USE OF VINYL PHENOL OLIGOMER OR POLYMER AS COLOUR DEVELOPER FOR LEUCO PIGMENT AND COLOUR DEVELOPER COMPOSITION AND THERMOSENSITIVE RECORDING ELEMENT COMPRISING SAME

摘要

Disclosed is a color developer for a leuco pigment, which comprises an oligomer or polymer of a vinyl phenol. When this color developer is used for developing the color of a leuco pigment, a color having a high density is developed even if the leuco pigment concentration is low.