SIMS IMAGING OF PAPER SURFACES .4. THE DETECTION OF DESIZING AGENTS ON HARD-TO-SIZE PAPER SURFACES

Hard-to-size bleached sulfite paper was examined by electron spectroscopy for chemical analysis, time-of-flight secondary ion mass spectrometry (TOF-SIMS) and ink penetration methodology. SIMS spectra indicated the presence of high mass fragment ions on the surface of the paper samples and SIMS images showed that these high mass peaks were present as aggregates as well as being dispersed on the paper surface. For the amount of internal size applied, relatively low sizing was measured. When the paper was exposed to acetone in a paper chromatography experiment, three areas having different sizing were obtained: the region exposed to acetone (improved sizing), the solvent front region (very poor sizing) and the one unexposed to acetone (same sizing as the original paper). The SIMS spectrum from the region of improved sizing showed a decrease in the intensity of the aforementioned high mass peaks and disappearance of the aggregates. Similarly, the SIMS spectrum of the solvent front showed a build-up in intensity of high mass fragments with disappearance of the clumps, while the spectrum from the region of the paper unexposed to acetone was the same as that from the original paper. Several of the high mass fragments which are linked to sizing loss are tentatively identified based on their molecular weights.