Annual Report 2015DEEN

Strong

bonds

Special additives from Evonik Industries ensure that adhesive tape and labels stick extremely reliably wherever it really matters. And they do that even when they are taken off and stuck back on.

Adhesives have to stay cool even when the going gets tough. That also applies fully to adhesive tape, no matter whether it’s used in sports or at home. However, the ugly brown spots that can be found on many bathroom tiles tell another story. Whereas adhesive strips that have just come off the roll seem to hold no matter what, the towel hooks they support eventually fall off the bathroom wall and only the adhesive itself remains permanently attached to the tiles. The adhesive was weakened by external influences such as temperature fluctuations, cleaning agents, and ultraviolet light. This is an area where Evonik can demonstrate its skill. As a result of post-application UV crosslinking, one of the company’s additives, VISIOMER® 6976, can greatly increase a tape’s adhesive force. In endurance testing, it stuck 400 times better than a non-crosslinked adhesive.

A typical property of the adhesive used in adhesive tape is its permanent stickiness. This distinguishes it from many types of adhesive, which don’t become hard and adhesive until they dry or undergo a chemical reaction. This permanent stickiness makes it possible to attach tape to almost any surface. But it’s precisely this versatility that makes the use of tape demanding because it limits the tape’s adhesive strength. As a result, it’s not just adhesive strips on hockey sticks and labels for frozen products that have to stay sticky at low temperatures and not become brittle. Stickers on hazardous materials also have to adhere reliably for a long time and when subjected to extensive wear and tear. Removable labels have to stick well but not leave any residue when they are taken off.

The incorporation of our UV-active monomer VISIOMER® 6976 increases not only a glue’s adhesiveness but also its resistance to many external influences such as moisture, temperature fluctuations, and chemicals.Dr. Sabine Kömmelt

Technical Manager Applied Technology,
Acrylic Monomers Business Line

This is where the special methacrylate VISIOMER® 6976 from the Performance Materials Segment comes into play. When an adhesive containing this substance is exposed to ultraviolet light, the adhesive becomes crosslinked. The UV-active monomer VISIOMER® 6976 helps the individual polymers in the adhesive to link up with one another and thus increase the adhesive strength. What’s more, this process increases the adhesive’s ­chemical stability, insensitivity to temperature fluctuations, and resistance to moisture. By changing the dose, it’s possible to customize the type and duration of the UV influence and thus also the crosslinking to the respective application. 

Another benefit of adhesive tape containing VISIOMER® 6976 is that no solvents are needed to make them. This, in turn, reduces the environmental impact and increases the manufacturers’ productivity. Typical areas of application for such adhesive tape include electronic systems and the industrial assembly of components. The special methacrylate is also well suited for everyday applications, particularly those that require strong bonds under unfavorable conditions—ice hockey being a good example.

As a post-application crosslinking agent, VISIOMER® 6976 is also suited for other resin systems such as paints and coatings. Such paints are easy to apply before the crosslinking takes place. The natural ultraviolet light from the sun gradually causes the paints to harden and thus become more resistant to external influences.