Pressure sensitive recording materials

A pressure sensitive recording material utilizing a color forming reaction between a colorless or light-colored basic dye and a color acceptor, and in which (1) a basic dye-containing layer and color acceptor-containing layer are formed on one surface of different substrates respectively, (2) a basic dye-containing layer and color acceptor-containing layer are formed on one surface and the other surface of a same substrate respectively, (3) a basic dye-containing layer and color acceptor-containing layer are superposed on one surface of a substrate or (4) a layer containing both basic dye and color acceptor is formed on one surface of a substrate, the pressure sensitive recording material being characterized in that the basic dye is at least one diarylmethane compound represented by the formula (1) given below, the basic dye being enclosed in synthetic high polymer microcapsules having a mean particle size of 3 to 15 .mu.m and an average film thickness of 0.1 to 0.7 .mu.m, the color acceptor being an activated clay mineral containing 65 to 80 wt. % of silicon oxide SiO.sub. 2 ##STR12## wherein R.sub.1 to R.sub.4 are each C.sub.1 .about.C.sub.5 alkyl or benzyl, R.sub.5 is C.sub.1 .about.C.sub.5 alkyl, C.sub.1 .about.C.sub.5 alkoxyl or halogen atom, R.sub.6 is hydrogen atom, C.sub.1 .about.C.sub.5 alkyl, C.sub.1 .about.C.sub.5 akoxyl or halogen atom, A is a saturated or unsaturated 5- or 6-membered heterocyclic group of the formula (2), or a group of the formula (3), (4), (5) or (6) ##STR13## wherein R.sub.1 to R.sub.6 are same as above, and R.sub.7 is C.sub.1 .about.C.sub.12 alkylene or a group of the formula (7), R.sub.8 is phenyl;

• phenyl substituted with C.sub.1 .about.C.sub.4 alkyl, C.sub.1 .about.C.sub.4 alkoxyl, halogen atom or hydroxymethyl;
• C.sub.3 .about.C.sub.7 alkoxycarbonylalkyl, R.sub.9 is C.sub.1 .about.C.sub.20 alkyl;
• C.sub.2 .about.C.sub.20 alkoxyalkyl;
• benzyl;
• benzyl substituted with C.sub.1 .about.C.sub.4 alkyl, C.sub.1 .about.C.sub.4 alkoxyl or halogen atom ##STR14## wherein X.sub.1 .about.X.sub.8 are each hydrogen atom, C.sub.1 .about.C.sub.4 alkyl, C.sub.1 .about.C.sub.4 alkoxyl or halogen atom, Z is direct bond, --O--, --S--, --SO.sub.2 -- or C.sub.1 .about.C.sub.6 alkylene.