[article]
| Titre : |
The chemistry of zirconium tannage |
| Type de document : |
texte imprimé |
| Auteurs : |
A. L. Hock, Auteur |
| Année de publication : |
1975 |
| Article en page(s) : |
p. 181-188 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Tannage au zirconium
Tannage minéralTannage dans lequel interviennent différents minéraux. Le plus répandu est le tannage aux sels de chrome, mais aussi à l’aluminium
|
| Index. décimale : |
675.2 Préparation du cuir naturel. Tannage |
| Résumé : |
Zirconium tannage, i.e. the mechanism by which zirconium-containing ions present in acid aqueous tanning solutions of varying compositions and complexity react at pH values ranging from about 1 to 3 to form the pattern of cross-linkages which imparts to skins the properties associated with leather, is still far from being elucidated.
One underlying reason is undoubtedly the present imperfect knowledge of the structure of collagen fibres themselves. The fibrils appear to consist of twined triple units of polypeptide chains of differing lengths, the repeating pattern of amino acid residues, joined together by peptide links being based roughly one-third on glycine, one-third on alanine plus other amino acids, and one-third on imino acids comprising about equal parts of proline and hydroxy-proline.
The links which join the polypeptide chains together to form the triple chain structures are mostly hydrogen bonds, but there may also be some covalent bonds of the aldol type which are derived from the basic amino acid lysine in adjacent chains. It has also been shown that collagen chains have primary structures containing more amorphous regions, rich in polar amino acid residues (with acidic and basis ionising properties) and more crystalline regions rich in imino acid and non-polar amino acid residues.
However, the present lack of a generally accepted explanation of zirconium tannage chemistry seems to be due at least as much to want of knowledge concerning the structure of the dissolved zirconium with which collagen combines at the moment that the tanning reaction takes place. This applies to published laboratory investigation of tannage chemistry as well as to conclusions based on more practical tannage.
The complexity of aqueous zirconium chemistry, particularly that of the sulphate salts which prevail in the leather industry, has long been recognised. Attempts to rationalise the often conflicting published information were made before 1960, notably by Blumenthall, but it is fair to say that true appreciation of the complex structure of zirconium ions-and therefore their likely bonding characteristics-only began to be possible within the last 15 years or so.
Better understanding of aqueous zirconium chemistry has corresponded with higher consumption of zirconium compounds by various industries and increased interest in the mechanisms of the reactions involved. Much of the published work has been done in USA and USSR. It was, of course, not available to the Somerville school, Lassère, Reed and co-workers, and others who pioneered zirconium tannage and have sought to explain its chemistry.
The hydrolytic and polymerisation reactions of zirconium cations which take place spontaneously, or can be promoted, in zirconium oxychloride solutions and their effects on the structure of these ions were discussed by Clearfiels about ten years ago. He also speculated on the structure of zirconium ions in sulphate solutions. Zirconium oxychloride solutions have been recently investigated more fully by Rijnten. The aqueous chemistry of zirconium and the bonding between hydrous zirconium oxide and other substances in industries other than leather tannage were reviewed in 1974. |
| Note de contenu : |
- Structure of zirconium ions
- Review of theories of zirconium tannage
- General comment
- Older comment
- Recent comment
- Ranganathan and reed
- Williams-wynn
- Babich and shapilskaya |
| En ligne : |
https://drive.google.com/file/d/1-9PtSYX_dNeYvKlQ2YH8KP5DaIl2_uD6/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31864 |
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 59, N° 6 (11-12/1975) . - p. 181-188
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The chemistry of zirconium tannage in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 59, N° 6 (11-12/1975)
