Màster universitari en Enginyeria del Cuir
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Treballs de fi de màster universitari en Enginyeria del Cuir de l’Escola Politècnica Superior [Més informació del màster].
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- ItemOpen AccessThe Future of polyurethane applications in leather: are NIPUs suitable candidates?(2024-09) Gil i Rosselló, MontseLeather is a durable material obtained from tanning or chemical treatment of animal skin, it is a by-product of the slaughter of the meat industry with great variety of applications. But it is far-away from green chemistry principles, it is a very unsustainable activity which consumes large amount of resources and generates a great number of pollutants. For this reason tanning industry is continuously focused in developing new greener production strategies. The production of leather goods is done in different processes by stages: first operations involves from raw hides to wet blue/white (from freezing to tanning), followed by the process from wet blue/white to crust leather (from sammyng to staking) and last process, the finishing, covers from crust leather to cut pieces (from buffing to cutting). Polyurethanes (PUs) are the most common polymers used in leather in the finish process as coating layer. PUs are based on the reaction of isocyanate (NCO) with polyol/amine groups followed by dispersion in solvent. The key of the polyurethanes is the high reactivity of the isocyanate group due to its resonant structure that promotes the reactivity towards nucleophilic attack and allows its versatility. But Isocyanates are in the spotlight both for the synthesis from phosgenation of amines and for the toxicity emanating from isocyanate monomers. On the other side, there is an increasing availability of polyols and amines of natural origin that reduce the pollutant load of polyurethanes and “promotes” its sustainability, beside the use of aqueous dispersion which eliminates the VOCs emission during finishing process. This work proposes more eco friendly and non-toxic alternatives to conventional PUs, using bio-products and/or novel route named NIPU (non-isocyanate PUs) to diminish the use of petroleum-based materials and solvents. To increase the sustainability of polyurethanes, research is being carried out to eliminate the isocyanate component from the synthesis of PUs, i.e. NIPUs. From the proposed routes to generate PUs isocyanate-free: poly-condensation, rearangement, ring opening polymerisation and poly-addition,[1] , the last one seems to be the most encouraging, based on the reaction of polycarbonates and polyamine. This option does not produce by products, it is solvent-free and the raw material used are non-toxic. Polyol are made from crude oil that is a limited resource, many investigations and efforts are done in searching raw material alternative sustainable, either by using agricultural by-products or materials that can be easily regenerated, as vegetal oils, forming the family of bio-polyols. NIPU (Non-isocyanate PU) combine biological and chemical carbon dioxide fixation. They are obtained by reacting polycyclic carbonate oligomers and aliphatic polyamines containing primary amino groups. As intermediate for the synthesis of cyclic carbonates renewable materials as vegetable oils, terpenes and lignin are, later they are cured with group amino. Once the NIPU is synthesized it is dispersed in aqueous media to obtain water-borne PUD
- ItemOpen AccessSaliva i suor en cavalls: Impacte en el cuir des d’una perspectiva química i física(2024-07) Pérez Fosalba, Eirene ZhenAnàlisi química de la saliva i suor equina i anàlisis físiques de les diferents pells i com aquestes reaccionen a la saliva i la suor.
- ItemOpen AccessStudy on The Application of TANEX LF and TANEX LW In Leather Tanning Process(2024-06) Xiaokun, ZhangThis paper studies the application of two isoprene resins, TANEX LF and TANEX LW, in leather tanning. Systematic experiments, the effects of TANEX LF and TANEX LW in the tanning process were analyzed, including their improvements in leather tensile strength, tear strength, waterproof properties and appearance. This study focused on several specific objectives. First, the effect of different pH on leather before tanning was tested. The effect of different pH of resin on the shrinkage temperature during the tanning process was tested. Second, the effect of different concentrations of resin on the shrinkage temperature during the tanning process was tested. Then, the time of resin addition during the tanning process was changed. The results show that isoprene resin shows significant effects in improving the strength and elasticity of leather, but there are certain differences in specific properties. TANEX LF excels in enhancing the strength of leather and is particularly suitable for leather products that require high durability. On the other hand, TANEX LW significantly improves the waterproof properties of leather, making it better in moisture resistance and weather resistance. Taking all factors into consideration, both tanning agents show unique advantages in different application scenarios. This paper also explores the applicability of the two tanning agents under different process parameters and proposes suggestions for optimizing the tanning process. The research results provide important theoretical basis and practical guidance for the leather industry to select suitable tanning agents, and promote the development of green leather tanning technology.
