화학공학소재연구정보센터
Langmuir, Vol.25, No.18, 11021-11031, 2009
A Comparison of Tackified, Miniemulsion Core-Shell Acrylic Latex Films with Corresponding Particle-Blend Films: Structure-Property Relationships
Tackifying resins (TRs) are often added to pressure-sensitive adhesive Films to increase their peel strength and adhesion energy. In waterborne adhesives, the TR is dispersed in water using surfactants and then blended with colloidal polymers in water (i.e., latex). In such waterborne systems, there are problems with the colloidal stability and difficulty ill applying coatings of the particle blends; the films are often hydrophilic and subject to water uptake. Here, all alternative method of making waterborne, tackified adhesives is demonstrated. The TR is incorporated within the core of colloidal polymer particles via miniemulsion polymerization. Atomic Force microscopy (AFM) combined with force spectroscopy analysis reveals there is heterogeneity ill the distribution of the TR in films made from particle blends and also in films made from miniemulsion polymers. Two populations, corresponding to TR-rich and acrylic-rich components, were identified through analysis of the AFM force-displacement curves. The nanoscale maximum adhesion force and adhesion energy were found to be higher in a miniemulsion film containing 12 wt % tackifying resin in comparison to all equivalent blended film. The macroscale tack and viscoelasticity are interpreted by consideration of the nanoscale structure and properties. The incorporation of tackifying resin through a miniemulsion polymerization process not only offers clear benefits in the processing Of the adhesive, but it also leads to enhanced adhesion properties.