Birth Of Saranex

The article on the successful use of Dow Chemical’s Saranex as an odor-barrier film in the packaging of 2,4-D triggered personal recollections of the origin of that product (C&EN, June 23, page 33). The concept of a heat-sealable barrier film with a saran resin core and polyolefin outer layer was conceived circa 1964 at Dow by Norman Peterson, director of plastics technical service and development.

As manager of the films group, I had dropped by to brief Peterson on a new non-Dow two-layer polyolefin film being used as a bread wrap film. It was a “lightbulb” moment for Peterson, and Saranex was born.

Conception to product took a bit longer. Walter Schrenk, a 1986 inductee into the Polymer Processing Hall of Fame, was responsible for developing a coextrusion process to provide film for product development. The poor adhesion between saran and the olefin layers in a three-layer film was solved with a tie-layer.

I had instigated the addition of ethylene vinyl acetate (EVA) copolymer resins to manufacture a clear, heat-sealable commercial saran film sold as Saran Wrap 3. A coextruded layer of EVA between the saran and polyethylene layers provided the required adhesion. The five-layer PE/EVA/saran/EVA/PE heat-sealable coextruded barrier film was introduced as Saranex.

The first public presentation of the product was made on Oct. 5, 1966, at the Packaging Institute Forum in New York City. The first significant application of Saranex was for colostomy bags. Odor control was as important then as it is now.

Jacob Eichhorn
Midland, Mich.