| 1. |
- Vyörykkä, J., et al.
(författare)
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Characterization of paper coatings - Review and future possibilities
- 2006
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Ingår i: 2006 TAPPI Advanced Coating Fundamentals Symposium. ; , s. 32-57
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Konferensbidrag (refereegranskat)abstract
- Paper coating obviously plays an important role in printing and converting performance and thus a thorough knowledge of coating structure and chemistry, its generation from the wet state of the colour layer and its reaction to downstream processing, end-use and recycling, is needed to understand current products as well as to develop new products. Coating characterization methods may be divided into two subcategories; research methods and quality control methods. The latter category typically contains methods based on standards and are fast tools to evaluate the quality of the coatings, on-line, at-line or off-line. The instruments used in paper coating research aim to provide absolute rather than relative information, with the goal of offering greater insight into mechanisms underlying paper performance. These methods are accordingly often more demanding in terms of sample preparation and analysis time, and in some cases are still under development. This paper summarizes the achievements, limitations and future challenges faced by established analysis methods as well as emerging methods which could be used in paper coating characterization.
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| 2. |
- Jääskeläinen, A-S, et al.
(författare)
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Application of UV-Vis and resonance Raman spectroscopy to study bleaching and photoyellowing of thermomechanical pulps
- 2006
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Ingår i: Holzforschung. - 0018-3830 .- 1437-434X. ; 60, s. 231-238
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Tidskriftsartikel (refereegranskat)abstract
- The chemistry of thermomechanical pulp bleaching and brightness reversion was studied. First, UV-Vis reflectance spectroscopy was used to obtain information on the reactive structures in pulp. Based on these data, a Raman excitation wavelength was chosen close to the absorption bands of the chromophores formed to take advantage of the resonance enhancement (resonance Raman spectroscopy). Fluorescence was rejected with a picosecond Kerr gate. The results revealed that coniferyl aldehyde structures were partly removed by alkaline peroxide bleaching and these structures were further degraded during light exposure. However, this reaction was obviously not responsible for chromophore formation in the pulp. On the other hand, based on the resonance Raman spectra, formation of quinonoid structures, possibly para-quinones, was a more prominent explanation for the brightness reversion
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| 3. |
- Lozo, B, et al.
(författare)
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Nondestructive microscopic and spectroscopic mehtods for depth profiling of ink jet prints
- 2006
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Ingår i: Journal of Imaging Science and Technology. - 1062-3701 .- 1943-3522. ; 50:4, s. 333-340
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Tidskriftsartikel (refereegranskat)abstract
- The binding process of printing inks on the printing substrate is one of the final phases in the creative chain of a new product formation—the print. It is not only the expected mechanism of ink drying that influences the ink distribution on the substrate surface, but also the properties of the substrate itself. Many factors, like hydrophobicity, roughness, and porosity influence the ink distribution on both coated and uncoated papers. The aim of this study was to evaluate the applicability of several nondestructive methods in the analysis of vertical and radial ink distribution on diverse ink jet prints. What are the limits and the extent of confocal Raman, ultraviolet (UV) Raman, CLSM and Fourier-transform infrared (FTIR) PAS in the analysis of ink jet ink distribution in the z direction of the print? In the experiment, both dye- and pigment-based ink jet inks were printed on different types of coated and uncoated papers. The results show a correlation between the confocal Raman and CLSM methods for depth profiling. UV Raman proved useful in the surface analysis of prints while FTIR PAS was useful for measurements at low depth in the z direction. The applied microscopic and spectroscopic methods provide a precise distinction between the upper homogeneous and the inside nonhomogeneous ink layers. Sporadic streams of deeply penetrated ink jet ink were also detected.
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