| Titre : |
Waterborne dimethylolpropionic acid-diisocyanate adducts with alkali-deblockable isocyanate groups as pretanning agent for chrome tanning |
| Type de document : |
texte imprimé |
| Auteurs : |
Jie Liu, Auteur ; Zhou Xu, Auteur ; Chen Yi, Auteur ; Haojun Fan, Auteur |
| Année de publication : |
2015 |
| Article en page(s) : |
p. 43-53 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Agents de tannage
Bisulfite de sodium
Caractérisation
Collagène
Cuirs et peaux -- Propriétés organoleptiques
Cuirs et peaux de chèvres
Diisocyanates
Eaux usées -- Analyse
Isocyanates
Morphologie (matériaux)
Propionique diméthylol, Acide
Réticulation (polymérisation)
Stabilité au stockage
Structure chimique
Tannage au chrome
|
| Index. décimale : |
675.2 Préparation du cuir naturel. Tannage |
| Résumé : |
Diisocyanates qualify as tanning agent by virtue of their strong tendency to crosslink collagen molecules by reacting with amino groups. However, due to their sensitivity to water, these compounds cannot be used directly in aqueous environment, which is the basis for leather processing. To address this problem, waterborne dimethylolpropionic acid-diisocyanate adducts (WDDAs) with temporarily-blocked isocyanate terminals were prepared in the present paper by using NaHSO3 as blocking agent, and further evaluated as a pretanning agent for chrome tanning. Fourier transform infrared (FTIR) spectra revealed that the isocyanate terminals in WDDAs were successfully blocked by NaHSO3. The blocked isocyanates were stable under ambient temperature, but prone to deblocking under alkaline condition. The regenerated isocyanates were found still capable of crosslinking collagen molecules to impart hydrothermal stability. In leather tanning, a high shrinkage temperature (Ts>110°C) was achieved by successively treating goat skin with 5 wt% WDDAs and 4 wt% chrome powder. Stereomicroscope and SEM observation further indicated that the WDDA-chrome tanned leather exhibited tight grain surface and well opened up fiber structure in comparison with semi-chrome tanned leather. Due to the presence of carboxyl group in dimethylolpropionic acid, it was also found that WDDAs enhanced the absorption of chromium in the resultant leathers (% chrome uptake> 90%), resulting in significantly less Cr residual in the tanning wastewater. In addition, it is important to note that the usage of salt in pickling process was avoided owing to previous crosslinking of amino groups, which is very helpful for overcoming the problem of total dissolved solid (TDS) related to neutral salts. The tanning effect of WDDAs and their auxiliary function for chrome tanning allow them to be applicable as a pretanning agent, which efficiently alleviates the environmental impact of traditional chrome tanning for sustainability. |
| Note de contenu : |
- EXPERIMENTAL PROCEDURES : Materials - Synthesis of WDDA - Characterization of WDDA - Preparation of gelatin modified by WDDA - Characterization of gelatin modified by WDDA - Tanning trial - Assessment of properties of tanned leathers - Stereomicroscope and scanning electron microscope (SEM) observation - Determination of total chromium in tanning wastewater
- RESULTS AND DISCUSSION : Chemical structure of WDDAs - Storage stability of WDDAs - Conversion ratio - Reaction between WDDA and collagen - Tanning and tanning wastewater analysis - Organoleptic properties of the tanned leather - Morphologies of grain surface and fibers of the tanned leather |
| En ligne : |
https://drive.google.com/file/d/1LnUCMds_IewQVvlX8zlBD7CViyxjvVgo/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23199 |
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 2 (02/2015) . - p. 43-53
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Waterborne dimethylolpropionic acid-diisocyanate adducts with alkali-deblockable isocyanate groups as pretanning agent for chrome tanning in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 2 (02/2015)
