Printech Archives, March 1997: Re: fountain solution alternatives to IPA

Re: fountain solution alternatives to IPA

Robert Gifford (
gifford@epd.engr.wisc.edu)
Thu, 27 Mar 1997 18:21:32 -0600



		

The following discussion is occuring on printech, parts are repeated for
printreg-only subscribers. Please add you comments in a reply.

Original question:

Does anyone know of any fountain solutions that do not contain isopropyl
alcohol or ethylene glycol ethers and are less than 15% volatile organic
compounds? If yes, please send me their composition, VOC %, and the
contact information, or fax me the MSDS. Thanks very much...

Lois N. Epstein, P.E.

First answer:

Lois:
The answer is YES. Contact K-B Litho Supply Company, Kansas City, MO @
816-241-3070 and ask about their Alcoplus T5 Series. 0% VOCs, vapor
pressure17.5 mmHg., no SARA reportables, no hazardous ingredients, flash point >
212 degrees F. Product was developed in Great Britain by Hydro-Dynamic
Products (HDP). K-B Litho Supply is their U.S. distributer. This is a two part
product that needs to be combined with either their product, Capital-R, or with
another such as Tower AR-1. Both of these do have VOCs, with Capital-R
having about half that of AR-1. However, please note that as mixed for use, the
VOC content of the fountain solution would be below 15%! This is an
excellent product that we have been running for the past four years, at least.

Jeff Adrian, jeffadrian@johnroberts.com

******************************

DALE.KALINA@rrd.com wrote:
>
> One thing that has failed to be mentioned regarding the vapor pressure of the
> fountain solution issue is that water has a vapor pressure as well. At 25 C,
> water has a vapor pressure of about 24 mm Hg. In other words, the vapor
> pressure that this fountain solution exhibits is probably just the vapor
> pressure of water. The vapor pressure of the alcohol substitutes commonly used
> are less than 1 mm.
*************************************************************

George Frantz wrote:

_________________________________
> Subject: Re:fountain solution alternatives to IPA
>
> Re: vapor pressure in printing chemistry... Bob Gifford's description of
> vapor pressure was helpful.
>
> I'm not a chemist, but from working w/ these issues pretty frequently, I've
> developed some home-spun understanding. If there are technical
> errors/omissions, I trust our colleagues will set me straight.
>
> Following the lead of EPA (and several states) in the Alternative Control
> Techniques document (ACT), which I believe was promulgated in 1992, vapor
> pressure was included as an optional method for measuring the potential for a
> substance to volatilize (evaporate). The older printing CTG had set a limit
> of 30% VOC for blanket washes for non-heatset litho, but the new document
> allowed using the alternate measure of 10 mmHg vapor pressure. So altho a
> fountain solution w/ a VP of 17 mmHg is still pretty low, it's above that
> threshold.
>
> The VOC/vapor pressure model is not used by all states, so you'll need to
> refer to your state's regulatory group to check status before adopting new
> chemistry.
>
> George Frantz*MA/OTA

******************************

New Addition:

Like George, my chemistry training is limited, mostly from my
meteorology background in which the major vapor pressure of concern is that of water
vapor. My meteorology textbook formula gave the following saturation vapor
pressures for water:
T: 25.00 C saturation vp: 23.74 mm Hg (as Dale suggested)
T: 20.00 C saturation vp: 17.53 mm Hg
T: 10.00 C saturation vp: 9.20 mm Hg
T: 5.00 C saturation vp: 6.54 mm Hg
T: 0. C saturation vp: 4.58 mm Hg

This is the maximum amount of water vapor that air at this temperature
can hold. (100% relative humidity, which is actual vapor pressure /
saturation vapor pressure expressed as a percentage, your meteorology lesson for
the day.)

(The following was determined with help from a WI DNR air permit
engineer.)
Now, if the vapor pressure measured is the saturation vapor pressure of
the entire fountain solution, partly from the water and partly from other
constituents, the saturation vapor pressure would be an addition of the
saturation vapor pressures of the constiuent partial vapor pressures,
(as Dale implied), but with a weighting for each equal to their molar
fraction within an ideal solution. This can be intuitively reasoned since each
molecule which evaporates has to come from the surface of the solution. If there
are X moles of constituent 1 and Y moles of constituent 2 mixed together,
the fraction of moles of constituent 1 at the surface of the liquid will
be X/(X+Y). Non-ideal solutions also introduce a vapor pressure factor dependent
upon the constituents, temperature, and pressure.

The CTG which George mentions for blanket washes states that the vapor
pressure is measured at 68 F (20 C), a standard EPA measuring point, and
that the regulated constituent's vapor pressure must be less than 10 mm
Hg. This implies that a blanket wash with multiple constituents can
have a total vapor pressure greater than 10 mm Hg, the same could hold
for fountain solutions.

Can any chemists or regulators on the list add to this?

*************************************************************
* Robert Gifford


 

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