Reactive dye give good results (even dyeing) on cellulose materials in textile industry.
What is Reactive Dye?
Reactive dyes are a type of synthetic dyes that are commonly used to color natural fibers such as cotton, wool, and silk.
These dyes are called “reactive” because they chemically react with the fiber molecules to form a covalent bond, which makes the dye molecules part of the fiber itself.
Reactive dyes are preferred over other types of dyes because they offer a wide range of bright and vivid colors, excellent color fastness, and good wash and light fastness. reactive dyes can also be used to dye a wide range of shades, from pastel to deep and intense colors.
The process of dyeing with reactive dyes involves several steps, including preparation of the fabric or yarn, application of the dye, fixation of the dye with a chemical reaction, and washing and finishing.
Reactive dyes can be applied to the fiber by several methods, including exhaust dyeing, pad-dry-cure, and continuous dyeing.
The choice of method depends on the type of fabric, the desired color, and the production requirements.
Read More – Azo dyes – Azo dye test, Azo dye test for phenol?
Definition of Reactive Dye
Or, A dye which is capable of reacting chemically with a substrate to form a covalent dye substrate linkage, is known as reactive dye. reactive dye can be dyed such as cotton, wool, and silk materials. reactive dye are make a proper covalent linkage with fibre. but there are different types of dyes are used in textile process house for colouration of textile goods. dyes have specific quality to dyed a particular textile fibre/materials.
Reactive Dyes – Cellulose Materials.
This dyes have specific quality for colouration of cellulose (Cotton) materials. this dyes give good results on cotton materials. so, this dyes are used for colouration of cotton materials in textile process house. Reactive dye is more suitable and profitable for cellulose materials.
it’s gives positive effect on cellulose materials. this is the reason that, reactive dyeing is windly used for dyeing of cellulose materials in textile industry.
Reactive dye have capability to makes covalent linkage with the fibre. and work as a integral part of fibre.
This covalent is formed between the dye molecules and the OH hydroxyl group of cellulosic fibers on between the dye molecules and the terminal – NH2 group of polymer.
Read More – Vat dyeing Process, dyeing of cotton with vat dye?
Structure of Reactive dyes
Reactive dyes are a type of dye that forms a covalent bond with the fiber molecule, resulting in excellent color fastness properties. The structure of reactive dyes consists of a chromophore, a reactive group, and a solubilizing group.
Chromophore: The chromophore is the part of the molecule responsible for color. It consists of an aromatic ring or a conjugated system of double bonds. The chromophore determines the wavelength of light that the dye absorbs and therefore its color.
Reactive Group: The reactive group is the part of the molecule that reacts with the fiber molecule to form a covalent bond. Reactive dyes contain one or more reactive groups, such as chlorotriazine, vinylsulfone, or epoxy, which allow them to react with the hydroxyl, amino, or carboxyl groups of the fiber molecule.
Solubilizing Group: The solubilizing group is a polar or ionic group that makes the dye soluble in water. Reactive dyes typically contain one or more solubilizing groups, such as sulfonic acid, carboxylic acid, or quaternary ammonium, which allow them to dissolve in water and be applied to the fiber.
The combination of chromophore, reactive group, and solubilizing group determines the properties of the reactive dye, including its color, reactivity, and solubility.
History of reactive dye in textile
Reactive dyes were first introduced in the mid-1950s as an alternative to traditional direct and vat dyes. These dyes are so-called because they react chemically with the fiber, forming a covalent bond between the dye molecule and the fiber.
The first reactive dye was synthesized by Paul Schlack at the Hoechst AG company in Germany in 1954.
The dye was a reactive derivative of the azo dye diazotized 4-nitroaniline and coupled with N-methyl-N-ethyl-beta-hydroxy ethyl aniline.
Reactive dyes quickly gained popularity in the textile industry due to their ability to provide bright and long-lasting colors on cellulosic fibers, such as cotton, rayon, and linen.
The dyes are also highly soluble in water, making them easy to apply in the dyeing process.
Since their introduction, reactive dyes have undergone significant improvements, including increased wash and light fastness, better dyeing properties, and expanded color ranges.
Today, reactive dyes are widely used in the textile industry and are the most commonly used dyes for dyeing cotton fabrics.
Reactive Dye Properties
Trade Name for reactive dyes used in textile industry
There are many trade names for reactive dyes used in the textile industry, as different manufacturers may have their own proprietary names for their products.
Some common trade names for reactive dyes include:
These dyes are known for their ability to form strong covalent bonds with the fibers, resulting in durable and vibrant colors that are resistant to fading and washing.
