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tenfingers
10-20-2006, 03:26 PM
I know the pro's can somehow impregnate anodized surfaces with ptfe. Is this something that a home-shopper can do?

10F

Evan
10-20-2006, 03:38 PM
Yes, if you can find a source for the PTFE in dispersion. You need to be careful with that stuff, especially if you are a smoker. Traces of it on your fingers can be transferred to a cigarette and when burnt generate gasses ten times more toxic than phosgene gas.

BobWarfield
10-21-2006, 11:50 AM
Interesting.

Evan, sounds like you could have gotten the equivalent of Turcite on your ways with this process then? Any idea where to get the appropriate PTFE for anodizing?

Best,

BW

Evan
10-21-2006, 03:08 PM
I don't know where to buy it as I haven't bought any for many years. 30 years ago I bought half a dozen spray cans of teflon coating. I still have a couple left. They have lost their phttt but I just poke a little hole near the top and dispense to a rag, then put tape over the hole.

It will make nearly anything slicker than snot on a glass doorknob. The solvent is mean stuff and doesn't smell like something good for you.

The part about smoking is printed in big red type on the cans.

lazlo
10-21-2006, 03:30 PM
I don't know where to buy it as I haven't bought any for many years. 30 years ago I bought half a dozen spray cans of teflon coating.

McMaster, Brownell's, and many cooking supply stores sell spray PTFE coatings, but I'm pretty sure that's not what Ten Fingers is looking for.
http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=1145&s=4088
http://www.ekitchengadgets.com/cosp10.html

By the way Bob: Turcite-B/Multifil/Rulon-142 is not just spray Teflon: it's a bronze wear strip impregnated with PTFE.

BobWarfield
10-21-2006, 07:16 PM
McMaster, Brownell's, and many cooking supply stores sell spray PTFE coatings, but I'm pretty sure that's not what Ten Fingers is looking for.
http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=1145&s=4088
http://www.ekitchengadgets.com/cosp10.html

By the way Bob: Turcite-B/Multifil/Rulon-142 is not just spray Teflon: it's a bronze wear strip impregnated with PTFE.

Yes Lazlo, I know.

BW

Evan
10-21-2006, 10:32 PM
Lazlo,

Neither of those products are similar to what I have. The first is a phenolic resin loaded with PTFE and Molydisulphide. It's more like paint.

The second is not likely PTFE at all but probably food grade silicon spray. PTFE spray is too hazardous to be sold as a consumer item for kitchen use.

rsr911
10-21-2006, 10:42 PM
Search PTFE aqueous dispersions on Google. Dupont makes a bunch of them. In my line of work I've played around a little with them for various coatings. If you only need a small amount you can call under a company name and get a free sample. Working for an adhesives and coatings company my sample shelves are full of various chemicals, dispersion and emulsions.

I'm currently working on a 1973 Porsche 911 and plan to use many of the automotive coatings my company has developed on it as a show piece, the car will be primarily a track car. We've developed a highly weather resistant coating that will be used as the "paint" for the exterior.

Anyway whatever you get be sure to read the tech data and MSDS, tech data often has sample formulations or application suggestions. What is the intended use BTW?

Todd Tolhurst
10-21-2006, 10:45 PM
And yet they coat all those pots and pans with PTFE. Why should the spray be so much more hazardous?

Odd, too, that plenum-rated cables are PTFE-coated.

Evan
10-21-2006, 11:12 PM
And yet they coat all those pots and pans with PTFE. Why should the spray be so much more hazardous?

It isn't very hard to imagine somebody spraying the pan near the stove and having overspray get on an element on the stove. People are accustomed to that from using products like PAM.

Birds btw, are acutely sensitive to the toxic gas that PTFE produces when it degrades at around 800F. The slightest traces from a PTFE coated pan that is overheated on the stove can kill a parrot.

lazlo
10-22-2006, 12:54 AM
Neither of those products are similar to what I have. The first is a phenolic resin loaded with PTFE and Molydisulphide. It's more like paint.

PTFE spray is too hazardous to be sold as a consumer item for kitchen use.

They're both spray-on PTFE coatings. The "NON-STICK SURFACE REPAIR SPRAY" is manufactured by HEDDY Corp. Patterson NJ. You have to bake it at 500 degrees for 3 hours for it to cure.

There's also a PTFE spray coating that mold-makers use.

in any event, none of these will work on hard annodize, and you wouldn't want an aluminum oxide coating rubbing on a precision machine surface anyway...

