stage are known as tow.

The dye penetration is excellent in fiber dyeing, therefore the amount of dye used to dye at this stage is also higher. Fiber dyeing is comparatively more costly than yarn, fabric, and product dyeing. The decision regarding the selection of colors has to be made early in the manufacturing process. Fiber dyeing is typically used to dye wool and other fibers that are used to produce

yarns with two or more colors. Fibers for tweeds and fabrics with a “heather” look are often fiber dyed.

Yarn dyeing

Yarn dyeing adds color at the yarn stage. Skein, package, beam, and space dyeing methods are used to dye yarns.

In skein dyeing the yarns are loosely wound into hanks or skein and then dyed. The yarns have good dye penetration, but the process is slow and comparatively more expensive.

In package dyeing yarns that have been wound on perforated spools are dyed in a pressurized tank. The process is comparatively faster, but the dye uniformity may not be as good as that of skein dyed yarn.

In beam dyeing a perforated warp beam is used instead of the spools used in package dyeing.

Space dyeing is used to produce yarns with multiple colors.

In general, yarn dyeing provides adequate color absorption and penetration for most materials. Thick and highly twisted yarns may not have good dye penetration. This process is typically used when different colored yarns are used in the construction of fabrics (e.g. plaids, checks, iridescent fabrics)

Fabric dyeing

Fabric dyeing, also known as piece dyeing, is dyeing fabric after it has been constructed. It is economical and the most common method of dyeing solid colored fabrics. The decision regarding color can be made after the fabric has been manufactured. Thus, it is suitable for quick response orders. Dye penetration may not be good in thicker fabrics, so yarn dyeing is sometimes used to dye thick fabrics in solid colors. Various types of dyeing machines are used for piece dyeing. The selection of the equipment is based on factors such as dye and fabric characteristics, cost, and the intended end use.

Union dyeing

Union dyeing is “a method of dyeing a fabric containing two or more types of fibers or yarns to the same shade so as to achieve the appearance of a solid colored fabric”.[1]Fabrics can be dyed using a single or multiple step process. Union dyeing is used to dye solid colored blends and combination fabrics commonly used for apparel and home furnishings.

Cross dyeing

Cross dyeing is “a method of dyeing blend or combination fabrics to two or more shades by the use of dyes with different affinities for the different fibers”.[1] The cross dyeing process can be used to create heather effects, and plaid, check, or striped fabrics. Cross dyed fabrics may be mistaken for fiber or yarn dyed materials as the fabric is not a solid color, a characteristic

considered typical of piece dyed fabrics. It is not possible to visually differentiate between cross dyed fabrics and those dyed at the fiber or yarn stage. An example is cross dyeing blue worsted wool fabric with polyester pin stripes. When dyed, the wool yarns are dyed blue, whereas the polyester yarns remain white.

Cross dyeing is commonly used with piece or fabric dyed materials. However, the same concept is applicable to yarn and product dyeing. For example, silk fabric embroidered with white yarn can be embroidered prior to dyeing and product dyed when an order is placed.

Product dyeing

Product dyeing, also known as garment dyeing, is the process of dyeing products such as hosiery, sweaters, and carpet after they have been produced. This stage of dyeing is suitable when all components dye the same shade (including threads). This method is used to dye sheer hosiery since it is knitted using tubular knitting machines and then stitched prior to dyeing. Tufted carpets, with the exception of carpets produced using solution dyed fibers, are often dyed after they have been tufted. This method is not suitable for apparel with many components such as lining, zippers, and sewing thread, as each component may dye differently. The exception is tinting jeans with pigments for a “vintage” look. In tinting, color is used, whereas in other treatments such as acid-wash and stone-wash, chemical or mechanical processes are used. After garment construction, these products are given the "faded" or "used" look by finishing methods as opposed to dyeing.

Dyeing at this stage is ideal for quick response. Many T-shirts, sweaters, and other types of casual clothing are product dyed for maximum response to fashion’s demand for certain popular colors. Thousands of garments are constructed from prepared-for-dye (PFD) fabric, and then dyed to colors that sell best.