They are widely used in the dyeing and printing of natural and synthetic fibers, such as cotton, wool, silk, and polyester.
Basic Advantage of reactive dyes
Reactive dyes are highly popular in the textile industry due to their ability to form a covalent bond with the fabric, resulting in excellent color fastness properties.
Reactive dyes are highly water-soluble and can react with the fabric’s fibers under mild conditions, resulting in strong and durable bonds.
Compared to other types of dyes, reactive dyes offer several advantages, including:
High color yield: Reactive dyes have a high degree of fixation on the fabric, resulting in bright and vibrant colors.
Good wash and light fastness: Reactive dyes are highly resistant to fading or bleeding, even after repeated washing or exposure to sunlight.
Wide color range: Reactive dyes offer a broad range of colors, from bright and bold to subtle and pastel shades.
Environmentally friendly: Reactive dyes are relatively safe to use and produce minimal waste.
Due to their excellent color fastness and broad color range, reactive dyes are widely used in the production of textiles, including clothing, home furnishings, and industrial fabrics.
Chemicals used in reactive dyeing
(a) Increases absorption.
(b) Decrease hydrolysis rate of dyes.
(c) help in extra energy for pantration.
(d) NaCl is widely used for reactive dyeing.
(e) improve affinity energy of dye.
(a) high PH is required in reactive dyeing because without high PH,
Dye will not fixed properly or permanently to the materials.
Sodium carbonate is used to maintain PH in case of reactive dyeing.
The role of time is very important in case of Dyeing because accurate or proper fixation is depand upon time. If increase of the time then fixation of dye will increase.
Its give good, wash fastness, rubbing fastness, light fastness, perspiration fastness.
In case of cellulose materials, if used high temperature caused the cotton material to have no or poor ability to be dyed. It effects on cellulose materials. Cellulose materials is not gives good results.
And increase the ability to reaction mechanism during dyeing.
Two phases occur during dyeing
1. Exhaustion phase
( Proper dye absorption)
2. Fixation phases
(Proper dye reactions)
Shade is devlop with the help of salt and soda ash during dyeing
The role of salt and soda ash in reactive dyeing is very important because its gives proper shade
On dyed materials.
There are three types of shade is devlop with the help of salt and soda ash.
• Light shade
• medium shade
• deep shade
But it is depand upon quantity of salt and soda ash during dyeing.
Reactive dye having capacity to dyed textile goods such as,
• cotton ( yarn, knit, woven)
• natural fibre ( cellulose materials)
Read More – Direct dyeing Process, Dyeing of cotton with direct dye, eco – friendly direct dyes?
Characteristics of Reactive Dyes
Reactive dyes are a class of synthetic organic dyes that are widely used in the textile industry to color cellulosic fibers such as cotton, linen, rayon, and viscose.
These dyes have several important characteristics that make them unique and highly desirable for textile dyeing applications. Some of the key characteristics of reactive dyes include:
High solubility: Reactive dyes are highly soluble in water and can be easily dissolved in the dyeing bath, which makes them easy to use for textile dyeing.
Covalent bonding: Reactive dyes form strong covalent bonds with the cellulose fibers, resulting in excellent color fastness properties.
Good color yield: Reactive dyes produce bright, vibrant colors that are highly resistant to fading, washing, and light exposure.
Wide color range: Reactive dyes are available in a wide range of colors, including bright shades that are difficult to achieve with other types of dyes.
Low environmental impact: Reactive dyes are relatively low in toxicity and have low environmental impact compared to other types of dyes.
Versatility: Reactive dyes can be used on a variety of fibers including cellulosic, wool, silk, and nylon, making them highly versatile.
Reactive dyes are highly desirable for textile dyeing applications due to their excellent color fastness properties, wide color range, low environmental impact, and versatility.
Fector effecting of reactive dyes
Some of the factors that can affect the effectiveness of reactive dyes are:
pH: Reactive dyes require an alkaline pH to react with the cellulose fibers. The optimum pH range for dyeing with reactive dyes is typically between 10-12. If the pH is too low or too high, the reaction between the dye and the fiber may be incomplete, leading to poor dye uptake, low color yield, and decreased color fastness.
Temperature: The reaction between reactive dyes and cellulose fibers is typically carried out at high temperatures, typically around 50-60°C. Higher temperatures can accelerate the rate of the reaction, leading to faster dye uptake and higher color yields. However, excessively high temperatures can damage the fiber and lead to poor color fastness.
