[in Japanese]

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This report shows my survey of the relation between wire support materials which are widely used nowadays and bronze wire wear by thee test device.
As test piecesne, I applied high density polyethylene, monomer casting nylon, polyurethane type synthetic rubber, phenolic plastic treated laminated materials, ceramics and etc. which are widely used for wire support equipments as wire suction boxes, foils, wet suction boxes and deflectors, and applied 13 Cr. steel and bronze which are commonly used for rotating wire support equipments as a couch roll etc. and for the purpose of comparison also applied metallic materials-phosphorus bronze, etc.-same material as machine direction wire.
Woods and natural rubbers are omitted as already numerous reports were published for these materials.
I also measured the coefficients of dynamic friction between bronze wire and wire support materials by dynamic friction measuring device and inspected the relation between such coefficients and wire wear.
The relations between wire support materials and wire wear are as per Fig. 8, 9 and dynamic friction is as shown in Fig. 10.
Non metallic materials, which are used for stationary wire support equipments, are to be investigated separately in case of wire suction box and of the equipments applied within the forming length. My test result shows that, for the former, polyurethane type synthetic rubber is superior and for the latter ceramics.
Between 13 Cr. steel and bronze, which are used for rotating wire rupport equipments (couch rolls), no distinctive difference was detected.
For the synthesis of all above test results, I could not find any clear relation between the coefficient of dynamic friction, hardness and wire wear, and I confirmed these problems by method of the dimensional analysis.
These test results are made under the comparatively simplified experimental conditions. Therefore, in case of actual operations of paper machine, in which wire runs under the complicated conditions, sprung up by the tangle of mechanical, thermal, chemical and many other factors, these results cannot necessarily be applied as they are. I assume that these results are to be referred in actual design and operation as a basic data for general trends of the relation between each wire support material and bronze wire wear.

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A study was made on the kraft pulping of domestic mixed hardwoods at low sulfidities ranging from 5 to 10% in search of the means to improve the odor problem of Kraft mills.
Compared with the normal kraft pulping at 25% sulfidity, a dramatic reduction of the amount of malodorants in the exhaust gas from the digester was observed at the low sulfidity pulping, methyl mercaptan concentration at 10% sulfidity and 5% sulfidity being one-fifth and one-tenth of that at 25% sulfidity respectively. The pulping rate, the yield of pulp, the amount of screening residues, and K-value and pentosan content of the unbleached pulp in the low sulfidity pulping were not substantially different from those in the usual pulping, while the pulp viscosity was found to be slightly lower in the former case. It was also noticed that the low sulfidity pulping could produce pulps of sufficient bleachability. Although the mechanical properties of papers, prepared on a laboratory test machine according to the condition specified for a writing and printing-grade paper, showed a slight tendency to deteriorate with lowering of sulfidity, it was judged that they were still practically good enough for most applications even when the pulping was carried out at 5% sulfidity.
It was concluded from the results abovementioned that to carry out the pulping of hardwoods in the low sulfidity range of 5 to 10% could provide an effective way to alleviate the odor problem of kraft mills. For softwoods such as red pine, larch, etc., however, the kraft pulping in this low sulfidity range did not prove to be suitable because of difficulty of delignification during pulping and the subsequent poor bleachability of pulp, even though more detailed studies might be needed before coming to a conclusion.

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Dissolving pulp from mangrove wood contains a large quantity of EDTA ash due to their existence in the form of Ca-oxalate crystals in the parenchyma cells. We have verified the effectiveness of HCl treatment for eliminating EDTA ash. Ordinarily, HCl treatment is employed for elimanating EDTA ash at the final stage. But another method is to use HCl treatment at the stage of chlorination. With the last method, HCl produced by chlorination of lignin contributes also to the elimination of EDTA ash in the pulp. In spite of the anxiety of occurence of oxidation and degradation of cellulose by HCl teatment at the chlorination process, decrease of α-cellulose content was litte and no drop of relative viscosity of cupri-ammonium solution was found. It was confirmed by optical microscopic observation that decrease of EDTA ash by HCl treatment was caused by dissolving Ca-oxalate crystals. Satisfactory results were obtained by steeping the pulp in an aqueous 0.1 N HCl solution for 30 minutes. The pulp prepared by the simultaneous treatment of HCl and Chlorine was found to have better reactivity according to the filterability test of viscose than that treated with HCl only at the final stage. Especially the pulp from which parenchyma cells were thoroughly removed in the screening process showed the best reactivity. This fact is clarified by the fact that the fraction rich in fibers of mangrove pulp has better reactivity than the fraction rich in parenchyma cells. Owing to the difficalties in thorough elimination of parenchyma cells in the screening process of productional scale, the HCl treatment of mangrove pulp is efficient from the viewpoints of the subsidiary elimination of EDTA ash and improvement of reactivity.

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