As paper machine speed increases, that of the super calenders is also getting higher. Internal heat generation of the elastic rolls accordingly increases and that causes bad effect to the final sheet quality by roll vibration swelling, many burning accidents of elastic covers and difficulty of roll maintenance, all of which cannot be ever overlooked. This report calculated the internal heat generation theoretically, and calculated the internal beat generation of actually operated super calender of 3, 400mm roll face length and 500m/min operating speed by theoretical formula.
Secondly this report measured the total driving power consumption and compared the both figures. The result was that the former (65kW) occupies one fourth of the latter (250kW) and that this amount cannot be neglected.
On the contrary the total driving power consumption of the 4 or 8 roll machine calender of 3, 400mm face length and 500m/min operating speed is only about 50kW, as shown in Fig. 5. This fact also shows that the former mentioned internal heat generation reaches upto relatively large amount.
So far the designing of the elastic rolls employed the conceptional try and error method from the experiences, however above results shows that the elastic rolls of super calender shall furnish following features and the investigation of the elastic roll shall be directed to the same direction hereafter.
(1) The elastic rolls shall have same character in every direction to keep the heat swelling evenly.
(2) The cover material shall have the big heat conductivity to discharge generated internal heat immediately.
(3) The cover material shall have heat proofness to prevent from burning down.
(4) The crown of the elastic rolls shall be kept adequately.

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Peracetic acid (PA) is an effective bleaching agent for bleaching chemical pulps to a high degree of brightness. A study was carried out on the effect of stabilizer during PA bleaching of Kraft pulp (KP) in vapor-phase under mild condition.
Chelating agents such as Daiseru stabilizer, 1, 2-cyclohexane DTA, chelespar 7 G and dipicolinic acid among stabilizers employed depressed effectively the auto-degradation of PA under bleaching conditions. According to the main experimental results, PA vapor-phase bleaching of KP in the presence of above stabilizers was necessary to carried out in an air-tight apparatus under following conditions ; pulp consistency 33%, PA addition 22%, stabilizer addition-Daiseru stabilizer 0.018%, chelespar 7 G 0.47%, dipicolinic acid 0.18%, pH 4, 0, temperature 90°C time, NUKP 1 hr and LUKP 15 min.
The brightness of BKP such obtained was about 90%. The yield of BKP was nearly quantitative. The amount of PA used could be decreased about 4 o per pulp by adding the small amount of stabilizer into PA solution, which was prepared by Greenspan's method, The properties of BKP were greatly unaffected by using stabilizer, as indicated for viscosity, K value and pentosan content. Tear factor and Folding end. of BKP decreased considerably by bleaching with PA in the presence of dipicolinic acid. But, the influence on the mechanical properties of the pulp by the other chelating stabilizers was little.
One of the most important variables for the brightness of BKP.was an effective bleaching with hydrogen peroxide present in PA solution during vapor-phase bleaching. This fact revealed that KP prepared with hydrogen peroxide-containing PA solution give higher brightness than the pulp bleached with PA solution in the absence of hydrogen peroxide under same conditions.

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The present paper deals with the brightness stabilization of bleached kraf t pulp with metalic salts and organic acids. Four kinds of metalic sulfates stabilized the brightness of bleached pulp under restricted range of dosage. They are MnSO₄, CdSO₄, ZnSO₄, and MgSO₄. Among them, MgSO₄ stabilized the brightness most effectively. Monobasic organic acids; formic, acetic, and propionic acids, stabilized surprisingly the brightness of bleached pulp, and the effective range of dosage was rather wide than that o metallic sulfates.
The model color reaction for the brightness reversion of bleached pulps was proposed for the screening of stabilizer; the coloration of 2 % aldose solution heated at 95 for 90 min. in 2 N-HCl. The above mentioned stabilizers were proved to inhibit this coloration.

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