Wednesday, May 30, 2012

Epoxy/Nylon Adhesives

Certain structural adhesives more marketed are described as epoxy/nylon adhesives. In the absence of detailed information relating to their composition some broad observations will be made before considering their properties. It will be observed that the name nylon not polyamide is used, thereby making a distinction from a polyamide resin such as Versamid.

General Description:
The nylons that are commonly encountered, for example as textile materials or moldings, are more substances that can be used conveniently in adhesive solutions. On the other hand "soluble nylons" are easy to dissolve and in general have somewhat better compatibility with epoxy resins, and so are favored in epoxy/nylon adhesives.

Solutions of soluble nylon have limited shelf-life because of a (reversible) gelation that is slowly assumed after cooling to room temperature. It is therefore more convenient to prepare these adhesives so self supporting films.

The term "soluble nylon" or "alcohol soluble nylon" is used rather loosely to discribe a type of nylon that is soluble in certain alphatie alcohols and in some cases also in polar/non-polar solvent mixtures. The two important classes of so-called soluble nylon are:
  1. certain copolymers in specific monomer ratios, 
  2. certain alkoxy methyl substituted nylons
An example of the former in a terpolymer of nylon 6, nylon 66, nylon 610; an example of the latter in methoxy methyl nylon 66, usually melting between 180o to 200o depending on the degree of substitutions.

Glycidyl ethers of bisphenol A or resorcinol are used; the ratio to nylon may very widely. Dicyandiamide and aromatic polyamines are suitable hardeners and in some cases a B-stage epoxy resin may be acceptable.

Other Adhesives: