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!
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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.
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.
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 applicator from Infinity Bond offers a powerful 500-watt heater and a dual (high and low) temperature settings. When using the Infinity PUR 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.
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 CartridgeDid 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.
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 AdhesivesPUR 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.
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.
Before you understand how to choose and buy conventional, summer, and winter types of pur edge banding hot melt adhesives, you first need to know the differences between them and the impact of different environments on their use. As a manufacturer with more than ten years of experience in the application of PUR hot melt adhesives, Blue Rhino Adhesives has long customized various types of PUR hot melt adhesives for furniture factories and woodworking manufacturers. Let’s analyze this issue from multiple angles.
Pur(Polyurethane Reactive) edge banding hot melt adhesive is a moisture-curing reactive polyurethane hot melt adhesive specially used for bonding the edges of panels. Compared with traditional EVA hot melt adhesive, Pur edge banding hot melt adhesive has better bonding strength, water resistance, weather resistance, and other properties. It is deeply loved by the furniture and wood processing industries, and its market share has been gradually increasing in recent years.
When using pur hot melt adhesive, first heat the adhesive to a molten state, then apply it to the surface of the substrate to be bonded, and then the two adherents will be attached. The colloid will cool quickly to produce an initial adhesion and positioning effect (physical curing); at the same time, the glue will continue to react with moisture in the air or trace moisture in the substrate to produce chemical cross-linking reaction and chain extension (chemical curing).
After the chemical reaction, a high molecular polymer with high cohesion is generated. Once cured, it has excellent waterproofness, ultimate bonding strength, chemical corrosion resistance, and extremely high weather resistance.
The curing process of pur hot melt adhesive involves physical and chemical reactions. Therefore, the ambient temperature and humidity will affect the initial viscosity, open time, and curing time of the glue.
High temperature (summer): In summer, the ambient temperature becomes higher, which will slow down the cooling of the pur edge banding hot melt adhesive, resulting in lower initial viscosity. If the production line speed is relatively fast, it is easy to cause the edge banding strip to fall off. At the same time, the higher ambient temperature will also cause the subsequent glue curing time to become faster.
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Low temperature (winter): In winter, the ambient temperature drops, which will cause the PUR edge banding hot melt adhesive to cool down faster, resulting in a shorter open time. If the production line is fast, the glue will lose its adhesion before being applied to the edge banding, which will also cause the edge banding to fall off. At the same time, the lower ambient temperature will also slow down the subsequent curing time of the glue.
High humidity (summer): In summer, the temperature is high, it rains a lot, and the water vapor content in the air is high, which leads to high humidity. The high content of water molecules in the air will accelerate the chemical reaction with PUR hot melt adhesive and accelerate the overall curing speed.
Low humidity (winter): In winter, the temperature is low, there is little rain, and the water vapor content in the air is low, resulting in low ambient humidity. The low content of water molecules in the air will slow down the chemical reaction between water and PUR hot melt adhesive and reduce the overall curing speed.
In summary, the changes in temperature and humidity in different seasons will change the initial viscosity, open time, and curing time of the hot melt adhesive. Choosing the wrong type of hot melt adhesive for edge banding can easily cause the edge banding strip to fall off, and shift, and the glue cannot be cured.
Applicable environment: temperature is 10°C-35°C (each pur hot melt adhesive supplier will be different), relative humidity is 50%-70%. Such a stable environment generally appears in spring and autumn or in a constant temperature and humidity workshop.
When designing conventional pur hot melt adhesives, factories will design them with moderate initial viscosity, open time (30-120 seconds), and curing speed, so that users can choose according to the conventional environment. High-end custom furniture factories have relatively high requirements for production stability and generally build constant temperature and humidity workshops. Conventional pur hot melt adhesives are very suitable for use in such factories.
Applicable environment: temperature above 35°C (different for each pur hot melt adhesive supplier), relative humidity above 70%, usually in summer. In such a high temperature and high humidity environment, plus many furniture factories are in confined spaces, summer-type pur hot melt adhesive is the most suitable.
