Working with PUR Hotmelt
Recent developments in reactive Hot Melt Polyurethane (HMPUR) adhesive technology have made these products viable candidates for use in high performance applications. Specifically, technical advantages that combine desirable properties such as past set (curing), rapid green strength development, and exceptional environmental resistance, are now available.
What is PUR Hotmelt (hmpur) ?
HMPURs are the reaction product of the combination of a polyol and an isocyanate. Once reacted, the product formed is an isocyanate terminate prepolymer, which is moisture
sensitive. After application, this product cross-links through a reaction with moisture in the air and surrounding substrates, forming a thermoset polyurethane polymer. Once thermoset, the HMPUR will possess exceptional
strength and durability. Because these products contain isocyanates and must be heated for application, our partners work with lesser volatile isocyanates, such as MDI (diphenylmethane diisocyanate).
how does it work?
HMPURs work through two distinct stages to develop the characteristics of a high-performance adhesive. In the first stage, the HMPUR is heated to become molten or fluid for application. At this stage, HMPUR is similar to conventional hot melts because thermal cooling solidifies the adhesive after application. Accordingly, HMPUR has an open time and set time. It will develop enough strength upon cooling to allow for trimming in line and other handling of parts.
In the second stage, the HMPUR reacts with moisture to form a thermoset polymer resistant to heat, moisture, cold and solvents. This reaction occurs over time and under normal conditions 75% cure is reached within the first 24 hours. As the cross-linking continues, assembled substrates will continue to build strength Normal conditions at 50% relative humidity and 21°C.
Laminated substrates bonded with HMPUR become very durable. The adhesive bond shows many important properties:
Please contact us if you need in depth advise on working with HMPUR. There is an enormous scope of different HMPUR types. It is therefore very important to understand all the
requirements of the lamination before choosing the right HMPUR.
HMPUR is used for many different applications, mostly lamination. Some examples are:
Flat lamination: Wood to panel, wood to foil, metal to wood, etc.
Flexible lamination (roll to roll): Textile to textile, textile to membrane, textile to foam, etc.
Profile wrapping: Film to PVC profile, film to aluminium profile, etc.
Assembly: Parts glued into structure, etc.