Takayuki Okayama

A New Technique for Strengthening Book Papers Using Cellulose Derivatives

SUMMARIES Samples of groundwood paper (70%) were treated by spraying them with dispersions of aqueous cellulose derivate 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 measured. 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. Des échantillons de papier à pâte mécanique (70%) ont été traités par des émulsions qui contenaient des solutions aqueuses fabriquées avec différents dérivés de cellulose dans du méthanole avec un additif de carbonate de magnésium. Afin de vérifier leffet de la concentration et de la désacidification ainsi que leur stabilité à long terme des mesures relatives au pH et aux propriétés mécaniques ont été effectuées avant et après le vieillissement artificiel à 129°C pendant 5, 10, 15 et 20 jours. Une modification de la clarté du papier en tant queffet secondaire éventuellement négatif a également été étudié. Comme résultat général on constate leffet positif du traitement qui peut être aussi appliqué aux livres reliés. Le résultat le moins bon et même insuffisant est donné par les substances de cellulose hydroxyle propyle. Une poursuite de la recherche prévoit dutiliser cette méthode pour étudier des échantillons fabriqués à base dautres fibres et des papiers qui ont déjà été endommagés. Proben aus Holzschliffpapier (70%) wurden mit Emulsionen besprüht, die aus wäßrigen Lösungen verschiedener Cellulosederivate in Methanol und einem Zusatz von Magnesiumcarbonat hergestellt waren. Um die Festigungs- und die Neutralisierungswirkung sowie ihre langfristige Stabilität namhaft zu machen, wurden pH und verschiedene mechanische Festigkeitswerte vor und nach beschleunigter Trocenalterung bei 120°C über 5, 10, 15 und 20 Tage gemessen. Als möglicher negativer Nebeneffekt wurde auch Helligkeitsveränderung gemessen. Als generelles Ergebnis wird die Wirksamkeit der Methode konstatiert. Sie kann auch auf das Papier in gebundenen Büchern angewandt warden. Den geringsten Festigungseffekt zeigten die Präparate aus Hydroxypropylcellulose. In Fortführung der Forschung wegen der höheren Sicherheit äthanolische Lösungen untersucht, und weiterhin sollen Proben anderer Faserzusammensetzung und auch bereits geschädigte Papiere nach der Methode behandelt werden.

A New Technique for Strengthening Book Papers with Cellulose Derivatives. Part 2: Effect of Cellulose Derivatives on Different Types of Paper

