Mass Deacidification of Paper and Books Study of the Limitations of the Gas Phase Processes
| Hlavní autori: | , , |
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| Médium: | Článok |
| Jazyk: | angličtina slovenčina |
| ISSN: | ISSN 0034-5806 |
| On-line prístup: | http://www.viks.sk/chk/res_4_03_227_239.doc |
| Abstrakt: | CONCLUSION. The current state of the art a gas phase process does not really meet the well defined requirements for the satisfactory deacidification of paper works. The main drawback is that no alkaline reserve is achieved if the treating molecule does not react with the paper substrate. Another is the contamination of the atmosphere in the library by residues of the treatment compound, if this is not firmly linked to the paper. In the diethylzinc process the treating molecule effectively reacts with the moisturized cellulosic substrate resulting in the neutralizing substance. Processes resulting in a deposit of particles of reactant inside the web will always suffer from the limitations linked with the heterogeneous situation26. Thus, it seems that a process using a homogeneous treating solution has the best chance of meeting the different requirements for mass deacidification. It has been shown in this paper that the silazanes do not achieve a permanent deacidification because the treating molecules are not covalently bound to the fiber surface, and that the aminosilanes can present an interesting alternative, because they produce a covalent bond between the alkaline molecule and the fiber surface. It is well known that alkoxysilanes can produce self condensation upon reaction with residual moisture. However, the vapor tension of the aminosilanes, whatever they are, is very low, and at the low pressure required for vapor diffusion, paper will dehydrate before reacting with them. It can be concluded that the use of such molecules in a deacidification process must be carried out in a liquid phase rather than a gas one. This will be the topic of another report. The network produced in the paper web by self condensation can increase the mechanical strength of the treated materials26. SUMMARIES. After an overview on the existing mass deacidification processes and the statement that none of them fulfill the conditions that would constitute an "ideal" one, these conditions are denned: raising the pH to ca. 7.5, producing an alkaline reserve, not significantly reducing mechanical strength, not altering the optical properties of the documents, not provoking bleeding of the inks and colours, etc. As it might be possible that nitrogen containing organic compounds would fulfil these conditions, some such compounds were tested, namely some silazanes and some silanes, with the preliminary result that aminosilanes, used in a liquid phase, might be promising. |
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| ISSN: | ISSN 0034-5806 |
