Glass lubrication by a film of polymer

Un article de Surface du verre et interfaces.

Benoît Piezel, Faride Hamidi, Mélanie Villalobos, Muriel Beauvais, Davy Dalmas, Etienne Barthel

Surface flaws generated by sliding contacts between glass bottles on production lines and transport affect both their mechanical strength and visual aspect. To improve their scratch resistance and prevent surface damage, glass bottles are subjected to two successive surface treatments: the “hot-end coating” (Chemical Vapour Deposition of a SnO₂ thin film) and the “cold-end coating” (spray deposition of an organic water-based formulation with polyethylene, waxes, or oleic acid). The organic layer is stabilized by the oxide resulting in lubrication and surface damage prevention. The metal oxide film is reported to act as an anchor or primer for the organic coating to the glass surface container.

The roles of surface chemistry, roughness and morphology in the anchoring function of the primer are evoked in the litterature but remain unclear. The purpose of our work is to understand why the SnO₂ primer is able to anchor the organic layer.

The anchoring function of the primer was assessed for a mixture of polyethylene with a dispersion of polymethylmethacrylate (PMMA) spheres. The primer was a rough tin dioxide deposited on flat glass by chemical vapour deposition (CVD). Surface chemistry alteration and roughness modulation of the primer were realized by sputtering oxide and nitride films on flat glasses. The contact properties (friction, adhesion through infrared microscopy in wear track) of such coated glasses were investigated after the polymer deposition. This was completed by the characterization of the wear tracks morphology by optical and atomic force microscopies.

We have showed that the enhanced scratch resistance of the polymer-coated SnO₂ – CVD film on glass is due to the strong adhesion of the polymer to the primer, as revealed by the persistence of the C =O stretching band from PMMA over large sliding distances. Good wetting results in well dispersed PMMA spheres on the surface and the strong adhesion leads to the formation of a continuous organic film under the mechanical stress by coalescence of flattened spheres. Moreover, the results suggest that the roughness and the surface chemistry of the primer are both necessary to the glass bottle lubrication. The large plastic deformation of PMMA spheres results from the combination of the surface roughness sharpness and shear due to strong adhesion.

 

Collaborations

• E. Martin, C. Da Silva, Saint-Gobain Recherche

 

Publications

• M. Beauvais, B. Piezel, F. Hamidi, M. Villalobos, C. Da Silva, E. Martin, D. Dalmas, E. Barthel, "Film Formation Mechanism in Glass Lubrication by Polymer Latex Dispersions", accepted in Thin Solid Films, 2009