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[article]
Titre : Neutralising chemicals Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 108-111 Langues : Anglais (eng) Catégories : Neutralisants (chimie)
pH
Post-tannage
Wet-blue (tannage)Peau tannée au chrome (le chrome donne une couleur bleue)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : In the post tanning operations of a tannery, a heavy dependence is laid on the pH values of the wet end stage. It has been known rince the acceptance of chromium as a viable tanning method that the post tanning operations play a large role in helping to decide the final properties of the resulting leather.
For a chemist trained outside of the tanning industry, the term neutralisation means to take the bath pH value from either an alkaline or an acidic value to the neutral point (pH 7). This is not what tanners mean when they refer to neutralisation (the pH is very seldom pH 7). Others will refer to neutralisation as to the neutralisation of electrical charge in the leather collagen. Again, the state of electrical neutralisation is very seldom complete. Tanners seldom get to the iso-electric point, IEP (see Table 1), but the act of neutralising is certainly something that does take place.
The obvious way forward is not to refer to the operation in chromium tanned leather as neutralisation, but rather as neutralising. Another version of neutralising is taking the leather, electrically, to the IEP (neutralisation) and beyond, see Figure 1. This is often referred to as anionisation and is a common tactic in the preparation of water-resistant leathers. Another common anionisation or true neutralisation is seen in the manufacture of wet-white leathers or in vegetable tanned leathers.Note de contenu : - Objectives of neutralising
- Can we leave neutralising out ?
- Types of chemicals
- Table 1 : The theoretical iso-electric point pH values (taken from Sharphouse, 1989)
- Fig. 1 : Zeta potential showing the charge according to pH value
- Fig. 2 : Chemical groups of neutralising syntans and agents
- Fig. 3 : Buffering solution pH profileEn ligne : https://drive.google.com/file/d/12ig4wDHBKAasa3LrNUY5jbnVfd6NFnYf/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33627
in INTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 108-111[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21384 - Périodique Bibliothèque principale Documentaires Disponible Oxidized maltodextrin : A novel ligand for aluminum-zirconium complex tanning / Xueru Guo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVI, N° 5 (05/2021)
[article]
Titre : Oxidized maltodextrin : A novel ligand for aluminum-zirconium complex tanning Type de document : texte imprimé Auteurs : Xueru Guo, Auteur ; Yue Yu, Auteur ; Ya-Nan Wang, Auteur ; Bi Shi, Auteur Année de publication : 2021 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Aluminium L'aluminium est un élément chimique, de symbole Al et de numéro atomique 13. C’est un métal pauvre, malléable, de couleur argent, qui est remarquable pour sa résistance à l’oxydation13 et sa faible densité. C'est le métal le plus abondant de l'écorce terrestre et le troisième élément le plus abondant après l'oxygène et le silicium ; il représente en moyenne 8 % de la masse des matériaux de la surface solide de notre planète. L'aluminium est trop réactif pour exister à l'état natif dans le milieu naturel : on le trouve au contraire sous forme combinée dans plus de 270 minéraux différents, son minerai principal étant la bauxite, où il est présent sous forme d’oxyde hydraté dont on extrait l’alumine. Il peut aussi être extrait de la néphéline, de la leucite, de la sillimanite, de l'andalousite et de la muscovite.
L'aluminium métallique est très oxydable, mais est immédiatement passivé par une fine couche d'alumine Al2O3 imperméable de quelques micromètres d'épaisseur qui protège la masse métallique de la corrosion. On parle de protection cinétique, par opposition à une protection thermodynamique, car l’aluminium reste en tout état de cause très sensible à l'oxydation. Cette résistance à la corrosion et sa remarquable légèreté en ont fait un matériau très utilisé industriellement.
L'aluminium est un produit industriel important, sous forme pure ou alliée, notamment dans l'aéronautique, les transports et la construction. Sa nature réactive en fait également un catalyseur et un additif dans l'industrie chimique ; il est ainsi utilisé pour accroître la puissance explosive du nitrate d'ammonium.
Croûte (cuir)On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés.
