Durable Paper with Microencapsulated Biocide
Development of New Types of Biostable Durable Paper with Microencapsulated Biocide
Tech Area / Field
- CHE-POL/Polymer Chemistry/Chemistry
3 Approved without Funding
Russian Scientific Center of Applied Chemistry, Russia, St Petersburg
- Russian National Library, Russia, St Petersburg\nDelivery Systems International, Russia, St Petersburg
- Freie Universität Berlin / College of Pharmacy, Germany, Berlin\nCNRS / Centre de Recherches sur la Conservation des Documents Graphiques, France, Paris
Project summaryThe Project target is to develop technology and create new types of biostable durable paper with biocide microencapsulated into polymer shell with the purpose to ensure preservation of cultural monuments and other fine arts valuables.
Different nations all over the world are intensively looking for advanced technologies to ensure preservation of cultural monuments on paper carriers.
Library, museum, and archival funds contain publications and manuscripts which are largely made on paper inevitably deteriorating in the process of storing and use. Mass destruction of documents which are kept in storage for a long time makes the problem of preservation and conservation of fund especially urgent.
The condition of books in the libraries of Western Europe and the USA is the following: about 10% of the fund is seriously damaged and can not be used, 30% have small damages, and about 50% are under a threat of destruction. In the Russian National Library about 25% of book need conservation. A similar situation is observed in other libraries of Russia.
All over the world the search is going on for advanced technologies of conservation and methods are being developed to raise durability of paper by means of its strengthening with polymers and giving it biostability.
Alongside the traditional technologies of restoration, the methods of mechanical replacement of missing portions of paper in documents are used more and more widely. The idea of mechanical filling up was born within the walls of the Conservation Center of the Russian National Library as long back as in the late 50s, and it was realized through development of mechanized restoration technology, and invention of a few models of restoration-pulp filling machines (ROM). This equipment is used for restoration of valuable printed editions of the XVI-XVIIIth centuries. The same equipment is used for manufacturing special restoration paper with specified complex of properties. The developed technologies are protected by author’s certificates of the USSR and patents of the Russian Federation.
The need to ensure durability of a document being restored determines the choice of restoration material and restoration technology. In so doing the requirements to be met include strengthening of the document base and making the restoration complex «document-paper» biostable.
Very promising seems the idea of simultaneous raising the mechanical strength and biostability by introducing microencapsulated (MIC) biocide (imbricin) into paper. In so doing it was thought that the role of strengthening agent is played by the material of microcapsule shell. Microcapsules with biocide are introduced into paper mass. In the formation process the polymer penetrates into the structure of paper sheet. As a result, the paper and complex «restored document - restoration material» are strengthened and acquire bioprotective properties. The duration of the restoration process is not affected negatively. Quality and reliability of restoration improve, ecological safety of the processes increases.
To realize this idea it is necessary to solve two principal problems:
· to obtain biocide (imbricin) microencapsulated into a shell of polymer which increases the paper strength (gelatin, acetophtalate of cellulose, sodium salt of carboxymethyl cellulose);
· to develop a technology of producing durable biostable paper with MIC biocide.
In spite of a great number of published materials related to microencapsulation, the information on biocides microencapsulation and their use in such form for manufacturing biostable restoration paper is not available. The interest to biocides applications in microencapsulated form is due to a number of factors. First, the uniform distribution of water-insoluble biocides in paper pulp is difficult because of their poor wettability with water and very small dosage. Besides, they can be partially washed out in the process of paper manufacturing as biocide particles do not have, as a rule, adhesion to cellulose fibers and play the role of an inert filler. These shortcomings can be eliminated by means of microencapsulating biocides into shells of polymers with various functional groups, in other words, by modification of biocides surface in such a way as to improve biocide adhesion to cellulose fibers. It will contribute to better containment of biocide in paper pulp and ultimately result in improvement of performance characteristics of paper. Besides, microencapsulation might ensure sustained action of biocide in paper. All the above said makes it possible to claim expediency of producing biocide in microencapsulated form.
The Russian Scientific Center «Applied Chemistry» and AOZT "DELSI" are leaders in microencapsulation technologies in the Russian Federation and have at their disposal special laboratory and experimental-industrial equipment for producing microencapsulated products.
The work on microencapsulating various other chemical and biological materials in the RSC «Applied Chemistry» and AOZT "DELSI" were supported and financed by the ISTC from 1994 (Project 1056-98). The available knowledge, international scientific contacts, technological experience, equipment, instruments, and computers purchased due to the ISTC projects will be employed in full for realization of the given Project.
The FCCLF of the Russian National Library has at its disposal up to date technologies of mechanized restoration and equipped with restoration-filling paper-making machines, it is world-wide known in the field of book and document restoration.
Joining the efforts of these two organizations will make it possible to create a technology of manufacturing new types of durable biostable paper with microencapsulated biocide. The proposed technology is fundamentally new scientific study and it does not have any analogs.
The Project results will have important humanitarian value. The new types of biostable durable paper are promising for direct applications in restoration of written language monuments and preventive conservation of fine arts items. Besides, the developed technology can be successfully applied for creating a wide assortment of paper and cardboard used for ensuring safety of cultural valuables (making protective containers, boxes, files, cases, envelops, passe-partouts) in libraries, archives, and museums. It will allow to facilitate the access to and to preserve for future generations a great number of old and newly created documents which are kept in state cultural institutes and private collections.
The Project realization will not only allow to provide the restoration departments of various cultural institutes with new materials, but to introduce their development into cellulose and paper industry.
In case of industrial applications of the developed technology, it is certain that a commercial value of the proposed Project will become evident. The new types of biostable durable materials can be used as packing materials for items of various designation, especially for those designed for shipment, storage and operation in countries with warm and humid climate. The MIC biocides can find independent applications as active substances in disinfectant solutions, biostable dispersions on the aqueous basis (paints and coatings).