Ask Dr. Dave
by Dr. Dave Dunn
December 1, 2007
Question: Can you advise on the best non-toxic, water-based
adhesive for leather, rubber and fabric shoe soles, and folding of shoe uppers
and linings?
Answer: Traditionally, solvent-based polychloroprene
adhesives were used for this application. However, due to legislation on
solvent emissions, most manufacturers use water-based systems these days.
Water-based polychloroprenes are not as forgiving as their solvent-based
counterparts, and you may find it necessary to use a two-component version to maximize
performance. Aqueous polyurethane dispersions are another system that you
should consider. They are usually applied to the substrates, dried and then
heat-activated. Several types of these adhesives are available with different
performance characteristics in terms of cure speed, flexibility, etc.
Question:
I am looking for a good adhesive for bonding glass to metal. The application is
for trim on a lighting fixture. It will be subjected to heat (~100°C) and UV. I
currently use a silicone adhesive, but can you recommend anything with a faster
curing time?
Answer: You probably have several alternatives. First
of all, you could use a two-component silicone that can give you very fast cure
times. The drawback to this, of course, is that you will need to invest in and
use a two-component syringe/cartridge system or meter/mix equipment. However,
the increase in productivity often outweighs the investment required. You might
also look at fast-curing epoxies, although some yellowing of the adhesive may
occur under UV light. A third alternative is to look at using a fast-curing,
two-component acrylic system. This should give you a high-performance system
that will be resistant to both the heat and the UV.
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