What is PUR Reactive Hotmelt Adhesive

What is PUR Reactive Hotmelt Adhesive?
 
PUR reactive hotmelt adhesive is a 100% solid content, NCO-terminated polyurethane prepolymer designed to cure through reaction with moisture in the air or from the bonding substrate. This adhesive is highly viscous or solid at room temperature but melts readily at moderate temperatures. When molten, PUR reactive hotmelt adhesive develops bonding strength through physical cooling and chemical reaction with moisture. Initial bonding strength occurs rapidly, and the final bond exhibits high thermal stability and chemical resistance due to the polyurea-forming cross-linking reaction between the adhesive's free isocyanate groups and moisture. The chemical post-curing stage may take three to seven days, depending on moisture availability. The formulation of PUR reactive hotmelt adhesive can be adjusted to modify the flexibility and toughness of the adhesive layer. Characteristics such as crystalline proportions, melting point, glass transition temperature, and melt viscosity are all adjustable. Therefore, PUR reactive hotmelt adhesive is a modern, solvent-free, eco-friendly adhesive widely used in various applications to reduce environmental impact and health risks compared to traditional solvent-based polyurethane adhesives.
 

Processing PUR Reactive Hotmelt Adhesive

Using appropriate application equipment and a well-designed bonding or laminating process line is essential when processing PUR reactive hotmelt adhesives:

• Since PUR reactive hotmelt adhesive is sensitive to moisture, the adhesive containers need to be moisture-proof to prevent pre-curing of the prepolymer and pressure buildup in the container.
• The process line should preferably be continuous, melting and applying only the required minimum amount of PUR reactive hotmelt adhesive that can be used immediately.
• The process line needs accurate temperature control at all stages. Incorrect processing temperatures (too low or too high) can lower production efficiency and product yield. For example, if the substrate is too warm, the cooling rate will be inhibited, slowing the development of initial bonding strength. If the processing temperature is too low, the adhesive may solidify quickly, preventing even spreading on the substrate surface.
• The molten PUR reactive hotmelt adhesive can be applied by spraying, extruding, or roller coating.

 

Characteristics of PUR Reactive Hotmelt Adhesive

• 100% solid content, solvent-free, no VOC emissions
• Easy to process without the need for drying
• High initial strength and strong bonding
• Superior washability with water and chemical resistance
• Excellent yellowing resistance
• Decent thermostability, heat and cold resistance

 

Applications of PUR Reactive Hotmelt Adhesive

PUR reactive hotmelt adhesives are widely used in various applications, including:

• Textiles: Bonding and laminating fabrics, fibers, film, and other composites
• Footwear: Adhesion for rubber, synthetic leather, mesh materials, and other footwear components
• Woodworking: Laminating wood veneer and edge bonding
• Construction: Constructing metal doors, partition walls for offices, sandwich panels, and fabricating window frames
• Electronics: Bonding, sealing, protecting, insulating, and assembling electronic components
• Automotive Products: Bonding automotive lighting elements and interior decorations
• Furniture: Bonding furniture and door panels
• Medical Products: Bonding surgical gowns, bed sheets, and mattress covers
• Others: Bookbinding

 
For more information about PUR reactive hotmelt adhesives, please visit the following link:
ttps://www.taiwanpu.com/en/product/Reactive-hot-melt-PU-adhesive