David O Bringen

US Patent:

40627217, Dec 13, 1977

Filed:

Oct 26, 1976

Appl. No.:

5/735428

Inventors:

Vernon L. Guyer - Minneapolis MN
David O. Bringen - Edina MN

Assignee:

Conwed Corporation - St. Paul MN

International Classification:

D21D 300

US Classification:

162101

Abstract:

A surfactant foaming agent added to a wet fibrous sheet just before initiation of vacuum water extraction forms foam within the sheet. The foam expels water from the sheet while increasing the resistance to vacuum. Water removal time is lengthened and the fractional amount of water removed by suction is increased. The reduced residual water provides a proportional decrease in drying time and drying energy. The addition of an anti-foaming agent with the surfactant reduces the water drainage time as compared to the normal case. This increases the drainage rate but does not increase the amount of water drained from the sheet.