Low molecular weight PIB in adhesives

PIB has unique properties. PIB is chemical resistant, gas permeability, odourless, colourless, oxidation resistant, non-toxic, non-skin irritating and contains low moisture. Therefore, PIB can be used in a wide range of sealants and adhesive applications. It is a linear polymer with a narrow molecular weight distribution of approximately 2 (Mw/Mn). Rheological properties are controlled by molecular weight and temperature.

PIB is divided into three groups according to their molecular weight. PIB with a high molecular weight has an average weight of 500,000 to 1,200,000 g/mol. PIB with a medium molecular weight has an average weight of 5,000 to 150,000 g/mol. PIB with a medium molecular weight offers flexibility, cohesive strength and elongation.  PIB with a low (conventional) molecular weight has an average weight of 300 g/mol to 5000 g/mol. This last group contains the liquid polymers which could be split up into three groups (read more). The mentioned PIB with a low molecular weight will increase tackiness and lubrication in the sealants what will result in adhesion.

With a Tg of -60 degrees Celsius in adhesives PIB offers flexibility, permanent tackiness and moderate adhesion over a wide range of temperatures due to its excellent cold flow. PIB acts as a polymer extender, rheology modifier tackifier and lubrication or wetting agent. Due to its low polarity and adhesion to some surfaces PIB’s are formulated in (hotmelt pressure sensitive) adhesives in combination with a tackifier resins such as rosin ester and/or hydrocarbon resin. PIB has a good compatibility with these resins but also with a variety of elastomers, polymers, rubbers and aliphatic and aromatic solvents.

PIB is used in automotive tape applications because of its excellent sealing and dampening properties. PIB is also used in building and construction applications and in pressure sensitive hotmelt adhesives like butyl tape.

PIB’s from numerous producers are in compliance with FDA food contact requirements, therefore PIB can also be used in tapes and labels meant for food packaging.

 

 

Low molecular weight PIB in adhesives
Tagged on: