Making it stick
Extended exposure to many organic or carbon-based solvents, as can occur in the workplace, has been associated with cancer, reproductive hazards and damage to the nervous system. Recent environmental and health restrictions on organic solvent emissions have led to development of water-based PSAs (wb-PSAs), where polymer particles on the scale of nanometres are dispersed in an aqueous solution. Given that the wb-PSAs tend to have limited adhesive strength in general and limited ability to bond to certain substrates, the ‘Designed nanoscale heterogeneities for controlling water-borne pressure-sensitive adhesive performance’ (Nshape) project was developed to synthesise particles with nanoscale heterogeneities that enhance adhesion properties of wb-PSAs. The researchers focused on well known latex, a stable dispersion of polymer particles in an aqueous medium. They synthesised and characterised various latexes, choosing the most promising for further development. They then optimised the use of atomic force microscopy (AFM) to visualise nanoscale latex morphologies and develop guidelines for improvement of latex synthesis and adhesive film formation. Next, they identified screening methods and standards for performance, including key parameters for controlling the testing process. The Nshape project produced three prototype wb-PSA latexes and used them for coating in a pilot study to determine potential for commercialisation. One was particularly promising for use in chemical container and drum labelling applications, with high performance and reduced cost in comparison to conventional materials. In summary, the project produced new coating materials based on water emulsions rather than organic solvents in compliance with new environmental and health regulations. In addition, the materials demonstrated important enhancements in adhesive performance at reduced cost. Commercial implementation of the project outcomes should thus produce important health benefits for workers and end users and a positive impact on the European economy while protecting the environment. Now that’s a win-win situation for everyone.
