METHOD FOR PRESERVING POROUS MATERIALS

摘要

The present invention relates to a method for preserving porous materials, mainly paper, that involves precipitating polyparaxylylene from a gaseous phase. This preservation method essentially involves heating diparaxylene and/or derivatives thereof in order to sublime it, and pyrolysing the same in a vacuum chamber. The pyrolysis products are then polymerised and a conformal polyparaxylylene coating is formed on the material. Before carrying out the sublimation heating, the substrate (porous material mainly consisting of paper) is treated in this same chamber using gaseous morpholine in the presence of steam. The morpholine vapours (tetrahydro-1,4-oxazine, diethylenimidoxide C4 H9 NO) are used as a neutralising agent and the treatment is carried out using a 50 % morpholine solution in an amount depending on the acidity (pH) and the type of the material to be preserved. The preservation of porous materials according to this method not only protects them against the environment harmful activity and increases their strength, but also imparts to the above-mentioned characteristics the stability necessary for a long-term preservation.