Toyo Boseki Kabushiki Kaisha

Go Matsuoka

Fuyuhiko Kubota

Takaharu Ichiryu

Hiroki Murase

Tadao Kuroki

Yukihiro Nomura

Yukinari Okuyama

Hiroshi Tachimori

Kohei Kiriyama

Yukihiro Abe

Muneatsu Nakamura

Hironori Eguchi

The present invention relates to polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics containing in themselves an organic pigment having heat resistance as high as a thermal decomposition temperature of 200&#xb0; C. or higher, and soluble in a mineral acid and having group(s) of &#x2014;N&#x2550; and/or NH&#x2014; in the molecule, such as any of perinones and/or perylenes, any of phthalocyanines, any of quinacridones, and any of dioxazines, wherein they have a strength retention of 50% or higher when exposed to light from a xenon lamp for 100 hours and having a tensile strength retention of 85% or higher after exposed to an atmosphere of a temperature of 80&#xb0; C. and a relative humidity of 80% for 700 hours. The polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics can be used for cords for reinforcing rubber, sheets and rods for reinforcing cement/concrete, composite materials, sail clothes, ropes, knife proof vests and bullet proof vests.

Polybenzazole fiber and use thereof

Polybenzazole and fiber thereof

A method for stabilizing DAR during storage, comprising storing DAR in the presence of a reducing agent having a standard redox potential of not less than -0.20 volt and not more than 0.34 volt, in a proportion of not less than 100 ppm and not more than 10,000 ppm of DAR. The present invention improves storage stability of DAR. This in turn results in easy handling and long-term preservation of DAR. Thus, a high quality polymer PBO can be easily produced and the invention greatly contributes to the industrial field.

Method of stabilizing 4,6-diaminoresorcinol and salt thereof

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Otsu, Japan

Go Matsuoka