Selecting Acrylic Emulsion PSA Dispersion Particle Size Distribution
- Jan 9, 2012
Until recently the lack of control in emulsion polymerisations has meant that most acrylic PSA formulation knowledge came from solution polymerisation. But recent improvements have meant better polymer size distribution (PSD) control, which influences latex viscosity and solid content. High solid content is desirable for economical production and rapid drying, but achieving this while retaining a low viscosity is difficult, though modifying PSD can deliver this. Meanwhile, it's been thought that PSDs with the smallest particle size possible, which provide minimum viscosity, delivered the best adhesion. Recent results challenge that wisdom. When formulating pressure sensitive adhesives, it's easy to be overawed by the depth of the science underlying a product's character. Optimum PSA performance depends on skilfully controlling the adhesive's properties through its molecular characteristics, with parameters like glass transition temperatures (Tg) and low-frequency dynamic storage moduli (G') being especially important.
posted by Antonio Mader, R&D - Basic Research at Mapei
some years ago we had similar results as reported in your ref 5. One posible explanation, among others, is that mixing different PSD latexes the deformation of the particles during film formation is smaller, hence also the stored energy is lower.
Drawing conclusions from your report is not possible in my opinion, due to the many factors involved from polymerization to film formation and testing.
posted by madhusudan bhagwat, Consulting/ Training/ Education at retired from job
Controlling PSD is most important for achieving desired PSA performance has been known for quite some time but how to achieve multi modal PSD & broad PSD is not known very clearly & that is the main problem The article does not give the type of emulsifiers employed & other details. Getting that information would be of immense help.