Evan
10-22-2006, 01:37 AM
The PTFE liquid I have is a clear yellow liquid. It appears that the PTFE may be dissolved in it rather than a particulate dispersion. When it is sprayed or wiped on a surface the solvent evaporates and leaves a very thin layer of whitish haze behind. When that is buffed out then nothing is visible. However, nothing will stick to it, nothing at all. It sure works well on a snow shovel.

I suspect this is much like whatever they use in order to impregnate the hollow crystals that form when aluminum is anodized. The molecules must be small enough to enter the space within the crystal. This is normally used on hard anodizing where the crystal layer is much thicker than cosmetic anodizing.

This sort of application is commonly used metal to metal contact situations. The usual rule of thumb in that case is hard against soft. The anodize layer in hard anodizing is about the same hardness as sapphire so it certainly meets that requirement. The added PTFE helps to reduce stick-slip and reduces the friction even further. It should actually make very good way bearings. It is used on air compressor pistons.

[edit]

Lazlo, I'm curious. How do you know that non-stick repair product contains PTFE?

Todd Tolhurst
10-22-2006, 07:21 AM
The PTFE liquid I have is a clear yellow liquid. It appears that the PTFE may be dissolved in it rather than a particulate dispersion.

I wouldn't be so sure. PTFE is pretty insoluble stuff. I don't know of anything that will dissolve it.

Evan
10-22-2006, 08:07 AM
Todd,

It didn't take long to find the answer to that. You are partly right. But, it isn't just ground up PTFE in dispersion either.



DuPont Zonyl® fluoroadditives are finely divided white powders of polytetrafluoroethylene (PTFE) resin. They are a separate and distinctive new product line, very different from the well-known Teflon® PTFE molding and extrusion powders. The differences include:
Lower molecular weight
Smaller particle sizes (2 to 20 µm)http://www.dupont.com/teflon/fluoroadditives/about.html
As they claim this is "new" it doesn't explain what is in the product I have unless it isn't really new, just new marketing, which is likely.

From a different site:



Differences Between PTFE Lubricants

Micro Care designed it's family of thin-film lubricants based on two technologies, both from DuPont. First, Micro Care uses a unique form of PTFE which is manufactured at the lowest molecular weights — typically one-tenth of the cheaper grades of PTFE used by other manufacturers. Micro Care's materials are sufficiently small they never need further grinding or processing. In fact, a significant proportion of these materials are so small they are able to dissolve into the carrying solvent.
In addition, Micro Care prefers to use fluorinated solvents, like Vertrel®, as the carrying agents for our PTFE powders. The molecular weight of the PTFE materials are nearly identical to the molecular weight of the fluorinated Vertrel® solvents. That makes it easy for these fine, light and ultra-pure materials to stay in suspension and form the smoothest, most even microdispersions. When dried, they leave a thin, continuous film of PTFE on the substrate.
http://www.microcare.com/default.htm?http://www.microcare.com/faq/faq-55.AboutPTFE.html


The low molecular weight and extremely small size would be exactly what is needed to load unsealed anodized aluminum.

[edit]

A visit to the Vertrel web site confirms this:


Can PTFE Lubricants Mix With Vertrel® ?

Yes, absolutely. A number of companies make PTFE "dry lubricants" and coatings using Vertrel® as the carrying agent. These are normally applied in a dipping process. These processes work particularly well with Vertrel® because Vertrel® has some capability to dissolve PTFE and the densities of the material are similar to each other.

http://www.vertrelsolvents.com/faq/FAQ_Q19_PTFE.html


I am quite sure there were some older and less environmentally friendly solvents that can also dissolve PTFE. They are not many but the stuff that I have sure smells evil. I don't use it indoors.

lazlo
10-22-2006, 11:26 AM
The PTFE liquid I have is a clear yellow liquid.
...
Lazlo, I'm curious. How do you know that non-stick repair product contains PTFE?

That's a funny story. I have a Clausing 5914, which has a Vari-speed mechanism similar to the one on the original Monarch 10EE -- basially a hydraulic version of the Bridgeport 2J's vari-speed. The point of weakness on these vari-speed drives is the anti-friction sleeve on the moveable half of the vari-speed pulley.

The anti-friction coating on mine is starting to flake-off a little, so I was looking for ways to re-coat it.

There's been a bunch of discussions of PTFE coatings on finishing.com, and apparently that non-stick pot/pan repair stuff from eKitchen.com works great, just not for pots and pans :) Apparently it has a high return rate from eKitchen because the final PTFE coating is a clear/yellow, and not the black or grey that people expect from a non-stick pan.

My concern with either the Brownell's or the Pot/Pan Repair spray is that you have to cure it in an oven for 350° for 30 minutes. Does anyone know if a cast iron pulley will move/warp at 350°?

