Bonding in a Snap

Adhesives incorporating MagSilica® from Evonik are making it possible to construct electronic equipment more compact and will revolutionize automotive construction.

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The Magic Adhesive Tape

The Motorola International 3200, launched on the market in 1994, weighed half a kilo and was 33 centimeters long. It marked the beginning of a new cell phone generation that made mobility throughout Europe possible and replaced the analog system. Much has changed since the 1990s, with cell phones becoming increasingly smaller, lighter, and more powerful. If you had dropped the Motorola 3200 from a moderate height, you would have had to scrap it. Today's cell phones can take much more punishment. And now, a completely new adhesive technology could once again revolutionize design and functionality. It allows today’s cell phones to be built twice as small without a problem, and with no loss of performance or increase in price.

Tripled adhesive power

Lohmann GmbH & Co KG of Neuwied, Germany, an internationally active specialist in double-sided adhesive tapes, is using for this purpose an invention by Evonik: a novel adhesive additive called MagSilica®. This allows parts to be bonded much more rapidly than with conventional liquid adhesives, and at a much higher adhesive tensile strength than with current self-adhesive solutions. It is this higher adhesive power that allows the miniaturization of the parts to be bonded. Until now, these parts have had to be of a specified minimum size, in part so that the adhesive can adhere to them adequately.

This novel filler, along with innovative approaches from adhesives chemistry, yielded a solution combining the two worlds of liquid and pressure-sensitive adhesives. The new adhesive system developed by Lohmann is called Duplocoll RCD (Rapid Curing on Demand). It looks like, and is processed in the same way as classic pressure-sensitive adhesive tapes, but a downstream curing process allows bond strengths that cannot be achieved by conventional pressure-sensitive tapes.

Incorporating 5 to 15 percent of MagSilica® into the adhesive matrix dramatically reduces curing time. Instead of the 5 to 30 minutes that were once required, curing is now complete in no more than 30 to 60 seconds. This is achieved by inductive heating, a process in which the adhesive cures on application of an electrical current. A stress-free bonded joint can thus be obtained within seconds.

The adhesive power also increases by 300 percent. “Before the use of MagSilica® an improvement of this magnitude was totally inconceivable; an increase of even 50 or 60 percent would have been regarded as an enormous success,” says Dr. Hansjörg Ander, head of Research & Development at Lohmann.

Time and energy savings

This advance has been achieved partly through nanotechnology. Evonik researchers incorporated into conventional adhesives nanomaterials that behave superparamagnetically. This means that these particles can be heated by alternating electromagnetic fields, giving them entirely new properties. In In a matter of minutes, enormous bonding strengths are achieved, and long curing times are no longer necessary.

And the process is economical too, saving considerable time and energy.

Not confined to electronics

Another innovative field of application for the extra-strength adhesive system with MagSilica® is opening up in another sector. The automotive industry will benefit greatly from the new processes enabled by MagSilica® because bonded joints allow the use of lighter materials such as aluminum and plastics. One kilogram of adhesive used in this way reduces the weight of a car by 25 kilograms. It's immediately obvious that the use of the adhesion technology significantly lowers fuel consumption.

Potential for the automotive industry

Until now, the use of adhesion technology in automotive construction has had two serious disadvantages. First, adhesives needed extended curing times. Second, the bonding was not easily reversed, which is a major drawback in repairs and recycling. For this too, MagSilica® offers a solution. Because the adhesive additive has yet another magical property: it makes it possible to debond joints that have been specifically designed with this possibility in mind.

High-performance adhesives based on MagSilica® will clearly revolutionize the joining of plastic parts in automotive construction.