Restricted Azo Dyes

Restricted Azo Dyes:-

In Textile dyeing, color is the necessary elements. To color fabric or yarn there are various type of color dye. Azo dye is one of them. This azo dyes contains one or more nitrogen-nitrogen double bonds called azo group in their chemical structure –N=N-There are twenty above azo group of dye which are harmful to color fabric or yarn and many other purpose. These azo groups also hazard our health, environmental and also skin contact.

Under reductive conditioning using sodium dithionite, these azo groups can be cleaved to form two amines, which can be shown as figure below:

 There are 22 groups of amine which are restricted by European Union [EU] and this is called restricted azo dyes.

 Consumer goods which often come into contact with the skin. Examples of Consumer goods covered by the restrictions are: Clothing, bedding, towels, hairpieces, wigs, hats, nappies and other sanitary items, Sleeping bags, Footwear, gloves, wristwatch straps, handbags, purses/wallets, briefcases, chair covers, purses worn round the neck, Textile or leather toys and toys which include textile or leather garments, Yarn and fabrics intended for use by the final consumer.

 Azo dyes are used in special paints, printing inks, varnishes and adhesives. Azo-dyed textiles come into close contact with the body will be banned. Tests, based on the current German analysis method, will have to be made on dyed products coming from outside Europe. The group of products seen as potential dangers for skin/azo dye contact includes sleeping bags, neck-strap purses, clothes, bedding, towels, hairpieces, hats, footwear, gloves, wristwatch straps, handbags, purses, chair covers, textile or leather toys, and carpets apart from hand-made oriental ones. If any of these products contain azo dyes they will be banned.

 Restricted Azo Dyes:-

Azo colorants are the most important class of synthetic dyes and pigments, representing 60 - 80% of all organic colorants. They are used widely in substrates such as textile fibres, leather, plastics, papers, hair, mineral oils, waxes, foodstuffs and cosmetics. Hence azo colorants are part of our everyday colorful life, they are all around us and we could not do without them. The English term colorant includes both pigments and dyes. These 2 groups can be conveniently classified as follows; dyes are soluble in the medium of application and pigments are not. In the English version of the Directive the terminology clearly distinguishes between parent term “colorants” and the sub-category “dyes”.

Azo dyes contain one or more nitrogen-nitrogen double bonds called azo groups in their chemical structure, see Fig. 1.

-N=N -

      Fig. 1. Azo group

There are 22 groups of amine which are restricted by European Union [EU] and this is called restricted azo dyes

Table: - Restricted substances list

Substances	CAS Number	Restricted Limit
1.    Benzidine	92-87-5	30 ppm
2.    4-aminobiphenyl	92-67-1	30 ppm
3.    4-chloro-O-toluidine	95-67-2	30 ppm
4.    2-Naphthylamine	91-59-8	30 ppm
5.    O-Aminoazotoluene	97-56-3	30 ppm
6.    2-Amino-4-Nitrotoluene	99-55-8	30 ppm
7.    p-Choloroaniline	106-47-8	30 ppm
8.    4,4-Diamino Diphenylmethane	101-77-9	30 ppm
9.    3,3-Dicholorobenzidine	91-94-1	30 ppm
10.                     3,3-Dimethoxibenzidine	119-90-4	30 ppm
11.                     3,3-Dimethylbenzidine	119-93-7	30 ppm
12.                     3,3-Dimethyl-4,4-Diaminodiphenylmethane	838-88-0	30 ppm
13.                     P-Cresidine	120-71-8	30 ppm
14.                     4,4-Methodylene-bis-(2-chloro-aniline)	101-14-4	30 ppm
15.                     4,4-Oxidianiline	101-80-4	30 ppm
16.                     4,4-Thoianiline	139-65-1	30 ppm
17.                     0-Toluidine	95-53-4	30 ppm
18.                     2,4-Toluenediamine	95-80-7	30 ppm
19.                     2,4,5-Trimethodianiline	137-17-7	30 ppm
20.                     O-Anisidine	90-40-0	30 ppm
21.                     P-amino-azo-benzene	60-09-3	30 ppm
22.                     2,4-Diaminoanisol	615-05-4	30 ppm

     **www.bsr.org/rsl

Azo-dyed textiles and leathers that may come into close contact with the body will be banned. Tests, based on the current German analysis method, will have to be made on dyed products coming from outside Europe.

The group of products seen as potential dangers for skin/azo dye contact includes sleeping bags, neck-strap purses, clothes, bedding, towels, hairpieces, hats, footwear, gloves, wristwatch straps, handbags, purses, chair covers, textile or leather toys, and carpets apart from hand-made oriental ones. If any of these products contain azo dyes they will be banned. Oriental carpets were seen by both the European Parliament and Commission as low risk and have not therefore been added to the list of banned items.

Above the substances that appear on this list are based on global legislation, have been used in Textile processing and have been found in finished products. Substances listed should be restricted in products according to the limit and test methods provided. Therefore these listed substances are called Restricted Azo Dyes.