Abstract Continuing the work of our previous paper (Seki et al., Restaurator 26: 239–249, 2005), research was undertaken to improve the deacidification/strengthening method, using ethanol as a less toxic solvent in place of methanol. In order to evaluate the effects of deacidification/strengthening combinations of magnesium carbonate (MgCO3) with methylcellulose, carboxy methylcellulose (CMC), hydroxy propylcellulose (HPC) or ethyl cellulose (EC), tests were conducted on ligneous papers and acidic wood-free paper. The use of ethanol required approximately three times longer paper drying time compared with methanol. The acidic wood-free paper showed a significant strength improvement when treated with each deacidification/strengthening agent, and retained that strength even after accelerated ageing. Newspaper strength improved slightly as a result of the treatment. After accelerated ageing its strength did not decrease as remarkably as did that of untreated paper. The mixed pulp ligneous paper showed a strength improvement when the paper was deacidified and treated with all cellulose derivatives. However, the strength fell below that of untreated paper as accelerated ageing progressed. Of all the combinations tested, methylcellulose and MgCO3 was the most appropriate treatment to deacidify and strengthen the three common commercial papers. Zusammenfassung In Fortsetzung der früheren Arbeit (Seki et al., Restaurator 26: 239–249, 2005) werden weitere Untersuchungsergebnisse zu der kombinierten Methode einer Entsäuerung/Festigung von Papier vorgestellt. In den vorgestellten Versuchen wurde das zuvor verwendete Methanol durch das weniger toxische Ethanol ersetzt. Es wurde das Entsäuerungsmedium Magnesiumcarbonat (MgCO3) in verschiedenen Kombinationen mit den Festigungsagenzien Methylcellulose, Carboxymethylcellulose (CMC), Hydroxypropylcellulose (HPC) und Ethylcellulose (EC) auf eine Auswahl unterschiedlicher ligninhaltiger und ligninfreier Papiere aufgebracht. Der Einsatz von Ethanol verlangsamte die Trocknung der behandelten Proben im Vergleich zu Methanol um das Dreifache. An den behandelten Papieren wurden verschiedene Prüfungen vor und nach der künstlichen Alterung durchgeführt. Das saure, holzfreie Papier zeigte eine substantielle Verbesserung der Festigkeit nach der Behandlung, und einen verringerten Festigkeitsverlust nach der künstlichen Alterung. Zeitungspapier zeigte eine eingangs leicht verbesserte Festigkeit, und eine ebenfalls leicht geringeren Festigkeitsverlust nach beschleunigter Alterung im Vergleich zu der unbehandelten Probe. Das aus gemischten ligninhaltigen Fasern hergestellte Papier zeigte eine eingangs deutliche Verbesserung der Festigkeit. Im Zuge der künstlichen Alterung verringerte sich die Festigkeit allerdings noch unter die Werte der unbehandelten Probe. In der Behandlung der drei Testpapiere war die Kombination Methylcellulose und Magnesiumcarbonat am erfolgreichsten. Résumé En complément à notre travail de recherche publié précédemment (Seki et al., Restaurator 26: 239–249, 2005) nous avons entrepris de poursuivre nos investigations afin doptimiser la méthode de désacidification/de renforcement du papier en utilisant de léthanol en tant que solvant moins toxique au lieu du méthanol. Afin dévaluer les effets de désacidification et de renforcement possibles des traitements de carbonate de magnésium (MgCO3) combinés avec la méthylcellulose, ou la carboxyméthylcellulose, lhydroxyméthylcellulose ou léthylcellulose des tests ont été réalisés sur des papiers de pâte mécanique et des papiers acides de cellulose. Il sest avéré que lutilisation déthanol au lieu du methanol exigeait une durée de séchage trois fois plus longue. Les analyses ont démontré que le papier acide de cellulose était renforcé par cette méthode de façon significative et ceci peu importe quel éther de cellulose avait été utilisé en combinaison avec le carbonate de magnésium. Le renforcement obtenu est resté stable par rapport au traitement de vieillissement artificiel appliqué. La stabilité mécanique du papier à pâte mécanique par contre na pu être renforcée que très modérément par cette technique. Ici aussi le renforcement obtenu est resté dans une large mesure stable après le traitement de vieillissement artificiel. Les papiers qui avaient été fabriqués à base dun mélange de pâte à bois et de cellulose ont pu également être renforcés lorsquils furent soumis à tous les traitements utilisant les différents éthers de cellulose testés en combinaison avec le carbonate de magnésium. Cependant il faut noter que leur résistance mécanique a diminué après le traitement de vieillissement artificiel et est passé à un taux inférieur à celui des papiers dorigine non traités. Cest le carbonate de magnésium combiné à la méthylcellulose qui a été identifié comme étant lagent le plus approprié pour la désacidification et le renforcement ainsi que pour la stabilisation des papiers utilisés communément dans le commerce qui ont fait lobjet de la présente étude.

Preparation of fine fiber sheets from recycled pulp fibers using aqueous counter collision

The utilization of waste paper is very important for saving wood resources and reducing waste generation. Various techniques for preparing cellulose nanofibers, which is a material recently proposed for potential applications in the paper industry, have been investigated. In the present study, fine fibers were prepared using recycled pulp and a nanoengineering aqueous counter collision treatment, and sheets composed of these fine fibers were prepared by filtration under reduced pressure conditions. Measurement of specific surface area and optical microscopic observation of fine fibers showed the recycled pulp was not readily miniaturized by the treatment compared with virgin pulp. The tensile strength of sheets produced from recycled pulp by 5 times of the treatment was higher than of those prepared from recycled pulp by 60 times and from virgin pulp regardless of the number of the treatment. Furthermore, the density of the sheet produced from recycled pulp by 5 times was lower than other sheets.

