Identifier: TDX:3399
Authors: Guillem Parra, Maite
Abstract:
The synthesis of polyurethanes (PUs), based on the reaction of an isocyanate and an alcohol or polyol, offers a wide range of possibilities that leads to a large number of materials with different properties. However, the main drawback of this synthesis is the high toxicity of the isocyanates, as well as their reactivity and sensitivity to humidity. To solve this, this thesis focuses on the study of PUs with blocked isocyanate groups, so that the blocking agent is released with increasing temperature and / or in the presence of nucleophilic groups, leaving the isocyanate group free and enabling its subsequent reaction with said nucleophiles.
In this work, the use of conventional isocyanate blocking agents, such as methyl ethyl ketoxime (MEKO), 3,5-dimethylpyrazole (3,5-DMP), diisopropylamine (DIPA), imidazole and ε-caprolactam, has been studied. PUs with isocyanate groups blocked with said blocking agents have been synthesized for two applications: 'high solids' for synthetic leather and aqueous dispersions as color fixatives in textiles.
One of the great challenges of today's society is sustainability and at an industrial level, both the reduction of pollution and the toxicity of the materials used are of great interest. Most of the aforementioned blocking agents are toxic, which is the reason of studying the synthesis and use of new blocking agents: butyl formate and the oximes of methyl acetoacetate, methyl vinyl ketone, derivatives of levulinic acid and of methyl pyruvate.
The oxime of methyl levulinate is the one that has given the best performance, so it has been used for the synthesis and application of PUs in the mentioned applications. Due to the good results, a toxicity study has been carried out, its synthesis has been optimized for scaling up to a pilot plant and its use has been patented.
Repositori URV