TCTM-HABI

At that time, our coatings were made in Towanda with methylene chloride as solvent, but our custom coating was done with butanone and isopropyl alcohol. The samples of TCTM-HABI had good solubility in this solvent pair. When Green precipitated the product from the oxidation of the 2,4-bis(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)imidazole, he made a startling discovery. Some of it went into solution in the ketone solvent, but most did not. What did... 

Certain HABIs have remarkably prolonged free radical life. As part of an investigation of the improved performance of TCTM-HABI vs. CDM-HABI and o-Cl-HABI, visual colors of the radical, as well as ESR measurements showed that TCTM-HABI formed extremely stable free radicals. 

These data show that the radicals from the photolysis of TCTM-HABI have longer radical life versus the controls. The differences between the controls and hexaphenylbiimidazole compounds indicate that electronic effects, arising from substituents, as well as steric factors which may be present, as shown by 4-phenyl ortho-substituted compounds of this invention influence radical life. 

Triphenylimidazolyl dimer (TCTM-HABI) (one of compounds 1 to 10, Table 6) 0.434... 

TM. Sheets at Towanda sought to improve the economics of the coated product, and achieved success by co-oxidizing the triarylimidazoles from which TCTM-HABI and o-Cl-HABl are manufactured. Surprisingly, the mixture showed improved photofixing capability. 

In order to maximize the effectiveness of the HABI component, o-ethoxy-HABI, which was somewhat less stable thermally than TCTM-HABI or TCDM-HABI, used in DYLUX 503 proof papers was selected. 

The imidazolyl radicals may recombine to form the starting dimer. Considering the rather large molecular weight of o-Cl-HABI (MWt 660) or TCTM-HABI (MWt. 848) the bulky radicals may not move much in a viscous medium and show a tendency to recombine. This ability to recombine is responsible for the stability of HABI based imaging systems. 

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