preferably be used in an amount of from 10 to 400 by weight on the basis of the color developer more preferably from 50 to 250 according to the present invention the dispersion of the color former the color developer and heat fusible compound or the like is carried out using a water soluble binder a binder suitable for the present invention may preferably have a solubility of 5 by weight or more in water at 25 u00b0 c illustrative examples of such water soluble binders include a polyvinyl alcohol a methyl cellulose a carboxymethyl cellulose starch materials including a modified starch gelatin gum arabic casein a saponified product of a styrene maleic anhydride copolymer and the like these water soluble binders may be used not only at the time of the dispersion step but also for the purpose of improving film strength of a thermosensitive recording layer for this purpose the water soluble binder may be used jointly with a synthetic polymer latex binder such as a styrene butadiene copolymer a vinyl acetate copolymer an acrylonitrilebutadiene copolymer a methylacrylate butadiene copolymer a polyvinylidene chloride or the like the foregoing color former color developer heat fusible compound and the like are made into a coating solution by dispersing them separately or simultaneously using a mixer or a grinder such as a ball mill an attritor a sand mill or the like if desired the coating solution may be further mixed with other additives such as a pigment a metallic soap a wax article a surfactant an antistatic.