PUR Best Practices - Our Top Tips for Working With Polyurethane Hot Melt Adhesives

Polyurethane PUR hot melt is a great match for indoor and outdoor applications that need to stand up to the trials of time and harsh conditions. Today we will share our top tips for PUR adhesives, no matter the project! 

Overview of Polyurethane Hot Melt Adhesives

PUR hot melt has a hybrid chemistry designed to create and maintain a secure bond in wet environments, extreme temperatures, high-flexibility situations, and other less-than-ideal settings. 

It combines the advantages of traditional thermoplastic technology with the performance characteristics of reactive adhesive chemistries. It is extremely strong, can be engineered for flawless application in a variety of settings, and is the perfect choice in harsh environmental conditions.

PUR Best Practices

Dispensing Tips

Correct dispensing is vital to ensuring the performance of your adhesive. There are two main tips for preparing a cartridge for dispensing, first make sure to choose the correct temperature setting. Second of all, make sure to properly preheat your cartridge.

  1. Choosing the Best Temperature Setting

These adhesives can be applied at temperatures ranging from 185-285 degrees Fahrenheit, which is a lower temperature than other hot melt formulations. Choose the "low temp" setting on your PUR cartridge gun for the most effective dispensing. 

The PUR 3000 applicator from Infinity Bond offers a powerful 500-watt heater and a dual (high and low) temperature settings. When using the Infinity PUR 3000 choose the green "low temp" setting for all 50 gram PUR cartridges.

2. Properly Preheating the Cartridge

Another tip of working with PUR hot melt is to make sure to properly preheat your cartridge for at least 15-20 mins before attempting to dispense the adhesive. Failing to properly preheat the cartridge will cause the plunger in your gun to break from force. With a properly preheated cartridge, the plunger will extrude the adhesive easily. 

Shelf Life of Polyurethane Hot Melt Adhesives

The typical shelf life of Polyurethane hot melt adhesives is 12 months. This is significantly shorter than other traditional hot melts. Make sure to follow these tips to prolong the shelf life of your polyurethane adhesive.

1. Proper Storage to Prolong Shelf Life

If unopened, PUR hot melt should be stored in a foil pouch in a cool, dry place. Proper storage will prevent premature activation, and keep it dry from rain or any other moisture. 

2. How to Utilize a Partially Used Cartridge

Did you know that you can cap and reuse a cartridge? If done properly, it is a great way to minimize adhesive waste. To recap a cartridge, first, extrude a one-inch bead of adhesive to remove all air from the tube. Next, securely attach the cap and store in a cool, dry place. If recapped and stored properly you can extend the shelf life of your Infinity Bond 50-gram cartridge up to 12 months. 

Polyurethane Hot Melt Cure Time

Understanding the chemistry behind these adhesives can save you a lot of frustrations later on. Although it is dispensed like a traditional hot melt, it will take much longer to fully cure, a full 24 hours to be exact. 

1. Understanding the Cure Time of PUR Adhesives

PUR hot melt adhesives generally have a longer cure time than other types of hot melt adhesives. They undergo a chemical change when they react with moisture in the air. Although PUR seems super-strong after 20 minutes, we always recommend waiting the full 24 hours before placing stress on the substrates and bonds.

We carry a variety of different cartridges with different open times. Common open times are 30, 60, 90, 120, and 150 seconds. If you are looking for a 30 second open time, we recommend the Infinity PUR WW30. We recommend Infinity PUR WW60 for a 60 second open time, and Infinity MP75 for longer (75 seconds) open time. 

Have Questions? Contact Us For a Personalized Product Recommendation

No matter the application, there's a PUR hot melt that will produce great results. The Infinity Bond line are available in 50 gram and 10-ounce cartridges and bulk sizes. Check out our selection of PUR hot melts today. 

Whether you're a first-time buyer or a seasoned pro just looking to improve your processes, our experts have tons of experience with nearly every adhesive application. Contact us today for a personalized product recommendation. 

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