The other option I've been considering is fiberglass-backed PTFE tape. Page 3246 in the McMaster catalog...

Tenfingers: sorry for hijacking your thread... :o

Todd Tolhurst
10-22-2006, 12:34 PM
I didn't see anything on the DuPont page which mentioned a PTFE solvent. It explicitly mention dispersion in water or organic solvents, though.

The MicroCare site seems a little inconsistent in its description of Vertrel's role. Elsewhere on the site, it states (with less marketing puffery):



In addition, Micro Care prefers to use fluorinated solvents, like Vertrel®, as the carrying agents for our PTFE powders. The molecular weight of the PTFE materials are nearly identical to the molecular weight of the fluorinated Vertrel® solvents. That makes it easy for these fine, light and ultra-pure materials to stay in suspension and form the smoothest, most even microdispersions. When dried, they leave a thin, continuous film of PTFE on the substrate.

http://www.microcare.com/default.htm?http://www.microcare.com/faq/faq-55.AboutPTFE.html


As for the maker of Vertrel, here's what they have to say:



With silicones, the lubricant is actually dissolved in the Vertrel®; with PTFE coatings the lubricant is held in a chemical suspension in the bath. (This process usually requires some type of agitation to keep the suspension active.)


DuPont lists PTFE as compatible with Vertrel cleaning solutions, which would be strange if Vertrel dissolved the PTFE object it was meant to clean. (http://www.dupont.com/vertrel/pdf/k04159.pdf)

Based on this, I would conclude that if PTFE is at all soluble in Vertrel, and not some marketer's delusion, it's only to a very small degree.

Evan
10-22-2006, 12:50 PM
DuPont lists PTFE as compatible with Vertrel cleaning solutions, which would be strange if Vertrel dissolved the PTFE object it was meant to clean. (http://www.dupont.com/vertrel/pdf/k04159.pdf)

Safe for 15 minutes is what they say. Some things dissolve slower than others. I'm sure PTFE is in the slower catagory.

http://vts.bc.ca/pics/vertel.gif

Todd Tolhurst
10-22-2006, 12:56 PM
So that leaves us with MicroCare calling the PTFE-in-Vertrel a dispersion or suspension, and Vertrel's manufacturer saying the same thing.

Evan
10-22-2006, 04:05 PM
Hmm. Vertrel is an HFC compound designed to replace CFC compounds. One such related compound, chlorine difluoride, does react with Teflon. It would not suprise me if Vertrel does as well especially since they claim it does. One could ask Dupont.

Todd Tolhurst
10-22-2006, 06:17 PM
Reading DuPont's product bulletin for Vertrel, they certainly don't mention any ability of the product to dissolve PTFE. Since this would be the only solvent known to do so at temperatures under 300 C, you'd think they might mention that useful and unique property.

Perhaps it just slipped their minds.

Evan
10-22-2006, 06:38 PM
Perhaps they don't wish to mention it. It might discourage people from buying the product for cleaning. You could ask them.

Todd Tolhurst
10-22-2006, 06:42 PM
Or, it might encourage people to buy the product to dissolve PTFE, which nothing else on the market will do. That sounds like a valuable property to me.

This fellow seems to know something about fluoropolymers and solvents:



Before being active in solvents, I was working on fluoropolymers. Some
fluoropolymers, e.g. PVDF (often used for sheathing of optical fibres), are
soluble in polar aprotic solvents like DMF or DMSO. However, whatever solvent
that is suitable for PVDF will also dissolve PMMA.

Perfluoropolymers like PTFE or FEP cannot be dissolved in any solvent, to my
knowledge.

Andre Orban
European Chlorinated Solvent Association
Avenue E Van Nieuwenhuyse 4 bte 2
B-1160 Brussels (Belgium)
Tel.: +32 2 676 7354 - Fax: +32 2 676 7241
E-mail: aor@... - Web: http://www.eurochlor.org

(solvents_group (http://groups.yahoo.com/group/solvents_group/message/291))

Evan
10-22-2006, 06:55 PM
Dupont says to contact them about extended exposures to the product. They probably said that for a reason.

Todd Tolhurst
10-22-2006, 06:56 PM
You could ask them.

Indeed I could.

I wonder, though, that if their answer isn't to your liking, if you would accept it.

Before I go to all that trouble, perhaps we should test your reaction to what a qualified authority had to say about the meaning of the term "metal" in the field of astronomy? You'll recall that you argued at length against the definition I offered.

Evan
10-22-2006, 07:01 PM
Irrelevant. The people that sell the stuff said it dissolves teflon. Perhaps they are wrong, or not.

