Setting Rate

Determining the Open Time and Setting Time of Hot Melt Adhesives (PAPT II Instrument)

For hot melts, open time (see below) is often very short. It is important to match the open time of the adhesive with the requirements of the process and conditions. A hot melt with an open time of 1-2 seconds in an application where it takes 4-5 seconds to form the bond after the adhesive has been applied would give poor wetting of the second substrate and a poor bond.

However, short compression times are the very essence of hot melt bonding processes and the situation can arise where the adhesive is still liquid when compression is removed and stresses on the joint may then force the substrates apart (eg tray erection, carton sealing).

Expert Profile

  • Doug joined Pira in 1989 and has 20 years experience in the physical testing of packaging and packaging materials. He heads a team specialising in packaging and print related technical investigations. In 2004 Doug gained his postgraduate degree with distinction in Packaging Technology from Brunel University.

    Doug Leatherdale
    Doug Leatherdale

    Head of Physical Testing

    Pira International

    +44 1372 80 2108

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