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Re: Polyurethane Foam Mfg: Methylene Chloride Substitute



At 10:00 AM 7/2/97 PDT, you wrote:

>I should note that I already know of other alternatives, such as 
>high-pressure machines, self-cleaning mixing heads, etc.  This situation 
>requires a substitute for the methylene chloride, if any exist that work.
>
>I have also looked at the case study database in Envirosense, as well as 
>other Web sites, and the P2Tech archives.  I didn't find anything that 
>answers this question.
>
>So, if any of you out there have had experience with this sort of operation, 
>and have documented examples of substitutes that do the trick, please let me 
>know.  Thanks!  Please e-mail me directly as well as the listserve.
>
>Bob Goldberg
>Washington State Department of Ecology
>P.O. Box 47775
>Olympia, WA  98504-7775
>(360) 407-6350
>fax: (360) 407-6305
>e-mail: bgol461@ecy.wa.gov
>URL: www.wa.gov/ecology/hwtr/



Bob:

I'll paraphrase from an EPA document we prepared with the assistance of Bill
Battye of EC/R in Raleigh, NC.  The document is Best Management Practices
for Pollution Prevention in the Slabstock and Molded Flexible Polyurethane
Foam Industry (EPA/625/R-96/005, September 1996).  It's a very good summary
with up to date technical information.

Methylene chloride is used as an auxiliary blowing agent (ABA) to supplement
CO2, the primary blowing agent.  The vaporization of MCl increases the
blowing action and removes excess heat from the polymerization reaction.
Softer, lower density foams require more ABAs.  The corrolary is that
lowering the amount of ABA produces stiffer foam, and also increases risk of
scorching or even fires.

Options to reduce the use of ABA include use of foam softening additives and
systems and mechanical cooling systems.  Substitutes include:

-- Liquid CO2 (CarDio Process), available as a retrofit.  No U.S. firms had
installed at time of writing though several were expected to install it.
Licensed to Cannon USA in Mars, PA.

-- Reduced presure foaming, which increases foaming efficiency and can
eliminate the need for ABAs.  There are several technologies available.

-- Substitution of formic acid for some water in the formulation. Formic
acid generates both CO and CO2, boosting the blowing power of the reaction.
Not currently in use in the U.S. but licensed to Goldschmidt Chemical in
Hopewell, VA.



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