Cuirs et peaux -- Propriétés physiques
Maltodextrine
Oxydation
Poids moléculaires
Post-tannage
Taille des particules
Tannage minéralTannage dans lequel interviennent différents minéraux. Le plus répandu est le tannage aux sels de chrome, mais aussi à l’aluminium
ZirconiumIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Hydrogen peroxide (H2O2) oxidized maltodextrin was prepared as the ligand for aluminum–zirconium complex tanning. The effects of catalyst dosage, initiation temperature, and H2O2 dosage on maltodextrin oxidation were investigated. FT-IR analysis demonstrated that carboxyl groups were successfully introduced into oxidized maltodextrin. The carboxyl content and degradation degree of oxidized maltodextrin increased with the increase of H2O2 dosage. Maltodextrin oxidized by 40% H2O2 and 0.015% Cu–Fe catalyst at an initiation temperature of 70°C (OD-40) with moderate carboxyl group (6.75 mmol/g) and molecular weight (Mw 450) promoted the penetration and fixation of aluminum–zirconium salts in leather and showed better tanning performance, such as hydrothermal stability and porosity of leather, than traditional citric acid ligand. Note de contenu : - EXPERIMENTAL : Materials - Preparation of oxidized maltodextrin - Determination of decomposition rate of H2O2 - Determination of carboxyl content - Determination of colority - Fourier Transform Infrared (FT-IR) spectroscopy analysis - Determination of molecular weight and particle size - Tanning trials
- RESULTS AND DISCUSSION : Effect of catalyst dosage on maltodextrin oxidation - Effect of initiation temperature on maltodextrin oxidation - Effect of H2O2 dosage on maltodextrin oxidation - Tanning performance
- Table 1 : AlZr complex tanning process for cattle hide
- Table 2 : Post-tanning process
- Table 3 : Properties of tanned leather
- Table 4 : Physical properties of crust leatherDOI : https://doi.org/10.34314/jalca.v116i5.4293 En ligne : https://drive.google.com/file/d/1HVgMS3-lKqGrvz4WJbsKSv7H_dpO-003/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35758
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVI, N° 5 (05/2021)[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 22726 - Périodique Bibliothèque principale Documentaires Disponible Physical and fastness properties of leather dyed with a natural dye extracted from beetroot peels using a biomordant / Louret A. Andalo in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 107, N° 6 (11-12/2023)
[article]
Titre : Physical and fastness properties of leather dyed with a natural dye extracted from beetroot peels using a biomordant Type de document : texte imprimé Auteurs : Louret A. Andalo, Auteur ; Paul K. M. Sang, Auteur ; Rose Tanui, Auteur Année de publication : 2023 Article en page(s) : p. 226-231 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Acacia et constituants
Colorants végétaux
Cuirs et peaux -- Propriétés mécaniques
Cuirs et peaux -- Propriétés physiques
Cuirs et peaux -- Teinture
Cuirs et peaux de chèvres
Mordants (chimie)
Post-tannage
Tannage au chromeIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather dyeing is an essential process in the leather industry, where synthetic dyes are predominantly used. However, the environmental concerns associated with synthetic dyes have led to rising interest in natural dyes as sustainable alternatives. The use of biomordants is however, gaining attention due to their eco-friendly nature and potential to enhance dye fixation and colour fastness. This study aimed at determining the physical and fastness properties of leather dyed using natural dye extract from beetroot peels with the assistance of a biomordant derived from Acacia nilotica barks and banana pseudo stem sap. The dyeing process involved the use of the biomordant in both a pre and post-mordanting technique. Various fastness properties of dyed leather were investigated to assess the quality and durability of the dyeing process including water spotting fastness according to ISO 15700, mild washing fastness according to ISO 15703, and rub fastness (dry and wet rub fastness) according to ISO 11640. To determine the effect of the biomordant on the strength properties of the leather, the physical properties of the dyed leather were also evaluated. The tensile and tear strength of the dyed leather were measured on an Instron using IUP 6. The dye bath exhaustion was measured using spectrophotometric analysis. The dyed leatherʼs fastness properties were discovered to be good to excellent on a grey scale of 5. All of the samples exceeded the minimum recommended values (UNIDO 1996) for tensile strength (>20N/mm2), percentage elongation at break (>40%), and tear strength (>30N/mm). The samples dyed with Acacia nilotica bark as a biomordant had the highest dye bath exhaustion, followed by banana pseudo stem sap, and leather dyed without any mordant had the lowest dye bath exhaustion. According to the results obtained in this study, the use of biomordant in the dyeing of leather with natural dye from beetroot peels improved the fastness properties of the dyed leather as well as the strength of the resulting leather. Furthermore, the biomordant promoted dye uptake. Note de contenu : - MATERIALS AND METHODS : Materials - Methods - Physical properties of the dyed leather
- RESULTS AND DISCUSSION : Analysis of the physical properties of the dyed leather -
- Table 1 : Process for pre tanning goatskin
- Table 2 : Process for chrome tanning of goat wet-blue
- Table 3 : Post tanning process
