AZO

Japan updates azo limit requirements in textiles, scheduled to take effect on April 1, 2016

      AZO偶氮 compounds are compounds formed by the connection of the azo group -N=N- with two hydrocarbon groups, and their general formula is R-N=N-R. Terms related to AZO偶氮 compounds in daily life include: azo free, azo free certificate, azo free test, azo fuel, azo dye, etc. Materials involving AZO偶氮 compounds mainly include: cloth, leather, paint, plastic, rubber, coloring agents, etc.

      The structure and formation of AZO azo compounds, which exhibit cis and trans geometric isomers; the trans form is more stable than the cis form, and the two isomers can convert to each other under exposure to light or heat. Azo compounds are primarily synthesized through the coupling reaction of diazonium salts; hydrogenated azo compounds and aromatic amines can be oxidized to the corresponding azo compounds in the presence of oxidants such as NaOBr, CuCl2, MnO2, and Pb(OAc)4; oxidized azo compounds and nitro compounds can also be reduced to azo compounds in the presence of reducing agents such as (C6H5)3P and LiAlH4. The azo group serves as a chromophore, and azo dyes constitute the most diverse and widely used class of synthetic dyes. Certain azo compounds are utilized as acid-base indicators and metal indicators in analytical chemistry. Others function as initiators for polymerization reactions, such as azobisisobutyronitrile. 

      The hazards and restrictions of AZO azo compounds are significant. Many azo compounds have carcinogenic effects, such as crema yellow, which was once used for coloring margarine and can induce liver cancer, and is now banned; methyl red, used as an indicator, can cause bladder and breast tumors. Although some azo compounds do not cause cancer, their toxicity is similar to that of nitro compounds and aromatic amines. To protect human health and ensure consumer safety, the Netherlands, Austria, and Germany have successively adopted mandatory regulations to prohibit the use of azo-containing colorants in consumer products. On September 11, 2002, and January 6, 2003, the European Parliament and the European Commission also issued Directives 2002/61/EC and 2003/3/EC, respectively, restricting the use of carcinogenic azo colorants in certain textile and leather products and prohibiting the sale of goods colored with restricted azo colorants. Directives 2002/61/EC and 2003/3/EC have been gradually incorporated into national laws and have taken effect on September 11, 2003, and June 30, 2004, respectively. Among 22 types of aromatic amines, the content of azo colorants (aromatic amines) in one or more types of aromatic amines should be less than 30 mg/kg. Additionally, the content of the blue colorant with index number 611-070-00-2 in any product should be limited to 1000 mg/kg.

The twenty-four carcinogenic aromatic amine dyes currently banned by the European Union include:

1. 4-Aminobiphenyl

2. Benzidine

3,4-Chloro-2-methylaniline

4. 2-Naphthylamine

5,4-Amino-3,2'-dimethylazobenzene

6. 2-Amino-4-nitrotoluene

7, 2,4-dihydroxymethylether

8. 4-Chloroaniline

9,4,4'-diaminodiphenylmethane

10. 3,3'-Dichlorobenzidine

11. 3,3'-Dimethoxybenzidine

12,3,3'-Trimethylbenzidine

13. 3,3'-Dimethyl-4,4'-diaminodiphenylmethane

14. 2-Methoxy-5-methylaniline

15, 4,4'-Methylene-bis(2-chloroaniline)

16. 4,4'-Diaminodiphenyl ether

17. 4,4'-Diaminodiphenyl sulfide

18. 2-Methylaniline

19. 2,4-Dihydroxytoluene

20. 2,4,5-Trimethylaniline

21. 2-Methoxyaniline

22. 4-Aminoazobenzene

23. 2,4-Dimethylaniline

24. 2,6-Dimethylaniline

Standard No.   Standard Name

§64LFGB BVL B82.02.2 Textiles - Method for Testing Banned Azo Dyes: Part 2: Direct Measurement Method Without Extraction

§64LFGB BVL B82.02.4 Textiles - Methods for the Detection of Banned Azo Dyes: Part 4: Extraction and Determination Method

§64LFGB BVL B82.02.9 Textiles - Method for Testing Banned Azo Dyes: Part 9 - Method for Determining 4-Aminobenzidine

EN 14362-1 Textiles - Method for the Detection of Banned Azo Dyes: Part 1: Method for Direct Determination with and without Extraction

EN 14362-3 Textiles - Methods for the Detection of Banned Azo Dyes: Part 3: Method for the Determination of 4-Aminoazobenzene

GB/T 17592 Determination of prohibited azo dyes

GB/T 23344 Textiles - Determination of 4-Aminoazobenzene

GB/T 24101 Limit and determination of 4-aminoazobenzene in dye products