Abstract
Biodegradable polyester emulsion adhesives were investigated with respect to preparation methods and adhesive properties using physico-chemical considerations. Polybutylenesuccinate-co-adipate (PBSA) and polycaprolactone (PCL) were emulsified with PVA as an emulsifier using an extruder in a melt emulsification system and colloidal properties of the resulting emulsions were as follows: particle diameter 1-2 μm, solid concentration ≥ 50 wt%, and viscosity ≥ 1000 mPa · s/23°C. The PBSA emulsion and the PCL's both were evaluated to have similar potentiality as adhesives as PVAc emulsions from the view point of surface chemistry. Water dispersible aliphatic poly-isocyanate was recognized as an effective additive for the adhesion enhancement through a comparatively small number of chemical bonds formed between the polymer emulsion film as glue lines and adherends. Besides, a formula to estimate the life span of those emulsion adhesives was introduced, since aliphatic polyester emulsions are generally hydrolyzed easily and their adhesive properties will deteriorate, even in indoor atmosphere. Therefore, the development of the atmosphere-friendly-biodegradable polyester emulsion adhesives will be stimulated by this study, leading to more adequate and wider applications.
