Re: Call me a dreamer if you like...
Wow, Arend-Jan! You have got to be one of the most honest guys who speaks out loud I've ever known. I am thinking the same way you are thinking. If we can share everything that we know, who knows that we might end up making something a lot better than what we are doing today.
Count me in for sharing everything that one knows. I have no secrets, and am willing to share anything. I have learned a lot from here, and I'm willing to give many folds back.
Wachara C.
arend-jan said:
Wow, Arend-Jan! You have got to be one of the most honest guys who speaks out loud I've ever known. I am thinking the same way you are thinking. If we can share everything that we know, who knows that we might end up making something a lot better than what we are doing today.
Count me in for sharing everything that one knows. I have no secrets, and am willing to share anything. I have learned a lot from here, and I'm willing to give many folds back.
Wachara C.
A quick search for similar(?) material brought up Vermason C901 floor polish. It supposedly yields 10^7 - 10^10 ohms/square when applied in the usual concentration and >30% humidity. I'd be a bit concerned that their data sheet says it performs best between 30 and 65% humidity. That makes it sounds like its performance would be fairly humidity dependent--exactly what I'm trying to avoid.
Few
Few
For OEMs, an interesting alternative is to add some Ciba Irgastat P, maybe 10%, to Surlyn or similar ionomer. That would extrude and downgauge very nicely, and the films are very tough and flexible. In previous work, I found that the conductivity was pretty insensitive to humidity. As a bonus, the film is clear and with conductivity throughout the bulk, the charge distribution will be quite even.
Again, not practical for the diyer, but it would be nice if one of the larger manufacturers used some actual up-to-date technology instead of rehashing 30 year old methods.
Again, not practical for the diyer, but it would be nice if one of the larger manufacturers used some actual up-to-date technology instead of rehashing 30 year old methods.
Few said:
Perhaps the floor polish made by Techspray could work?
It is described as being humidity independent:
"This product is a high gloss floor finish designed for use in electronic production areas, computer rooms and other static sensitive areas. Contains a non-migratory, static dissipative polymer which will maintain a constant surface resistivity of 106 to 108 ohms throughout the humidity spectrum.Zinc free. High Gloss. Slip Resistant. Works in low humidity."
Attached is the spec sheet.
I found a website with prostat DPF 410. It did give me a malware warning but I decided to take a chance. The link is http://www.xsential.com/wor_floorstaticides.htm and the Xsential details off this website are
12624 Daphne Ave
Hawthorne, CA 90250
(800) 829-9994 Toll free
323-241-1800 Direct
323-241-1809 Fax
12624 Daphne Ave
Hawthorne, CA 90250
(800) 829-9994 Toll free
323-241-1800 Direct
323-241-1809 Fax
JonasKarud said:
There is a local supplier here in Fort Worth that I can get a gallon for $60. Not too painful. I could certainly send some out to those interested in experimenting with the understanding that they would share their results. I don't think the Post office would have any issues with mailing floor polish.
Assuming the chemical makeup of Techspray 1720 floor polish is very similar to the Prostat DFP-410 then to make a suitable high resistance coating:
1) Take 350mL of 1720 and add contents of one permanent marker. Sharpie markers should work? pick your color?
2) After mixing, dilute somewhere between 1:5 and 1:10 with distilled water to get the resistance you are looking for.
3) Application by rubbing on with cloth. Circular motion like waxing a car? or long extending strokes like painting?
Sound about right?
I like the idea of being able to mix up a lower resistance solution to use on the edges and around the perimeter of the panel. Then switch to the higher resistance solution for the active area of the diaphragm that will actually be moving and under the influence of the stator's electrostatic field.
Oh, I have sent off an email to Techspray inquiring about shelf life and best storage techniques since the data sheet did not provide this info.
Attachments
Hi Jonas,
you told me that you put the cartridge of a specific denish permanent marker into a 5 Liter bottle of DFP 410 and dissolved it for a few days. The marker brand isn't avaiable anymore
i did some measurements with your old recipe (which i have 50ml still on stock) and diluting with destilled water set conductivity proportional to diluting.
As others propose some kind of permanent marker i believe that only specific ones will work. Which one ? i do not know.
Maybe its better to go with black ink (Chinese ink), because its made of carbon black.
