Polyurethane Reactive hot melt glues, better know as PUR glues, are a more recent development in the adhesives industry. In recent years, we've had a number of customers looking to learn more about using PUR glues. But they always come back to us with the same question...
Why are PUR glues so expensive?
From book binding and woodworking to packaging and flooring, PUR glues have proven to be an effective industry standard for hard-to-bind materials, but are they really worth the higher price tag?
A PUR bond occurs when the chemicals in the glue draw moisture out of the air. This is why these types of glues require specific application equipment. This closed application system will ensure that the glue does come into contact with air before application. Unlike traditional EVA hot melts, PUR glues must cure for 24 hours to reach their peak bond strength.
The binding properties of PUR glues are quite different than EVA hot melts. For this reason, they are used in a variety of industries including:
But what is so special about a PUR glue bond? And why are they so much more expensive than other hot melt glues?
The short answer is: PUR glues offer a much stronger bond than other hot melt glues provide.
They bond to more difficult substrates which can require less adhesive. They offer excellent lay-flat and flexibility, they can better handle recycled papers and cross-grained stocks easily, they are resistant to print oils in the digital printing industry, and can survive in more extreme temperature/moisture conditions.
In terms of binding strength, PUR's offer page-pull and page flex ratings that can be up to 60% stronger versus EVA adhesives (Standard Finishing).
In other words, PUR glue is the "macho man" of the adhesive industry. They do have a higher price tag than other hot melt glues, but that's because they offer bonds that other hot melts just cannot match for certain applications.
At LD Davis, we carry ethylene-vinyl acetate (EVA) hot melt glue, metallocene hot melt glue, fugitive hot melt glue and polyurethane reactive (PUR) hot melt glue and can create a custom formula for your specific application. Our lab team can review and test your glue application to determine which formula and product