Molding shaped bodies of vegetable fibers uses a perforated mold where hot steam is used to break down the biodegradable bonding agent and an underpressure dries the body in the mold before removal

摘要

A perforated mold (1) is used to form a shaped body of fiber materials from vegetable matter, together with a biodegradable bonding agent. The bonding agent is broken down by a feed of hot steam. The molded body is dried by the application of an underpressure, after the bonding agent is broken down. The bonding agent is broken down by hot steam at a pressure of 2.5-8.0 bar absolute. The underpressure, to dry the molded body, is at a level of 0.4-0.8 bar absolute. When the molded body is taken from the mold (1), it is dried further in the ambient atmosphere. The bonding agent is a liquid water-glass, or a powder water-glass or starch. The fiber material is made wet with water, before the bonding agent is added. The water contains an additive as a foaming agent or a softener, and especially H2O2, or a hydrophobic agent and especially alumina cement or a dye. The steam is fed into the mold (1) and, in a second step, is allowed to expand through the mold. The underpressure is applied to the mold from a remote point. When the vacuum has been disconnected, air is passed into the mold (1) before the body is taken out. The fiber mixture is compressed in the mold (1) before the hot steam is applied. The hot steam is passed repeatedly through the mold.