An object of the present invention is to provide a heat sensitive recording material which can develop color at high density by the inclusion of a novel guanidine compound which is strongly basic and superior in diffusion resistance. The present invention for attaining the above-described object is a heat sensitive recording material comprising a substrate supporting thereon a heat sensitive recording layer containing a diazonium salt compound, a coupler which reacts with the diazonium salt compound when heated to develop color, and a base, wherein the heat sensitive recording layer includes as the base at least one of the guanidine compounds represented by the general formula (1):
1
, wherein, in the general formula (1), R
1
and R
2
represent an alkyl group or aryl group and may be the same or different, R
3
and R
4
represent a hydrogen atom, alkyl group or halogen atom and may be the same or different, and X represents a divalent connecting group.
本发明的目的是提供一种热敏记录材料,通过加入一种新型
胍化合物,该化合物具有强碱性和优越的抗扩散性,可在高密度下显色。为达到上述目的,本发明是一种热敏记录材料,它包括一个基片,基片上支撑着一个含有重氮盐化合物的热敏记录层,一个在加热时与重氮盐化合物反应而显色的耦合剂,以及一个碱基,其中热敏记录层包括至少一种由通式(1)表示的
胍类化合物作为碱基:
1
其中,在通式(1)中,R
1
和 R
2
代表烷基或芳基,可以相同或不同,R
3
和 R
4
代表氢原子、烷基或卤素原子,可以相同或不同,X 代表二价连接基团。