About 3M Scotch-Weld™ PUR Adhesives
3M Scotch-Weld™ Polyurethane Reactive Adhesives, (PUR) are our family of one-component, moisture-curing, urethane adhesives. These adhesives are applied warm and bond strongly to a variety of substrates such as wood, fiber reinforced plastic (FRP) and many other plastics to themselves, to metal and to glass. Our moisture-curing formula cures by reacting with moisture in the air or the substrate. In addition to spraying, they can also be extruded from hand held or bench mounted applicators and are primarily dispensed with bulk application equipment. Our one-part PUR adhesives work well for bonding a wide variety of plastics including polystyrene and polyacrylic. They are also effective on a wide variety of other substrates – from aluminum and glass to plastic and wood.
Wood and wood based surfaces
Military & Government
Our one component adhesives create high-strength bonds and can be used to bond many heat sensitive materials. Their 100% solids formula is highly plasticizer resistant and bonds firmly on a broad variety of substrates, both similar and dissimilar.
Apart from Two-Part
Our family of one-part, moisture-curing PUR adhesives begins curing when exposed to moisture or humidity. Unlike two-part reactive adhesives moisture-curing urethanes are not appreciably affected by temperature as much as they are by humidity. If the relative humidity is below 40% and the substrate has a very low porosity, the cure rate will be slowed dramatically due to the reduced amount of available moisture in the surrounding environment.
The Difference is in the Cure
How moisture-cure urethane adhesives cure is slightly yet significantly different from water or solvent based adhesives. Moisture-cure adhesives cure by means of a chemical and mechanical bond rather than just a mechanical bond of solvent and water based products. Their high-tack properties provide a strong grab onto the surface while its reactivity creates a chemical bond into the surface as well. A water/solvent based adhesive only grabs the surface of the substrate. A moisture-cure urethane adhesive will chemically bond to the surface and leave a permanent residue if not removed quickly. Once cured, the adhesive can only be removed by mechanical means, such as grinding or sanding, which can degrade the original condition of the surface as it is removed. This chemical/mechanical bond is why moisture-cure urethanes are among the strongest adhesives available. They offer a highly aggressive bond. They are also flexible and can expand and contract with natural movement of the substrate.