The simplest method for
separating a lens bonded with Norland Optical Adhesive is to immerse
the lens in a solvent combination made up of the following: methylene
chloride, 100 parts by weight -methanol, 15 parts - concentrated
ammonia (26 Baumé or 29% NH ), 2 parts. The methylene chloride
is the active solvent and the other solvents increase its activity.
A typical 1 inch diameter lens
will separate easily before the full cure by an overnight soak
in these solvents. A fully cured lens requires a longer soak because
the adhesive is more crosslinked and slows the solvent penetrations.
Some lenses may start to separate but the solvent does not penetrate
to the center even after a long soak. This is due to a very thin
layer of adhesive in the center. To separate these lenses a slight
thermoshock is necessary. Warm the lens up to 150°F and immerse
it in the solvent combination while still warm. The sudden contraction
will allow the solvent to penetrate to the center. Repeat if necessary.
Heating in hot mineral oil is another
method that is commonly used. Usually it will take 20 to 40 minutes
at 400 degrees F for the lens to separate. An alternate heating
method is to place lenses in a vacuum coater and heating them
under vacuum until they separate. Remove adhesive from glass surfaces
now by immersing in the solvent combination.
Large lenses may require even
higher temperatures to separate them. One method that has been
successful is a heated sand bath at a temperature of 800°F.
A fine sand or emery is heated in a pan on a hot plate. When it
is up to temperature the lens is placed on the surface and will
separate as it heats up.
Paint strippers containing
methylene chloride are usually available from local hardware stores
and will work as well or better than the solvent combination given.
A liquid formula will work better than the gel-type.
Brulin’s Safety Strip HT and AZ 300T photo resist strippers also can be used to debond our adhesives. You can get further information on these products at the links below.
Brulin's Safety Strip HT: http://www.brulin.com/productdetails.aspx?pid=142&cid=44
AZ 300T(Electronic Materials): http://imicromaterials.com/products/photoresist-removers
Protective goggles and gloves
should be used when handling chemicals.