Masao Takahashi

Recent Advances in High Solids Coatings

Abstract The following three items are general market needs in coatings and paints: 1. Air pollution control 2. Energy, materials, and labor saving 3. Higher levels of performance Developments of new techniques and materials are expected to meet these market needs.

Solvent Action of Mixed Solvent Containing Dimethyl Sulfoxide as a Constituent on Acrylonitrile Polymer

ジメチルスルポキサイド (DMSO) と種々の混合成分とよりなる混合溶媒を検討し, 次のような一般的傾向を認めた. すなわちDMSOはすぐれた良溶媒であるために, 混合成分はその溶解状態を変化させ, あるいは希釈剤としての役割を果すなどの効果をもたらすが, 溶解性を向上させるような効果はもたらしえない。したがって単独で溶解力のある成分との混合系の溶解温度は, 両成分の溶解温度の中間の値を示し, 単独で溶解力のない成分との混合系では, 混合成分の性質に応じた溶解限界組成が存在する。混合溶媒を用いた濃厚溶液の粘度は, DMSO単独の場合よりも低粘度を示す場合が多く, このような系では粘度安定性が低下し, 非ニュートン性も小さくなっている。さらに溶解力が小さくなれば粘度上昇, 非ニュートン性の増大などがみられる。

STUDIES ON ACRYLIC FIBER

The wet spinning of dimethyl formamide solution of acrylonitrile copolymer into the glycerine bath was investigated. The results obtained on the effect of bath temperature are as follows.(1) The spinnability that is, maximum spinning velocity, increases with increasing bath temperature and increases with decreasing output and the viscosity of polymer solution.(2) Decrease of maximum draw ratio of undrawn filaments with increasing bath temperature is not particularly large.(3) The effect of bath temperature upon dry tensile strengths of drawn filaments varies with the draw ratio of these filaments. When the draw ratios of the filaments are small, the above mentioned effect is not distinct. On the other hand, when the draw ratio of the filament becomes larger, the lower the bath temperature, the larger the dry tensile strength. As to the dry tensile elongation, this effect is also not distinct.(4) As to the dry knot strength and elongation, the effect of the draw ratio is larger than that of the bath temperature.(5) The initial moduli and the toughnesses calculated from stress-strain curves of drawn filaments become larger with decreasing bath temperature, The similar results may be obtained for the elastic recovery characteristics.(6) At lower bath temperatures, the textures of filaments obtained by wet spinning become compact or dense as the desolvation or the diffusion of the solvent is comparatively slow. On the contrary, at elevated bath temperature, owing to the higher speed of desolvation, the contrast between skin and core become clearer, and it may be seen that there are many microscopic holes in the core zone.These differences in the texture of the filaments coinside with those results obtained from the specific gravities and ratios of the cross sections.

STUDIES ON THE MANUFACTURE OF POLYETHYLENE FIBER

The melt spinnings by the so-called candle melt spinning apparatus of several low pressure polyethylenes, _??_n of which range from 4×104 to 15×104, were carried out at about 250°C, and temperatures higher at than 300°C. The hot drawing of undrawn filaments was carried out at 80°C and 95°C in the hot water bath.Mechanical properties, crystallinity of undrawn filaments are as follows. The characteristic values of the small deformation of filaments such as stress at yield point are scarecely dependent on the _??_n of the sample, while those of the large deformation of filaments such as constant stress range, tensile strength and elongation are largely dependent on the _??_n of the sample. The stressstrain curves of filaments having, larger _??_n obtained by the spinning at higher temperature than 300°C resemble to those of the filaments having smaller _??_n and spun at lower temperature. The densities of filament range from 0.928 to 0.944, varying with _??_n and drawing conditions and are largely effected by quenching at the spinning process.The maximum draw ratio at hot drawing is larger with smaller _??_n and the better results are obtained by drawing at 95°C than 80°C.Some properties of drawn filaments are as follows. The tensile strength and the initial elasticity increases and the elongation decreases with increas draw ratio. The tensile strength at 30% elongation obtained by the interpolations are remarkably affected by _??_n and generally higher than 4g/d, and as a rule at smaller elongation the tensile strength exceeds over 5_??_6g/d. The effect of _??_n on the initial elasticity is not large. Several percent increase of tensile strength and decrease of elongation are obtained by the heat treatment. The densities of drawn filaments increase by drawing and heat treatment.

STUDIES ON POLYVINYL CHLORIDE FIBRES

We generalized master creep curves at several temperatures bashing upon the simple assumption for the temperature dependence of retarded elastic deformation of master creep curves and obtained a distribution function of retardation times.Temperature dependence of some characteristic values for the generalization of master creep curves is also discussed.