Different Dyes Which Are Used To Dyeing

Natural dyesDirect Printing It is the most common approach to apply a color pattern onto a fabric. If done on colored fabric, it is known as overprinting. The desired pattern is produced by pressing dye on the fabric in a paste form. To prepare the print paste, a thickening agent is added to a limited amount of water and dye is dissolved in it. Earlier starch was preferred as a thickening agent for printing. Nowadays gums or alginates derived from seaweed are preferred as they allow better penetration of color and are easier to wash out. Most pigment printing is done without thickeners because the mixing up of resins, solvents and water produces thickening anyway.

Working Principle:1. Most natural dyes need both a plant extract and a mineral mordant make a permanent

color.2. The stronger the dye extract, i.e. the more plant used, the deeper the color.3. Mineral (metal salt) mordents are always used in the same proportion .4. One cab use less for a pale color , but never use more, as too much metal can harm the

fiber. 5. No rush work time is not that much, but process time can be several days.

Advantages of natural dyeing

1. The shades produced by natural dyes/colorants are usually soft, lustrous and soothing to the human eye

2. Natural dyestuff can produce a wide range of colors by mix and match system. A small variation in the dyeing technique or the use of different mordents with the same dye (polygenetic type natural dye) can shift the colors to a wide range or create totally new colors, which are not easily possible with synthetic dyestuffs.

3. Natural dyestuffs produce rare color ideas and are automatically harmonizing.

4. Unlike non-renewable basic raw materials for synthetic dyes, the natural dyes are usually renewable, being agro-renewable/vegetable based and at the same time biodegradable.

5. In some cases like hard, indigo etc., the waste in the process becomes an ideal fertilizer for use in agricultural fields. Therefore, no disposal problem of this natural waste.

Disadvantages of natural dyeing1. It is difficult to reproduce shades by using natural dyes/colorants, as these agro products

vary from one crop season to another crop season, place to place and species to species, maturity period etc.

2. It is difficult to standardize a recipe for the use of natural dyes, as the natural dyeing process and its color development depends not only on color component but also on materials.

3. Natural dyeing requires skilled workmanship and is therefore expensive. Low color yield of source natural dyes thus necessitates the use of more dyestuffs, larger dyeing time and excess cost for mordents.

4. Scientific backup of a large part of the science involved in natural dyeing is still need to be explored.

5. Lack of availability of precise technical knowledge on extraction and dyeing techniques.

Pigment DyesAlthough pigments are not dyes in a true sense, they are extensively used for coloring fabrics like cotton, wool and other manmade fibers due to their excellent light fastness. They do not have any affinity to the fibers and are affixed to the fabric with the help of resins. After dyeing, the fabrics are subjected to high temperatures

Working Principle:

The pigments are first mixed with water and a dispersing agent that imparts

an anionic charge to the pigments. This solution is added gradually to the dyeing machine. The temperature of the bath is slowly increased and the machine is held at the dyeing temperature for up to 20 minutes. The fabric is held at an elevated temperature to increase the adsorption of the

pigments. Advantages of Pigment Dyeing

1. Its applicable to a wide range of textiles and wide gamut of colors available. Some brilliant fluorescent pigments are available for special applications and fashion items.

2. The process of pigment dyeing can also be relatively cheap.3. The process chemicals are less toxic , environmentally friendly and least polluting.4. The color fades with the repeated use , just like denims.

Limitations of Pigment Dyeing

1. Color fading could be a problem if not desired, and can only be kept intact with further chemical treatments.

2. The abrasion resistance and hand could be unsatisfactory depending upon the pigment, binder and softener used.

3. Dark and deep shades are better produced with other dyestuffs rather than pigments.

Acid Dyes

A class of dyes used on wool, other animal fibers, and some manufactured fibers. Acid dyes are seldom used on cotton or linen since this process requires a mordant. Acid dyes are widely used on nylon when high wash fastness is required. In some cases, even higher wash fastness can be obtained by after treatment with fixatives.

Working Principle:

The wet and light fastness properties of the acid dyes varies from poor to excellent , depending upon the molecular structure of the dyes.

The fastness properties as per the category are as follows: Neutral acid dyes:-since these dyes have very good leveling and migration properties ,and have a low affinity for the fiber, therefore the wet fastness properties of this class are generally poor.