- Table 4 : Tensile strength and percentage elongation of the dyed leather
- Table 5 : Tear strength of the dyed leather
- Table 6 : Fastness properties of the dyed leather both the mordanted and the umordanted samples on a grey scale of 5En ligne : https://drive.google.com/file/d/1G2w2KoZPKkzUblyRJeLJYFRmat4LDXbz/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40242
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 107, N° 6 (11-12/2023) . - p. 226-231[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 24370 - Périodique Bibliothèque principale Documentaires Sorti jusqu'au 14/05/2024 Polyanionic bio-emulsifier : a heteropolysaccharide based bio-composite for leather post tanning process / Sharmila Selvaraju in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 3 (03/2019)
[article]
Titre : Polyanionic bio-emulsifier : a heteropolysaccharide based bio-composite for leather post tanning process Type de document : texte imprimé Auteurs : Sharmila Selvaraju, Auteur ; Sathya Ramalingam, Auteur ; Jonnalagadda Raghava Rao, Auteur Année de publication : 2019 Article en page(s) : p. 72-79 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage
Biomatériaux
Biopolymères
Composites
Cuirs et peaux
Emulsifiants
PolysaccharidesLes polysaccharides (parfois appelés glycanes, polyosides, polyholosides ou glucides complexes) sont des polymères constitués de plusieurs oses liés entre eux par des liaisons osidiques.
Les polyosides les plus répandus du règne végétal sont la cellulose et l’amidon, tous deux polymères du glucose.
De nombreux exopolysaccharides (métabolites excrétés par des microbes, champignons, vers (mucus) du ver de terre) jouent un rôle majeur - à échelle moléculaire - dans la formation, qualité et conservation des sols, de l'humus, des agrégats formant les sols et de divers composés "argile-exopolysaccharide" et composites "organo-minéraux"(ex : xanthane, dextrane, le rhamsane, succinoglycanes...).
De nombreux polyosides sont utilisés comme des additifs alimentaires sous forme de fibre (inuline) ou de gomme naturelle.
Ce sont des polymères formés d'un certain nombre d'oses (ou monosaccharides) ayant pour formule générale : -[Cx(H2O)y)]n- (où y est généralement x - 1). On distingue deux catégories de polysaccharides : Les homopolysaccharides (ou homoglycanes) constitués du même monosaccharide : fructanes, glucanes, galactanes, mannanes ; les hétéropolysaccharides (ou hétéroglycanes) formés de différents monosaccharides : hémicelluloses.
Les constituants participant à la construction des polysaccharides peuvent être très divers : hexoses, pentoses, anhydrohexoses, éthers d'oses et esters sulfuriques.
Selon l'architecture de leur chaîne, les polysaccharides peuvent être : linéaires : cellulose ; ramifiés : gomme arabique, amylopectine, dextrane, hémicellulose et mixtes : amidon.
Post-tannage
RetannageIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Biopolymer-based composites are attracting significant interest in leather processing due to their incremental substitution of petrochemical products as raw materials in the retanning stage. Several polymeric bio-composites were developed and studied as alternatives to synthetic tanning agents (syntans). Bio-composite was prepared by simultaneously dispersing cellulose (acting as syntan) and emulsifying soybean oil with a bio-emulsifier termed Emulsan (acting as fatliquor). The resultant dual propertied of fullness and softness is endowed as a leather supplement to reduce the negative impact on the environment. Hence polymeric bio-composites were prepared through ultrasonication by blending different amounts of cellulose with soybean oil with an optimised Emulsan ratio. In order to enhance the biocompatibility of this bio-composite, the Emulsan surfactant we chose was extracted from Acinetobacter calcoaceticus. The poly-anionic nature of Emulsan serves as a stable surfactant to emulsify soybean oil into cellulose in the composite preparation. The resultant composites were characterised for functionality and physical properties by FTIR, DSC, TGA, and DLS. The value of an example composite in leathers’ post tanning processes was evaluated by utilising it as a retanning agent. Leather treated with a bio-polymeric composite showed improved strength and physical properties versus control leathers. Note de contenu : - MATERIALS AND METHODS : Preparation of emulsan medium preparation and growth conditions - Preparation of extra-cellular emulsan - Preparation of composites samples - Characterisation of prepared bio-composites - Application of composite as a retanning agent during leather post tanning process - Physical testing of the leather samples
- RESULTS AND DISCUSSION : Characteristics of composite treated leatherEn ligne : https://drive.google.com/file/d/1lvynFi0y9G9EtFsCZqg91ON9abL4ISaP/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31927
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIV, N° 3 (03/2019) . - p. 72-79[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 20673 - Périodique Bibliothèque principale Documentaires Disponible
[article]
Titre : Saccharides in leather Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2022 Article en page(s) : p. 44-45 Langues : Anglais (eng) Catégories : Amidon dialdéhyde
Biomatériaux
Carboxyméthylcellulose
Carraghénanes
Cuirs et peaux -- Finition
Glucides
HémicelluloseLes principaux polysaccharides non cellulosiques du bois. Le bois est constitué d'hémicellulose (28 à 35%), de cellulose et de lignine.
