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What do you need to make UV-curing resins?

Posted by spota 
What do you need to make UV-curing resins?
March 07, 2008 08:42AM
What do you need for using UV-curing resins?

In this thread I will list a number of materials you will need to make use of UV-curing reins. I have decided to post this information here in the forum for now, as it seems the place where it's guaranteed not to be deleted and I can always link to in the future when asked these questions, as well as being able to receive comments from people engaging with me in experimenting this very promising technique.

We can divide the list of materials in resins, chemicals and UV lamps.

1) The resins I am using are off the shelve products. They can be Polyester, Epoxy or Acrylic/Alkydic resins. The catalyzers I will discuss below should work with all these resins.

2) The chemicals that will compose the catalyzer will make the resins harden under UV-light. Some of these chemicals will be photoinitiators to start the curing process, others will be activators and accelerators to make the curing reaction faster, others still will be stabilizers to make the pot-life of the mixed resin longer.

3) UV-lamps are the light sources you will need to make the resin mixes harden.

Edited 2 time(s). Last edit at 03/11/2008 11:11AM by Fernando.
Re: What do you need for using UV-curing resins?
March 07, 2008 08:43AM
1) Resins
* Polyester resins
These are cheap, very commonly available resins. They are, when not mixed with fillers, clear and have the consistency of syrup, the viscosity depending on the Styrene monomer solvent content it has. The resin sold in shops usually comes with a dual component catalyzer, generally Benzoylperoxide or MEKPeroxide. This catalyzer is of no use for our UV-catalyzed mix. The resin usually also comes pre-accelerated. This means it contains metal salts that accelerate the decomposition of catalyzers. These cause the pot-life of the mixed resins to be lower.

* Epoxy resins
Epoxy resins are usually more expensive resins than Polyester. They also show better hardness properties as well as adhesion and less shrinkage. The filler-free form has a similar viscosity to Polyester and is sold in shops, as Polyester, with a dual component catalyzer, generally Benzoylperoxide or MEK-Peroxide. This catalyzer is of no use for our UV-catalyzed mix.

* Acrylic/Alkydic resins
These are very varied in their composition and can also be initialized by peroxide dual component catalyzers. Not every Acrylic resin is a valid UV-curable resin. The higher reactivity ones are preferred, but prices can be pretty steep for these resins.
Alkydic resins are used in common varnishes. The price is significantly lower but the reactivity is lower too.
Both Acrylic and Alkydic resins need to be tested further for standardization purposes.

Edited 1 time(s). Last edit at 03/07/2008 08:49AM by Fernando.
Re: What do you need for using UV-curing resins?
March 07, 2008 08:45AM
2) Catalyzer Chemicals

These are the names of the chemicals used:
Benzophenone, CAS: 119-61-9 (+/- 44Euro kg)
Benzil, CAS: 134-81-6 (35Euro 500g)
Benzoilisobutylether, CAS: 22499-12-3 (36Euro 100g)
MDEA, CAS: 105-59-9 (31Euro 1kg)

Edited 3 time(s). Last edit at 06/07/2009 01:16AM by Fernando.
Re: What do you need for using UV-curing resins?
March 07, 2008 08:46AM
3) UV lamps

Here I will discuss the source of UV lights that can be used for curing the resins at hand.
The wavelength necessary for activating the photoinitiators is dependent on the chemical nature of each photoinitiator.
In our case, Benzophenone, Benzil and Benzoinisobutylether are all especially sensible to 2 wavelengths: 256nm and 365nm.

256nm UV-light is in the UV range generally described as UV-C (also called germicidal, or EPROM erasing).
365nm UV-light is in the UV range called UV-B (also called black light or actinic).
Whatever lamps you use, it is important that they emit a high percentage of their wattage in those bands.

Sadly, the lamps able to emit in both peaks simultaneously are rather expensive. They are called Medium-pressure mercury lamps and are in the range of 200W upwards and require a special power source and cooling assembly. They are also very effective and induce fast curing, but are crippled with a very high price!

There are also LEDs that have been developed lately that emit in these wavelengths but I haven't tested them. They should work properly if the beam is collimated enough so as to deliver powers in Watt/cm^2 high enough to deliver fast curing.

There may be powerful lasers in the ranges indicated but these are not commonly available and are probably very expensive also.

The solution I found to be best is to use 2 fluorescent lamps from well known fabricators, as Philips, GE or Sylvania. The 365nm fluorescent comes at around 5-10

Edited 2 time(s). Last edit at 03/07/2008 08:58AM by Fernando.
Re: What do you need for using UV-curing resins?
March 07, 2008 09:10AM
4) Recipes

Here I will list a number of possible recipes for UV-curable resins.
The list below is just a start and I'm sure a wild variety of different ones will emerge and evolve in time. I have created a small spreadsheet to calculate the prices of these mixes. I will show the price as well. Pot-life of all these resins can greatly be improved if they are kept away in dark places and in opaque containers.

