Switchable hydrophobic-hydrophilic layer obtained onto porous alumina by plasma-enhanced fluorination
Idioma
en
Article de revue
Este ítem está publicado en
Science in China Series E. 2009, vol. 52, n° 1, p. 104-110
Resumen en inglés
Conventional lithographic printing processes using porous alumina for offset applications generally use “wet” routes. Recently “dry” processes have been developed which are based on a heat-induced hydrophilic/oleophilic ...Leer más >
Conventional lithographic printing processes using porous alumina for offset applications generally use “wet” routes. Recently “dry” processes have been developed which are based on a heat-induced hydrophilic/oleophilic conversion of one or more layers of the coating so that a stronger affinity to-wards ink or water fountain is created at the exposed areas with respect to the surface of the unex-posed coating. Treatments involving rf plasma-enhanced fluorination (PEF) constitute exceptional tools for modifying the surface properties of materials. Many advantages of these techniques can be indeed outlined, when compared to more conventional methods: room-temperature reactions, chemical modi-fications limited to surface only without changing the bulk properties, possible non-equilibrium reac-tions. The influence of PEF treatments on porous alumina layer used in printing plates has been tested with various fluorinated gases (CF<sub>4</sub>, C<sub>3</sub>F<sub>8</sub> and C<sub>4</sub>F<sub>8</sub>) and characterized by XPS. The hydrophobic prop-erties of the fluorinated layer have been deduced from contact angle measurements. Using C<sub>4</sub>F<sub>8</sub> rf-PEF treatment, the outmost surface of the hydrophilic alumina substrate used for lithographic printing is hydrophobized, or in other words, the hydrophilic substrate is converted into a support with hydro-phobic properties. Once being hydrophobized, the surface layer may be rendered hydrophilic using a heat pulse, thus giving rise to switchable hydrophobic-hydrophilic properties of the material.< Leer menos
Palabras clave en inglés
Porous alumina
rf-plasma fluorination
Offset applications
Hydrophobic-hydrophilic
Switchable layer
XPS
Contact angle
Orígen
Importado de HalCentros de investigación