Hot melt glues, which have become increasingly popular in recent years, are thermoplastic polymer-based formulations that are normally 100% solid (no water or solvents are used). They are marketed in a solid condition at room temperature and ‘activated’ when heated above their softening point, which is typically between 50 and 160 degrees.
The hot melt glue melts at high temperatures and hardens when cooled, making it ideal for a wide range of applications across numerous materials. It is free of solvents, safe to use, and promises long-lasting performance.
Types
Unleash the power of bonding with a strong hot melt adhesive. Understanding the different types available can help in selecting the right one for your application. One of the most popular applications of hot melt glue is hot glue sticks. They will elevate all of your craft creations to new heights. You can glue paper and card stock together, or whatever comes to mind.
Hot glue sticks are renowned for their strong connections, ease of use, and clean-running properties, such as no stringing. However, they provide excellent temperature stability, so avoid getting burned in the glue tank. This distinct feature also eliminates the inconvenient nozzle blockages associated with less advanced adhesives.
1/2″ glue gun sticks are the most generally available size on the market. They can accommodate the widest range of formulations. However, the most important factor to consider when choosing a 1/2″ glue stick is to make sure that the temperatures of your hot melt gun and glue stick match up correctly. You must use a high-temperature glue stick with a high-temperature gun and a low-temperature glue stick with a low-temperature gun unless you have an adjustable temperature hot melt gun.
Because they are larger and can discharge more volume, 5/8″ hot gun sticks require fewer stick replacements, which is ideal for high-volume applications.
According to the classification of ingredients, the hot-melt adhesive film is classified into EVA (Ethylene-Vinyl Acetate) based hot melts, polyolefin-based as well as polyamide and polyurethane (PUR) hot melt adhesives.
EVA-based formulations are one of the most commonly used types of hot melt adhesives, offering a good balance between performance and cost. They are widely applied in packaging, bookbinding, and general product assembly.
Polyolefin-based hot melts are typically based on metallocene or amorphous polyalphaolefin (APAO) chemistries. They provide better thermal stability and oxidation resistance than EVA-based products.
Polyamide hot melts are designed for high-performance industrial use. They offer excellent resistance to heat, chemicals, and oils, making them ideal for challenging environments.
PUR hot melts combine the benefits of thermoplastic and reactive adhesive technologies. After initial setting by cooling, they continue to cure through reaction with moisture, resulting in a permanent, strong bond.
Additional Buying Factors
Besides being familiar with different adhesive types, there are several key considerations to help you make an informed decision when picking the ideal option for you.
Material Compatibility
Material compatibility is an important consideration when choosing a hot melt adhesive. Not all hot melt adhesives work with all materials. Some adhesives are versatile, while others are tailored to certain substrates. You should examine the porosity, surface energy, and chemical composition of the materials involved. For example, Ethylene Vinyl Acetate (EVA) is a flexible adhesive that is commonly used in packaging and can connect a wide range of surfaces. HMPUR and polyester hot melts, on the other hand, work especially well on low-energy substrates like plastics.
Resistance to Environmental Conditions
Various applications necessitate adhesives that can resist specified temperature ranges and environmental conditions. For instance, in aerospace and automotive applications where bonded parts will be subjected to excessive temperatures or extreme temperature swings, it is critical to use a high-temperature resistant adhesive, such as Polyamide hot melts. Another example is polyolefin hot melts, a type of adhesive commonly used in electronics to protect components from dampness and liquids.
Bonding Strength and Speed
Another crucial factor to consider is the hot glue’s bonding strength. Depending on the materials being bonded and the tension the joint will experience, you will want an adhesive with adequate bonding strength.
For heavy-duty applications like automotive manufacturing, where the adhesive must survive vibrations and intense stresses, a high-strength adhesive is required. In contrast, lighter applications such as bookbinding may benefit from a more flexible bonding option that produces a strong bond without excessive rigidity, such as polyurethane hot melts.
Adhesive bonding speed requirements vary depending on the application. A quick-setting adhesive is required in high-volume production operations, such as furniture manufacture, to preserve efficiency and productivity. Applications requiring longer curing durations, on the other hand, may benefit from adhesives with a longer open time, which allows for modifications before the bond entirely sets.
Keep in mind to consult the manufacturer’s guidelines and conduct thorough testing, to ensure that your adhesive choice meets the demands of your application.