Ricoh Company, Ltd.

Aimi Suzuki

Shigeru Kusakata

Yasuyuki Hosogi

Isao Shiojima

Shigeaki Kimura

Toshiaki Azuma

A thermosensitive recording paper comprising a support sheet and a thermosensitive coloring layer formed thereon, which support sheet comprises needle-leaf tree pulp in an amount ratio of 10 to 50 wt. % of the absolute dry weight of the support sheet, with the maximum length of the fibers in the needle-leaf tree pulp being 4 mm or less.

Thermosensitive recording paper

A cyanine dye having formula (I): ##STR1## wherein R.sup.1 represents Cl, Br or hydrogen; R.sup.2 represents Cl, Br, hydrogen, or a nitro group; R.sup.3 and R.sup.4 each represent a methyl group, an ethyl group, a propyl group or --(CH.sub.2).sub.n OR.sup.5 (in which n is an integer of 2 or 3, and R.sup.5 represents hydrogen or an acetyl group), and X.sup..crclbar. represents an acid anion, provided that the case where R.sup.3 and R.sup.4 are both an identical alkyl group, and R.sup.1 and R.sup.2 are an identical group, is excluded; and

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Numazu, Japan

Aimi Suzuki