When the factory designs summer-type pur hot melt adhesive, it will reduce the initial viscosity of the glue, shorten the open time, and reduce the curing speed to ensure that the position of the edge band is fixed and the curing is completed within the open time of the glue to avoid the edge of the edge band from warping and moving.
Applicable environment: temperature below 10°C (different for each PUR hot melt adhesive supplier), relative humidity below 40%, usually in winter. In such a low temperature and low humidity environment, coupled with the fact that many furniture factories are in closed and unheated production workshops, winter-type pur hot melt adhesive is the most suitable.
When the factory designs winter-type pur hot melt adhesive, it will increase the initial viscosity of the glue, extend the open time, and increase the subsequent full curing speed. Ensure that the glue can establish initial viscosity faster in a low temperature and low humidity environment to avoid the glue being unable to cure for a long time after being applied to the edge banding, which will cause the edge banding to shift or fall off after pressing.
Different pur hot melt adhesive suppliers have different technical parameters. Before use, you need to understand the technical parameters of different types of glue, focusing on the applicable temperature, humidity, and open time of the hot melt adhesive.
Different edge banding materials and production lines have different choices for pur hot melt adhesive. You need to communicate with the pur hot melt adhesive factory about the speed of your production line, how long it takes for the board and edge banding to be glued and pressed together, and how long the open time is needed to match.After the board is edge banded, how long it will take to proceed to the next process, and how long the curing time is needed to match.
Before changing seasons or changing the type of pur hot melt adhesive, be sure to conduct a small batch production test first. Verify whether the initial adhesion, open time, lamination effect, curing speed, final strength, trimming effect, etc. of the glue meet the production requirements to avoid large-scale losses caused by direct use.
Install a reliable thermometer and hygrometer in the edge sealing area of the production workshop, and record and monitor regularly. When the temperature and humidity change, the corresponding type of pur hot melt adhesive needs to be switched in time.
In summary, in order to choose various types of pur edge banding hot melt adhesive, buyers need to understand the parameters of the supplier’s pur hot melt adhesive, evaluate the production line requirements, conduct small batch tests in advance, and monitor the workshop environment in real-time.
In summer, the gluing temperature can be appropriately lowered (within the allowable range of glue melting) to improve the initial viscosity of the glue and reduce the curing time. Conversely, in winter, the gluing temperature can be appropriately increased to reduce the viscosity of the glue and improve fluidity.
The amount of glue applied will affect the open time. Different types of PUR hot melt adhesives have different open times. When used in factories, the amount of glue applied can be adjusted slightly within the range that does not affect the bonding strength.
The pressing time will affect the penetration of the pur hot melt adhesive. In winter, more pressing time may be required to ensure full contact between the board and the edge banding.
Due to the lower temperature and humidity in winter, a longer curing waiting time is required (from pressing to trimming) to ensure the strength of the glue and avoid the subsequent falling off of the edge banding.
Before purchasing conventional, summer, and winter PUR edge banding hot melt adhesives, manufacturers need to understand multi-dimensional factors such as environmental parameters, production requirements, supplier qualifications, and storage conditions. Among them, environmental parameters, production requirements, and storage conditions are factors that are easy to control, and choosing a reliable supplier is the key.
To choose a reliable pur hot melt adhesive supplier, you can examine it from aspects such as industry certification ( ISO, SGS test report, etc.), customization capabilities (supporting adjustment of development time according to production line speed and optimizing formula for special substrates), cooperation cases (investigating glue application experience), production scale, and service experience (including early technical development and later use services).
If you are using various types of pur hot melt adhesives in small quantities, you can consider buying them at a nearby hardware store or building materials market. However, if the usage is stable and the purchase volume is large, you can consider buying directly from pur hot melt adhesive manufacturers. After all, manufacturers have rich experience in glue application and can give reasonable suggestions based on your production line conditions.
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