UV-crosslinkable warm-melt pressure-sensitive adhesives based on acrylics
The target of this article is to show the preparation of new generation of UV-crosslinkable warm-melt acrylic pressure-sensitive adhesives (PSAs) and the experimental test of their adhesive properties in comparison with typical conventional hot-melts adhesives. New generation of UV-crosslinkable acrylic warm-melts PSAs containing unsaturated photoinitiator, incorporated during polymerization process into polymer chain, and photoreactive diluents added to PSA systems after polymerization allows producing of wide range of self-adhesive materials, such as labels, mounting tapes, masking and splicing tapes, and sign and marking films.
Vinyl ester resin (VEOCN) was prepared from o-cresol epoxy resin (EOCN) and methacrylic acid in the presence of triphenyl phosphine as catalyst and hydroquinone as inhibitor with acid value of ~ 7 mg of KOH per gram of solid. O-cresol based novolac resin (OCN), OCN based epoxy resin (EOCN) and VEOCN were characterized by Fourier transform infra red spectroscopy (FT-IR), 1H-NMR and 13C-NMR. The thermal and mechanical behavior of the samples prepared at 30°C from VEOCN using styrene and methyl-methacrylate respectively as reactive diluents, in the presence of benzoyl peroxide (2 phr) as initiator was studied using Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Universal Testing Machine (UTM). Chemical resistance of above VER samples was also evaluated as a function of % weight loss and with the help of Scanning Electron Microscopy (SEM), upon immersing the VEOCN samples in different solutions for 90 days.