Hiroshi Asaoka

A consideration for the studies on chemical pulping

The possibility of a chemical engineering approach with a simulation method to chemical pulping process was discussed. The chemical engineering would be expected to build up a new technology system for pulping.As the computer simulation is able to optimize the process condition by choosing a good combination of several factors, the approach would be applicable to the development of a new process, such as effective utilization of wood components, which had been studied from the standpoint of wood chemistry. The technology for the chemical pulping process would be improved by the application of chemical engineering as well as wood chemistry.

Energy Saving of Mechanical Pulping

The production of thermomechanical pulp (TMP) has been increasing in these several years for its physical properties. But it requires the largest amount of energy among the mechanical pulping methods, stone groundwood pulping, refiner mechanical pulping and thermomechanical pulping. So energy saving of thermomechanical pulping has become the most important problem to be solved. Observing the improvement of pulp strength by increasing the energy consumption, some researchers concluded that the good properties of TMP would be gained by giving excess of energy. In this paper the energy consumption of thermomechanical pulping and recent techniques in energy saving are reviewed and ways to approach the goal are mentioned from some standpoints including powder engineering.

Research and Development in Japanese Pulp and Paper Industry

Management, costing, funding and coordination of research and development activities in Japanese pulp and paper industry are reviewed. R and D in Japanese pulp and paper industry are characterized by two main concerns : shortage of raw materials and demand of high quality products. Considerable effort has been paid to modify available manufacturing processes and machinaries to accommodate the use of various fibre resources. Paper makers are also impelled to carry out R and D in order to satisfy strict requirements of quality, price and service by the Japanese market. Technical challenges of Japanese pulp and paper industry in the decade to come are numerous and hard to find a solution. Joint effort by the industry, academic circles and government will be the key to strengthen R and D in future.

Studies on Physical Properties of Dissolving Pulp

An investigation was made of some factors affecting the weight fractions of wood pulp separated with H.S. type fiber classifier.1) The residue on the sieve decreases rapidly as screening starts. The rate of decrease which is related with the ratio of mean fiber length of the sample to mesh size, falls off gradually in process of screening, but generally does not reach to zero.2) The considerable effect due to water pressure of the sprinkler and sample weight was found. Those operating conditions should be fixed, e.g. water pressure 1 kg/cm2, sample weight 5 g and sieving time 5 to 10 min. were suitable.3) The effect of pulp defibrating prior to the test was relatively so small, that slush pulp could be tested without disintegration.4) The approximate linear relations were found among a fraction and others which classified with the different meshes, therefore the measure of mean fiber length of the sample might given briefly with the result of one determination for the residue, when the classifier with a single sieve is applied.The schematic expression of this relationships was represented.

Determination of Sodium Xylene Sulphonate and Lignin Substances in the Hydrotropic Process with the Ultraviolet Absorption Method

The ultraviolet (U. V.) absortion of isomerics sodium xylene sulphonate (S. X. S.), lignin substances (hydrotropic, sodium lignin sulphonate of low and high degree of substitution etc.) and their mixtures in the aqueous solutions were measured.It was found that lignin structure-especially one represented by its molecular weight per phenolic OH had an effect on the extinction of lignin.Photometric determination method of S. X. S. in the hydrotropic and hydrotropic-SO2pulping waste or recovery liquor (mixture of lignin substances and S. X. S. in aqueous solutions) was found, applying the so-called “ duplication method ”.U. V. absorptions of an aqueous solution containingx% lignin substances andy% S. X. S. were measured with control ofz% S. X. S. aqueous solution. Here, extinction of solution was x+ (y+z) when x, y and z was extinction of x% lignin, y% S. X. S. and z% S. X. S. in the control respectively.In the range of y≥z, always x+ (y-z) ≥z. In y=z, absorption spectra of the solution might represent one of lignin substances. At spectra of lignin substances and S. X. S. in the range of wave length under 245 mμ, x<<y or x <<z were found. So, in the range y<z, the larger was the difference between z and y, the smaller became x + (y-z) to Therefore the spectra of the solution were curved downwards. Because the spectrum of lignin substances alone, in the range of wave length under 245 mμ had upward curves.In such a way, by measuring the spectra of hydrotropic and hydrotropic-SO2pulping waste or recovery liquor, varing the concentratration of S. X. S. in the control, they can determine the concentration of S. X. S. in the liquor.

STUDIES ON THE BURSTING STRENGTH TESTER

Three bursting strength testers were compared, one was a home-made, others were imports. In order to eliminate apparent differences of results, their correlativities were calculated. But the relationship between them were found to be variable by some unknown facters.The concentration of glycerin, pressure transference liquid, would be one of these factors which have caused the variation of data. The viscosity of glycerin is rapidly increased with its increased concentration. The time-lag may occur because of the high viscosity of the liquid and pressure of non-uniformity may work on the paper to be tested. Then the paper will be broken under its normal bursting strength.The experiments were made with varieties of the concentrations of glycerin and we found that within about 90% was the glycerin concentration, normal was the bursting strength and over that range, low strength was determined.These results will support our opinions.