Optical recording medium

An optical recording medium which is heat resistant at temperatures of at least 105.degree. C. comprising a substrate coated with a color developing layer, wherein the color developing layer comprises a dye precursor, a developer which reacts with the dye precursor to cause color development thereof upon heating, and a light absorber for converting light to heat, wherein the developer is at least one bisthiourea compound represented by the formula (4):

• ##STR10## wherein X, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are lower alkyl having 1 to 6 carbon atoms, alkoxy having 1 to 6 carbon atoms, cyclohexyl, nitro, cyano, halogen or hydrogen;
• and m is an integer form 1 to 3.

A heat resistant optical recording medium comprising a substrate having thereon a recording layer containing a dye precursor, a color developer reactable with said dye precursor to develop a color, and a light absorber for converting light to heat, wherein said color developer is at least one compound of the Formula (4);

• ##STR11## wherein X, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are lower alkyl having 1 to 6 carbon atoms, alkoxy having 1 to 6 carbon atoms, cyclohexyl, nitro, cyano, halogen or hydrogen;
• and m is an integer from 1 to 3, and wherein when a laser light is scanned over said optical recording medium, the optical recorded portion has a Macbeth optical density of greater than 0.7, and when said optical recording medium is pressed against a hot plate at 105.degree. C. with a pressure of 8 g/cm.sup.2 for 5 seconds, said optical recording medium other than the recorded portion has a Macbeth optical density of less than 0.2.