Patent ID: 7071145

Claim:
A thermosensitive recording material comprising an under layer comprising hollow particles and a thermosensitive layer provided on a substrate in this order, wherein the thermosensitive layer comprises a leuco dye and a color developer, the color developer is an oligomer composition obtained from the reaction of a polyvalent isocyanate compound represented by following Formula (I) with an aromatic amine represented by following Formula (II); in which X represents a tri- or more-valent group, a represents an integer numeral of 3 or more, b and c represent respectively integer numerals in the range of 0 to 5 and they satisfy a relation of b+c=1 to 5, Z represents hydrogen atom, alkyl group, allyl group or aryl group, and the aryl group may include condensed ring structure thereof, and d represents an integer numeral in the range of 0 to 4.