United States  Patent  [19J  Grossa  [11]  Patent Number:  4,698,293  [45]  Date of Patent:  Oct. 6, 1987  [54]  PROCESS FOR FORMING  POSITIVE  TONABLE IMAGES  USING A  PHOTOSENSITIVE  MATERIAL  CONTAINING  AT LEAST  1,4-DIHYDROPYRIDINE  [75]  Inventor:  Mario Grossa,  Dreieich, Fed. Rep.  of  Germany  [73]  Assignee:  E. I.  Du Pont de Nemours  and  Company,  Wilminton, Del.  [21]  Appl. No.:  929,376  [22]  Filed:  Nov. 12, 1986  [52]  U.S. Cl . ....................................  430/291;  430/270;  430/326; 430/328  [58]  Field of Search  ................  430/328, 291, 270,  326  [51]  Int. Cl. 4  G03C 5/00  A process for the  production  of patterns that  consist of  powders and that  are positive with  respect to the origi› nal is described,  according  to which a  light-sensitive  layer containing  at least one  1,4-dihydropyridine  com› pound is exposed  imagewise, treated  with a strong acid,  post-exposed diffusely  to produce tacky  areas, and is  subsequently toned.  [30]  Foreign Application  Priority Data  [56]  References Cited  U.S. PATENT  DOCUMENTS  [57]  ABSTRACT  Nov. 16, 1985 [DE]  Fed.  Rep.  of Germany .......  3540796  Primary  Examiner-Jack  P. Brammer  3,888,672  6/1975  Lee  ......................................  430/292  4,243,741  1/1981  Abele et al.  ......................... 430/270  4,346,162  8/1982  Abele et al.  ......................... 430/270  4,604,340  8/1986 Grossa  .................................  430/270  12 Claims, No Drawings 