Wet Tack and Dry Tack of Latex Based Adhesives
John Woon (Senior Latex Consultant): "Wet tack" is the ability of the latex to hold to layers of materials together before drying. This depends a lot on the nature of the substrates concerned. A solid impermeable substrate is more difficult to adhere to compared with, for examples, a porous textile or paper board.
Other factors involved in ensuring good wet tack are:
1) Surface tension and wetting - A good wetting with low surface tension is required for the initial spreading and wetting of the substrates.
2) Total solid content - Higher TSC is required for higher initial tack.
3) Mechanical stability - Lower mechanical stability is needed for the quick development of the wet tack.
4) Types of stabilizers used - rosin acid soaps are preferred to fatty acid and non-ionic soaps.
5) Nature of polymer - Lower Tg is preferred to ensure the polymer is soft enough for better particle-to-particle integration and film formation.
As for "dry tack", I have already covered this in my earlier posting om "Nitrile Latex Adhesives" below.