* Best results yet! Excellent curing speed, great hardness and toughness:
For 100g of final resin mix (RM)
3g of Benzil
1g of Benzoilisobutylether (BIsoBE)
1g of MDEA
0.5g of EDTA or 0.1g of Hydrochinone
complete to 100g with Polyester resin.
Cost of chemicals: 0.74

Edited 4 time(s). Last edit at 03/12/2008 10:51AM by Fernando.
VDX
Re: What do you need for using UV-curing resins?
March 07, 2008 12:34PM
Hi Fernando,

... good to have all infos on one place!

I'll post the results here, when your stuff arrives and i can fiddle around a while ...

Viktor
Re: What do you need for using UV-curing resins?
March 07, 2008 12:53PM
Yup, that's great!
I somehow wanted to have everything together in one place.
Before you start mixing away with the chemicals I sent you, we should first discuss it here. I am sure the mixes I mentioned above can be made more economical, like 3g+3g+1.5g or such.

One question for you: do you have access to a chemical products store next to where you live?
You will notice pretty fast that once you start playing around with these mixes you are going to start spending a lot of it... it's really that fun!
I sent you enough to make around 500g of resin. Maybe soon you will have spent that printing objects! I'm very curious to see if you can get these products in Germany as easily as me here in Spain. The products mentioned here are very safe as you know, no big deal ordering them online.
VDX
Re: What do you need for making UV-curing resins?
March 08, 2008 10:55AM
Hi Fernando,

i'll post, when it's there ...

My easiest way to chemicals is my local apothecary shop - there i got my waterglass, wool-wax and some other stuff for the experiments with pastes.

Ciao, Viktor
Re: What do you need to make UV-curing resins?
March 19, 2008 11:42AM
I discovered by keeping the resin mixes in the dark that the pot-life they have is mainly dependent on light exposure. For three weeks I have had a mix isolated from light and it hasn't changed in any way. Good news, as keeping the resin unexposed to light until usage is pretty easy to achieve.
VDX
Re: What do you need to make UV-curing resins?
March 19, 2008 12:22PM
Hi Fernando,

your stuff is ready to use, but i didn't find time until now (some trouble around), so the experiments delayed, maybe i'll find some time next week.

The pneumatic dispenser i borrowed from a previous company wasn't usable (all tubes filled with hardened epoxy), so i have to build a new one from scratch - i think a mechanical dispenser with a motor-piston should work better ...

Viktor
Re: What do you need to make UV-curing resins?
March 19, 2008 01:16PM
OK, no problem! Whenever you have time.
I also guess the mechanical dispenser is probably easier to build and maintain, as well as cheaper. Will you be using Polyester or Epoxy resin?
VDX
Re: What do you need to make UV-curing resins?
March 19, 2008 03:10PM
... i want to try with all types at hand.

The hint with polystyrene-foam (styropor) solved in acetone should be interesting too - maybe with a heating-break per slice to harden the surface ...

Viktor
Re: What do you need to make UV-curing resins?
March 20, 2008 01:13AM
Great! I'm curious about other resins too. Will get me some epoxy soon.

Yeah I read upon the polystyrene and acetone, I will type an answer in the other thread now.
Hi there, does anyone know where i can get multi-purpose epoxy laminate resin
thanks
Re: What do you need to make UV-curing resins?
March 26, 2008 02:03PM
I've got a sample of Swell


best wishes

Adrian

[reprap.org]
[reprappro.com]
Re: What do you need to make UV-curing resins?
March 27, 2008 02:21AM
@Paul:

Here a couple of sites for epoxy resins I have found online:

[www.shopmaninc.com]

[www.cfsnet.co.uk]

@Adrian: All of the shelve UV-resins you will find are hugely expensive. Refer to the post above if you want to have a cheap version that you can mix yourself and are between 10 to 100 times cheaper (sometimes 1000 times cheaper for rapid prototyping mixes, they are really ripping people off)
Hi Fernando,

Thanks for the great posts.

Like Adrian, I am interested in using a bio-based resin material. UV-hardener is a plus.

I would like to make a resin that is non-toxic and made from more renewable resources that has similar properties to traditional Polyester and Epoxy. Unfortunately, I have become sensitized to Polyester and Epoxy resins and can no longer use them in my art.

