Patent ID: 8518477

Claim:
A process to apply a foamable water-based adhesive, which is an aqueous polymer solution or dispersion, comprising: a) providing a first aqueous polymer solution or dispersion that has a pH-value above 6 and that contains a dissolved or dispersed salt that liberates a gas when it is combined at a pressure of 1.01 bar (1 atm) with an acidic solution with a pH-value of lower than 5, this first solution being contained at a pressure higher than ambient pressure by about 0.59 atm (60 kPa) when the ambient temperature is 22° C., b) providing a second aqueous polymer solution or dispersion that comprises an acid and that has a pH-value of lower than 5, this second solution being contained at a pressure higher than the pressure at which the first solution is contained, c) combining and containing at least partially, the first and the second aqueous polymer solutions or dispersions at a pressure at least 0.59 atm (60 kPa) higher than ambient pressure when the ambient temperature is 22° C., d) releasing the combined aqueous polymer solutions or dispersions, which form the water-based adhesive, onto a substrate at a pressure lower than the pressure at which the combined first and second aqueous polymer solutions or dispersions are contained, whereby a gas liberated from the dissolved or dispersed salt during and after step c) forms gas bubbles in the combined aqueous polymer solutions or dispersions, thus foaming the aqueous polymer solution or dispersion.