Polyurethane adhesives from CO2-based polyols and their applied use in footwear, wood and furniture industries

The decarbonisation of industry is becoming a serious commitment in our society and it is now possible to transform CO₂ captured from industrial emissions into high added value chemical products. In this respect, chemical precursors can be obtained for use in the synthesis of highly demanded polymers on an industrial scale, such as polyurethanes, which are the basis for many formulations of adhesives, varnishes and coatings.

In this work, reactive polyurethane hot-melt adhesives have been obtained from the revalorisation of CO₂ for use as bioadhesives in the footwear, wood and furniture industries. The CO₂-based reactive polyurethane hot-melt adhesives obtained by the prepolymer method were first characterised with different experimental techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), softening temperature and melting viscosity. The adhesion properties of these adhesives were subsequently measured with T-peel tests on leather/HMPUR adhesives/SBR rubber joints in order to ensure that they met the minimum requirements for use in footwear.

The performance of these new reactive polyurethane hot-melt adhesives on wood and other furniture materials was also analysed. Initially, for non-structural applications, different adhesives were tested according to standardised methods for their classification considering the use conditions and the tensile-shear strength of lap joints. The adhesives were subsequently characterised in terms of their suitability for bonding larger surfaces. In all cases, they yielded an optimal performance, and those showing the best results were validated for gluing laminated wood intended for structural purposes. Finally, the best adhesive obtained was applied to real furniture, observing no breakage nor any kind of damage.