Thermo-developable type diazo copying material

A thermally developable, diazo-type, copying material comprising a substrate and a photosensitive layer formed on said substrate, said photosensitive layer consisting essentially of a diazonium compound suitable for use in a two component diazotype copying material, an azo coupling component and a color assistant, wherein said color assistant is at least one member selected from the group consisting of fatty acid amides having the formula:

• R.sup.1 CONH.sub.2
• wherein R.sup.1 is a saturated or unsaturated aliphatic hydrocarbon group having 5 to 24 carbon atoms,
• N-substituted fatty acid amides having the formula:
• R.sup.1 CONHR.sup.2
• wherein R.sup.1 is the same as defined above and R.sup.2 is an alkyl group having 1 to 5 carbon atoms, phenyl, substituted phenyl, cyclohexyl or substituted cyclohexyl,
• and N-substituted fatty acid amides having the formula:
• R.sup.1 NHCOR.sup.2
• wherein R.sup.1 and R.sup.2 are the same as defined above respectively;
• and wherein said coupling component is in the form of fine particles encapsulated with an encapsulating material to form capsules, said encapsulating material being selected from the group consisting of non-polar wax-like substances having a melting point in the range of 50.degree. to 150.degree. C. and hydrophobic vinyl resins having a softening point in the range of 50.degree. to 150.degree. C.