Weak acid dyes or half milling dyes : These dyes have a medium to good affinity for the fiber and are generally applied in a weakly acidic bath, shows medium to good wet fastness properties. Strong acid dyes or super milling dyes :- These dyes have poor exhaustion properties, therefore applied under very strong acidic condition , exhibit good fastness properties.

Advantages of acid dyes �

1. Found in bright colours. 2. Widely used on silk. �3. Used for protein fibres, nylon, spandex, special type acid-dyeable acrylic.

Disadvantage of Acid Dyeing

1. Poor washing fastness.

Sulfur Dyes

Sulfur Dyes are insoluble and made soluble by the help of caustic soda and sodium sulfide. Dyeing is done at high temperature with large quantities of salt so that the color penetrates into the fiber.After dyeing the fabric is oxidized for getting desired shades by exposure to air or by using chemicals. Excess dyes and chemicals are removed by thorough washing. These dyes are fast to light, washing and perspiration and are mostly used for cotton and linen.

Working Principle:

Sulfur dyes are water-insoluble. In the presence of a reducing agent and at alkali pH's at elevated temperature of around 80 °C, the dye particles disintegrate, which then becomes water-soluble and hence can be absorbed by the fabric. Sodium sulfide or hydrosulfide is suitable reducing agents. Common salt facilitates the absorption. After the fabric is removed from the dye solution, it is allowed to stand in air whereupon the dye is regenerated by oxidation. The regenerated parent dye is insoluble in water. Oxidation can also be effected in air or by hydrogen peroxide or sodium bromated in a mildly acidic solution.

The low water solubility is the basis of the good wash-fastness of these dyed fabrics. These dyes have good all round fastness except to chlorine bleaches. Because the dye is water-insoluble, it will not bleed when washed in water and will not stain other clothes. The dye, however, may have poor fastness to rubbing. The dyes are bleached by hypochlorite bleach.

Different types of dyeing machine

Jet Dyeing Machine

This is the most modern machine used for the dyeing of polyester using disperse dyes. In this machine the cloth is dyed in rope form which is the main disadvantage of the machine.

Working Principle:In this machine, the dye tank contains disperse dye, dispersing agent, leveling agent and acetic acid. The solution is filled up in the dye tank and it reaches the heat exchanger where the solution will be heated which then passed on to the centrifugal pump and then to the filter chamber. The solution will be filtered and reaches the tubular chamber. Here the material to be dyed will be loaded and the winch is rotated, so that the material is also rotated. Again the dye liquor reaches the heat exchanger and the operation is repeated for 20 to 30 minutes at 135o C. Then the dye bath is cooled down, after the material is taken out.

Metering wheel is also fixed on winch by external electronic unit. Its purpose is to record the speed of the fabric. The thermometer, pressure gauge is also fixed in the side of the machine to note the temperature and pressure under working. A simple device is also fixed to note the shade under working.

Advantages Jet Dyeing Machine

 Dyeing time is short compared to beam dyeing.  Material to liquor ratio is 1:5 (or) 1:6  Production is high compared to beam dyeing machine.

Disadvantages Jet Dyeing Machine

 Cloth is dyed in rope form  Risk of entanglement  Chance for crease formation.

Winch Dyeing Machine

A dyeing machine consisting essentially of a dye vessel fitted with a driven winch ( usually above the liquor level) which rotates and draws a length of fabric, normally joined end to end, through the liquor.

Working Principle:

The basic principle of all winch dyeing machines is to have a number of loops or ropes of the fabric in the dye bath, these ropes are of equal length , which are mostly immersed in the liquor in the bath. The upper part of each rope runs over two reels which are mounted over dyebath. At the front of the machine , above the top of the dye liquor , is a smaller reel, which is called jockey or fly roller.

The fly roller remain free wheeling along with fabric rope. At the back of winch tank is the winch wheel, which pulls the fabric rope from the dye bath over the jockey reel for dropping in the dye bath for immersion. From the dropped location , the fabric rope travels back . to be lifted and fed to winch wheel.

The dyeing process on winch dyeing machines is based on higher M:L as compared with other dyeing machines. The process is conducted with very little tension . The total dyeing time is lengthier as compared to other machines.

