Dialkyl-tin-di-carboxylates, dialkyl-tin-di-alkoholates and metall-β-di-carbonylic compounds were obtained as effective catalysts for the reaction of uretdione groups with OH- groups. Using low molecular weight model systems and zinc(II)-acetylacetonate as catalyst a reduction of the reaction maximum T_(max) of about 90K compared with the non catalyzed system could be detected by non-isothermal DSC measurements. The mechanism of the reaction between uretdione and OH-groups was studied by the use of temperature dependent FTIR measurements, ~1H and ~(13)C NMR spectroscopy. For isothermal curing at temperatures below 160°C a new reaction mechanism was proved for reactions in melt. The catalayzed reaction between uretdione and OH-groups lead to allophanate structures and showed a high selectivity. The results were successfully transfered into reactive polymeric models. Initial studies of film properties obtained with the catalyzed reaction were evaluated using powder coating model samples.
展开▼