hydrocolloïdes
Lignocellulose
Polymères
Post-tannageIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : The November/December 2020 issue of International Leather Maker (page 42) covered the new bio-based materials that are being looked at for the post-tanning and finishing. This article will examine the practical use of the chemistry in today's modern process and will try to explain why these are advantageous. To remind the reader, the materials covered in that editorial article were:
- Nano-biocomposites
- Cellulose grafts
- Regenerated cellulosics
- Lignocelluloses
- Finishing cellulosics.
Since that edition of ILM in 2020, many more polysaccharides have been examined in the use of hydrogel technology, but also a look back in time shows the experience of tanners, the textbooks, leather journals and product sheets shows that saccharides have been used as monosaccharides, disaccharides or polysaccharides for a long time. Substances used include:
- Glucose for the manufacture of chromium salts
- suppression
- Dialdehyde starch
- Disaccharides in heavy vegetable manufacture (filling and grain plasticisation).
The use of dialdehyde starch was first examined in the leather industry in the 1970s. It was used by a few tanner leathers, but then seemed to fade away as other priorities in the industry started to materialise. The industry was also not prepared for the extensive post-tanning that was needed for these leathers. The perfection of the glutaraldehyde tannage would only corne through mastery of chrome-free, post-tanning that was mainly invented in the late 1990s.
Starch structure opening through oxidative ring opening allowed the starch to react, through the Maillard reaction, with the collagen. Large, bulky dialdehyde starch did not always penetrate well and many companies dropped it when they realised that the tannage may result in a raw centre.
Oxidation of saccharides that opens the compound has been modified and tweaked numerous times since the 70s. If the density of the starch opening is high the result will be a polymer that can react with the collagen in several places as the compound can bind with amine, hydroxyl and amide groups along the way. If the leather is not retanned and fatliquored correctly, the leather will be stiff and will have an unpleasant break.Note de contenu : - Biocomposites
- Hydrogels
- Lignocelluloses
- Fig. 1 : The dialdehyde starch polymer
- Fig. 2 : Carboxymethylcellulose
- Fig. 3 : Chemical structure of carrageenan
- Fig. ' : The lignin, cellulose and hemicellulose mass in plantsEn ligne : https://drive.google.com/file/d/1XKQy8bFSD2i3kqaG2C94mfBE2hMHs9b5/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37951
in INTERNATIONAL LEATHER MAKER (ILM) > N° 54 (07-08/2022) . - p. 44-45[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 23483 - Périodique Bibliothèque principale Documentaires Disponible Salinity reduction in the production of nappa skins by using agents with non-swelling capacity in pickling/tanning / Agusti Marsal in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 89, N° 6 (11-12/2005)
PermalinkStudies on the correlation between surface and sewability properties of crust leather / C. Niklesh in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 5 (05/2023)
PermalinkStudies on the physico-chemical behavior of synthetic tanning agents in non-aqueous medium / Gladstone Christopher Jayakumar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXII, N° 8 (08/2017)
PermalinkThe development of an integrated rechroming-neutralization-post tanning proces manufacture of upper leathers from goatskins / T. Ayyasamy in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 89, N° 2 (03-04/2005)
PermalinkTransposition of chrome tanning in leather making / Chao Wu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 6 (06/2014)
PermalinkVegetable tannage for leather fancy goods / N. J. Cutting in WORLD LEATHER, Vol. 6, N° 7 (12/1993 - 01/1994)
PermalinkWet-pink leathers-zirconium-THPS tannage / N. Nishad Fathima in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 91, N° 4 (07-08/2007)
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