Pressure-sensitive adhesive tapes (PSA) are playing an increasingly important role in door and window manufacturing and are being used in technical bonding and barrier applications that enhance the performance and lifespan of the end product.
Selecting the right adhesive and tape construction is essential to ensure the proper performance of a PSA in every application. Different materials and applications require different adhesives. It’s always important to work with your tape or component manufacturer early in the design process to ensure the adhesive is engineered to meet the specific requirements of your substrate and application.
Equally important, however, are the processes used to apply PSAs and the conditions in which tapes are applied. Poor application processes can prevent manufacturers from realizing the full benefits of the adhesive.
Benefits of PSAs
The versatile nature of PSAs makes them ideal for a broad range of window and door applications. Their flexibility, strength and ability to join different types of materials have resulted in uses that extend from external sealing to internal assembly.
PSAs can have a broad operating temperature range and, as such, are appropriate for extreme climates. In assembly applications, tapes bond on contact, eliminating the cure times silicone sealants require. They can also fit the shape of any die-cut material and compensate for varying expansion and contraction rates among different materials. In some applications, they can even provide vibration and noise dampening characteristics.
PSA benefits are also being realized in a new application: that of enabling the transition from aluminum to warm edge spacers in insulated glass units. Using a multi-layer laminate instead of a thermally conductive aluminum spacer can enhance the thermal resistance of multi-pane window units and increase R values. In addition to their thermal performance attributes, these components create an ultra-high barrier to moisture, have very low gas permeation and offer corrosion resistance equal to or better than aluminum. As more manufacturers move to warm edge spacers using PSAs, proper application practices become even more important.
Best Practices for Using PSAs
Regardless of how tapes are being used, consistently adhering to best practices helps ensure a strong bond that will hold throughout the life of the product.
Once the proper adhesive is selected, the key factor in determining the strength of the bond is the ability of the adhesive to wet out (when the adhesive completely covers and fills the substrate surface without any bubbling or other occlusions that restrict bonding) during application. Even apparently smooth surfaces have a texture that an adhesive can flow into, and environmental conditions and application processes influence adhesive flow.
While the operating temperature range of PSAs can be very broad, the application range is narrower. If application temperatures are below the manufacturer’s recommended range, the adhesive can lose some of its viscosity and may not wet out properly. Similarly, temperatures above the recommended range can create too much viscosity and cause excessive flow. Proper control of the environment in which PSAs are applied is the most important step any manufacturer can take to ensure the proper performance of a PSA.
Application pressure can also be matched to substrate characteristics. Increasing pressure is often necessary with textured substrates and helps ensure the adhesive wets out fully and makes the needed contact.
Dirt, dust, oil and other material on a substrate that may be invisible to the human eye can reduce the ability of the adhesive to wet out and fully adhere to the substrate. Instead of adhering to the substrate, the adhesive will bond to these microparticles. Routinely cleaning substrates prior to tape application is a good practice for every tape application.
Material storage and handling
Tape manufacturers provide specifications for the safe storage of tape rolls. Precise environmental control isn’t always possible in manufacturing plants, but extremes in temperature, such as those that occur when tapes are stored in a trailer over the summer, should be avoided. Excessive temperatures can cause the adhesive to flow, and the pressure created by the weight of the roll can force the adhesive to ooze, which will be visible when inspecting the roll. The short-term solution is to cut off the end where oozing has occurred and freeze the roll before bringing it to ambient temperature for processing. If tapes are stored in freezing temperatures, they should be allowed to warm to recommended temperatures before using.
When specified and appropriately applied, PSAs support a variety of window and door manufacturing requirements by creating a strong bond that can withstand extreme environmental conditions over the life of the product. They also now enable window manufacturers to transition from aluminum to warm edge spacers to improve barrier performance in multi-pane windows.