Salt: Salt is typically added to the dye bath to promote even dye uptake and to prevent the dyes from migrating or bleeding. The salt concentration should be carefully controlled, as too little salt can result in poor dye uptake, while too much salt can cause the dyes to migrate, leading to uneven dyeing and reduced color fastness.
Dye concentration: The concentration of the reactive dye in the dye bath can also affect the efficiency of the dyeing process. Higher concentrations of dye can lead to higher color yields, but excessive dye concentrations can lead to uneven dyeing and poor color fastness.
Time: The length of time that the fabric is immersed in the dye bath can also affect the effectiveness of the dyeing process. Longer dyeing times can lead to higher color yields, but excessively long dyeing times can cause the fiber to become damaged, leading to reduced color fastness.
Reactive dyes classification
1. Reactivity system in dyeing
PH is maintained 11-12 by using Na2CO3 in dye bath.
PH is maintained 10-11
2. temperature system of dyeing
a) cold brand
this type of dyes contain reactive group of moderate reactivity so dye is done in higher temperature then
b) Hot brand
Reactive dye mechanism
Salt addition: The material to be dyed is treated with an electrolyte (salt), which helps to promote the adsorption of the dye molecules onto the fiber surface.
Alkali addition: The material is then treated with an alkali, such as sodium hydroxide, which raises the pH of the solution and activates the reactive group on the dye molecule.
Dyeing: The reactive dye is added to the solution, and the material is immersed in the solution. The dye molecules diffuse through the solution and react with the fiber surface, forming a covalent bond.
Washing: After dyeing, the material is washed thoroughly to remove any unreacted dye molecules and other impurities.
The reactive group on the dye molecule typically contains a chlorotriazine or vinyl sulfone group, which reacts with a nucleophilic group on the fiber surface, such as a hydroxyl or amino group. The reaction forms a covalent bond between the dye molecule and the fiber, which is resistant to washing and fading.
Reactive dyes are commonly used to dye cellulose fibers, such as cotton, rayon, and linen. They can produce bright, intense colors and are widely used in the textile industry.
Function of NaCl
Fixation system of reactive dye
In case of reactive dyeing, maintain PH with the help of alkali. If alkali is add in dye bath its creat proper PH in dye bath. In other words, it is also called dye fixing agent.
Washing system of reactive dye
If dyeing is completed then washing is must be required for textile materials because if unfixed dyes persent on the surface of the materials it is easily removed with the help of washing. and it’s also help in wash-fastness.
It is done with the help of hot washing and then again cold wash.and after this soaping is also required for textile materials.
Reactive Dyeing Methods
Reactive dyeing is a common method of coloring fabrics, particularly cellulosic fibers such as cotton, linen, and rayon. Reactive dyes form covalent bonds with the fiber molecules, resulting in excellent color fastness and durability.
There are several methods of reactive dyeing, including:
Exhaust dyeing: In this method, the fabric is immersed in a dye bath containing the reactive dye, salt, and alkali. The dye molecules react with the cellulose fibers, and the excess dye is removed by rinsing and washing.
Pad-batch dyeing: This method involves applying the dye solution to the fabric using a padded roller, followed by batch processing to allow the dye to react with the fiber.
Continuous dyeing: In this method, the fabric is continuously fed through a series of rollers that apply the dye solution and then washed and dried.
Printing: Reactive dyes can also be used for printing designs onto fabric. The dye is applied to the fabric in the desired pattern using a screen, roller, or other printing method.
Cold pad-batch dyeing: This is a variation of pad-batch dyeing that is carried out at room temperature, reducing energy costs.
Jet dyeing: In this method, the dye is injected into the fabric using a high-pressure jet, allowing for more even and efficient dyeing.
The choice of dyeing method depends on the type of fabric, the desired color, and the production requirements of the manufacturer.
(a) Discontinuous methods
• Hot brand
• Cold brand
(b) Continuous methods
• Pad system methods
• Pad thermo fixation methods
(c) Semi – continuous methods
• pad roller methods
• pad jigger dyeing methods
recipe of cold brand reactive dyeing methods
• Dye – 1- 3%
• salt – 60 gm/c
• soda ash – 15 gm/c
• H2O – 10 times
• Temp – 40°C
• Time – 1 hours
take required water in dye bath
Add soda ash in dye bath
After 10 mint add salt
Add materials in dye bath
Continue Dyeing at 40°C for – 1 hours
Reactive dyes are a type of dye that react chemically with the fibers of a fabric, forming a strong bond that results in excellent color fastness. However, reactive dyes can sometimes experience striping, which is a problem where the fabric appears to have streaks or uneven color distribution.
