Help - Two part epoxy dispenser

Hi All – As far as two part epoxy adhesives are concerned I am not the brightest crayon in the box – so please forgive any termalogical
inexactitudes.
As an ‘add hoc' user of two part epoxies I have found that selecting the correct type of adhesive, the measuring, mixing, cleaning up etc a pain – even when it comes to using the ‘new type' dual syringe dispensers.
Rather than accept the situation I designed a dispenser that I believe will solve my problem – now all I need to do is make it (the dispenser that is) – this is the help I'm after (for what it's worth I have taken out a provision patent and who knows maybe I'll make some money).
In essence the envisaged dispenser is a sealed sachet about 1.25 inches square holding about 5ml of adhesive. INSIDE the sachet (and this is the ‘embodiment' of the patent as my lawyer calls it) is a rupturarble capsule. The sachet contains one adhesive component and the capsule the other. Come adhesive using time the capsule is ruptured by a firm thumb/forefinger squeeze and the two components are knead together in the still sealed sachet. Once well mixed the ‘nozzle' of the sachet is pierced and the adhesive is directly applied (to the broken plate/tooth/A1M1/CVN etc) – the sachet containing the residue is then disposed of and all is well. Hopefully if painted an understandable picture? Although similar to ‘two/twin pack' epoxies the main difference is that sachet contains both the polymer and the curing agent – and consequently has a much smaller foot print etc, etc (plus everyone loves popping bubble-wrap – or in this case the capsule).
The bit I need some help with – I'm thinking of using clear sixteenth of an inch x 1.25" x 1" LDPE tube for the sachet – when sealed I'll have an approx 1.25" square sachet. For the capsule I'm thinking of using PVC or PET. The two real problems I have are what would really be the best materials and how to seal them (the sealing bit I really know very little about).
Any help/comment would be greatly appreciated.
Bill
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Hi!
First of all I do not see any advantage of your system compared to the existing ones which use a static mixer (after the pot time you have to dispose the mixer but can still use the rest of the 2K adhesive). Each adhesive producer has a proprietary design which takes into account the right mixing ratio of resin and hardener.
And I hope you've already filed that patent...
Oliver
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I could see the proposal having an advantage for someone that very seldom uses the adhesive - they use it only once before they have to toss the static mixer.
John Aspen Research, - www.aspenresearch.com "Turning Questions into Answers"
Opinions expressed herein are my own and may not represent those of my employer.
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LDPE and other olefins are easy to heat seal. Lay the parts together, apply heat and pressure and you're done. You could do prototypes at home using an iron. On a larger scale, a form-fill-seal machine (FFS) could be used for mass production.
Your big concern is that the containers do not react with the contents. Such a reaction would either cause the container to dissolve and leak, or would cause the epoxy to be ruined. PVC is known for leaching plasticizers and not having great solvent resistance. PET would be a better option, but you will want to verify its durability.
John Aspen Research, - www.aspenresearch.com "Turning Questions into Answers"
Opinions expressed herein are my own and may not represent those of my employer.
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message

Thanks for the feedback – Point(s) taken – but consider a roll of Elastoplast versus a box of Band Aids – each one has its place.
3m has a dental product called L-PoP – but this is still a ‘twin pack' concept (plus they throw in a swizzle stick) see http://multimedia.mmm.com/mws/mediawebserver.dyn?OOOOOOxV2&bOhr5OAr5OOOKUpznnnnnM -
Anyway thanks for the feedback.
Bill
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Yes, medical and dental applications are definitely single use applications, thank goodness. Imagine the alternatives: trying to get all the lung repair surgeries scheduled at the same time so that one bottle of surgical sealant could be used before the adhesive in the static mixer set up. Or doing all the crainial operations in adjoining rooms so that a batch of hydroxyapatite can be shared.
Ketocem (3M ESPE) is a glass-ionomeric cement (two part) used in dental repairs. It has 3 pieces of specialized hardware to 1) bring the two parts together, 2) mix them and 3) dispense the cement. But you better work quickly or it will set up before your eyes (30 - 60 seconds working time depending on temperature).
John
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On 13 Apr 2005 02:14:36 -0700, snipped-for-privacy@tka.co.za (Bill) wrote:

1) What would be the advantage over standard "twinpack" adhesive sachets? You can see something standard here:
http://www.intertronics.co.uk/products/opt5012.htm
2) Would you have to have a special "outer" packaging, quite rigid, to prevent accidental rupture of the capsule?
3) In my experience, getting quite inert plastic packaging isn't easy. There is also moisture to contend with - how hydroscopic are the contents and how hermetic is the plastic?
Peter
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snipped-for-privacy@yahoo.co.uk wrote in message (Bill) wrote:

Hi Peter -
1) I am looking at a 5/10ml sachet - so 'one handed' mixing will be posible. i.e. - a firm press of the sachet with thumb/forefinger to ruprure the inner capsule - 'massage' the sachet with the thumb/fore finger. When the sachet is nice and warm prick a hole in it and apply.
2) I don't think so - what would be nice (and this is what I'm looking for)is an 'elastic' outer packing.
3) Given that 'two packs' work - and I think they are great for 50ml plus single applications (but that's a hell of a lot of adhesive to 'glue' a crown on with) - the most obvious initial choice would be to use the plastic that two part packs are made from. My idea is in essence a two pack with one pack inside the other.
The market I'm looking at is single application of small amounts of two part adhesive - the most obvious being dentistry.
Bill
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