Transparent flexible adhesive

A number of adhesives had been tried but under stress tests were too brittle for the substrates which were silicone rubber and cotton backed PVC. Furthermore the contours of the mouthpiece made applying the adhesive by hand very tricky. A 1-part flowable silicone adhesive was recommended by Steve Green, one of Techsil’s Application Development Engineers who says: “Momentive IS5628E silicone adhesive cures at room temperature, requires no mixing and its flowable consistency makes it easy to apply. It adheres well to silicone rubbers and cures to make a tough durable bond which can withstand very high and low temperatures."

For the production process, a semi-automated system was chosen. A circular, even bead of adhesive was required and a Nordson EFD Ultimus 1 dispenser with a 310 cartridge assembly was deployed and a fly press to deliver the adhesive. The hood and mouthpiece is placed on a turntable and is rotated 360 degrees during dispense.

This project has increased the speed of the manufacturing process and eliminated adhesive wastage.