Kanto Denka Kogyo Co., Ltd.

Ituo Orihara

Moriyuki Fukushima

Shiro Yamashita

Akira Suzuki

Akira Ishida

Eisaku Mogi

A waste gas stream containing toxic NF.sub.3 and optionally other gases, such as acidic fluoride gases, for example, HF, SiF.sub.4, MoF.sub.6 and WF.sub.6 is first treated with particles or ribbons of a Cr-containing Fe alloy at about 300-600.degree. C. to remove the NF.sub.3 content and, if desired, subsequently with an alkaline neutralizing agent in the form of pellets to remove the acidic fluoride contents, if any; said alloy containing preferably about 16-26% Cr and being used in a form of bed packed with said ribbons

Treatment of NF.sub.3 -containing gases

A significant improvement in thermal stability and decreased gas permeability and water vapor transmission of vinylidene chloride copolymer resin are achieved by the presence of about 0.5 -- about 10% by weight of glycidyl methacrylate as an internal heat stabilizer in the polymer chain.

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Gunma-ken, Japan

Ituo Orihara