Need Help With Swelling of Neoprene
Peter Mott
dmond wrote:
>
> I am working with neoprene rolls and am seeing a swelling problem that
> is being caused by one of the lubricants present on the machine. The
> makeup of the lubricants is a combination of natural oils (coconut),
> high mw mineral oil, ethoxylated alcohols and esters, and various
> anionic salts (primarily fatty acid soap, alkyl sulfonates, or
> ethoxylated phosphate esters).
>
> I don't see anything in the lubricant composition that would
> aggressively attack the double bond in the neoprene and thought that
> neoprene's oil resistance would provide it enough protection. Could
> anyone offer a suggestion to eliminate the swelling or a mechanism of
> what is happening? Unfortunately changing the roll to another rubber
> is not an option so changing the lubricant composition is the only way
> to solve the problem.
Swelling of rubber generally is not a chemical attack.
It is physical phenomenon -- the solvent is trying to
dissolve polymer. If the rubber is not crosslinked,
the polymer will dissolve; if the rubber is crosslinked,
the polymer swells.
Neoprene has good solvent resistance to oils and
non-polar compounds, but you've got a soup of polar
and semi-polar chemicals. Divide your lubricant
into chemical "types" -- anionic salts, esters, alcohols,
mineral oils, natural oils -- and place a small
sample of your rubber into a jar with each type;
let it soak over the weekend. The type that swells
neoprene the worst is the one you need to eliminate.
Peter Mott
dmond
Gene Fuss
I don't have the definitive answer, but I'll offer my understanding of
the application.
Neoprene has Moderate resistance to oils, better than almost all other
rubbers except nitrile rubber (NBR). The swelling is not necessarily
indicative of 'attack', rather it is behaving a little like a sponge.
The swelling would probably go down as the oil is squeezed back out.
It's not like the oil is degrading the molecular structure at a
significant rate.
Can you adjust the rollers to compensate for the swelling and call it
even? The swelling should max out swelling and then stay fairly
steady. I don't think the rollers are going to fall apart just because
of the swelling with what I see in the ingredients. Maybe there is an
amine or amide antirust/anticorrosion additive which will degrade the
roller over time, but that should be pretty slow.
What do other people do who use this same type of machinery in this
application?
You're already using one of the 'water soluble' cooling/cutting fluids,
so you might try diluting it and seeing if that helps; maybe bake out
the rollers at 200F to 'sweat out' some of the oil then wipe it off; or
else rolling/squeezing/wiping what's in there out of the rollers if need
be).
You could use a fluid with just the anionic surfactants and ethoxylated
esters and go easy on the nonionic surfactant (ethoxylated alcohols),
other esters and less mineral oil.
Gene
Bruce Hamilton
dm...@ibm.net (dmond) wrote:
>I am working with neoprene rolls and am seeing a swelling problem that
>is being caused by one of the lubricants present on the machine. The
>makeup of the lubricants is a combination of natural oils (coconut),
>high mw mineral oil, ethoxylated alcohols and esters, and various
>anionic salts (primarily fatty acid soap, alkyl sulfonates, or
>ethoxylated phosphate esters).
>
>I don't see anything in the lubricant composition that would
>aggressively attack the double bond in the neoprene and thought that
>neoprene's oil resistance would provide it enough protection.
Neoprene has very poor oil resistance, and what you are seeing
is the dissolution of some of the components ( probably the
mineral oil, but could also be some of the other components
as well ) into the rubber. a wide range of organic liquids will
cause neoprene to swell.
I would talk to the supplier of the machine, the
supplier of the neoprene ( or any supplier of neoprene
products ), and a lubricant supplier, to identify a
suitable alternative lubricant.
Bruce Hamilton
Brent Viers
If you want to change the lubricant, make it a whole lot more polar,
i.e. add water, and you shouldn't have any other swelling problems,
since neoprene is organic and organics and water don't mix.
Another possible option is to change the temp. of the roller You might
be able to go either way- at higher temps, the rubber would tend to
collapse and possibly squeeze out solvent. A more preferable way would
be to cool the system , in which case the solvating capacity of your
lubricant would lower, and hence not affect the neoprene.
Good luck. ;)
Brent
dmond wrote:
>
> I am working with neoprene rolls and am seeing a swelling problem that
> is being caused by one of the lubricants present on the machine. The
> makeup of the lubricants is a combination of natural oils (coconut),
> high mw mineral oil, ethoxylated alcohols and esters, and various
> anionic salts (primarily fatty acid soap, alkyl sulfonates, or
> ethoxylated phosphate esters).
>
> I don't see anything in the lubricant composition that would
> aggressively attack the double bond in the neoprene and thought that
> neoprene's oil resistance would provide it enough protection. Could
> anyone offer a suggestion to eliminate the swelling or a mechanism of
> what is happening? Unfortunately changing the roll to another rubber
> is not an option so changing the lubricant composition is the only way
> to solve the problem.
--
Brent D. Viers
Department of Chemistry
Polymer Research Center
Mail Location 0172
University of Cincinnati
Cincinnati, OH 45221-0172
Telephones: 513-556-9291
513-556-9290
Fax: 513-556-9239
e-mail:vie...@ucbeh.san.uc.edu
br...@jemcom.crs.uc.edu
http://www.jem.research.uc.edu/~brent
Gerald Munson
Brent,
Assuming that changing the lubricant is impractical, Talk to the machine
supplier to see if:
A. a viton roller is available, Viton is much more impervious to both
attack, and penetration by wide range of oils.
B. Lower cost alternative may be having the supplier provide roller of
Silicon rubber. This is less costly but should do the trick for the
materials you cite.
Good Luck
Gerald Munson