Hot Melt Polyurethane Used for Textile
There has been great interest in the use of hot melt polyurethane adhesives for textile applications in recent years. Generally, advantages of using hot melt polyurethane adhesives for textile applications include:
1. Low viscosity behavior, which allows for rapid machining and high line speeds at relatively low temperature. This means that heat-sensitive materials can be rapidly coated and laminated.
2. Excellent hydrolysis resistance of specifically designed products allows hot melt polyurethane-bonded fabrics to be washed or autoclaved multiple times. This is important for medical and protective apparel applications that require autoclaving for decontamination.
3. Reactive flame retardants have now been incorporated directly into the backbone of the hot melt polyurethane adhesives. This has allowed textiles coated with these products to pass fire tests and some automotive standards. Since the fire-retardant materials are part of the chemical structure of the adhesive, there is no problem with blooming or extraction.
4. Products have been developed for bonding very soft, low-surface-energy materials such as porous polytetrafluoroethylene (PTFE) or Teflon and low-basis-weight polyurethane films for active-wear applications. Methods have been developed to produce breathable laminates using hot melt polyurethane adhesives.
Also, there are other applications of hot melt polyurethane adhesives. Profile wrapping is a major growing application for this adhesives. This application makes use of the short set times and rapid green-strength development possible with proper formulation of hot melt polyurethane products. Some profile-wrapping applications involve the bonding of printed papers and plasticized vinyls onto MDF profiles. These wrapping materials require relatively low application temperatures and low viscosity of the hot melt polyurethane adhesive.
At the other extreme, wrapping high-pressure laminate to PVC extrusions or wood profiles requires the application of high temperatures, very rapid green-strength development, and short set times to wrap the stiff high-pressure laminate material.
One of our recent unique developments is a highly electrically conductive adhesive for applications requiring antistatic behavior or electrical conductivity. This has the potential of replacing other conductive adhesives such as epoxies or solvent-based adhesives with a product that has all the advantages of the hot melt polyurethane adhesives described in this article. In addition, hot melt polyurethane adhesives are being used in applications as diverse as bookbinding, automotive interiors and insulated garage doors.
As you have seen from the applications described above, hot melt polyurethane adhesives can be developed with a wide variety of properties to provide high performance for specific application requirements. These adhesives can provide highly efficient bonding operations with high line speed and efficient use of plant-floor space since their short set time and excellent green strength allow parts to be handled quickly. The fact that they are 100% solids and require no drying or solvent handling makes them environmentally friendly and minimizes the use of heat energy for application.
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