Method for manufacturing powdery, vitreous carbon useful for making pastes having predetermined electrical conductivity

US6231787A · kind A · utility

Assignee

• Preh-Werke GmbH & Co. KG · DE

Inventors

• Peter Ambros · Leutershausen, DE
• Hugo Johannes · Bad Neustadt an der Saale, DE
• Franz Kissner · Bad Neustadt an der Saale, DE

Key dates

• Filing date: Dec 1, 1999
• Grant date: May 15, 2001
• Expiry date: Dec 1, 2019

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C04B35/524
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The invention relates to a method for producing powdery, vitreous carbon, and a paste made therefrom for producing resistive films having predetermined electrical conductivity. In production methods known in the art, pyrolysis of acrylamides is performed in mixture with water-soluble salts and, following pyrolysis, the powdered portion of the vitreous carbon is recovered by dissolving the salt component in water. The vitreous carbon is then dried, and the powder obtained in this manner is pulverized once again, as needed. A disadvantage of this method is that it is very time-consuming. In the solution now recommended, a preferably aromatic polymer is cured into a resin that is cross-linked in three dimensions, and in this state is ground to a powder prior to pyrolysis. Pyrolysis of the resulting powder is performed in a nitrogen atmosphere, so that powdered, vitreous carbons having different resistivities are obtained by using different final pyrolysis temperatures in each pyrolysis process. The vitreous carbon having a specific electrical resistivity obtained through pyrolysis is then dispersed into a binding agent and is ground in a mill together with the binding agent to a grain…