[in Japanese]

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In the previous paper it was shown by X-ray diffraction diagram method that the clays coated on papers orientated.
In this paper, in order to estimate quantitatively the degrees of orientation of clays, three methods are investigated by means of X-ray diffractometer. The three methods are as follows :
(i) rotation of the clay-coated surface,
(ii) rotation of the clay-coated surface which are overlapped and are put in parallel with the direction of X-ray, and
(iii) comparison between the relative intensities.
[In this work the (00l) clay-crystal plane are used.] Clay-contained films, handcoated papers (non-supercalendered and supercalendered) and commercial coated papers are examined.
The results obtained are as follows :
(1) when the plate-like clays are used, the majority of orientation takes place on coating and the effect of supercalendering on the degree of orientation is comparatively slight,
(2) the nonplate-like clays have no tendency to orientate either on coating or supercalendering, and
(3) the three methods have merits and demerits respectively. They should be used suitably case by case.

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Influence of the drying condition, such as moisture content in sheet before drying, temperature and drying method, on the strength of paper containing readily soluble vinylon was examined.
In order to cause the readily soluble fibers to exert effect as binder, it was necessary to dry wet sheets containing sufficient moisture at a higher temperature than the dissolving temperature of the fibers. Further, pressure during drying was also very effective.
It was observed that when paper containing the readily soluble fibers was dried once, then was rewetted and was dried again, the strength, such as tensile, burst and folding, of the paper was further improved.

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500gr of unbleached kraft pulp from Pinus densiflola (Permanganate. number 33.3) was suspended in a 15l of 0.5N NaOH solution and beaten in a nitrogen atmosphere for up to 30 hours.
About 20gr of residual thiolignin (RTL) consisting of thiolignin, carbohydrate and another component was obtained.
The RTL thus obtained was divided into alcohol soluble fraction (RTL-I) and insoluble fraction (RTL-II) and analyzed (Table II).
1) The distribution of the thiolignin and carbohydrate on the paper strip was shown in Fig. 2, when RTL-II was brought into paper electrophoresis. As is seen from the figure, carbohydrate and lignin migrate quite porallel (the method of estimation of both components is same as reported in No. IV of this series) and the section containning the maximum amount of thiolignin contains also the maximum amount of carbohydrate.
2) The components of RTL-II' obtained from RTL-II with zone electropholesis was nearly same as that of RTL-II (Table III). Hence, it may safely be concluded that thiolignin and carbohydrate in the RTL obtained from unbleached kraft pulp are combined chemically.
3) In both Table II and Table III, the total amount of thiolignin and carbohydrate does not reach 100%. It may therefore be supposed that RTL contains some amount of unknown components.
4) When slightly sulfonated thiolignin was treated with chlorine water, 0.7/CH₃O of carbonyl group was formed (Fig. 3) and the decrease of optical density of UV-absorption at 280mμ was nearly same as in the case of lignosulfonic acid.
5) As shown in Fig. 5, when thiolignin was treated with sodium hypochlorite solution, the amount of sodium hypochlorite consumed after three hours was 4 NaClO/CH₃O and 0.4/CH₃O of carbonyl group was formed.
6) Curve I, Fig. 7 shows the decrease of optical density of ultraviolet absorption spectra at 285 mμ of both thiolignin and the slightly sulfonated thiolignin reduced with NaBH₄ after chlorination of various degrees.
The tendency of decrease was same as in the case of lignosulfonic acid or vanillyl sulfonic acid.
When thiolignin was treated with sodium hypochlorite solution, the optical density, however, decreased remarkably.
In this connection, it may be concluded that the linkage between thiolignin and carbohydrate and /or degenerated carbohydrate is difficult to sprit by chlorination with chlorine water and is easily cleaved by treatment with NaClO.
It may be thought to be the reasons, why the treatment of kraft pulp with NaOCl solution is more effective than chlorination.

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