PU (PolyUrethane) was firstly invented and introduced in the market in the first half of the 20th century. Recently, its economic value has been grown constantly [1,2]. In a worldwide view, PU represents only 5% of the consumption of polymers [3]. There are two different types of PU: Poly-Ether (PE) PU and Poly-Ester (PES) PU. They differ for their chemical structure, reactivity and mechanical properties. However, for the PE polyurethane, colour is an important parameter to be considered. A low colour value increases the commercial value meaning that polyether structure has been unaltered without chain destruction and formation of new compounds. IR analysis shows that this parameter is connected to carbonylic groups next to double-bonds [3]. A large number of normative of International Standard Organisation (ISO) requires a high value on the grey scale. The yellowing of PE PU, in footwear industry, in particular types of articles, can be linked to yellowing of the synthetic leather. In particular, some degradation products can react with the refinement agents of the leather. This situation has been analyzed by different point of view (chemical and physical analyses) in order to have a better understanding of this drawback and to find a solution of the problem.
PE based polyurethane/leather yellowing in footwear industry: a case study
Riccardo Vallesi;Maura Pellei;Carlo Santini
2020-01-01
Abstract
PU (PolyUrethane) was firstly invented and introduced in the market in the first half of the 20th century. Recently, its economic value has been grown constantly [1,2]. In a worldwide view, PU represents only 5% of the consumption of polymers [3]. There are two different types of PU: Poly-Ether (PE) PU and Poly-Ester (PES) PU. They differ for their chemical structure, reactivity and mechanical properties. However, for the PE polyurethane, colour is an important parameter to be considered. A low colour value increases the commercial value meaning that polyether structure has been unaltered without chain destruction and formation of new compounds. IR analysis shows that this parameter is connected to carbonylic groups next to double-bonds [3]. A large number of normative of International Standard Organisation (ISO) requires a high value on the grey scale. The yellowing of PE PU, in footwear industry, in particular types of articles, can be linked to yellowing of the synthetic leather. In particular, some degradation products can react with the refinement agents of the leather. This situation has been analyzed by different point of view (chemical and physical analyses) in order to have a better understanding of this drawback and to find a solution of the problem.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
