[in Japanese]

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J. TAPPI has been conducting the technology exchange between Japan and Canada since 1976.
This year.J. TAPPI has planned the Environment Improvement Conference jointly with CPPA, T. S.
The conference was held in Victoria, B. C. Canada, attended by 150 people including Japanese 15 delegations.
The conference was successful with 19 technical presentations including 7 Japanese ones.
After the conference, J. TAPPI group visited some research institutes and paper mills.
Here the conference and mill visit tour have been reported.

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Hokuetsu Paper Mills, Ltd. was estlabished in 1907. It has four paper making factories, that is, Niigata Paper Mill, Nagaoka Paper Mill, Ichikawa Paper Mill, and Katsuta Paper Mill. The first two are in Niigata Prefecture, the third is in Chiba Pref. and the last is in Ibaraki Pref.
Niigata Paper Mill, which we are going to introduce now, is the most important main plant of these four. It was established in 1915, in Niigata City. It is equipped with the most modernized facilities, which are enough to make raw materials and to convert them into paper.
The area of this factory is 432, 837 square meters. About six hundred people are working for it. The producing capacity of pulp and paper are as follows.
Pulp B K P 670 t
B G P 60t
Paper Wood free paper and mechanical paper 430.4 t
Ivory and Card board 74 t
As it was installed in town, we have taken measures not to disturb the happy life of the people living around there. As for Anti-pollution problems, we have invested a great amount of capital into various control systems for waste water treatment anti-air pollution, dust control, odor removal and noise abatement.

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Theoretical expressions have been derived for the two methods of the reflectance measurement using the integrating sphere. The one method, in which both a sample sheet and a standard white board are set simultaneously on two different windows of the sphere and illuminated alternatively, gives a correct reflectance value of the sample relative to the standard. The other method, in which a sample sheet and a standard white board are set alternatively to a common window of the sphere, is accompanied with an inherent systematic error.
The amount of error measured by using the better method, increases with the increase of the inner wall reflectance of the sphere and depends also on the reflectances of the sample and the standard.
The maximum error between two methods, attains to 3.8% for 50% reflectance sample in 97 % reflectance sphere.
The results were confirmed by experiments and the spectral reflectance of the inner wall of the sphere was also determined experimentally.

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The influence of gamma-irradiation on the beating properties of unbleached kraft pulps was studied, and the changes of the mechanical and chemical properties of the sheet made from those pulps were also investigated. The results obtained were as follows :
(1) When the unbeaten pulp was treated with gamm-ray, the degree of polymerization of cellulose was decreased rapidly and the formation of aldehyde and carboxyl groups in pulp was observed in addition to that the beating time of irradiated pulps was reduced comparing with non-irradiated pulp. These effects increased roughly in proportion to the radiation dose.
(2) Gamma-irradiation was more effective in wet state (moisture content=7085%) than air dry state. This may be due to the degradation products of water by gamm-irradiation.
(3) The mechanical properties (breaking length, tear and burst factors) of the sheets made from irradiated pulps were considerably deteriorated at 10⁷R, but there was a slight deterioration up to 10⁶ R.
(4) Comparing the result of the mechanical properties, the strengths of the various sheets were shown in the follwing order : the sheet irradiated after paper making > the sheet irradiated before beating (air dry state) > the sheet irradiated before beating (wet state).

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Alkali-dioxane pulps prepared from oak wood were bleached in two stages with ozone and hydrogen peroxide, and the influence of bleaching conditions on pulp properties was studied. The results are summarized as follows.
1) The pulps showed reasonable properties after ozone bleaching under the conditions of 50 % of pulp consistency and pH 2. The sheet strengths of ozone bleached pulp decreased rapidly over 3% ozone consumption.
2) The optimum brightness and viscosity were obtained after peroxide bleaching under following conditions : hydrogen peroxide 2%, pulp consistency 20%, temperature 70°C, time 2 hr, pH 11.
3) In comparison with CEDED bleached kraft pulp, alkali-dioxane pulp bleached with ozone and hydrogen peroxide had better brightness stability and beatability, while its sheet strengths were somewhat inferior.

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