Disperse Dyes
What are advantages of Disperse Dyes
Disperse dyes are a type of dye primarily used for coloring synthetic fibers, especially polyester and acetate.
High Sublimation Fastness
Disperse dyes exhibit high sublimation fastness, meaning that they resist fading or discoloration when exposed to heat. This property makes them suitable for applications where the dyed material may be subjected to elevated temperatures.
01
Wide Color Range
Disperse dyes offer a wide range of color options. This versatility allows manufacturers to achieve a broad spectrum of colors, meeting diverse aesthetic preferences and design requirements.
02
Ease of Application
Disperse dyes can be applied to fibers through various methods, including dyeing, printing, or padding. This flexibility in application methods makes them convenient for different manufacturing processes.
03
Water-Insolubility
Disperse dyes are characterized by their low solubility in water, which is beneficial for certain dyeing processes. They are often dispersed as fine particles in water or other suitable solvents before application to the fibers.
04
Durability
Dyed fabrics with disperse dyes tend to have good color retention and durability. This makes them suitable for various end-use applications, including clothing, upholstery, and outdoor textiles.
05
Brief Introduction to Disperse Dyes
Unlike many other types of dyes, disperse dyes are far less water soluble than other dyes such as acid dyes.
As a result, disperse dyes are more commonly used in dye bath solutions. Of all the dyes, they are of the smallest molecular size.
Disperse dyes have substantivity for one or more hydrophobic fibres like cellulose acetate, nylon, polyester, acrylic and other synthetic fibres.
Disperse dyes achieve their best results when the dying process takes place at high temperatures.
Specifically, solutions around 120°C to 130°C enable disperse dyes to perform at their optimal levels, enabling the dye to be more evenly distributed and more bold.
How Disperse Dyes Work?
Disperse dyes is a class of non-ionic dye, which has low water solubility and exists in water primarily in a highly dispersed state by means of the effect of the dispersing agent in the process of dyeing. The chemical structure of most disperse dyes belong to monoazo type, which accounts for about 80% of all the disperse dyes.
And then , anthraquinone accounts for about 15%, and other types of structures about 5%. It is enerally believed that the dyeing mechanism of disperse dye in water is : In dyeing temperature, part of the disperse dyes dissolves into dye molecules in the dye bath by means of the effect of the dispersing agent, and then is adsorbed on the fiber surface in the form of the molecule.
At the same time, the amorphous region in poly ester fiber expands to form a hole, which is large enough to accommodate the dye molecules in dyeing temperature.
So it is easy to make the dye molecules diffuse in the fiber, and at the end of staining, the previously puffed hole shrinks as the temperature decreases and makes the dye molecules encased within the fiber, so that the dye molecules can eventually form a single molecule or low molecular weight aggregates to be encased within the solid fiber.
Properties of Disperse Dyes
Disperse dyes are molecularly dispersed in the liquor at the time of dyeing.
It is very less soluble in water which makes fine dispersion.
It crystalline material with a high melting point (>150°C).
The saturation level of pure disperse dyes in the fiber is relatively high.
Its good sublimation power due to its stable electron arrangement.
The color will fade due to heat application on dispersed dye.
In the presence of nitrous oxide, textile material dyed with certain blue and violet disperse dyes with anthraquinone dye structure will be faded.
It is used for dyeing hydrophobic thermoplastic fibers including nylon, polyester, acrylic, and other synthetics.
The general structure of dispersed dyes is small and planar, and it contains polar functional groups like hydroxyalkyl, –NO2, and –CN.
It is characterized by the absence of solubilizing groups and low molecular weight.
The good migration properties of disperse dyes result in problem-free level dyeing.
These dyes have a bulk density of 0.4–0.6, a pH value of 7.0–9.0 (10 g/L water).
It is usually containing anthraquinone or azo groups which do not have charged cationic or anionic groups within the structure.
It does not require any specific fixing agent because the dyes become substantive to the fibers through phase changes initiated by temperature.
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Standard |
Light Fastness |
Soaping |
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Fading |
Stain |
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ISO |
4-5 |
4 |
5-6 |
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Perspiration Fastness |
Oxygen bleaching |
Fastness to seawater |
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Fading |
Stain |
Fading |
Stain |
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5 |
4-5 |
5 |
4-5 |
5 |
Advantages of Disperse Dyes
Excellent Color Fastness
Disperse dyes provide excellent color fastness properties, such as resistance to fading, washing, and sunlight exposure. This makes them ideal for use in outdoor and sportswear applications.
Compatibility with Synthetic Fibers
Disperse dyes are mainly used for dyeing synthetic fibers such as polyester, nylon, and acrylic. They have good compatibility with these fibers and provide even and consistent dyeing results.
Good Leveling Properties
Disperse dyes have good leveling properties, which means they penetrate the fibers evenly and produce uniform color shades.