Advantages of Winch Dyeing Machine1. Construction and operation of winch are very simple.2. The winch dyeing machines are suitable for types of wet processing operations from desizing to softening.3.The winch dyeing machine is suitable for practically all types of fabrics ,which can withstand creasing in rope form processing.4. Thr tension exerted on winch is less than jigger dyeing machine,the material thus dyed is with fuller hand.5. The appearance of the dyed goods is clean and smooth on winch dyeing machines.

Limitations of Winch Dyeing Machine1. Batch dyeing operations needs trimming, sewing, opening out the rope , loading and unloading for individual lots separately.2. Since several lengths of fabric are run over the winch reel into the liquor and sewn end to end, Continuous length processing is not possible in a single batch.3. Fabric is processed in rope form which may lead to crease marks , particularly in heavy , woven , thin and light synthetics.4. Most of the machine work under atmospheric conditions.

Beam Dyeing Machine:A machine for dyeing yarns or fabrics that have been wound onto a special beam that has evenly perforated holes along its barrel. The dye is forced through the barrel into the yarn/fabric from inside to outside and vice versa. The beam dyeing machines may be capable of dyeing a single beam or to dye multiple beams. The fabric or yarn have better dyeing results because of there is no dimensional changes as well as there is no mechanical force applied to it. The high performance pumps circulate the dye liquor in efficient manner to achieve even dyeing results.

Working Principle:The working principle is same as that of HTHP yarn dyeing machines. The process of beam dyeing is as follows,

1. The fabric or yarn in open width is rolled on to a perforated beam.2. The beam then subsequently inserted into a dyeing vessel.3. The machine is closed and pressurized.4. The dye liquor is circulated in to out and out to in directions , under pressure and

temperature is employed as per the process requirement.5. The chemicals and auxiliary are injected as per requirement of the process.

Paddle Dyeing MachinePaddle dyeing machines are generally used to dye many forms of textiles but the method best suits to dye garments. Heat is generated through steam injection directly into the dyebath. The machine works like this, the paddle circulates both the bath and garments in a perforated central island. It is here only that the chemicals, water and steam for heat are added. The overhead paddle machine is nothing but a vat with a paddle that has blades of full width. The blades generally takes a dip of few centimeters into the vat. This action stirs the bath and pushes the garments down, thus keeping them totally submerged in the dye liquor.

Working Principle:

A process of dyeing textiles in a machine that gently move the goods using paddles similar to a paddle wheel on a boat. This is a slow process, but there is extremely little abrasion on the goods. Horizontal Paddle Machines (over head paddle machine) consist of a curved beck like lower suction to contain the materials and the dye liquor. The goods are moved by a rotating paddle, which extends across the width of the machine. Half immersed paddles cause the material to move upwards and downwards through out the liquor. The temperature can be raised to 98o C in such system.

In lateral / oval paddle machines consist of oval tank to enhance the fluid flow and the processing the goods. In the middle of this tank is a closed oval island. The paddle moves in a lateral direction and is not half submerged in the liquor and the temperature can be increased up to 98o C.

HT Paddle Machines work according to the principle of horizontal paddle machine, however, the temperature can be raised up to 140o C. PES articles are preferably dyed on HT paddles. In paddle machines, the dyeing can be carried out with 30:1 to 40:1, lower ratios reduces optimum movement of the goods, lead to unlevel dyeing, crease formation. For gentleness, the blades of the paddle are either curved or have rounded edges and the rotating speed of the paddle can be regulated from 1.5 to 40 rpm. Circulation of the liquor should be strong enough to prevent goods from sinking to the bottom. Paddle machines are suitable for dyeing articles of all substrates in all forms of make ups. The goods are normally dyed using PP/PET bags.

Conclusion

It was concluded that the synthetic textile dyes represent a large group of organic compounds

that could have undesirable effects on the environment, and in addition, some of them can pose

risks to humans. The increasing complexity and difficulty in treating textile wastes has led to a

constant search for new methods that are effective and economically viable. However, up to the

present moment, no efficient method capable of removing both the color and the toxic properties

of the dyes released into the environment has been found.

References

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