content_image/936642.jpg
# United States Patent [19J 

# Grossa 

# [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 

## [30] Foreign Application Priority Data 

Nov. 16, 1985 [DE] Fed. Rep. of Germany ....... 3540796 

[51] Int. Cl. 4 G03C 5/00 

[52] U.S. Cl . .................................... 430/291; 430/270; 430/326; 430/328 

[58] Field of Search ................ 430/328, 291, 270, 326 

# [11] Patent Number: 4,698,293 

# [45] Date of Patent: Oct. 6, 1987 

## [56] References Cited 

## U.S. PATENT DOCUMENTS 

<img src='content_image/936642.jpg'>

Primary Examiner-Jack P. Brammer 

## [57] ABSTRACT 

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. 

## 12 Claims, No Drawings 

