Process for making gypsum fiberboard

US4966739A · kind A · utility

Assignee

• Babcock BSH Aktiengesellschaft Vormals Buttner-Schilde-Haas AG · DE

Inventors

• Josef Stipek · Bad Hersfeld, DE
• Friedrich Bahner · Lengede, DE
• Horst Hose · Kassel, DE
• Karl Freisinger · Bad Hersfeld, DE
• Helmut Eidam · Schenklengsfeld, DE

Key dates

• Filing date: Jan 10, 1990
• Grant date: Oct 30, 1990
• Expiry date: Jan 10, 2010

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02W30/91
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

In the process for making gypsum fiberboard the boards are formed or molded rom a mash containing calcium sulfate dihydrate and fiberous material. By heating and subsequently cooling the boards the dihydrate is first converted into the hemihydrate and subsequently recrystallized again to the dihydrate. Known processes require day line setting times which are economically disadvantageous. According to the present invention these times are shortened by pulling or drawing water, an aqueous solution or a water containing mixture through the boards after the cooling step. Advantageously a setting accelerating agent can be dissolved in the water. By these features the setting time can be shortened to less than two hours. By addition of a binding agent, e.g. starch, to the fluid drawn through the boards the strength of the boards is increased.