Pressure sensitive hot melt vs. setting hot melt adhesives

What are hot melt adhesives?

Hot melt adhesives are adhesives based on thermoplastic polymers and consist entirely of solids. They are solid at room temperature. They become liquid on heating, which is when the adhesive can be applied. The main difference with other adhesives is that the pressure sensitivity of hotmelt adhesives is realized through cooling. There is therefore no chemical curing process and no evaporation of solvents or water.

The consistency makes hot melt adhesives especially suitable for porous and permeable substrates, which are sometimes more difficult to bond with other adhesive systems. Another important advantage is that they build up their internal strength very quickly during cooling. This makes fast assembly and processing possible. And because they are based on thermoplastic polymers, hot melt adhesives can be repeatedly heated and cooled.

The advantages of hot melt adhesives

Hot melt adhesives have a number of important advantages, including:

• High initial tack
• Rapid curing
• Suitable for porous substrates
• No drying or curing necessary: immediate packing of finished goods
• Solvent-free; better for the environment and human health
• Bonding process that is simple to automate

Curious about the differences between hot melt and water-based adhesives? You can read more about that here. 

Pressure-sensitive Vs. Setting

Hot melt adhesives are often divided into two categories:

• pressure sensitive hot melt adhesives (PSA)
• setting hot melt adhesives

Pressure Sensitive Adhesives (PSAs)

PSAs create bonding when pressure is applied to bond two substrates together. As the name shows, the degree of bonding is influenced by the amount of pressure applied. Because the adhesive remains sticky, it has high bonding strength but less cohesive strength. As a result, this adhesive does not create a strong tensile bond, but its tack makes it ideal for applications where the bond needs to be restorable or it must be possible to reposition parts.

Setting Adhesives

Setting adhesives are most frequently used in mattress manufacturing. These adhesives are the opposite of PSAs. They are not permanently tacky and lose tack as soon as the adhesive is fully cooled. Most setting adhesives have high bonding strength and high cohesive strength. At room temperature, little or no tackiness can be felt on the surface of the adhesive, creating a permanent bond. This means the hot melt has a high bond strength as well as a high cohesive strength. It therefore creates a strong bond that is perfect for mattresses and pocket springs.
 

The best adhesive is the one that suits your product, equipment and process. We would be pleased to work with you to ensure that you have the right adhesive solution for optimal results. Feel free to call us or send an e-mail for advice. We will be happy to share ideas with you!

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