Leather Technology

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http://etd.aau.edu.et/handle/12345678/131

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Browsing Leather Technology by Author "Aravindhan, R. (PhD)"

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    High Performance Glove Leather from Goat Skin: Role of Physico-Chemical Properties
    (Addis Ababa University, 2014-09) Tarekegn, Jida; ChandraBabu, N.K. (PhD); Aravindhan, R. (PhD)
    The chemical and physical characteristics of the goat skins are essential to make glove leathers. The characteristic of skin can be analyzed by using Scanning Electron Microscope (SEM), light microscope and studying histological structure of the skin as well as through various chemical characteristics. The fiber opening operation as well as the post tanning auxiliaries like syntans and fatliquors are known to significantly influence the properties of glove leathers. The right choice of lyotropic agents, fatliquors and syntans are critical to obtain the leathers with good gloving property. Hence, in this thesis an attempt has been made to study the physico-chemical properties of the skin and to study systematically the influence of various lyotropic agents, fatliqours and syntans on the gloving properties of leather made from goat skins. Care was taken to ensure that the properties of gloving leathers viz.run, softness, strength properties and other subjective properties like smoothness and stretch based on the physico-chemical properties of the skin were obtained.
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    Improvement of Colour Uniformity During Dyeing Operation: The Case of Dress Gloving Leather
    (Addis Ababa University, 2018-06-17) Wondwossen, Mamuye; Berhanu, Assefa (PhD); Aravindhan, R. (PhD); Jawahar, Malathy (Mrs.)
    In leather industry, the tanner produces a production lot with large number of leather samples to match a colour provided by a client. However, even when the leathers are dyed with the same colorants under well monitored conditions may show some colour non-uniformity. This is highly challenging today for leather manufacturers, especially glove producers to sort colour of leathers consistently. The present study is focused on identifying the factors of colour variation during dyeing operation and reducing colour non-uniformity by managing the factors with welldesigned dyeing recipe. Dyeing properties of the dyestuffs was investigated, by choosing two commercially available dye stuffs. Factors of colour non-uniformity are identified by conducting dye trials on possible causes of colour non-uniformity with four different well-designed dyeing recipes. When concentration of dyestuff, substance of skin or length of dyeing float are varied individually keeping others factors the same, a perceivable total colour difference (∆E*≥0.5) is observed. Controlling and monitoring of colour non-uniformity is analyzed by conducting dye trials using four different well-designed dyeing recipes viz. reverse dyeing recipe, regular dyeing recipe, the multiple stage dyeing recipe and regular dyeing recipe with dye levelling agent. The total colour difference (∆E*) values obtained using multiple stage dyeing recipe was smallest as compared to the other three recipes by varying all possible factors of colour non-uniformity individually. From these observations, multiple stage dyeing recipe was the best alternative way to manage colour non-uniformity.
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    Manufacture of High-Performance Sheep Upper Leather From Low Quality Sheep Skins in Selection Through Process Upgradation and Optimization
    (Addis Ababa University, 2018-06-27) Wondimu, Wolde; Abubeker, Yimam (PhD); Aravindhan, R. (PhD)
    The quality of a raw material for any manufacturing industry or firm is one of the decisive factors controlling its productivity and profitability. Leather processing industries are no exceptions to this fact. The decline of quality raw material supply for the leather processing industries is a great challenge to be competent and survive in the industry these days. The quality of the raw material is largely affected by different factors. The problems leading to lower selection of raw skins or semi-processed skins in industry are categorized as ante-mortem and post-mortem defects. Especially the ante-mortem defect caused by ecto-parasite attack on the skins surface is one of the major problems for downgraded selection of sheep and goat skins. In this research work, an attempt has been made to upgrade poor and reject wet blue leathers due to mange disease damage or “Ekeke” on sheep skin. The problem of lower quality selection of skins could be improved and upgraded into better quality shoe upper leather by working on suitable leather processing techniques for covering the defects of mange damaged skins in wet-finishing and finishing by upgradation and optimization. In wet- finishing process, filler waxes and pigments combination were employed for upgradation. This has resulted in improved coverage of defects on dyed crust leathers. Physical strength tests and organoleptic property assessments performed on the treated leathers are found to be good. The optimized process of dyed crust leather is taken further for finishing, where five finishing methods were chosen for upgrading the uncovered defects in wetfinishing. Waxy, metallic, corrected grain and cationic finishing were employed against the conventional resin finishing. With cationic finishing, an improved and upgraded leather was obtained with better natural look or appearance of grain, good covering and comparable physical and organoleptic properties and better grade.