Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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:.vertline.n.sub.z -n.sub.x .vertline. smaller than 4.times.10.sup.-4 ; and.vertline.n.sub.z -n.sub.y .vertline. smaller than 4.times.10.sup.-4.The recording medium is produced by an injection molding process wherein the pressure on the molten resin filled into the molding cavity of a mold is decreased or increased, as appropritate, in order to maintain the desired differences between the refractive index n.sub.z in the direction perpendicular to the flat surfaces of the transparent substrate, and the refractives indexes (n.sub.x) and (n.sub.

Abstract: 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:.vertline.n.sub.z -n.sub.x .vertline. smaller than 4.times.10.sup.-4 ; and.vertline.n.sub.z -n.sub.y .vertline. smaller than 4.times.10.sup.-4.The recording medium is produced by an injection molding process wherein the pressure on the molten resin filled into the molding cavity of a mold is decreased or increased, as appropriate, in order to maintain the desired differences between the refractive index n.sub.z in the direction perpendicular to the flat surfaces of the transparent substrate, and the refractives indexes (n.sub.x) and (n.sub.