Qualitative analysis of tackifier resins in pressure sensitive adhesives using direct analysis in real time time-of-flight mass spectrometry.

Tackifier resins play an important role as additives in pressure sensitive adhesives (PSAs) to modulate their desired properties. With dependence on their origin and processing, tackifier resins can be multicomponent mixtures. Once they have been incorporated in a polymer matrix, conventional chemical analysis of tackifiers usually tends to be challenging because a suitable sample pretreatment and/or separation is necessary and all characteristic components have to be detected for an unequivocal identification of the resin additive. Nevertheless, a reliable analysis of tackifiers is essential for product quality and safety reasons. A promising approach for the examination of tackifier resins in PSAs is the novel direct analysis in real time mass spectrometry (DART-MS) technique, which enables screening analysis without time-consuming sample preparation. In the present work, four key classes of tackifier resins were studied (rosin, terpene phenolic, polyterpene, and hydrocarbon resins). Their corresponding complex mass spectra were interpreted and used as reference spectra for subsequent analyses. These data were used to analyze tackifier additives in synthetic rubber and acrylic adhesive matrixes. To prove the efficiency of the developed method, complete PSA products containing two or three different tackifiers were analyzed. The tackifier resins were successfully identified, while measurement time and interpretation took less than 10 mins per sample. Determination of resin additives in PSAs can be performed down to 0.1% (w/w, limit of detection) using the three most abundant signals for each tackifier. In summary, DART-MS is a rapid and efficient screening method for the analysis of various tackifiers in PSAs.