Striping can occur for several reasons, including:
Uneven dye concentration: If the dye concentration in the dye bath is not uniform, the resulting color can appear uneven.
Uneven fabric absorption: If the fabric is not evenly wetted before dyeing or if the fabric is not uniformly exposed to the dye bath, the resulting color can appear uneven.
Uneven dye fixation: If the reactive dye is not properly fixed to the fabric, the resulting color can appear uneven.
To prevent striping, it is important to ensure that the dye concentration in the dye bath is uniform and that the fabric is evenly wetted before dyeing. Additionally, it is important to ensure that the fabric is uniformly exposed to the dye bath and that the dye is properly fixed to the fabric.
If striping does occur, it may be possible to correct the problem by re-dyeing the fabric using a more uniform dye concentration or by using a different dye fixation method. However, prevention is always better than correction, so it is important to take steps to avoid striping from occurring in the first place.
Hydrolysis of reactive dyes
Reactive dyes are a type of dye that chemically react with the fibers of textiles to form a covalent bond, resulting in a strong and permanent color. These dyes are widely used for dyeing natural and synthetic fibers such as cotton, wool, silk, and polyester.
Hydrolysis of reactive dyes occurs when the dye molecule is broken down by water, resulting in the release of the dye molecule from the textile fiber. This process can occur due to several reasons, including exposure to high temperatures, acidic or alkaline conditions, or prolonged exposure to water.
The hydrolysis of reactive dyes can result in several negative effects, including:
Fading of the color: The hydrolysis of the dye molecule can cause the color of the textile to fade over time.
Reduced wash fastness: Hydrolyzed dyes are more easily removed from the textile during washing, resulting in reduced wash fastness.
Staining of other textiles: Hydrolyzed dyes can transfer to other textiles during washing, resulting in staining.
To prevent the hydrolysis of reactive dyes, it is important to use proper dyeing techniques and to avoid exposing the textiles to extreme conditions. Additionally, using appropriate washing and care instructions can help to maintain the color and wash fastness of the textiles.
Reactive dye Uses
Reactive dyes are versatile water-soluble dyes that are commonly used in textile dyeing and printing applications.
Reactive dyes are a type of dye that react chemically with the fibers of a fabric, forming a strong bond that results in excellent color fastness.
They are chemically react with the fibers of the fabric to form a covalent bond, resulting in excellent color fastness and wash-fastness.
Here I m going to explain about some specific uses of reactive dyes:
Reactive dyes are a type of water-soluble dyes that are widely used in textile dyeing and textile printing.
They are called “most reactive dye” because they chemically react with the fibers of the fabric to form a covalent bond, resulting in excellent color fastness and wash-fastness.
Some common uses of reactive dyes include:
Textile dyeing: Reactive dyes are commonly used for dyeing natural fibers such as cotton, silk, wool, and viscose. They provide bright, vivid colors and excellent color fastness.
Textile printing: Reactive dyes are also used for printing on textiles. They offer good penetration into the fabric and produce sharp, crisp designs.
Paper dyeing: Reactive dyes can be used for dyeing paper and producing vibrant, colorful prints.
Inkjet printing: Reactive dyes are also used in inkjet printing, particularly for printing on textiles.
Leather dyeing: Reactive dyes can be used for dyeing leather, providing long-lasting, vibrant colors.
Reactive dyes are versatile and give excellent color fastness and wash-fastness.
This dyes are most popular choice for textile and other applications.
Color fastness Importance
Color fastness refers to the ability of a material to retain its original color under certain conditions, such as washing, exposure to light or other environmental factors. It is an important characteristic of textiles, as well as other materials that are colored or dyed, such as paper or plastics.
Color fastness is measured using various testing methods, such as the Grey Scale for assessing staining, or the Crockmeter for measuring color transfer. These tests are used to determine the degree to which a material is likely to change color over time due to exposure to certain conditions.
There are several factors that can affect color fastness, such as the type of dye used, the fiber content of the material, the temperature and pH of the environment, and the duration and intensity of exposure to light or other environmental factors.
In the textile industry, color fastness is an important consideration in the production of clothing and other textiles, as it affects the durability and appearance of the finished product. Manufacturers use a variety of techniques to improve color fastness, such as selecting high-quality dyes and fibers, using special finishing processes, and incorporating UV inhibitors or other additives into the material.
Color fastness is also important in other industries, such as printing and packaging, where color accuracy and consistency are critical. Testing for color fastness is typically performed in specialized laboratories, using standardized testing methods and equipment.