International. A new study by researchers at the University of Alicante shows that thermoplastic polyurethane coatings with good stickiness at 10-37ºC can be prepared using mixtures of polyethers of different molecular weights.
Thermoplastic polyurethane (PU) coatings with pressure-sensitive adhesion property were synthesized by reacting 4,4'-diphenylmethane diisocyanate (MDI) with 1,4-butanediol and polypropylene glycol (PPG) mixtures of different molecular weights (1000 and 2000 Da).
Good adhesion was obtained at 10-37 ° C in PU coatings prepared with PPG2000 + PPG1000 mixtures containing 50% by weight or more of PPG2000.
The pressure-sensitive adhesion properties of PU coatings were related to their minority content of bonded urethane groups and a significant degree of phase separation.
In addition, these PU coatings followed Dahlquist's criterion, showed low glass transition temperatures, high adhesion and low detachment resistance of 180 °. Therefore, PU coatings had potential as pressure-sensitive adhesives. Finally, the PU coating made with PPG of molecular weight 1000 Da, showed no pressure-sensitive adhesion property.
Source: https://www.sciencedirect.com
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