Todd Tolhurst
10-22-2006, 07:06 PM
The same people say that the PTFE is held in suspension. Any solvent effect must be quite small.

In any case, we'll know soon enough. I've sent an inquiry.

tenfingers
10-24-2006, 12:16 AM
Thanks everyone for all the information.

RSR911 asked about the use and it's just to make a anodized shaft a little slipperier. I thought maybe someone would know of a can of something that would load up the pores with teflon right after anodizing. It sounds like there is quite a bit of controversy over whether that can be done at all -- let alone done by a guy with a pail of acid, some ice, and a battery charger.

I looked up the size of typical anodized pores and they seem to be quite a bit smaller than even the smallest dispersion particle size advertized by Dupont. The key seems to be getting the teflon to disolve and I look forward to Todd's inquiry to clear that up. Evan's nasty brew or something similar might be the answer, but it sounds a little too toxic for me -- I'm as proud of my two good lungs as I am of my ten fingers! While I'm on the subject, thanks Evan for pointing out how toxic burning teflon can be. If I ever see a smoking pan on the stove, I'll be sure to get the kids out of the house.

Thanks again for the great responses.
10F

rsr911
10-24-2006, 12:53 AM
Reading Dupont's tech literature I get the impression that the particles somehow coalesce during the drying/curing process. If you'd like I can ask our chemist his thoughts on the subject. With over 50 years in the adhesives and coatings industry and somewhere north of 90 patents to his name he enjoys this type of question.

An aside which is relevant to your inquiry. I have my shop setup in a corner at work, our chemist is the founder of the company and also my mentor, he encourages me to have outside hobbies for those times when work has me stumped. He also appreciates my ability to machine things for our lab as well as our production machines in less time and for less cost than farming it out. As a result of his style of management he offered to pay to have the bed of my large Polamco lathe reground at the companies expense. It turns out I've saved them quite a bit of money with my little shop. Anyway we touched on a chemical coating for the bed once finished, like turcite etc. He suggested perhaps we engineer our own as a learning experience and during that conversation PTFE was brought up by him several times so I know he understands the chemistry.

Me I'm just a lab tech, turned salesperson who's had the immense benefit of learning to compound coatings and adhesives under his tutelage.

rsr911
10-24-2006, 12:57 AM
Check here:

http://www2.dupont.com/Teflon_Industrial/en_US/products/product_by_name/teflon_ptfe/aqueous.html

I like this one, good for metal adhesion:

http://www2.dupont.com/Teflon_Industrial/en_US/assets/downloads/h58352.pdf

Todd Tolhurst
10-24-2006, 08:52 AM
Perhaps they don't wish to mention it. It might discourage people from buying the product for cleaning. You could ask them.

Here's the response from DuPont's North American Distributor, Micro Care:

Return-Path: <marke@microcare.com>
Subject: Re: Technical information regarding Vertrel solvents
Date: Tue, 24 Oct 2006 08:41:06 -0400
Message-ID: <DFE6CCAD1BD9D347B822551C743E26358CDD01@ibm235.mcc. com>
Thread-Topic: Technical information regarding Vertrel solvents
From: "Ed Mark" <marke@microcare.com>
To: "Maryann Macri" <MaryannM@microcare.com>, <todd@toddtolhurst.com>

Dear Todd,
Vertrel solvents based on Vertrel XF do not dissolve PTFE, however we sell very good dispersions of PTFE and Vertrel XF. Would you be interested in more information on these dispersions?

----- Original Message -----
From: Maryann Macri
To: 'Todd Tolhurst' <todd@toddtolhurst.com>
Cc: Ed Mark
Sent: Mon Oct 23 15:46:39 2006
Subject: RE: Technical information regarding Vertrel solvents

Todd,
I am forwarding your request to Ed Mark.

Ed,
Please see Todd's question below and reply via email as requested.


Thank you,
Maryann


-----Original Message-----
From: Todd Tolhurst [ mailto:todd@toddtolhurst.com]
Sent: Sun 10/22/2006 7:03 PM
To: microcare
Cc:
Subject: Technical information regarding Vertrel solvents




Hello.

I have an application which would benefit from a solvent capable of
dissolving PTFE. I am aware of no such solvents, but Vertrel looked
like a possibility. Can you provide any information on the solubility
of PTFE in Vertrel solvents?

Thank you for your time and attention.

--
Todd Tolhurst
todd@toddtolhurst.com


Whatever it is you have in those old cans, Evan, it is not a solution of PTFE; it's a dispersion.