Influence of addition of bulking promoter on AKD-sizing performance

Paper density, tensile index, sizing degree, and other properties of the handsheets were measured in term of addition level of bulking promoters and alkyl ketene dimer (AKD). Bulking promoters had clear bulking effects, and in subsequent addition of the AKD, the sheet density was further decreased slightly. Although the density of the handsheet decreased from 0.64 to 0.61 g/cm3 when 0.2% AKD was added with the 0.8% bulking promoter, tensile strength decreased from 20.3 to 19.8 Nm/g. The addition of AKD led to suppression of the decrease in the tensile index. The bulking promoter may also have potential to give sizing effects to the paper sheet as well as the increase in paper thickness. When 0.05% AKD was added together with 0.8% of bulking promoter, the sizing degree of the handsheet was 25.6 seconds, and it was almost the same, 27.3 seconds, as the addition of 0.1% AKD only. AKD retention in the handsheet was determined by pyrolysis-gas chromatography (Py-GC). The addition of the bulking promoter contributed to AKD retention in the handsheet regardless of the sizing degree. Wetting characteristics of the handsheet were determined by contact angle measurements. Surface free energy, γs, of the handsheet as calculated from the contact angle decreased as the level of AKD addition increased.

A New Evaluation Method for Paper Deterioration: The Rolling Test

Abstract: A new evaluation method for paper deterioration tentatively called the ‘rolling test’ is described. The paper to be tested is rolled using cylinders of different diameters, and paper which can be safely rolled on cylinders of smaller diameters is considered more “flexible”. The rolling test was shown to have a good correlation with artificial ageing. Correlation between conventional mechanical measurements and the rolling test was studied on paper samples of varying levels of degradation. While the formers are suited to the characterization of papers which are not much deteriorated, the rolling test revealed to be a more effective measurement method for artificially aged and weakened papers. The rolling test performed on a limited number of pages from the Kyocera Collection of British Parliamentary Papers (Kyoto University Library) showed that samples from the second half of the 1800s are comparatively less “flexible” than samples from the other periods. The analysis of the fibre composition suggested that the use of groundwood pulp was a potential cause of the deterioration seen in the papers of this period.

Relationship between wettability and sizing degree of paper containing bulking agent

The addition of a bulking agent achieves the bulking of paper and increases the pore volume. In this study, the effect of adding bulking agents with various alkyl chain lengths (C14, C18, and C22) on the bulk of paper, the sizing performance, and sheet wettability was evaluated. The bulking effect of a bulking agent with a short alkyl chain length (C14) was large, and reduction in the sheet tensile strength was confirmed to be suppressed. Good sheet sizing performance was achieved when a bulking agent was used with an alkyl ketene dimer (AKD). When 0.1% or more of AKD was added, using a bulking agent with a shorter alkyl chain length increased the improvement in the sizing degree. Pyrolysis gas chromatography measurements of the amount of reacted AKD revealed that the addition of a bulking agent increased the AKD content of the sheet. The sheet contact angle measured by the two-liquid method tended to increase with increasing alkyl chain length. However, the sheet contact angle was not directly correlated with the Stöckigt sizing degree. By using 1% ferric chloride (FeCl3) and 2% ammonium thiocyanate (NH4SCN) aqueous solution, which are used for measuring the Stöckigt sizing degree, the time-dependent change in the contact angle on the paper sheet surface was measured to evaluate wettability. The Stöckigt sizing degree of paper sheets was found to be greatly influenced by the sheet wettability by NH4SCN solution. In the case of 2% NH4SCN aqueous solution, different samples exhibited large wettability differences. When 0.2% or less of AKD was added, the effect of the concentration on the contact angle was confirmed to be large at all NH4SCN concentrations.