| Abstract: | SUMMARIES. Samples of groundwood paper (70%) were treated by spraying them with dispersions of aqueous cellulose derívate solutions in methanol containing some magnesium carbonate. To asses the strengthening and deacidification effects and their stability over time, pH and several mechanical properties were measured before and after dry heat ageing 120°C for 1, 5, 10, 15 and 20 days. As a possible negative side effect the reduction in brightness during treatment and ageing was meas¬ured. As a general result the positive effect of the treatment, which can be applied to paper in bound books is stated. The least effective result was found with hydroxy propyl cellulose. Further research will investigate the use of ethanol in the interest of greater safety, and apply the method to both other types of paper and already deteriorated samples.
CONCLUSION. Cellulose derivatives were selected as strengthening agents because of their chemi¬cal similarity with paper. Compounds such as MC and CMC, the long-term sta¬bility of which has been proven, are not soluble in organic solvents. However, we succeeded in obtaining an emulsion of such a cellulose derivative by completely dissolving it in the minimum amount of water, and then dispersing it homogene¬ously in an organic solvent. This contributed to shortening the drying time and preventing the deformation of the paper materials due to moisture. Spraying the dispersions provided a relatively even application to the paper surface and thus enabled easy application. Spraying these dispersions can deliver almost the same amount of strengthening agent as used in a roll coating method, and presents an adequate strengthening effect. The spraying method is applicable not only for loose sheets, but also for paper in bound books. Adding a deacidification agent such as magnesium carbonate to the strength¬ening emulsion results in simultaneous strengthening and deacidification. In terms of physical properties, MC showed the best results for internal tearing strength and folding endurance, which are often used as deterioration indexes. Water-soluble MC and CMC presented a strengthening effect both just after treatment and after artificial ageing. Meanwhile, the solvent-soluble HPC control was less effective, even though the amounts applied to the paper were greater than those of the water-soluble types. Specifically, a low viscosity HPC (low mo¬lecular weight) did not demonstrate any effect. |
|---|