- ItemOpen AccessTanex JG and Tanex L-KRIS two new tanning agents on sheepskin(2024-06) Zhang, YepengThe tanning industry, as a traditional industry with a long history, has always relied on all kinds of animal skins as raw materials for processing, and finally transformed into common leather products in our daily life. However, in the production process of leather, especially in the tanning stage, the traditional process uses some harmful substances that can not only pose a threat to the health of workers, but also cause serious pollution to the environment. Therefore, finding a tanning method that is both environmentally friendly and efficient has become an urgent problem for the tanning industry. In this context, the emergence of two new tanning agents, TANEX JG and TANEX L-KRIS, brings new hope to leather production. These two tanning agents belong to isoprene resins, which are resin materials synthesized from isoprene as the main raw material. Here are the details and features of isoprene resins: Main raw material: isoprene, also known as 2-methyl-1,3-butadiene, is an important organic compound, commonly used in the synthesis of rubber, resins and other polymer materials. Synthesis method: Isoprene can be copolymerized with other monomers (e.g., styrene) to produce resin materials with specific structures and properties. Stickiness: Isoprene resins generally have good adhesion and can be used to make adhesives and sealants. Elasticity: Some isoprene resins have the properties of thermoplastic elastomers, such as TPR resins, which exhibit good elasticity and abrasion resistance during processing and use. Stability: The thermal stability of isoprene resins can be affected by catalyst residues during their synthesis. During the synthesis process, care needs to be taken to control the amount of catalyst and the amount of residue to ensure the thermal stability of the resin. As an alternative to traditional tanning agents, they not only have excellent tanning properties, but are also environmentally friendly, non-toxic, and have minimal impact on the environment and human health. Therefore, this study aims to optimize the tanning process by using these two new tanning agents to improve the quality and performance of the leather.In our research, we focused on two key operational processes:tanning and retanning. In the main tanning stage, we first observe the changes in the tanning effect under different conditions by adjusting the pH value. This is because pH is one of the key factors affecting the binding of tanning agents to leather fibres, and the right pH promotes an effective binding between tanning agents and leather fibres, thereby improving the quality and performance of leather. Next, we adjusted the dosage of the two tanning agents, TANEX JG and TANEX L-KRIS, and observed the difference in tanning effect at different amounts. The aim of this step is to find the optimal amount of tanning agent to do, which will guarantee the tanning results and reduce the cost. Through comparative experiments, we determined the optimal range of tanning agent dosage, which provided strong support for subsequent industrial production. During the retanning phase, we compared the tanning effects of TANEX JG and TANEX L-KRIS to two tanning agents. Through comparative experiments, we found that both tanning agents can significantly improve the softness and elasticity of the leather during the retanning process, while maintaining the strength and stability of the leather. This discovery provides an important reference for us to further optimize the tanning process. Overall, this study provides strong support for the production of high-quality, sustainable and non-toxic leather by exploring the optimal conditions and factors for the two new tanning agents, TANEX JG and TANEX L-KRIS. Although there are some limitations in this study, such as the use of only specific types of leather and laboratory conditions, our results still have important guiding significance for the future development of tanning technology. With the continuous advancement of technology and the growing market demand, we believe that these two new tanning agents will play an increasingly important role in the future tannery industry.
- ItemOpen AccessCombination Tannage with THPS and Different Metals(2024-06) Yang, JinThe tanning process transforms raw hides into leather utilizing a range of specialized physicochemical techniques and distinct tanning agents. Following the invention of the chrome tanning method in 1858, chromium-based tanning agents have been extensively utilized in modern leather production processes. Today, more than 90% of leather production enterprises globally employ chromium-based agents. However, chromium resources are non-renewable, and their excessive consumption has led to a gradual depletion of these resources. Additionally, the management of chromium-containing wastewater and solid waste presents significant challenges, with direct discharges posing severe environmental pollution risks. Moreover, under oxidative conditions, often exacerbated by industrial processes, trivalent chromium can convert into hexavalent chromium, a highly toxic variant that poses serious health risks when accumulated in the human body. Therefore, chrome-free tanning as a clean technology has been a focal point of research within the field of leather chemistry aimed at reducing chromium usage. Currently, chrome-free tanning agents are categorized based on their fundamental characteristics into three main types: metal-free tannins, organic non-chrome tannins, and combined organic-metal (non-chrome) tannins. Metal tannins excluding chromium often suffer from issues such as weak tanning properties, poor water resistance, and inferior leather performance; organic non-chrome tannins are challenged by their strong negative charge which complicates re-tanning and dyeing processes. Consequently, the integration of organic and non-chromium metal tannins represents a promising direction in chrome-free tanning. This study investigates the synergistic effects of combining Tetrakis (hydroxymethyl) phosphonium sulfate (THPS) with metal tannins. This research provides a comprehensive analysis and experimental validation of an innovative chrome-free tanning methodology. The results demonstrate that this approach significantly enhances tanning performance and ultimately improves leather quality, possessing potential for commercialization.