John Stevenson
10-24-2006, 03:17 PM
Birds btw, are acutely sensitive to the toxic gas that PTFE produces when it degrades at around 800F. The slightest traces from a PTFE coated pan that is overheated on the stove can kill a parrot.

Does Monty Python know about this ??

.

Todd Tolhurst
10-24-2006, 03:18 PM
Do you think it would work on the penguin on my telly?

Todd Tolhurst
10-24-2006, 10:37 PM
I am quite sure there were some older and less environmentally friendly solvents that can also dissolve PTFE. They are not many but the stuff that I have sure smells evil. I don't use it indoors.

Have you had any success identifying these PTFE solvents you are sure exist? I've found nothing but categorical statements that PTFE is insoluble in any known solvent, unless you count highly fluorinated oils near PTFE's melting point, or supercritical CO2.

Evan
10-24-2006, 11:32 PM
Liquid ammmonia + sodium will attack PTFE. Chlorine trifluoride at elevated temperature will also attack it.

Also, see here:

http://www.actontech.com/fluor7.htm

These are quite old etchants for PTFE and work at "room" temperature (or lower).

I also recall (perhaps incorrectly) that some or one CFC compound(s) also will attack PTFE. Also, for some reason that I haven't discovered PTFE is listed as having poor compatibility with WD-40.

Todd Tolhurst
10-24-2006, 11:38 PM
Liquid ammmonia + sodium will attack PTFE. Chlorine trifluoride at elevated temperature will also attack it.


Solvent, Evan, solvent. I know you know the difference, so why the attempt to change the subject?



These are quite old etchants for PTFE and work at "room" temperature (or lower).

I also recall (perhaps incorrectly) that some or one CFC compound(s) also will attack PTFE. Also, for some reason that I haven't discovered PTFE is listed as having poor compatibility with WD-40.

Attack != dissolve. Etchant != solvent.

What is that you like to say? Oh, yes: non sequitur.

Todd Tolhurst
10-24-2006, 11:54 PM
Chlorine trifluoride at elevated temperature will also attack it.

I gotta admire your chutzpah for putting ClF3 forward as a "solvent". Not because it's not a PTFE solvent, but because it's about the nastiest compound you can think of. From Wikipedia (http://en.wikipedia.org/wiki/Chlorine_trifluoride):


It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water — with which it reacts explosively.

Is this is what you meant by "less environmentally friendly solvents"?

Evan
10-25-2006, 12:18 AM
Attack != dissolve

I don't think there is a clear distinction in chemistry Todd.

definition of dissolve:

The process by which atoms of a molecule dissociate into ions after being placed in a solvent.

What do you think happens to the molecules of PTFE?

Further, the action of a solvent is commonly called an attack on the material in question.

Some more usage:



Strong acids will attack many metals, converting them to soluble ions and liberating bubbles of hydrogen gas in the process.
...

Bases also are useful for dissolving water-insoluble substances, especially oils, greases, and other organic compounds. Sodium hydroxide, for example, will attack the oils of the skin and turn them into soap, which is why solutions of household lye feel slippery to the touch.

http://www.chem.ox.ac.uk/vrchemistry/chapter16/pag01.htm



Regardless, PTFE is not entirely impervious. Also, although the answer to your query is quite definitive, you may have asked the wrong question.

The material in question isn't exactly the same as the "ordinary" PTFE that Dupont makes. From the link I already provided:



DuPont Zonyl® fluoroadditives are finely divided white powders of polytetrafluoroethylene (PTFE) resin. They are a separate and distinctive new product line, very different from the well-known Teflon® PTFE molding and extrusion powders. The differences include:

Lower molecular weight
Smaller particle sizes (2 to 20 µm)
Different particle shapes and morphologyIn particular, the low molecular weight may well expose the carbon atoms to solvents where it isn't exposed in high molecular weight PTFE.

Perhaps it would be worthwhile to ask if Vertrel dissolves (attacks) DuPont Zonyl® fluoroadditives. This is what is claimed to be dissolved in the other link I found.

I'm only going by what was said on the sites in question as to the solubility of the product. I don't have any special knowledge or even informed opinion in that regard.

rsr911
10-25-2006, 12:44 AM
And the answer is:


(directed to my post about asking our chemist) "It should work fine but as I recall you need to drive off the water at around 200F, then 400F or so to drive off the dispersing aids and the coalescing temp is up around 650F, if properly applied and coalesed i would think there would be a nice coating left behind."

Of course this was from memory (from a man of 79) but he's darn close on those temps. My suggestion, call Dupont under a company name and request as sample or samples and test in on some scrap parts. Or contact me and I'll do it for you if you pay shipping from my place to yours. This might be better as I order samples all the time.

