No abstract

The surface chemistry of gravure printed décor paper and its effect on the adhesion of melamine formaldehyde (MF) coatings were studied. Two industrially printed decor papers with different designs were used for the study. A combination of the attenuated total reflectance Fourier transform Infrared (ATR FT-IR) and FT-IR spectroscopy techniques were employed to determine the effect of the gravure printing ink on the printed paper surface chemistry. Then, the influence of the surface chemistry on the adhesion of MF coatings was characterized according to the abrasion resistance test. The ATR IR results suggested that the printing ink components had a noticeable effect on the surface characteristics of the printed décor paper. In addition, it was indicated that the use of an organosilane adhesion promoter in the gravure ink formulation could significantly affect the adhesion strength of the MF coatings through the formation of ring siloxane structures. It seemed that siloxane bridges formed between the molecules of ink binder and UF resin could enhance the adhesion strength of subsequent MF coatings and could reveal better Taber abrasion resistance performance.

The preparation of Melamine-formaldehyde (MF) resins was found to be catalyzed by TiO 2 -mica silver white pigments, the presence of small proportions of these advancing considerably the resin during its preparation under the same conditions. These pigments are composed mainly of TiO 2 -mica, as ascertained by X-ray diffraction (XRD), with the TiO 2 being mainly in its rutile phase but presenting alsosome traces of the anatase phase. FT-IR and 13 C NMR inferred clearly the presence of a catalytic effect of the TiO 2 -mica and appeared to indicate that the catalytic effect involved mainly the -NH 2 groups of melamine and on formaldehyde. According to the peak reaction temperature measured by DSC, the highest catalytic activity of TiO 2 on MF curing appears to be achieved at a 2% addition level by weight. Different possible explanations of this effect have been proposed, the most likely one being the catalytic effect caused by TiO 2 -promoted coordination complexes, the effect of acceleration being due to the Ti charge being stronger than that of H + , and the complex formed being unstable, thus not inhibiting the progress of the reaction.