What is Polyurethane PUR Hot Melt?
Polyurethane hot melt, commonly called PUR hot melt, is an adhesive that is heated and dispensed from a cartridge or slug, unlike traditional hot melt which is in stick or pellet form. PUR is also unique because it solidifies through moisture in the air to form a super-strong bond that will not re-melt.
Because of its strength, durability, and fast set time, PUR is ideal for a wide variety of applications like woodworking, finish carpentry, shoe repair, furniture repair, broken glassware repair, laminate countertops, construction and remodeling, ceramic ceiling tiles, and more. Check out this guide to PUR hot melt for a more in-depth explanation.
Frequently Asked Questions about Polyurethane Reactive Hot Melts
Are PUR hot melts stronger than traditional hot melts?
Polyurethane hot melt usually does provide a stronger bond than a traditional hot melt. This is because the PUR hot melt forms a strong initial bond and then continues to strengthen as the adhesive reacts with moisture in the air. This is a chemical process known as cross-linking where the PUR hot melt attaches to the object being glued and itself to form a strong, permanent bond.
Check out the difference between traditional hot melt and PUR hot melt in this strength test:
Where does the moisture come from that continues to cure PUR adhesive?
The answer is the air and the object being glued. There is plenty of moisture in the air to continue curing PUR hot melt, however, drier conditions may extend open times.
How can I prolong the shelf life of the adhesive?
If unopened, the adhesive should be stored in a foil pouch in a cool, dry location. Do not expose the PUR tube to rain or moisture. Before shutting down for the day, extrude a one-inch bead of adhesive to ensure that air has been extracted from the tube. CAUTION: Do not touch the applicator heat cylinder or cartridge when at maximum temperature. Always wear gloves.
PUR Dispensing Systems
50 Gram vs. 10 Ounce PUR Products
PUR hot melt can be dispensed either from PUR cartridge guns or from bulk equipment, choosing what system is best for you will depend on your application and volume being dispensed.
For lower-volume needs, the 50-gram cartridge system will do the trick. It’s low-cost, simple, and works for a variety of applications like woodworking, light product assembly, and repairs.
The 10-ounce cartridge systems are great for higher volume applications that don’t quite require a bulk dispensing system. They are also a good middle-ground price between the 50-gram cartridge system and the bulk dispensing systems. The 10-ounce system is usually connected to an air compressor which allows for effortless air-powered dispensing and can be purchased for both bead and spray dispensing applications.
If you’re using a 10-ounce cartridge system and are going to be going through cartridges quickly, a cartridge preheater is a handy accessory. Because PUR takes longer than standard hot melt to heat up, having cartridges warmed and ready for use is helpful in manufacturing settings so your production isn't slowed waiting for a cartridge to heat up.
Bulk Dispensing
For extremely high-volume or automated dispensing needs, bulk PUR is a great option. In the long-term, bulk PUR can save you a lot of money! Some of the most common bulk PUR sizes are the HOLZ-HER slugs which are used with edgebanding equipment. Foil-wrapped slugs are used in high-volume and automated PUR equipment.
Still Have Questions?
Navigating the world of PUR hot melt can be challenging and you may not find the answers you need for your specific application by browsing online, our team of glue experts are ready to assist you to find the right adhesive solution for your application needs. Fill out a contact form or give us a call to learn more.
Related Products: Infinity Bond Flex 50 PUR Hot Melt Applicator