Friday, February 14, 2020

Acrylic Foam Tapes

Just over 40 years ago 3M shocked the tape world (as they often do) with a new product group called VHB (Very High Bond) tapes.  These tapes featured a very dense foam core paired with ultra high performance acrylic adhesive that creates a very permanent bond on most non-porous surfaces.  The combination created tapes that offered unbelievable performance when used correctly. When these tapes first came out there were only a limited number of varieties for fairly straightforward applications.  Today there are dozens of different products for almost any application you can think of. Industries that use these types of tape include aerospace, automotive, appliances, signs, and displays.

These tapes have properties that make them superior to mechanical fasteners (rivets, screws, nuts and bolts, even welding).  Because the foam core of the tape expands and contracts with the ambient temperature they can eliminate stress fractures on exterior signage.  Their ability to absorb vibration makes them perfect for machinery and motor vehicle applications. Last but not least they are fast, clean and easy to use saving significant time and money over mechanical fasteners.

For many years (decades) 3M enjoyed a virtual monopoly on these type of tapes because no other company could make anything that had close to the same level of performance.  This lead to the two biggest issues with them: they were extremely expensive and they had limited distribution. Well all that has recently changed.

Today there is a competitor to the VHB line from the upstart company AFTC.  AFTC was started in Europe and today it is a global organization that offers acrylic foam tapes that offer the same or better performance than VHB products yet they are 35% to 50% less expensive. They are marketed under the Silver Tape brand and I can say that they do everything they promise.

The key to getting a permanent bond is to choose the right tape and then prepare the surface correctly. Then you have to apply it correctly to insure a perfect bond. If you do these things you will have great results and happy customers. Let's talk about the tapes first.

One of the most popular styles are the clear foams.  They aren't really foam but rather solid clear urethane that acts like a foam.  These tapes are perfect for acrylics and glass.  They work really well on metals and painted surfaces as well. Because they are clear they aren't as visible in the finished product.  They are very popular in signs and displays where seeing the tape would detract from the finished product.

There are also standard tapes that are white or light gray in color.  They are designed for use on metals (bare or painted), some plastics and painted or varnished wood.  They can also be used on brick and finished concrete with very good results. They are widely used where the use of mechanical fasteners is impractical from an installation or appearance standpoint. Recently a cold temperature version has been developed that can be applied at temps as low as 30 degrees Fahrenheit.

Another newcomer is tape designed to stick to powder coated metals.  Powder coating has become very popular in recent years because it produces a very durable finish.  The downside is that you can't really bond to it effectively because one of the components of the powder is wax.  The wax allows the powder to flow together when it melts and create that durable finish.  This same tape can also be used on low surface energy plastics like polypropylene and ABS.

Next is proper surface preparation.  These tapes can be extremely finicky and they won't give you maximum performance if you skip this.  The key to success is to make sure the surface is clean and dry.  If you use a standard cleaner like Fantastik or Formula 409 you should get a nice clean surface.  Some surface require a little more than this. If you are sticking to glass you should use a silane treatment to prepare the glass for adhesive.  The silane treatment fills in any imperfections in the surface of the glass.  Here is a link to a 3M technical bulletin on the subject: http://multimedia.3m.com/mws/media/111553O/vhbtm-tape-glass-bonding-and-silane-coupling-agents.pdf

Another surface that needs prep is aluminum.  When aluminum is extruded into bars or angles it is covered with a lubricant to help the process.  This lubricant can get into the surface imperfections of the aluminum and it will prevent a strong bond.  It is recommended that in addition to cleaning you should use an abrasive pad (Scotch Brite or similar) to rough up the surface to help get a clean surface. Do this before you use the cleaner.

I also want to talk about acrylic sheet.  One of the components that go into making acrylic sheet is acrylic oil.  If the acrylic isn't cured correctly there could be significant amounts of acrylic oil left in the acrylic.  You can tell if this is the case by touching the acrylic.  If it feel greasy then you have a problem.  It will be very difficult to achieve a strong bond.

Finally comes the actual application of the tape.  One of the worst things you can do is touch the adhesive with your fingers.  The oil in your skin will contaminate the adhesive and reduce the ultimate bond strength.  It could cause the tape to fail in the field.  Handle the tape by the edges of the roll.  If you do have to touch the adhesive to start the roll try not to use the end where you touched it.  Cut it off and throw it away. Once the tape is applied rub it down with a squeegee or roller to obtain maximum contact of the adhesive.

One of the interesting properties of these tapes is that the adhesive bond gets stronger over the course of 72 hours (3 days).  If you can, try to avoid maximum stress on the tape for that period.

If you have questions regarding the use of acrylic foam tapes please feel free to get in touch at Sales@taperite.com or give us a call at 1-800-882-7348.

Happy Taping!!!




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