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Letter 35988
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Ted,
Thanks for the suggestion, and yes indeed, that type of durability is
what we are looking for. My question however is about finding a
conductive base coat that will adhere to plastic resin and not
delaminate in the electropalting process. so far, we have been
experimenting with conductive paints (which mostly delaminate) and
shielding marerials (which seem to lack enough conductivity and
provide uneven finish)
We tried vacuum metslizing, and were unable to find a local shop that
could provide an acceptable finish. (too heavy a hand with the base
coat)
We often work under tight timelines and are looking for solutions
that can be applied in-house. We are setup for electroplating and
have been loking for a way to get metal finish on cast plastic
parts.
Tahnks,
Paxton Downard
- Vancouver, B.C., Canada
I think we're almost communicating but still slightly off
frequency. I'm saying if you like what the auto makers have achieved,
why not do the same process they do instead of hunting around trying
various conductive lacquers and vacuum metallizing? What is the
substrate--automakers use mostly ABS, sometimes plating grade
glass reinforced nylon. ABS is best because its
composite nature allows etchability for good tooth.
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 Ted Mooney finishing.com Brick, New Jersey |
In our R&D department people want to chrome glass reinforced
nylon.
I'm new to plating on plastic, so can you please tell about this
plating grade glass reinforced nylon ? In what way if any is it
different from normal glass reinforced nylon ?
And maybe more important, where can I get it ?
Bo König
Food industry - Odense, Denmark
I know little about nylon, but I believe it's Nylon-6, whatever that means. I know that some American resin manufacturers offer plating grades of it, but I don't remember which, and it would take some effort to dig through old project files. But a google search on "plating-grade nylon" gives a Japanese supplier of plating grade nylon-6 as the first hit.
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Ted Mooney finishing.com Brick, New Jersey |
Paxton,
I am a bit confused as to what you are trying to do. If you select
the correct polymer, it can be easily metallised with excellent
adhesion. I would recommend either ABS or MIPS, although
polycarbonate and numerous other polymers can aslo be used. This will
give you excellent conductivity and if done correctly, good adhesion.
Alternatively, have you considered using conducting polymers such as
PEDOT? They are not very cheap, but althesame they are beginning to
approach the electrical conductivity of bulk metals, so that may
help. Vacuum metallisation should give you a very good surface finish
and it can be put down in very thin layers.
As far as Ted's questions about nylon are concerned, I think I can
shed some light here. Nylon is not a very suitable polymer for
metallising as the majority of the types are hygroscopic and swell in
water. This causes dimensional instability. Saying that, they are
still metallised by conventional wet chemical processing.
I believe in the USA the only nylons allowed to be used in air brake
pipes are nylon 11 and 12; this is because they are the least
hygroscopic and are safe to use. However, I have seen adverts for
brake pipes made from nylon 6 and nylon 6/6. Whilst these are
available in Asia, I would be very retiscent about using them in more
humid climates.
I also believe that electroplating grade nylons are usually filled
with a mineral, such as calcium carbonate, as this can be easily
etched out to form physical keys for the metallising process (in a
manner very similar to ABS). I would expect glass filled nylons to be
quite difficult to successfully metallise because of the inertness of
the glass. However, no doubt someone out there will be doing it very
successfully on a commercial basis!
As far as the chemistry of nylon is concerned, the different nylons
are prepared by either reacting a diamine with a dibasic acid or by
self condensation of a single compound with an amine group attached
to the end of the chain. In the case of the self condensation nylons,
the number (eg 6, 11 or 12) refers to the number of carbon atoms in
the amino acid. So nylon 6 is made from aminocaproic acid, whilst
nylon 11 is made from w-amino undecanoic acid.
In the case of a diamine/dibasic acid product, such as with 6/6 or
6/10, the first number refers to the number of carbon atoms in the
diamine and the second to the number of carbon atoms in the dibasic
acid. So, for nylon 6/6, the precursors are hexamethylene diamine and
adipic acid, whilst for 6/10 they are hexamethylene diamine and
sebacic acid.
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Trevor Crichton |
Thanks Trevor and Ted You really put some light on my trouble. I
now know at least one company who succesfully can plate my items, but
they claim that their bath is ruined by the process.
I think you are right Trevor it has to do with the hygroscopic nature
of the nylon, besides releasing the glasspartickles. Any idea how to
solve that problem ?
Chroming of the item is decorative, and we only need the outerside to
be chromed, would it because of dimensional instability be good or
bad idea to chrome the innerside also ? The product will also be sold
in the UK.
Bo König
Food industry - Odense, Denmark
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