The effect on using PVA-converted starch and latex as pigmented coating adhesive when mixed in various ratios was studied. PVA with medium viscosity was used, and oxidized starch and hydroxyethylated starch (HES) were used for the converted starch.
The flow properties of the coating colors were modified considerably by using together PVA and converted starch. Particularly, the conveging capacity of the coating colors is improved markedly by using a PVA-converted starch blending ratio of 50 : 50 and almost no “orange peel” pattern or ridges on the coated surface was observed.
In case of coated paper, smoothness (both macro and micro), porosity and gloss which are superior to those when PVA and converted starch are used independently were obtained when a mixing ratio of 75 : 25 was used and the synergism of both was observed.
The author also made comparative studies on the surface properties and printability of this coated paper and 5 kinds of commercial coated papers.

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A new method for analyzing the coated clays of the clay-coated papers is reported. It was found that the coated clays were peeled off quantitatively by submerging the coated papers into the concentrated sulfuric acid during 1015 seconds. The peeled off clay was subjected to the X-ray diffraction analysis. The amount of the coated clay was obtained from the difference in ash content between the coated paper and the base paper. This method was applied to the analyris of the commercial coated papers and gave satisfactory reults.

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When a Japanese paper yarn is stretched and then cut, some fibers in the yarn are broken, and the rest slipped out.
If the breaking strength in the former case is to be expressed by ηP, and by (1-η) P_R in the latter, then the resultant breaking strength of yarn P is
P=P₀/1+6R₀ cot² β₀/t{1-1.43 cot² β₀ω₀/R₀ sin β₀(1+6R₀ cot² β₀/t)}(1)
P_R=P₀{(1+μl' cot² β₀/R₀)+0.25κtμl' cot² β₀/R₀ ω₀}
P=ηP+(1-η)P_R(3)
where, P₀ : Breaking strength of the cut materials.
P : Breaking strength of a yarn on the assumption that a yarn is cut due to breaking of all fibers.
P_R : Breaking strength of a yarn on the assumption that a yarn is cut due to slipping-out of all fibers.
β₀ : Pitch angle at the beginning of twist.
R₀ : Radius at the beginning of twist.
ω₀ : Width of the cut-materials.
t : Thickness of the cut-materials.
μ : Friction-coefficient.
l' : Average length of the fiber-element.
η : Ratio of broken fiber in %.
The significances of the above formula are tested and studied under various conditions.

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