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The effect of retannage and nature of the finish on water vapour permeability / A. W. Landmann in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 1 (01/1970)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 54, N° 1 (01/1970) . - p. 3-26 Titre : The effect of retannage and nature of the finish on water vapour permeability Type de document : texte imprimé Auteurs : A. W. Landmann, Auteur ; A. Sofiat, Auteur Année de publication : 1970 Article en page(s) : p. 3-26 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux -- Finition Perméabilité Retannage Vapeur d'eau Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : A number of retannages have been compared with an unretanned control after applying acrylate, butadiene acrylonitrile-polyvinylidene chloride and nitrocellulose finishes by normal pad and spray or airless spray techniques. It has not been found possible to relate water vapour permeability with the percentage set achieved in the laboratory preforming test. There is some evidence that preforming results in a reduction in break and a loss of flexibility of the finish. Impregnation with an acrylate resin reduces water vapour permeability and the percentage set in preforming but prevents the reduction in break due to preforming. Other properties assessed were substance, area changes due to retannage, water absorption, wet rub resistance, whiteness, cover, gloss, cold crack, wet adhesion, the heat resistance of the finish and heat resistance of the leather by the nip line test. Note de contenu : - PLAN OF THE EXPERIMENTS : Factors varied and levels of the factors - Statistical Plan - Experimental details - Tests applied - - RESULTS : Substance - Water absorption - Break - Whiteness - Gloss - Cold crack resistance - Wet rub fastness - Wet adhesion - Heat resistance - Water vapour permeability - Preforming - Flexing resistance - - The effect of the principal factors on all the properties of the finished leather retannage - Type of finish - - Impregnation - Quantity of finish - Method of application En ligne : https://drive.google.com/file/d/1B-e0ErKkB8yPKFwWryB5v8ipIlFwESSR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40720 [article]

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Consideration of the vegetable tannin chromium-collagen system / D. A. Williams-Wynn in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 1 (01/1970)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 54, N° 1 (01/1970) . - p. 27-35 Titre : Consideration of the vegetable tannin chromium-collagen system Type de document : texte imprimé Auteurs : D. A. Williams-Wynn, Auteur Année de publication : 1970 Article en page(s) : p. 27-35 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux pH Prétannage Retannage Tanins végétaux Tannage au chrome Tannage combiné Le tannage combiné se dit des tannages qui allient deux familles ou genre de tannage pour obtenir un résultat additionnant les qualités complémentaires des tannins mis en Å“uvre par exemple Chrome-Végétal ou Chrome-Synthétique Tannage végétal Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Conclusions drawn from the experimental evidence of a series of publications are discussed and co-ordinated. Chromium pretannage of the collagen increases its reactivity towards vegetable tannins by liberating charged amino groups and other sites not normally available, with the result that vegetable tannins are rapidly absorbed in the surface layers of the skin, and this in turn causes over-loading of the fibre and increased cross-Iinking, both of which tend to give weak leather. In addition, it has been shown that vegetable tannins and non-tannins form co-ordination compounds with the chromium in the leather, displacing sulphate with a consequent increase in acidity. The possibility exists, especially in retanning with hydrolysable tannins, that protein carboxyl groups may be displaced from the chromium-collagen complex with the result that a degree of detannage occurs. Moreover, on ageing, the reaction of the vegetable tannins with the chromium-collagen complex continues, with the displacernent of additional sulphate groups and a further increase in acidity which is thought to promote the hydrolytic degradation of the protein and results in the deterioration of this type of leather. The strength of the leather can be improved by reducing the avidity of the chromium tanned pelt so that a more uniform distribution of the vegetable tannin is obtained, and durability is increased by the inclusion of compounds which react preferentially with the chromium-collagen complex and inhibit the entry of vegetable tannins so that the acidity of tne leather is maintained at a satisfactorily low levet. Choice of the type of vegetable tanning extract is also of importance; members of the hydrolysable group of tannins should be avoided because of their greater reactivity with chromium compared with the condensed tannins. Note de contenu : - Quantity of chromium offered - Basicity of chromium salt - Masking of chromium salt - Type of retanning material - Non-tannins in vegetable tanning extracts - Quantity of tannins offered - Temperature of retannage - pH of retannage - Type of collagen substrate - Ageing En ligne : https://drive.google.com/file/d/1vKDGZrdPAEOGIwDCaUcAkdzFfcQWcs08/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40721 [article]

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