Resin formulations

[John]

Has anyone tried any formulations or comercial resins other than Prof.
Fang's? The trick is finding a formula that has the right properties.
Viscosity, UV range, cure in seconds not minutes, toxicity,
volitility, shelf life, hardness of the cured polymer, and others.
Finding the right mix of properties at the best price point is the
goal. I don't think I'm alone in not being able to afford to buy in
industrial quantities (and if I did it is likely that I would not be
able to use it all before it exceeded it's usable shelf life) so I'm
going to have to buy in smaller retail quantities.

Prof. Fang's formula is about $220/ liter. A bit more than I would
like but we know it will work (I'm not saying it's the best. Just that
it has been demonstrated to work) FYI I found a datasheet on the base
monomer that lists the viscosity at 5 to 15 cps.

I looked at some of the Dymax conformal coatings. Dymax 987 is a quick
UV/Visible cure with a heat secondary cure. The Viscosity is 150cps.
Hardness is D85. On the downside, It has a linear shrinkage if 1.3%
and adheres to silicon (not good if you plan to use silicon as the non
stick surface). There would also still be a need to add a Sudan1 or
other blocker to control the depth of cure. Dymax has other UV/Visable
cure products with a variety of properties. Dymax 9663 has viscosity
of 600cps, D80, linear shrinkage of .4% and adheres to PET. Most of
their products retail for about $150 /liter. You can buy it in 15
liter pails and get a price break but be aware of the shelf life.

As 4Ddabbler said, there are plenty of inexpensive monomers but
without a background in chemistry I couldn't begin to predict what the
properties of the polymerized state might be.

[4Ddabbler]

I am still at what I consider novice or amateur involvement in the
chemistry knowledge behind this but narrowing down the photo-initiator
first is best goal that I am seeing. You could work backwards from the
monomer or resin base as well but in either case a big factor to be
aware of is the solubility of the PI in the monomer or vice-versa. If
the two components cannot be pretty much dissolved to homogeneous
solution state the chemistry is already doomed before it starts. This
is your cornerstone to build on about a formula or recipe. Determining
desired density, flexibility and strength will be important to the
resin base obviously but if you cannot find a working PI or activator
agent to fire up the action your recipe is a deadend. I am looking at
broadband solubility properties for a given chemistry family or specie
based on the PI and then hoping for some good best matches in the
mating monomer/polymer base to react it with. Also I am not seeing too
many options that have non-toxic input components as far as base and
activator but the majority of the polymerized yields are fairly non-
toxic or at least moderately safe after the PI activation is
terminated and the resultant polymer is handled and treated normally.
I am not seeing too much promise for anyone dreaming of 3D printing
food safe or children safe objects out of this though with respect to
chemical volatility etc.

[John]

I'm concerned less with the toxicity of the fluid itself and more
concerned with any noxious fumes before or during polymerization. The
wife will FREAK if I fill the house with smelly poisionous fumes. I
hope I don't have to go to the added trouble of venting the printing
chamber to the outside.

[TJ.]

What do u mean???? Don't u want plastic children????????
lol........
John, I can assure you, I don't think any UV Resin is that toxic. at
the exposure temperatures.???,its only when you go into 300 degree F
that you start getting bad fumes.

You will also see that all the comercial printers call them safe
for ...."a indoor office environment"
TJ

[John]

Yes, the comercial resins for 3D printing should be ok. I was thinking
more of any low budget concoctions we may come up with.

[4Ddabbler]

As long as the radicalization activation is not allowed to go rampant
or exothermically overdriven fumes should be minimal. I would still
recommend external vented exhaust venting of the fumes or vapor for a
safety and sensibility measure anyway. The commercial 3D prototyper HW
units almost certainly have some sort of fumes extractor and capture
systems something similar to those used in commercial desktop laser
cutters and reflow or hot soldering oven systems. IMO you cannot be
cautious enough when working with radicalized organic or other
chemical reactants ESPECIALLY when performing a conversion or
polymerization reaction. You could get a small lab or industrial
vented fumes hood or cabinet and I would not be setting up and
operating a machine of this nature in regular habitation or living
space or closely proximate to it at all! Also I would stick to outdoor
or outbuilding testing and trial runs with open to outside venting
until you are sure that the chemicals and byproducts as well as yield
are stable and well behaved. It's been a while since college chemistry
for me but they didn't have to tell me twice about safe and sensible
practices or common sense preparation and routines. I spent a summer
in high school before actually starting college working with some
lethally toxic organic compounds and with sense and routine and
listening to the professors and lab instructors no one in our advanced
studies group ever had any issues or accidents. Also I can still
clearly remember how foul and putrid and far reaching the vapors and
stenches of even some of the much more mundane less toxic organic
compounds can be.

[4Ddabbler]

I was not trying to scare anyone with my previous comments. I would
recommend some caution and common sense as this is talking about using
chemical components that are not going to be non-toxic with regards to
inhalation or exposure to vapors or liquids of the input reaction
components. If any potential formulations are done with well
engineered "click-chemistry" reactions with the right or properly
calculated input reactant components it should be possible to produce
practically fume-less or odorless recipes that allow proper cure and
finishing with very little to nil volatile leftovers. Hopefully I'll
some more specific or targeted selection criteria outlined to add to
the thread to aid others here in hunting or searching for suitable
monomer or resin base components by a table or list of properties or
values for any candidate chemical component to be evaluated on.
Solubility as was mentioned previously will need to be top of the
list. Next price point and handling or safety issues. Characteristics
and properties such as flexibility adherence or adhesive tendencies
and shrinkage or deformity plus photo sensitivity degradation etc. I
spoke with the pro resin guy recently and issues of shrinking or
volumetric reduction or contraction are definitely going to need to be
right up there after soluble properties and cost/safety though as
every type of resin or polymerization process regardless of curing or
setting method has a shrink factor due to the combination process of
the component input. That's another consideration factor for other
areas of design such as slicing SW and skein/rafting/overhang etc with
respect to mechanical design and graphics likewise.

[Dave Cowden]

Hi, John:

If you can find a good formulation, a business partner and i are looking to get into the RP materials distribution business-- we could be a supplier and buy the larger quantities and different colors and all that stuff...

Dave