Лако-красочные материалы — производство

Opening remarks

Surface pretreatment involves:

(a) cleaning

(b) removal of weak surface layers

(c) re-cleaning.

The exact procedures required depend upon the nature of the adherends, and an indication of their inherent suitability for bonding is shown in Table 3.3. (The ranking order might be anticipated from the list of material surface energies collected in Table 3.1.) The first and main purpose of pretreatment is to clean the substrate, to remove contaminants and surface detritus (adsorbed principally through the van der Waals’ forces referred to earlier). The next stage is to remove weak surface layers, usually by abrasion or etching, to provide a stable and coherent surface ‘receptive’ to the adhesive. The nature of the surface is directly affected by such treatments so that if, for example, the chemistry or topography of the surface is changed, its interaction with the adhesive will vary. The final (and commonly overlooked) stage is to re-clean the prepared surface to remove contamination, introduced by the various treatments, such as oil-mist, moisture, dust and chemical residues. Experimental evidence, however, suggests that solvent degreasing by brushing is not recommended.

Together with the literature detailing practical information on pretreatment procedures(25-33), there exist many research publi­cations concerned with the optimisation or development of methods directed towards particular adherends. A visual appreciation of the effects of pretreatment has been facilitated in particular by electron microscopy in its various forms (e. g. Figs 3.6 and 3.7).

Safety precautions should be observed strictly where chemical solutions and solvents are employed for pretreatment procedures.