Todd Tolhurst
10-25-2006, 08:47 AM
I don't think there is a clear distinction in chemistry Todd.

definition of dissolve:

The process by which atoms of a molecule dissociate into ions after being placed in a solvent.


There most certainly is a clear distinction between solvation and reaction. Solvents never chemically react with the solute, and the solute may be recovered by distilling off the solvent. But you know that, and are once again simply trying to confuse the issue by playing word games.



What do you think happens to the molecules of PTFE?


When exposed to ClF3? I think they get oxidized, like everything else ClF3 comes into contact with.



Further, the action of a solvent is commonly called an attack on the material in question.


And are you claiming that ClF3 is dissolving PTFE, not reacting with it?



Regardless, PTFE is not entirely impervious. Also, although the answer to your query is quite definitive, you may have asked the wrong question.


I don't think so. Quick review:

(1) You said have some cans of a liquid PTFE lubricant of some kind
(2) You stated you believed the PTFE may be dissolved in the liquid
(3) I expressed skepticism, stating my belief the PTFE is generally regarded as insoluble
(4) You disputed this, citing both the Vertrel solvents, and your memory of "older and less environmentally friendly solvents that can also dissolve PTFE".
(5) I contacted Vertrel's US distributor, who stated flatly that their product does not dissolve PTFE
(6) We're still waiting to hear about those older solvents you recall



The material in question isn't exactly the same as the "ordinary" PTFE that Dupont makes.


I don't see how that matters, since we are talking about "ordinary" PTFE. You know, the stuff in your cans.



I'm only going by what was said on the sites in question as to the solubility of the product. I don't have any special knowledge or even informed opinion in that regard.

I did follow up with Micro Care regarding the claim on their site that Vertrel has "some ability" to dissolve PTFE. Thus far, they have not chosen to reply.

Todd Tolhurst
10-25-2006, 12:01 PM
I'm only going by what was said on the sites in question as to the solubility of the product. I don't have any special knowledge or even informed opinion in that regard.

Then what do you say we consult somebody who does have special knowledge in the field? I give you J W Nicholson, University of Greenwich, UK, author of The Chemistry of Polymers, 3rd Edition, in which he writes:



1.4.10 Poly(tetrafluoroethylene), PTFE

This polymer is the completely fluorine-substituted analogue of poly(ethylene)
i.e. [CF2CF2—]n. The amount of this polymer produced commercially is very
small compared with the output of many other synthetic polymers, but it has a
number of important specialised uses and so is worth considering briefly.

PTFE is a white solid with a waxy appearance. It is very tough and flexible,
with a good electrical insulation properties. The surface energy and coefficient
of friction are both very low, the latter being the lowest of any solid.
The combination of low surface energy and low coefficient of friction cause
PTFE to have excellent non-stick characteristics, a feature which underlies
many of the everyday uses of this polymer.

In addition to its unique mechanical properties, PTFE has excellent chemical
resistance to a very wide range of reagents, with the exception of molten
alkali metals and fluorine. There is no known solvent for PTFE.

PTFE is a linear polymer of the addition type, formed by polymerisation
of the unsaturated monomer tetrafluoroethylene, CF2=CF2. Despite the fact
that this structure ought to impart thermoplastic character to the polymer,
PTFE does not show conventional melting behaviour. It does not apparently
liquify on heating, nor does it give a melt that will flow. Instead it forms a
high-viscosity translucent material which fractures rather than flows when an
appropriate force is applied.

Because PTFE cannot be dissolved or melted, there are problems with fabricating
articles out of the polymer. These are overcome by using a technique similar
to powder metallurgy, in which granular particles are fused under high pressures
and temperatures.

The main domestic use for PTFE is on non-stick utensils such as frying
pans. Industrially, the polymer is used for gaskets, pump parts, and laboratory
equipment.

Good enough for you?

Evan
10-25-2006, 12:59 PM
And are you claiming that ClF3 is dissolving PTFE, not reacting with it?

Why are you so focused on the CLF3? I mentioned more than a couple of others. The CLF3 is very atypical.


And are you claiming that ClF3 is dissolving PTFE, not reacting with it?

See above


(1) You said have some cans of a liquid PTFE lubricant of some kind

True

(2) You stated you believed the PTFE may be dissolved in the liquid

Operative word is MAY.

(3) I expressed skepticism, stating my belief the PTFE is generally regarded as insoluble

I agree.

(4) You disputed this, citing both the Vertrel solvents, and your memory of "older and less environmentally friendly solvents that can also dissolve PTFE".