Capaciti
you told me that you put the cartridge of a specific denish permanent marker into a 5 Liter bottle of DFP 410 and dissolved it for a few days. The marker brand isn't avaiable anymore
i did some measurements with your old recipe (which i have 50ml still on stock) and diluting with destilled water set conductivity proportional to diluting.
As others propose some kind of permanent marker i believe that only specific ones will work. Which one ? i do not know.
Maybe its better to go with black ink (Chinese ink), because its made of carbon black.
Capaciti
Has anyone investigated Semitron products from Quadrant? I had considered them at one time for a static dissipative turntable mat but one or more of their products may work for diaphragms.
http://www.quadrantepp.com/default.aspx?pageid=192
John
Capaciti, the marker pen was added for better hardening, and as I remember it, one of the many markers I used was very big and had zebra stripes on the label. I do not remember the brand.
To much ink destroyed the conductivity.
Bolserst, do a test first without diluting and marker pen.
After that You can experiment with different marker pens.
I always used a ordinary foam roller when applying the coating, rolling very slowly to avoid small irritating bubbles. I recently have discovered is that its good to warm up the coating to fingerwarm before applying.
It would be very nice to receive a sample of this 1720 polish.
To much ink destroyed the conductivity.
Bolserst, do a test first without diluting and marker pen.
After that You can experiment with different marker pens.
I always used a ordinary foam roller when applying the coating, rolling very slowly to avoid small irritating bubbles. I recently have discovered is that its good to warm up the coating to fingerwarm before applying.
It would be very nice to receive a sample of this 1720 polish.
JonasKarud said:
Jonas,
Can you describe what you mean by hardening? Did the DFP 410 remain slightly soft or tacky without the marker pen additive? or did it just help it cure more quickly?
Also, do you happen to know what chemical it was in the marker that was beneficial for hardening?
I got a response back from Techspray. They said that shelf life was typical more than a couple of years if kept at room temperature away from sunlight. They did say that if the product gets too cold(near freezing) it can separate.
I called and placed the order only to find out that it was a non-stocked item, so shipped directly from manufacturer. Delivery time is typically 2 weeks.
I will let you know when it arrives and we can arrange for shipment of a decent size sample for you to experiment with.
Yeah, I didn't see whether they were available as film or not - my only dealings with the stuff were on the surplus market. So polyethyleneimine film is not suitable? I've always wondered about the performance of films with higher internal friction than Mylar (although I'm not saying that's the case with PEI - I don't know).
John
PEI is difficult to make into a good film. For years, when GE made the resin, their extruded film was terrible- I had to source it from an independent extruder. Even then, getting anything of quality below 0.005" was pretty much impossible. Unfortunately, for an ESL, you need something ten times thinner....
The damping of these engineering thermoplastics is not great- the films are "crinkly" compared to PET. PEN might be a good candidate, too. I still like Clysar the best from that standpoint (and the ability to really shrink it!), but I no longer have access to thin enough gauges.
The damping of these engineering thermoplastics is not great- the films are "crinkly" compared to PET. PEN might be a good candidate, too. I still like Clysar the best from that standpoint (and the ability to really shrink it!), but I no longer have access to thin enough gauges.
bolserst said:
The coating cured more quickly and stuck to the film in a better way. Sorry, I do not know the chemical that was beneficial for
hardening.
The coating could be used without adding marker pen ink, but subjectivly, I thought it worked better with the ink. You know, its very hard to experiment with these things, as the test periods may last up to a year!
JonasKarud said:
I did a little research on the Sharpie website to find out what chemicals their different markers use:
1) Standard and industrial fine point: Dyes, n-propanol, n-butanol, diacetone alcohol
described as quick drying, permanent on most sufaces
2) Industrial Magnum and Kingsize: xylene, dyes (these are the super stinky nearly instant drying types)
descriped as water resistant, quick drying, marks on wet and oily surfaces
3) Industrial professional: Nitroparaffin solvent, naphtha solvent, resins, dyes
described as quick drying, permanent on most surfaces including wet, oily, abrasive, and nonporous surfaces
4) Industrial Meanstreak: Ethylene glycol monobutyl ether, pigments, resins, gelling agents
described as waterproof formula, resists fading, adheres to virtually any surface
Other than the xylene, the data sheets indicate that the chemicals are considered non-toxic.
3) & 4) look the most promising to me for improving adherance to PET film.
Anybody with a little chemical background or experience with coatings have any comments?