LOCTITE UR 7221 is a solvent-free and a moisture curing one-component sandwich panel PU adhesive . It obtains sufficent strength in the joint after approximately 2 to 4 Hrs. The joint should be at room temperature with the required humidity. Curing by LOCTITE UR 7221 is in a heated press for faster curing . Maximum temperature must not be above 70°C.
Application Areas of PU Adhesive
LOCTITE UR 7221 used for the manufacture of sandwich elements with porous surfaces (e.g. wood) which contain humidity. The surfaces can bond to one another. They can also bond to metals, laminated panels, various plastics, rigid foams made of polystyrene, polyurethane and others.
How to Apply Sandwich Panel PU Adhesive:
Temperature : 10 to 35 °C.
LOCTITE UR 7221, one part PU adhesive is applied to the substrate by spatula or doctor blade, but one can also apply by spraying or rolls. When bonding substrates without sufficient humidity or which are not moisture permeable, other methods provide the required amount of moisture. A proven procedure is the combined spraying of the adhesive simultaneously with water in a fine mist. In the case of separate adhesive and water mist application, no spraying of water onto the bare metal but on the other substrate or ideally on the adhesive. Bonding surfaces should be brought together immediately after adhesive application, assuring sufficient contact pressure while curing, preferably in a press.
Proper sealing of open containers and protected against moisture immediately after taking out the quantity needed as LOCTITE UR 7221 cures by reaction with humidity . For the same reason we recommend to use up opened containers as soon as possible.
Fresh, uncured material (cleaning application equipment, surface contamination etc.) can be removed with LOCTITE SF 8040.Remove the cured adhesive mechanically.
Our solvent-free 1K PU adhesives require moisture during the sandwich panel production process to fully cure the adhesive layer and achieve the final bond strength.
1K PU adhesives are typically used in (semi)-discontinuous processes, where the production speed is relatively low. Moisture control at the point of lamination can help to influence curing speed. Provided that the target substrates are suitable for 1K PU, the adhesive allows for more frequent changes of laminated substrates on the same line and can bring more flexibility.