Bio-based compounds for wires and cables

Teknor Apex Company has developed BioVinyl for applications as diverse as automotive window encapsulation, medical tubing, and footwear. Development work continues on compounds for other applications, such as blood bags and for wire and cable jacketing. Commercial uses have already been found for Bio Vinyl. Two of these are a line of fashionable "flip-flop" sandals produced by Okabashi Brands, Inc. and a range of shoe welting manufactured by custom extrusion processor Barbour Plastics, Inc.

The phthalate-free Dow Ecolibrium bio-based plasticisers used in BioVinyl is manufactured using plant byproducts by the Dow Electrical and Telecommunications (Dow E&T), a unit of The Dow Chemical Company. The plasticisers were developed to meet growing demand for more sustainable options in wiring applications such as personal electronics and appliance wiring, residential and commercial building wiring, communications and data cabling, and automotive wiring. They offer specific benefits in terms of processing, electrical and temperature performance, and end-use for low and high temperature wiring applications in several key wire and cable market segments such as in personal electronics and appliances with its outstanding balance of flame retardance, flexibility and heat performance.

Under a joint collaboration agreement, Teknor Apex has been granted the exclusive right to market in North America flexible vinyl compounds containing Dow Ecolibrium in certain applications. Life cycle analysis tests conducted by Dow and reviewed by a third party indicate that every tonne of vinyl compound made flexible with Dow Ecolibrium bio-based plasticiser helps the industry reduce carbon dioxide equivalent emissions by 0.7 tonne, or 41%.

Applications for which Teknor Apex is prepared to supply commercial quantities of BioVinyl compounds include: window seals, interior and exterior trim, and instrument panel skins for automotive; medical tubing, masks, and collection bags; and consumer products such as footwear and toys.

Property benefits stressed

Since half of the PVC polymer is derived from seawater and typical plasticiser loadings are 33%, the substitution of the new plasticisers for conventional phthalates makes the carbon footprint of BioVinyl compounds dramatically smaller than that of many plastics. Teknor Apex has compiled comparative data indicating that the global warming potential of BioVinyl compounds, in terms of CO2 emission equivalents, is half that of polyolefin resins and is even lower than that of PLA bioplastic. The cumulative energy demand of BioVinyl compounds, including feedstock and processing, is the lowest in comparison with a wide range of plastics.

Another advantage of BioVinyl compounds stems from the fact that Dow Ecolibrium plasticisers are derived from naturally occurring vegetable substances that are not used for food and so are unaffected by supply/demand forces impacting other bio-derived plastics feedstocks such as corn starch.
In work on formulations, Teknor Apex researchers developed and tested BioVinyl grades for a number of standard flexible vinyl applications, such as building and construction seals and gaskets and irrigation tubing. The most pronounced property change discovered in comparison with conventional phthalate-plasticised compounds was an improvement in heat stability, enabling extrusion processors to carry out longer product runs without prohibitive levels of polymer degradation. In addition, compounds that were developed for weather stripping and gasketing showed significantly less colour change than standard vinyl after accelerated weathering.

Teknor Apex researchers also found that the Dow bio-based plasticiser exhibited greater plasticising efficiency than most common phthalates. In preparing developmental BioVinyl grades, the company was able to use less plasticiser to obtain the same level of flexibility as in corresponding pJunior