I cited the Vertrel solvent for the reasons already explained, they said so. There are older solvents that do attack PTFE. PTFE is susceptible to attack from various fluorinated compounds, in particular certain CFCs.

(5) I contacted Vertrel's US distributor, who stated flatly that their product does not dissolve PTFE

You chose to ignore the difference clearly stated between the "normal" PTFE and the specific product claimed to be dissolved.

(6) We're still waiting to hear about those older solvents you recall


I have done a little looking for compatability information between PTFE and CFCs but since CFCs have been mostly banned it isn't easy to find much. HCFCs have replaced most CFCs and HCFCs have different properties.

I just read your next post. PTFE can't be melted because of it's highly crystalline nature. That doesn't prevent solids from dissolving. It is however a thermoplastic nonetheless. Most references to the chemical inertness of PTFE do not say "there is no known solvent" but rather say something like "it is resistant to virtually all solvents". There is a difference.

PTFE is rated by one manufacturer as incompatible with benzene. It didn't say why. PTFE also undergoes halogen exchange with a variety of fluorinated products.

As for your charge of changing the subject, you originally changed the subject from treating anodized aluminum. I merely said "It appears that the PTFE may be dissolved in it rather than a particulate dispersion."

You disputed that although it is not relevant to the discussion at hand. Whether it is dissolved or not doesn't change the fact that some sort of PTFE dispersion (as I originally referred to it) or solution is used to treat hard anodized aluminum. I only said that the product I have "appears" to have dissolved the PTFE, and it does look that way. It is possible that the specific gravity of the solvent exactly matches the specific gravity of the suspended particles in which case the particles would not settle or appear visible.

So far, I haven't seen you post anything that helps to answer the original poster's question. All you have done in this thread is to try and instigate an argument. I, on the other hand was trying to provide some information to the original poster that might be of some help in answering his question.

Do you have anything to add to this discussion that might actually be useful to answering the question at hand?

Ian B
10-25-2006, 01:19 PM
So Ronson's lighter fluid won't work then?


Ian

Todd Tolhurst
10-25-2006, 01:43 PM
Evan, all I did was try to correct your claim that you have a teflon solution, not dispersion, in a can. I didn't try to start an argument; you did that by insisting that PTFE solvents exist. I have produced more than adequate evidence from authoritative sources that this is not possible, at least not anywhere near standard temperature and pressures.

I do not know why you find it so necessary to always be right, and for all other comers to be wrong, but it is quite unbecoming. I, for one, find your scope of knowledge and experience to be quite impressive. You have nothing to prove. If only you'd stop trying.

tesswalker
10-25-2006, 01:46 PM
I do not know why you find it so necessary to always be right, and for all other comers to be wrong, but it is quite unbecoming.

It's called Narcissistic Personality Disorder:


Characterised by a pervasive pattern of grandiosity and self-importance, need for admiration, and lack of empathy, people with narcissistic personality disorder overestimate their abilities and inflate their accomplishments, often appearing boastful and pretentious, whilst correspondingly underestimating and devaluing the achievements and accomplishments of others.

Often the narcissist will fraudulently claim to have qualifications or experience or affiliations or associations which they don't have or aren't entitled to. Belief in superiority, inflating their self-esteem to match that of senior or important people with whom they associate or identify, insisting on having the "top" professionals or being affiliated with the "best" institutions, but criticising the same people who disappoint them are also common features of narcissistic personality disorder.

Narcissists react angrily to criticism and when rejected, the narcissist will often denounce the profession which has rejected them (usually for lack of competence or misdeed) but simultaneously and paradoxically represent themselves as belonging to the profession they are vilifying.

Fragile self-esteem, a need for constant attention and admiration, fishing for compliments (often with great charm), an expectation of superior entitlement, expecting others to defer to them, and a lack of sensitivity especially when others do not react in the expected manner, are also hallmarks of the disorder. Greed, expecting to receive before and above the needs of others, overworking those around them, and forming romantic (sic) or sexual relationships for the purpose of advancing their purpose or career, abusing special privileges and squandering extra resources (google) also feature.

Tess

Evan
10-25-2006, 01:54 PM
Fixation. Need I say more? I thought not.

I do have one thing to add, it a component of ODC and it is treatable Tess.

tesswalker
10-25-2006, 02:17 PM
I do have one thing to add, it a component of ODC and it is treatable Tess.

If it's treatable, then why don't you seek treatment?

