Vat dyes are made from naturally not synthetically. these dyes are windly used for coloration of cellulose materials such as cotton.
This dyes is also used as a indigo dye for colouration of jince or denim materials. this dyes are given good overall fastness property. its application process is near similar as Sulphur dyes.
If you want to know about vat dye, dyeing of cotton with vat dye, vat dyeing process and more then hold your seat and be with the end of guide.
Vat dye is used for coloration on textile materials, such as cotton materials. vat dye are made from naturally, so vat dye is called indigo dye. it is natural Colouring materials. Vat dye are insoluble in water but with the help of vatting process vat dye is easily soluble in water. then dyeing is done. i mean to say that vatting is required for before dyeing.
• this dye is the oldest base dye. This dye are made from natural plants.
• This dye are normally made from naturally not synthetically.
• Vat dye is more suitable for cellulosic fiber for best overall fastness properties.
• This dye is also be called indigo dye which is windly use for dyeing of denim fabric.
• Vat dye is the one of the most important or popular dye in the world in present time.
• Vatting process is must be necessary before dyeing.
• It can be converted insoluble to soluble form with the help of vatting process.
• This is the reasons, that vatting process is very important before dyeing.
• This dyes have good affinity for cellulose materials.
• In case of vat dyeing, vatting process is necessary to required before dyeing.
• In case of vatting process, converting insoluble vat dye by strong reducing agent.
• Vat dye displays no substantivity towards cellulose but with the help of suitable reducing agent and alkali convert the insoluble vat dye to its soluble leuco form results in change of colour.
•They are substantively for cotton. Reducing agent is used in vat dyeing.
• most commonly (Na2S2O4) it’s helps to convert easily in leuco form.
• This vat dyeing process is used from very long time in textile industry for dyeing of cellulose materials.
• vat dyeing process is used for production of denim, jeance products.
• Vat dyeing process is very complex compared with other dyeing methods such as reactive dyes,basic dyes.
vat dye are more difficult to reduced then sulphur dye.
vat dye displays no substantivity towards cellulose but with the help of suitable reducing agent and alkali convert the insoluble vat dye to its soluble leuco form results in change of colour.
Sodium dithionite (work as a reducing agent) they are windly use in vatting.
Sodium dithiouite are more popular reducing agent are mostly used in case of vatting process.
Dihydropyrane, Na2S2O4.2H2O and hydrose are mostly used in case of vat dyeing.
Dyeing Process
• Vat dyeing process is one of the best or profitable methods for cellulose materials.
• This vat dyeing process is gives satisfactory results especially on cellulose materials.
• This vat dyeing process is complex compared with other dye process.
• This dye is not proper soluble in water this is the reason, can not be used directly for dyeing.
• in case of vat dyeing, vatting process is necessary to required before dyeing.
• In case of vatting process, converting insoluble vat dye by strong reducing agent.
Recipe
vat dye – 1 %
wetting agent – 1.5 g/L
sequestering agent – 0.75 g/L
caustic – 4%
hydrose – 3%
salt – 20 g/L
M:L – 1:10
Temp – 60-100C
The vatted dye are substantive to the cellulose material.
Vat Dyeing is carried out at lower temp for proper exhaustion.
on electrolyte is added to the dye liquor.
temp should be 20-60°C and agitated for 15 mint.
the cellulose materials are total immersed to prevent premature oxidation.
3. Re-oxidation treatment
• In this case dye in its soluble leuco form is converted to the original pigment by oxidation.
• This process is carried out in the source of wet treatment With the help of addition of oxidants such as hydrogen peroxide.
4. After Treatment
• In this process, after dyeing some pigment particles is present on the surface of materials.
this is carryout with the help of detergent at boiling temp.
• But removing pigment particles is necessary with the surface of the fabric because these treatment gives final or proper shade.
• Soaping are required for removing pigment particles with the surface of the fabric.
• Which gives the material final shade and improved the fastness properties typical of vat dye.
It gives different type of shade.
Advantage of vat dyes
• Excellent light fastness.
• Vat dyes have good stability for cotton dyeing and printing.
• High reproducibility.
• produce full range colours.
• vat dyes are produce better shade for blend materials.
• vat dyes are produced excellent wet fastness.
Disadvantage of vat dyes
• Poor rubbing fastness.
• costly process
• In this process, first vatting is required before dyeing.
Frequently Asked Question
1. What is diffrence between Vat dyes and solubilised vat dyes?
Vat dyes
• Water insoluble
• More affinity for cell-OH in form of sod salt of leuco vat.
• No affinity for protein fibre.
• Chemically it is sod salt of leuco vat dye.
Solubilised vat dyes
• Solubilised vat dyes are properly soluble in water.
• Low affinity for cell-OH (cellulosic materials).
• Good affinity for protein fibre or materials.
• Chemically it is sod salt of sulphuric ester of leuco vat dye
• this dyes is not able to dye protein materials such as wool and silk materials.
2. What is oxidation dyeing vat?
oxidation dyeing vat, in this process wet treatment (washing) is carried out after dye absorption by the fibre.
In case of wet treatment ( washing is carried out with hydrogen peroxide).
In this case vat leuco form is converted to pigment by oxidation.
3. What is indigo dyes?
Indigo dye is an organic compound.
Indigo dyes are made from naturally.
In other words, indigo dyes are made from extracted of leaves of certain plants.
Colour of indigo dyes is light blue.
This dyes is also called natural indigo dyes.
This dyes are using vary old time for dyeing purpose in textile industry.
Indigo dyes are used for dyeing of denim materials.
It gives good results on denim materials.
4. What is Anthraquinone vat dyes?
Anthraquinone dyes are insoluble in water.
Anthraquinone vat dyes have good quality to produce brilliant colours and good washing fastness.
Anthraquinone dyes are insoluble in water.
In other words, the solubility ability of Anthraquinone dyes is not good in water.
Some important treatment is required for improving solubility in water.
All medium hydro sulphite is used as a reducing agent for improving solubility in water.
If treatment is done properly then the dye is easy to penetrate into the fabric.
It is given even dyeing.
5. What is dyes and classification?
Dyes are colorful organic compound that are used to impart color on Different materials such as leather, hair, cosmetics, plastic and textile materials.
dye is used in solutions form on textile materials and dye have able to fixed to a fabric.
6. How are vat dye applied to cotton?
Vat dye are insoluble in water.
It become soluble with the help of vatting process.
This process is done with the help of strong reducing agent.
They make water soluble pigment is called leco form.
Vat dye are more sensitive to cotton.
vat dye are more suitable for dyeing of cellulose materials.
7. What is the difference between vat dye and reactive dye?
Vat dye – vat dye are insoluble in water and its required solubilized form for dyeing purpose and then oxidation is done after adsorption. these are the process of vat dye.
Reactive dye – reactive dye are soluble in water so this dye is easy to make a covalent bond with the hydroxyl group of cellulose. then dyeing is done. these are the process of reactive dye.
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