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Thermo-activatable polyurethane adhesives – easy to apply with a high bond strength

Thermo-activated polyurethane adhesives are dispersion adhesives that become tacky after decrystallization. In contrast to hotmelt adhesives, they do not undergo a melting step before application, so they can be processed more easily. These adhesives are particularly interesting when the production process generates intrinsic heat and when a very high initial bond strength is required. Thermo-activated adhesives formulated with Bayer MaterialScience's raw materials show outstanding adhesive properties leading to destinct advantages:

High initial and final bond strength
Can be applied via most common application methods, including spray coating.
Very good heat resistance and long-term durability, especially in combination with isocyanate crosslinkers
Application of adhesive and bonding are two separate processes (this allows interim storage or transportation of the pieces to be bonded)

This method can easily be applied with materials that are not too sensitive to heat. The adhesive is applied to at least one of the surfaces of the composite parts to be bonded. After drying the parts are pressed together under heat and pressure. The approximate range of activation temperatures is 50 to 100˚C depending on the adhesive type.

The principle of thermo-activation (example: bonding of shoe soles)
Thermo-activation is a method which can easily be applied with materials that are not too sensitive to heat. The adhesive is applied to at least one of the surfaces of the composite parts to be bonded. After drying the parts are pressed together under heat and pressure. The approximate range of activation temperatures is 50 to 100˚C depending on the adhesive type. A chart on thermo-activation in a shoe bonding application example here.

Applications:

Thermo-activated bonding in a 3D lamination process

Thermo-activated bonding in a vacuum deep draw process

Suitable raw materials for thermo-activated adhesives (examples)

	Waterbased polyurethane dispersion
Dispercoll® U 53	Standard grade for thermo-activated adhesives with fast crystallization
Dispercoll® U 54	Standard grade with high solid content and long Hot-Tack-Life (slow crystallization)
Dispercoll® U 56	For low temperature activation, like those required for sensitive substrates
	Polyisocyanates for waterbased systems
Desmodur® DA-L Desmodur® DN	Polyisocyanate crosslinkers for the crosslinking of largely pH-neutral waterborne polymer dispersions, for polyurethane, polyvinylacetate, polyacrylate and synthetic rubber dispersions and other substrates, increases heat resistance long-term durability of adhesive bonds
	Polyurethanes for solventbased adhesives
Desmocoll®	Hydroxyl polyester polyurethanes for solventbased adhesives in a thermo-activated process. Very good solubility in many organic solvents