A variety of chemical treatments were employed in the production of high yield pulps from softwood (spruce) and hardwoods (birch, oak) by thermo -mechanical pulping. The effects of these chemical treatments on the physical, chemical and morphological properties of pulps were investigated.
Of the pretreatment chemicals investigated, neutral and bisulfite appeared to offer the greater potential for strength development of high yield pulps than that of alkaline and acid sulfite. Motphological studies on the fibers and fines show that the fiber surface of the pulps from neutral and bisulfite pretreated chips were smooth and the fines fractions of them after defibration consisted of compound middle lamella fragments and undamageed ray cells. On other hand, pretreatments with alkaline and acid sulfite yielded damaged fibers and fines fraction of them contained the fragments generated from secondary wall as well as from middle lamella and ray cells. These results show that the fiber separation of the chips pretreated with neutral and bisulfite occurred mostly in the middle lamella, while the fiber separation of chips pretreated with alkaline and acid sulfite occurred between middle lamella and secondary wall. These behavior are supported by the results of determination of lignin contents in the cell wall by the method of UV microscopy. The results showed that topochemical preference for the removal of lignin from the secondary wall was found in the case of acid sulfite pretreatment, while bisulfite pretreatment not showed the topochemical effect on the lignin removal.
Significant improvements in physical properties of pulps were obtained by chemical pretreatments of hardwood chips. However, the qualities of the pulps from pretreated hardwood chips were inferior to that of the pulps from pretreated softwood chips. Therefor, ozone treatment was used after defibration to obtain higher quality pulps from hardwood. The effects of ozone on the beatability and physical properties of the pulps were remarkable with only a little reduction of pulp yield. Treatment with ozone for 5 min resulted in 50-70% decrease in the beating energy. In breaking length, 90-100% increase were obtained after 30 min ozone treatment. Lignin contents of the pulps were decreased with the progress of the reaction with ozone. The mode of dissolution of lignin from cell walls of the pulps by the ozone treatment was also followed by means of UV microscope spectrometry. In the ozonization process, lignin was dissolved stepwise from the outermost layer of the cell walls, and lengthening of the reaction time led to an increase in the area of the lignin-free region in the cell walls of fibers. UV spectra in limited areas in the cell wall showed that small amount of aliphatic conjugate structure were remained in the areas where no absorption at 280nm was observed under the UV microscope. Residual lignin in the area where distinct absorption was observed under the UV microscope was subjected to chemical change during ozone treatment.

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The system and equipment for treating old corrugated waste are continued to be improved from the viewpoint of energy-saving and efficient removing of impurities, resulting in getting clean stock.
Sulzer Escher Wyss, West Germany has been offering unique technology not only in paper -making, but also in waste paper-treating.
In this paper, the tasks which should be overcome in domestic systems are summerized and the modern system and equipment from Sulzer Escher Wyss to solve these are introduced.
One of the equipment, Rejectsorter has already been accepted with the customer's satisfaction. Almost thirty (30) Rejectsorters are operated in the domestic market.

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The printing world was dull especially in the field of the commercial printing, due to small demand in the depression that was caused by the high power of “YEN”, but it is becoming active as the economy in Japan grows up by promotion for inner demand.
In the commercial printing field, we print matters in high quality, for instance catalogues, pamphlets, posters, handbills, and so on.
Customers claims strictly for high qualitly, so about 90% of the papers we use is occupied by coated paper, including low-low weight coated paper.
It is general that we select papers considering some factors that is the result of finished products, costs etc. Those papers are various in the grade and the basis weight.
Recent trends are the tendency of the increasing of low-grade, low-basis weight, and the tendency of multi-colors and high speed for printing which is expected to last from now on.
Therefore they are important subjects that we maintain and improve the printability for papers, as well as that we improve inks and printing machines.

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The paper introduces a new continuous retention monitoritoring system capable to measure the first-pass retention of fibers or total solids and filler separately. The system consists of optical sensors installed in the headbox and white water lines and a central unit where the calculations are carried out. Both filler and total consistencies in each line as well as the corresponding first-pass retention values are available for further processing.

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Numerical simulation of history-dependent curl has been made on the basis of the viscoelastic laminate model [5]. Curl behavior of paper under varying humidity conditions depends not only on the present value of moisture content but also on the moisture history that paper has experienced in the past, such as typically seen in Figs. 1 to 3. In order to predict such complex curl behavior, a computer simulation model was developed by using the classical lamination theory and the general linear theory of viscoelasticity which was proposed by Coleman [4]. Drying stress effects were incorporated by assuming presence of stresses in the reference state, which was taken in the final drying stage [5].
Simulation results for curvature response to repeated humidity cycling showed that the paper curl can be separated into two components, i. e., reversible and irreversible componets. The reversible component is essentially determined by difference in hygroexpansion coefficients between top and bottom sides of the sheet, whereas the irreversible curl is governed mainly by mechanical causes, i. e., asymmetric distribution of drying stresses and two-sidedness in relaxation moduli. When the top and bottom sides of the sheet are subjected to different moisture histories and returned to the original uniform moisture distribution, such as often seen in printing and xerography processes, paper shows residual curl after the process in the absence of non-uniformity in paper properties in the thickness direction. This phenomenon is caused by viscoelastic relaxation of hygro-stress gradient which is produced during the process. In this case it is, therefore, important to control the “average” values of hygroexpansion coefficients and relaxation moduli through the thickness, as well as the two-sidedness of these properties.
Since paper curl is a complex manifestation of different effects of non-uniformity, a measure for curl control varies with practical situations. The computer simulation model developed in this study provides a rational design tool for various paper products by clarifying each contribution of the different curl mechanisms.

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It is useful to have some practical formulas describing a particular strength property of paper as a function of a few easily measurable fundamental sheet and fiber properties. Such formulas will be helpful for designing paper and predicting strength properties of paper before it is made.
In this study, the author tried to determine statistically optimal formulas for tensile breaking length, MIT double folds, burst index and tear index of handsheets based on the extended Clark type formula.
First, eighteen kinds of abaca handsheets were prepared with varying fiber length, beating degree, fiber strength and wet pressing pressure. Multiple regression analysis and Akaike Information Criterion (AIC) were applied to a linear function given by taking logarithm of the extended Clark type formula so as to construct the optimal extended Clark formula for each strength property of abaca as a function of weighted average fiber length, bulk, zero-span breaking length and Z-directional tensile strength. Correlation coefficient of over 0.97 between observed and calculated values was found for each strength property.
Secondarily, modifications of the formulas for abaca by introduction of fiber coarseness as an additional fundamental property were carried out so that the formulas would be applicable to handsheets made of other fibers than abaca fiber. As the result, the generalized formulas for breaking length and burst index were obtained, both of which showed correlation coefficients of over 0.94 between observed and calculated values.
The formulas for abaca and the generalized formulas are expected to be used as the Paper Design Functions.

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