Method for producing expandable graphite intercalation compounds using phosphoric acids, and graphite foil
AssigneeSGL Technik GmbH
InventorsOswin Öttinger, Hubert Malik
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Abstract
A method for producing expandable graphite intercalation compounds uses a thermal polyphosphoric acid which is added to an intercalation agent or to graphite. Preferably, the thermal polyphosphoric acid is used in a mixture with red, fuming nitric acid. Products produced from the graphite intercalation compounds through the expanded graphite stage, such as graphite foils, graphite laminates or graphite seals, have a comparatively high fluid tightness, are relatively resistant to oxidative attack, and can have comparatively high strengths. A further advantage is a good handling ability of the thermal polyphosphoric acids. A graphite foil is also provided.
Claims39
A method for producing an expandable graphite intercalation compound, which comprises:
- reacting crystalline graphite particles having a lamellar structure, in a temperature range from −10° C. to +80° C., without an additional supply of water, with a reaction mixture formed of at least one strong concentrated acid selected from the group consisting of sulfuric acid and nitric acid, an oxidizing agent selected from the group consisting of concentrated nitric acid, hydrogen peroxide and peroxo sulfuric acid for oxidizing the graphite, and a thermal polyphosphoric acid, and avoiding any contact of the graphite compound reaction product with water, producing an expandable graphite compound with a bulk weight of at most 3 g/l.
Dependencies are inferred from the claim text.