Daicel Chemical Industries, Ltd.

Akihiro Izuka

Mitsuru Yamashita

Yoshio Onizawa

Tatsuya Kanno

Ikuo Takahashi

Kenichi Sasaki

Takaaki Fujiwa

Kiyotaka Inokami

Kiyoharu Mizumoto

Ken-ichi Kawai

Tsunehisa Katsuki

A recording sheet is provided by forming, on at least one side of a substrate sheet, an ink absorbing layer comprising a cationic polymer having at least crosslinking groups. The ink absorbing layer may comprise (1) a cationic polymer containing a crosslinking monomer (e.g. a monomer having a hydrolyzable condensing group such as alkoxysilyl) as a comonomer unit, (2) a cationic polymer containing a crosslinking monomer and a hydrophilic monomer (e.g. a monomer having a polyoxyalkylene unit) as comonomer units, or (3) the above cationic polymers (1) and (2), and a hydrophilic polymer. The cationic polymer and the hydrophilic polymer may have interacting reactive groups. This recording sheet is useful for the improvement of the water resistance and ink absorption in an ink jet recording sheet.

Recording sheet with an ink absorbing layer

A new aromatic polycarbonate is obtained from (1) 2,2-bis(4-hydroxy-3-isopropylphenyl)propane, (2) 2,2-bis(4-hydroxyphenyl)propane and 2,2-bis(4-hydroxy-3-isopropylphenyl) propane or (3) 4,4'-dihydroxy-2,2,2-triphenylethane and 2,2-bis(4-hydroxy-3-isopropylphenyl)propane through a carbonate linkage and is useful as a starting material for an optical disk.

Polycarbonate and optical disk therefrom

A recording medium for optical high-density data storage and retrievel, comprising a flat transparent plastic substrate characterized by the following relationship between the refractive index (n.sub.z) in the direction perpendicular to the flat surfaces of the transparent substrate, and the refractive indexes (n.sub.x) and (n.sub.y) in the direction parallel to the flat surfaces of the transparent substrate:

Process for producing plastic substrate for optical disks

A recording medium for optical high-density data storage and retrieval, comprising a flat transparent plastic substrate characterized by the following relationship between the refractive index (n.sub.z) in the direction perpendicular to the flat surfaces of the transparent substrate, and the refractive indexes (n.sub.x) and (n.sub.y) in the direction parallel to the flat surfaces of the transparent substrate:

Plastic substrate for optical disk and process for producing the same

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Himeji, Japan

Akihiro Izuka