Easy Application
Disperse dyes are relatively easy to apply and can be used in various dyeing techniques such as jet dyeing, beck dyeing, and pad dyeing.
Cost-effective
Disperse dyes are generally less expensive compared to other types of dyes, making them a cost-effective option for textile dyeing.
Environmental Safety
Disperse dyes are non-toxic and have no harmful effects on the environment. They do not contain heavy metals and comply with various environmental regulations.
Classification of Disperse Dyes
Disperse Dyes Can Be Divided Into Five Series
E-type - They have good leveling properties that are suitable for dip dyeing. In addition, some of them can be used in the thermal transfer printing process.
SE-type - They are disperse dyes with general leveling properties and good color fastness, which can be used for dyeing and pad-dry-dye dyeing processes of polyester fibers.
S-type - With high sublimation color fastness, these disperse dyes are mainly used for the pad-dry-dye dyeing processes of polyester blend fabrics.
P-type - They are used for anti-discharge printing of polyester fiber and cellulose fiber blended fabrics.
RD-type - They are dyes that can be used for rapid dyeing of polyester fibers. According to the molecular structures of disperse dyes, they can be divided into azo, anthraquinone, nitrodiphenylamine, heterocyclic ring and so on. Due to the lack of water-soluble genes, few disperse dyes are dissolved in water.
According To Fastness Property
According to fastness property there are following 4 types of disperse dyes
Group A - These dyes have excellent dyeing properties and good fastness properties.
Group B - These dyes are excellent in high temperature and for carrier dyeing with moderate fastness.
Group C - These dyes are moderate for carrier and high temperature dyeing with higher fastness property than group B dyes.
Group D - These dyes are of excellent fastness to heat but for dyeing properties on carrier method.
According To Energy Requirement
According to energy required for dyeing there are following 3 types of disperse dyes
Low Energy Dyes - These dyes are used to dye with carrier. For dyeing 77°C temperature is required. They have extremely poor resistance to sublimation.
Medium Energy Dyes - These dyes are used to dye mostly in between temperature 104°C-110°C which provides better sublimation fastness than that of low energy dyes.
High Energy Dyes - These dyes are used to dye at temperature above 129°C and are suitable for continuous dyeing. They provide all round fastness properties.
1. Thermosol Method (180° – 220°C)
Mechanism of Thermosol Method
In the thermosol process, the dye dissolves directly into the fiber using heat instead of a aqueous medium. The dye is deposited on the fiber surface, and exposure to dry heat at a temperature of approximately 220°C leads to the direct dissolution of the dye into the fiber. Complete penetration is achieved within 60 seconds.
Procedure of Thermosol Method
- Apply the dye solution onto the fabric through padding using the provided recipe.
- Dry the fabric at 100°C by means of hot flue or infrared(IR), adjusting based on the dryer used; excessive temperature may hinder solid shade formation.
- Fix the dyes at (180°-220°)C for 60-90 seconds, dependent on the fabric type, dye, and desired shade depth.
- Wash off unfixed dyes and chemicals with warm water.
- Perform soap washing or reduction clearing if necessary, as before.
- Conclude the process by washing the fabric and allowing it to dry.
2. Carrier Method (80° – 100°C)
Carriers
Carriers are dyeing assistants which alter the dispersing properties of the dyes and physical characteristics of the fibre so that more of the dye can be transferred from the dye bath to the fibre than in the absence of these assistants. It is a are kind of organic compound that acts as a substantive swelling agents. In case of hydrophobic fiber such as polyester fiber carrier is added to dye bath or print paste for increase of dye take up.
Mechanisms of Carrier
- Inducing fiber swelling and relaxation.
- Formation of a dye film on the fiber surface.
- Transporting dye to the fiber through dye-carrier association in the bath.
- Increasing dye solubility.
- Enhancing the diffusion rate of products with hydrophilic groups in polyester fibers.
- Augmenting fiber swelling.
- Improving dye uptake through covalent bonding with fiber liquid.
- Potentially acting as molecular lubricants.
- Penetrating the fiber polymer chain, reducing inter-chain attraction, and facilitating dye molecule entry into the polymer structure.
Procedure of Carrier Method
- Prepare the dye sol with cold water (1
10) and let it stand for 15 minutes.
- Set the dye bath at 60°C and sequentially mix carrier, dispersing agent, and salts.
- Add the material and maintain it for 15 minutes without increasing the temperature.
- Introduce the dye sol, and regulate the pH with CH3COOH.
- Increase the temperature to 100°C, then proceed with dyeing 1 hour.
- Reduce the temperature to 70°C, followed by rinsing and potential reduction clearing.
3. High Temperature Method (HTM) (180° – 220°C)
Procedure of High Temperature Method
- Prepare dye solution by adding cold water (1
8) and let it sit for 15 mins.
