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How much pressure should be applied?
The aim of applying pressure is to achieve 100% wet–out of the adhesive. To achieve good wet-out and ultimately a good bond, it is essential to ensure that this is firm and even. As a rule, a minimum of 15 PSI (100 Kpa) should be used for rigid materials. More flexible components may need less pressure. The size, shape of the components being bonded and tape placement will also need to be considered in determining how much pressure should be applied.
Why does acrylic foam tapes not feel very sticky to the touch?
While acrylic tapes tend to be firm and dry to the touch, this is not an indication of their final funding properties. And acrylic foam tapes adhesion builds over a 72 our period to form and unsurpassable bond. Adhesives such as rubbers and hot melts, while feeling very tacky, do not have the same physical properties from a temperature, plasticiser or solvent resistant point of view.
What is the purpose of having varying thicknesses of tape?
The thickness of an acrylic foam tape allows it to compensate for mismatch between two surfaces. By choosing a tape that accommodates mismatch, the tape is allowed to achieve optimum coverage of the surfaces that it is bonding. The greater the surface coverage achieved, the more effective the bond will be. For rigid materials, a good rule of thumb is that the tape should be twice as thick as the material mismatch. Acrylic foam tapes are designed to provide stress relaxation properties. It’s acrylic foam core allows the tapes to elongate and relax when stressed. This means the stress is distributed throughout the foam core and not concentrated in the adhesive bond line, which is often a cause of adhesive failure. Acrylic foam tape can stretch up to 3 times its thickness to accommodate thermal expansion.
Bonding to difficult substrates
The surface energy of any substrate that requires bonding will determine how easy or difficult it will be to bond to that surface. Surfaces with a high surface energy are easier to bond to and surfaces will low surface energy more difficult. The surface energy of a substrate will ultimately determine the ability of acrylic foam tapes to “wet-out” surfaces to allow for adhesion. Wet-out refers to how well the acrylic foam tapes flows and ultimately covers the surfaces that it is bonding. Maximum adhesion occurs when the acrylic foam tapes thoroughly wets out the surfaces being bonded. The better the wet-out, the greater the surface coverage, which in turn will allow the attractive forces between the adhesive and the substrate to develop to its fullest potential. Low surface energy substrates often require special surface preparation to raise surface energy and make them easier to bond to. Surface preparation usually takes the form of cleaning with solvents, abrasion, priming, flame treatment, plasma, and acid or Corona treatment.
The affect of these treatments is that the surface of the substrate will be improved to allow adhesives to key to it.