Do you know how to make a linseed oil based resin like Swell
Re: What do you need to make UV-curing resins?
April 12, 2008 10:38AM
Hello Nathan!
There seems to be a real lack of online sites that sell an of-the-shelve acrylic casting resin. I have been looking for it for over an hour now and have found nothing that would be usable.
If I recall well, there was a page i found some time ago that talked about a MMA (methylmethacrylate) and BMA (butyl methacrylate) mix that was used to produce glass clear castings of objects. You could buy that resin-mix as a kit, to embed insects, leaves and whatnot into a block of glass clear resin. I can't find the page anymore, but that's what you should aim for.

Otherwise, another place to look for aAcrylic resins are art shops. They may have acrylic resins or varnishes (the glossy ones) that you could use. They also dry on contact with air, so that you may use acrylic thinners to extend the drying time. They can be mixed with the UV curing agents mentioned above.

I am very interested about the linseed resins, as a possible polymer. It may neverthelss form uneven blocks of polymer and the chemistry of polymerization is quite specific and involves an oxidyzing agent (air oxygen). I could try to see if I can get this to work with the radical UV catalyzers above and see if I can get the linseed to set faster. I don't know about the resin brands you mention but I will read up on them and see if they would be of any use.

Cheers!
VDX
Re: What do you need to make UV-curing resins?
April 12, 2008 11:34AM
Hi Fernando,

i found kits with resin and hardener in our toy-shops for generating artificial water-surfaces for railway-/train-landscapes, but it's very expensive, so i'm searching some online-sources for pure resins too ...

My spare time is actually complete consumed by other essential tasks, but i hope to get some resin-samples and time the next weeks.

I'll post, when receiving some results with UV-curing ...

Another idea with UV and waterglass: i found out, that waterglass hardened at once when in contact with an acidic ingredient or acetone.

Maybe it's possible to mix waterglass with a fluid, which change from basic/neutral to acidic by some sort of curing (air, heat or UV)?

This could be a good trick for a fluid room-temp support-material or for fabbing temporary objects (casting or moulding)

Viktor
Re: What do you need to make UV-curing resins?
April 18, 2008 04:42AM
@nathan:
I have tried out the upper UV-catalyzers with rectified linseed oil I got from an art-shop and it didn't work out. Looks like the double bonds available in the linseed are not available to the radicals created by the above catalyzers. sorry...

@viktor
In some other posts abouy phenolic resins i was trying out an organic acidic solid, solved in ethanol, called Tolueneparasulfonicacid that was blocked by an amine (an organic base). This acid blockage was reversible by heat. Maybe something like that could serve in what you are investigating... I have over a kilogram left of that stuff and would be happy to get rid of part of it if you wanted to investigate that branch (yet another one?? winking smiley )
Thanks for the response, Fernando. I have been tied up lately.

I have done experimentation with off-the-shelf art shop acrylic and you can only build it up in thin layers. It typically has lots of small bubbles in it (because the top skins over before the lower layers dry and the bubbles get trapped). They also shrink quite a bit making for funny corners.

One problem I have herd about the Linseed oil UV plastics is that they continue to yellow over time and are kind of soft.

I actually experimented with air-drying waterglass several years ago but the result was very brittle. It is no wonder they use this stuff for stage-props like wine bottles being broken over ones head.

At this time, I am still waiting to experiement with UV curing linseed oils (from a sustainable and non-toxic point of view). I am also looking into refined filtered beeswax but it is very soft and expensive and can't be built up to thick layers like I use with Epoxy and Viny (around 3 cm.).

There are some great bio-resins coming out but they either require sophisticated equipment or still have some iso-cyanide in them (which I am alergic to).

If you have any other ideas, please let me know.

Best,

Nathan
VDX
Re: What do you need to make UV-curing resins?
April 18, 2008 12:08PM
Hi Fernando,

... i think it's worth a try.

I didn't receive any other resin until now and start in May at my new daywork, so the comming two weeks are reserved for the family.

I'll try anyway - so when you give me some of your probes and resins i hope to bring the experiments to work in May ...

Viktor
Re: What do you need to make UV-curing resins?
April 28, 2008 08:15AM
fernando,

what is the required UVC wattage output?

i'm looking for uvc fixtures, and they are really expensive... can i get by with 5 watts? i'm looking at this model: [www.goodmart.com]

i would really prefer not to have to wire up my own lamp. i can see that going badly. if that doesnt work, would this lamp suffice? [www.1000bulbs.com]

how do i go about finding a ballast / base to use it with? i'd hate to be stuck with the lamp and nothing to power it.

thanks!
Re: What do you need to make UV-curing resins?
April 28, 2008 11:42AM
Holddd your horses, Zach!
Those links you sent me are for some really expensive stuff!
Here is a list of lamps with more reasonable prices: [prolight.info]
Here's an online shop with the germicidal kind:
[www.lamps-on-line.com]
Click on the GERMICIDAL - COMPACT FLUORESCENT (can't link directly here)
And under ULTRAVIOLET - BLACKLIGHT BL350 - FLY KILLER they have the blacklight model.

