Imparting Barrier Properties in Flexible Packaging Application: Part 2

Posted on 3/14/2017 10:38:28 AM By Deb Bhattacharjee
  

In an earlier blog HERE, the discussion centered on the fundamentals of barrier properties, how it can be best achieved in a practical and cost effective manner through judicious selection of multilayer polymer films necessary for success in a specific application.While most of the barrier properties to oxygen would come from the plastic layers, design of the polymer backbone in adhesive could also play a very important part in improving the barrier properties.  This is quite intriguing as adhesives constitute a very small fraction (~1wt.%) of the total mass of the overall packaging material. The purpose of this blog is to discuss several approaches of improving barrier properties through modification in adhesives composition and incorporation of fillers. 

 These include:

  • Acrylic adhesive composition containing (meth)acrylate component and a cure system including naturally occurring filler (e.g. a tannin-containing cellulosic material, such as wood flour) which inhibits free radical cure, and oxygen scavengers like triphenylphosphine and phenyl dihydropyridine, was also reported to impart barrier characteristics in packaging applications (US8231758)
  • Epoxy hardener obtained by reacting m-xylylene or p-xylylene diamine with unsaturated carboxylic acid was claimed to have improved gas barrier properties (US20150082747)
  • Solventless laminating adhesives with barrier properties was claimed (US6589384 and US6462163) by incorporating crystalline, linear hydroxyl terminated polyester chain with melting point 55⁰C or lower.
  • Adhesive of epoxy resin and curing agent with xylylene diamine structure (meta- and para-)(US7425598)
  • Reaction product of isocyanate terminated prepolymer and aminosilane, blended with radiation curable isocyanate terminatedmethacrylate was also claimed as binding agent with barrier properties (US7419564)
  • One or two component barrier adhesive composition containing a compound having at least one NCO group and at least one reactive functional group that can be cured by irradiation and a nanoscale filler, has been reported (US20060247326).
  • Fillers having a platelet-like crystalline structure with an aspect ratio of >100 can be incorporated in adhesive composition exhibiting barrier characteristics against migration of oxygen, flavors and water vapor (US2005/0228096)