- Set dye bath at 60°C, adding dispersing agent and salt.
- Treat the material for 15 minutes without raising the temperature.
- Add the dye solution and control the pH with CH3COOH.
- Raise the dye bath temperature to 130°C within 30 minutes.
- Continue dyeing at 130°C for 1 hr.
- Cool the dye bath as quickly as possible.
- Allow the fabric to undergo hot rinsing.
- Perform reduction clearing if required, as before.
- Rinse the fabric again and then dry.
Reduction Clearing
A clearing process of polyester dyeing employing heavy reduction (NaOH+Na2S2O4) actively washes away non-penetrated, adsorbed dye. Reduction clearing is specifically applied for medium and deep shades to enhance wash fastness.
Effect of Various Conditions on Disperse Dyeing
Effect of Temperature
In case of dyeing with disperse dye, temperature plays an important role. For the swelling of fibre, temperature above 100°C is required if high temperature dyeing method is applied. Again in case of carrier dyeing method, this swelling occurs at 85-90°C. In case of thermosol dyeing method, if temperature is kept more, fabric is kept for less time in thermosol unit. Because in higher temperature, less time is enough for thermo fixation of dye. If it is kept for more time, then dye sublimation and loss of fabric strength may occur.
Effect of pH
For disperse dyeing the dye bath should be acidic and pH should be in between 4.5-5.5. For maintaining this pH, generally acetic acid is used. We may also use any mineral acid like H3PO4. But those are strong and costly. So mild acid like acetic acid is used for controlling pH of the bath. At this pH dye exhaustion is satisfactory. During colour development, correct pH should be maintained otherwise fastness will be inferior and colour will be unstable.
Choose the Right Dye for Your Fabric
Dyeing your fabric is a great way to give it a fresh, new look. With so many different types of fabric available, it's important to choose the right dye to get the desired result. The following will discuss some of the things you should consider when choosing dyes for fabrics.
Fabric Type
When it comes to dyeing fabrics, choosing the right type of dye is essential for achieving the desired colour and texture. While some dyes may work well on certain types of fabrics, they may not be suitable for others. Therefore, it is crucial to consider the type of fabric you'll be dyeing before selecting a dye. Different fabrics, such as synthetics and natural fibres, require different types of dyes and dyeing techniques to achieve the desired shade. Natural fibres like cotton, wool, and silk are more porous and can absorb dyes more easily, while synthetic fabrics such as polyester, nylon, and acrylic require a different approach as they don't absorb dyes easily. Choosing the wrong type of dye for fabric can lead to poor results, such as uneven colour distribution, fading, or bleeding of the dye. Additionally, using the wrong type of dye can damage the fabric, altering its texture and feel.
Dye Type
There are several types of dyes available, each with its own set of advantages and disadvantages. Some common types of dyes include
Fibre Reactive Dyes - These dyes are designed for use on natural fibres, such as cotton, silk, and wool. They create vibrant colours and are highly wash-fast.
Acid Dyes - These dyes are designed for use on protein fibres, such as silk, wool, and nylon. They are highly concentrated and create bright, bold colours.
Direct Dyes - These dyes are designed for use on cotton, rayon, and other cellulose fibres. They create a range of colours and are easy to use.
Disperse Dyes - These dyes are designed for use on synthetic fibres, such as polyester and nylon. They create vibrant colours and are highly wash-fast.
Colorfastness
When choosing a dye, you always want to consider how well the colour will hold up over time. Some dyes are more colourfast than others, meaning they won't fade or bleed as easily. For example, fibre-reactive dyes are highly colourfast and won't fade in the wash, while direct dyes are less colourfast and may fade over time. Some dyes offer vibrant colours on a wide variety of fibres and blends, from cotton and linen to silk, wool, rayon, ramie, and nylon as well as less conventional materials such as wood, wicker, paper, and cork.
Ease of Use
Some dyes are easier to use than others. For example, direct dyes are simple to use and require only hot water to activate. Other dyes, such as fibre-reactive dyes, require more preparation and may be more difficult to use.
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Ultimate Guide
Q: What are the raw materials of disperse dyes?
Q: What are the properties of disperse dye?
Q: Why disperse dye are insoluble in room temperature?
Q: What is the fastness of disperse dye wash?
Q: How are disperse dyes applied?
Q: What is the difference between reactive and disperse dyeing?
Q: Are disperse dyes synthetic?
Q: Can you use disperse dye on cotton?
Q: Why disperse dye is suitable for polyester?
Q: What is the class most important of disperse dye?
Q: What is the difference between solvent dye and disperse dye?
Q: Why reduction clearing is necessary after disperse dyeing?
Q: How to strip disperse dye?
Q: At what temperature does disperse dye sublimate?
Q: What is the difference between sublimation and disperse dye?
Q: Do disperse dyes undergo chemical changes during the printing process?
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