Thermosensitive recording sheet

A thermosensitive recording sheet comprising:

• a support;
• a primer layer formed on said support, said primer layer consisting essentially of 2 to 30 g/m.sup.2 of a first filler in the form of particles having an average particle size not greater than 5 .mu.m, and 10 to 50 wt. % of a first binder;
• a thermosensitive coloring layer formed on said primer layer, said thermosensitive coloring layer consisting essentially of:
• an effective amount of a leuco dye, an acidic material capable of developing color in said leuco dye when heat is applied to said thermosensitive coloring layer, the amount of said acidic material being 2 to 6 times the amount of said leuco dye, 3 to 10 wt. % of a second binder, a first thermofusible material in an amount of from zero up to an amount effective to bring the melting point of said leuco dye and said acidic material present as a mixture thereof in said thermosensitive coloring layer to a selected value in the range of 70.degree. C. to 120.degree. C., and a second filler in an amount of from zero to 3 times by weight of the amount of said leuco dye;
• and
• a protective layer formed on said thermosensitive coloring layer in an amount of from 1-6 g/m.sup.2, said protective layer consisting essentially of 30 to 90 wt. % of a water-soluble polymeric third binder, 0 to 20 wt. % of a second thermosfusible material, said second thermofusible material having the same properties as said first thermofusible material, and the balance is essentially a third filler.