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FLEXO Magazine : July 2009
TECHNOLOGIES & TECHNIQUES BEGINNER FLEXOGRAPHER All art courtesy FLEXcon Inc. Choosing the Right Adhesive Solutions for Pressure Sensitive Applications By Philip Emery C hoosing the best pressure-sensitive adhesive can be a challenging process. Some decisions are readily apparent, such as the choice between a permanent and removable adhesive. Other decision factors may not be so obvious. For example, you will need to decide which adhesive family to choose from, which may depend on specifi c end-use requirements. You also need to consider the role of shear, tack and peel when deciding on the best adhesive system. Let’s look at each of these considerations. UNDERSTANDING ADHESIVES Within the realm of pressure-sensitive adhesives, there are three main polymer families: silicone, acrylic and rubber. Each of these families offers particular characteristics that make it well-suited for particular applications. The rubber and silicone families of adhesives are often ideal for niche applications. If you know you will be bonding something that will be exposed to temperatures as high as 1,000°F, a silicone-based adhesive might be the best choice. Silicone adhesive bonds survive exposure to the highest temperatures. Likewise, an application that requires a strong, permanent bond within a normal range of room temperatures (e.g., 60°F to 80°F) may allow for the use of a rubber-based adhesive. In most cases, however, acrylic adhesives provide you with the widest range of performance characteristics. 26 FLEXO JULY 2009 MAKING THE RIGHT CHOICE Just as there are different adhesive families to choose from, there are also many different members within each family. To help narrow the search for the right adhesive, you can begin by determining the answers to three basic questions: What type of surface do you plan to bond to? What type of material do you plan to bond? What conditions will the end use application face? After answering these main questions, you may need to pose more detailed queries, depending on the application. For example, you may need to ask, “How will it be applied?” (By hand or by machine), or “How much time will pass before the product needs to show ultimate performance?” Many more questions may follow from the initial answers before you select the best adhesive to meet your needs. SHEAR, TACK AND PEEL Many of the questions about your adhesive choice may bring you back to the physical characteristics of the adhesive, which can weigh heavily on any decision. These attributes include the frequently misunderstood trio of shear, tack and peel. Although sometimes challenging to measure and to relate to end-user performance needs, these characteristics can anticipate the performance of a construction in your processes, as well as in the fi nal application. www. f le xography. org
Sustainable Spring 2009