Tess

Evan
10-25-2006, 02:46 PM
http://vts.bc.ca/pics/feedtroll.jpg

Todd Tolhurst
10-25-2006, 03:28 PM
As long as we're beating dead horses, this just in from DuPont itself, which knows a thing or two about PTFE:



From: Phyllis J Flynn <Phyllis.J.Flynn@USA.dupont.com>
Subject: Fw: New Lead - Todd Tolhurst, MIN LLC
To: todd@xxxxxxxxx.com
Date: Wed, 25 Oct 2006 15:16:35 -0400


Todd. DuPont Teflon* is inert to solvents.

Phyllis Flynn, Technical Services

----- Forwarded by Phyllis J Flynn/DuPont on 10/25/2006 03:16 PM -----
CONTACT INFORMATION
Name & Company: Todd Tolhurst, MIN LLC
Title:
Address: xxx xxxxxx xx, xxxxx xxx
Augusta, ME 04330
Country: United States
Phone: (207) xxx-xxxx
Mobile:
E-Mail: todd@xxxxxxxx.com
URL:

LEAD INFORMATION
Inquiry Type: Product Information
Product: Teflon® Industrial Resins®
Application: Not Specified
Comments: I am trying to identify any solvents which may dissolve PTFE.
Can you provide any information?

Response via email is preferred.
Market Segment: Manufacturing

LEAD SOURCE
Origin: Website
Origin Name: www.teflon.com
Lead Source: Website
Lead Detail: Phyllis Flynn
Lead Status: Route
Response Type: Referred to Business

LEAD CREATOR
Created By: Ginger Brown
Created Date: 10/25/2006
Comments:

Evan
10-25-2006, 05:44 PM
Time to revise the knowledge base.



Although "Teflon" was invented more than 40 years ago, an absolute determination of the molecular weight represents an interesting challenge by any analytical techniques. To date, no solvents that are suitable for Teflon have been found. Thus, in our approach to create a Teflon solution, we used oligomers of Teflon-like polymers, e.g., oligomers of poly(chlorotrifluoroethylene), with the following criteria:
(a) a boiling point sufficiently high so that the oligomer
melt forms a liquid at temperatures greater than 330 "C,
(b) a refractive index sufficiently different from that of the Teflon polymer so that a reasonable refractive index increment exists, and ( c ) the oligomer molecular weights sufficiently low so that the characteristic decay times are distinctly different from those of Teflon. The same approach could be applicable to other difficult to dissolve polymers.
Oligomers of poly(chlorotrifluoroethy1ene) appear to be poor solvents for Teflon. We were able to study only a low molecular weight Teflon polymer in detail.

As a delicate balance exists among the three criteria above, higher molecular weight Teflon polymers can be expected to dissolve in higher molecular weight fractions of polyperfluorocarbons.
http://pubs.acs.org/cgi-bin/abstract.cgi/mamobx/1988/21/i02/f-pdf/f_ma00180a019.pdf?sessid=8084

Note the date on the paper, 1988.

While it is at high temperature it is a "true" solvent.

[edit]

I should also point out the TFE is also branded as Teflon. TFE is soluble in some solvents at room temperature. That may well be what I have as the cans are labled as Teflon lubricant, not PTFE. Also, Teflon AF is soluble.

Todd Tolhurst
10-25-2006, 06:29 PM
It's been repeatedly mentioned that there are high-temperature (near-melting-point) solvents for PTFE, but that's clearly not what we've been discussing. We're talking about PTFE solvents that work at or near standard temperature and pressure. After all, this is all about the cans of lubricant you have out in the shop. Unless you keep the shop at 330C, high-temperature solvents are not relevant.



I should also point out the TFE is also branded as Teflon. TFE is soluble in some solvents at room temperature. That may well be what I have as the cans are labled as Teflon lubricant, not PTFE. Also, Teflon AF is soluble.

Quite right; strictly speaking, Teflon(R) is a trademark for a product line, not a specific chemical substance. Teflon AF is indeed soluble in certain solvents, but it's not PTFE. However, I think it's fair to say that when people informally use the term 'teflon', they're referring to PTFE, and not non-PTFE product that bear the Teflon(R) brand.

Not that it matters; you referred to your lubricant as a "PTFE liquid", so that's the compound we're talking about. Of course, if it's not really PTFE in those cans, then you might very well have a solution. But PTFE still has no solvent under ordinary conditions.

Evan
10-25-2006, 06:44 PM
However, I think it's fair to say that when people informally use the term 'teflon', they're referring to PTFE, and not non-PTFE product that bear the Teflon(R) brand.

Exactly. However, the fact that the cans say Teflon does not guarantee they contain PTFE. I made the same connection as you point out and automatically assumed they contain PTFE. Perhaps not. TFE has very similar properties. It would make a lot of sense to use something that actually dissolves so that it may be dispensed from a spray can.