Actually I got mine from a regular lighting shop here in my neighborhood. I gave them the model numbers and they ordered it for me and had them a couple of days later. They also told me which ballasts to use. Best use the 36-40W lamp models or higher, especially if you want to use them in a non-focused setup.

I'll attach the circuit diagram for the lamps I'm using. It's really easy stuff: 5 cables to screw in and voila!

As for the ballast to use for the lamp models above, here are the specs:
(I use the same ballast and base for both germicidal and black light lamps)

Ballast:
230V/50Hz
36W, 430mA, lambda 0.45, 4,5 microF

Base and starter:
Just get the regular base with the regular starter, same stuff as your ordinary fluo. Don't need to build one yourself!
Philips S10
220/240V
4-65W Single

Edited 1 time(s). Last edit at 04/28/2008 11:46AM by Fernando.
Attachments:
open | download - Fluorescent_circuit.png (6.9 KB)
Re: What do you need to make UV-curing resins?
April 28, 2008 01:07PM
Nathan

Thanks for making me feel good.

I thought I was a freak as I was the only person I knew who had developed an allergy to Polyester, It makes finding clothes problematic.

Your a star....

cheers

aka47


Necessity hopefully becomes the absentee parent of successfully invented children.
Anonymous User
Re: What do you need to make UV-curing resins?
April 29, 2008 01:35PM
I tried the styrofome/acetone concept earlier, it was different than what I expected. I'll see if I can get some pictures and/or a video together next time.

~Daniel
VDX
Re: What do you need to make UV-curing resins?
April 30, 2008 12:12PM
Hi all,

today i was in our "Bauhaus"-tool-store and found some 0,2mm-NiCr-wire (replacement for styro-cutter, 30m-spool = 4 Euros)

But the best part i found is a heat-resistant silicone-rubber for moulding which is capable of 450

Edited 1 time(s). Last edit at 04/30/2008 12:14PM by Viktor.
Re: What do you need to make UV-curing resins?
May 06, 2008 11:01AM
hey fernando!

no worries... i can be frugal at times. i held my horses, and researched a bit more.

for the americans, here are the bulbs i ended up getting:

uvc / germicidal: [www.1000bulbs.com] - $9.07/ea

uvb / BLB: [www.1000bulbs.com] - $5.42 / ea

unfortunately, they dont sell fixtures in the store. however, the bulbs are standard 15watt / T8 size. i'm going to go to the hardware store and purchase some of the T8 fixtures to put these bulbs in. if all goes to plan, i'll be able to do uv-curing stuff really soon.

now i just need to buy the chemicals, and test it all out.

yay!
Re: What do you need to make UV-curing resins?
May 06, 2008 04:07PM
Just because it is opaque in the visible wavelengths, it still can be transparent in the UV. for instance glass vs lexan in UV is quite dramatic. A cool effect is looking at someone holding a big pane of glass in an IR heat vision scope, the glass acts as an IR mirror, so you will see their IR reflection in it just as if it were a visible light mirror. likewise you can get by those tricky IR security cameras just by holding a pane of glass in front of you. shh.. don't tell. smiling smiley

I bought some UV LEDs once, they wern't very hard UV, but i wonder if they would suffice to cure something like this.. a UV led head on a reprap and some sort of 'resin pool' on the z axis might be something interesting... not sure how you would 'raise' the edges of your resin pool as the z axis lowers though...
Re: What do you need to make UV-curing resins?
May 08, 2008 12:36PM
Hey all!

@Viktor: I am very curious about what will happen with these catalyzers and the silicone resine. it would be a very interesting application if the same photoinitiators work. Please keep me posted on that!
As with the other idea you have, that's called live-polymerization. This is a very hot issue these days in polymerization chemistry. I'm a little green on that subject so I cannot tell you what would be needed for this to work.
As far as UV-shielding goes, it's indeed better to get the non-UV shielded ones, as these shielding chemicals will slow down the reaction quite a lot. Try it out and see if you can get it to harden in a reasonable time. Otherwise you may need to get some other epoxy.

@Zach: Great prices you found there! The germicidal I got cost me 4 times that price, although it's 2x more powerful. About the chemicals, if you have trouble getting a hand of it, PM me and maybe I can help you out.

@John: there are 2 factors to observe for a UV light source. First comes the emission bandwith, the wavelength of the emitted light. Do you have that information still? In a post above I link to a site which offers the right kind of LEDs. The next factor is the wattage, in the case of LEDs, you should check the W/cm
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