Color forming compositions with a fluoran leuco dye having a latent developer

A color forming composition or composite, comprising

• a) a polymer matrix;
• b) a thermally modifiable fluoran leuco dye comprising a latent developer attached thereto, and having the following structure:
• wherein R1, R2, R3, R4, and R5 are independently lower alkyl substituents or hydrogen;
• and
• c) a radiation absorber,
• wherein the thermally modifiable fluoran leuco dye is developable upon the color forming composition being contacted with electromagnetic radiation which causes the radiation absorber to become energized, wherein the energized radiation absorber causes the latent developer to undergo rearrangement to produce an intermediate dye form having a phenolic substituent, wherein the intermediate dye undergoes an acid catalyzed ring opening to produce a colored dye form.

A method of labeling a substrate, comprising:

• a) providing a substrate having a color forming composition coated thereon, said color forming composition, comprising:
• i) a polymer matrix;
• ii) a thermally modifiable fluoran leuco dye comprising a latent developer attached thereto, and having the following structure:
• wherein R1,R2, R3, R4, and R5 are independently lower alkyl substituents or hydrogen;
• and
• iii) a radiation absorber,
• wherein the thermally modifiable fluoran leuco dye is developable upon the color forming composition being contacted with electromagnetic radiation which causes the radiation absorber to become energized, wherein the energized radiation absorber causes the latent developer to undergo rearrangement to produce an intermediate dye form having a phenolic substituent, wherein the intermediate dye undergoes an acid catalyzed ring opening to produce a colored dye form;
• and
• b) directing electromagnetic energy from an electromagnetic radiation source onto the color forming composition at a wavelength and power level for a sufficient amount of time to cause the radiation absorber to generate enough heat to form the colored dye form.