| Résumé : |
These studies show that when the pigment volume content (PVC) of carbon black particles increases in polyurethanes (PUR), NCO consumption increases, and the extent of H-bonded C=O species near the film-substrate (F-S) interface is enhanced. During crosslinking, polyurea (PUA) is produced, and its concentration levels near the F-S interface are diminished for unpigmented coatings, whereas for the same system containing carbon black, the PUA formation is enhanced. Although the presence of carbon black particles at the F-S interface results in diminished adhesion of 2K PUR to acrylonitrile-butadiene-styrene (ABS), adhesion is also affected by the presence of OH and C=O functionalities on ABS, which are potential sites for H- bonding to PUR. Stronger hydrogen donor affinity of N-H functionalities in PUA as compared to the N-H groups on PUR leads to increased H-bonding in the presence of carbon black. Enhanced intermolecular H-bonding in PUR due to the presence of carbon black particles competes with the F-S interfacial H-bonding that promotes adhesion. |
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Effect of carbon black on adhesion to plastics in solventborne 2K polyurethanes in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 72, N° 903 (04/2000)
