Polyurethane Adhesive

Coating Kinetics

Viscosity behavior dictates how evenly liquid polymers transfer onto paperboard surfaces before curing occurs. Polyurethane adhesive reacts rapidly when exposed to ambient humidity conditions on high-speed production floors. Drying tunnels must extract moisture effectively without causing bubbling within the adhesive layer.

Surface energy matching between the substrate and polymer prevents delamination defects during subsequent folding and die-cutting operations. Shear forces inside the application head alter the flow rate significantly across wide web runs.

Thermal Performance

Heat seal integrity depends entirely on the glass transition temperature of the cured polymer network. Polyurethane adhesive withstands elevated temperatures encountered during retort processing and microwave heating without softening prematurely. Cold temperature flexibility prevents brittle fracture when frozen food cartons undergo impact testing during transit.

Environmental stress cracking resistance defines the boundary where packaging fails under sustained mechanical load.