Patent GB-1292458-A (GB)
Title: Methods of forming images by physical development
Inventor: YUDELSON JOSEPH SAMUEL
IPC: G03C1/72
Filed: 1969-11-21
Abstract: 1292458 Forming images by physical development EASTMAN KODAK CO 21 Nov 1969 [22 Nov 1968] 57113/69 Heading G2C An image is formed by treating a layer containing an imagewise distribution of catalytic metal nuclei (which catalyse the reduction of the heavy metal in the physical developer solution whereby a heavy metal image is formed corresponding to the distribution of the nuclei) which is formed by a method including the step of imagewise exposure to actinic radiation with a physical developer solution which contains (1) a reducible water-soluble heavy metal (i.e. nickel, cobalt, iron, chromium or copper) salt, (2) a complexing agent for the heavy metal ions and (3) a borane reducing agent. The catalytic metal nuclei may be formed by imagewise exposure when the radiation sensitive entity is a palladium compound e.g. potassium dioxalato palladate (II), potassium dimalonato palladate (II), potassium dimesoxalato palladate (II) or potassium tetroxamato palladate (II). The catalytic metal nuclei may be formed by imagewise exposing a silver halide layer, converting the exposed silver halide to silver by development, removing unexposed silver halide from the layer and converting the developed silver image into catalytic nuclei e.g. by treatment with an inorganic acid solution, a strong oxidizing agent or a strong reducing agent such as nitric acid, hydrochloric acid, sulphuric acid, sulphurous acid, potassium ferricyanide, hydrogen peroxide or sodium borohydride. The silver image may be converted into catalytic nuclei by first converting it to silver halide, e.g. using a solution of potassium ferricyanide and potassium bromide, and then reducing the silver halide so formed with a physical developer solution. Alternatively catalytic metal nuclei may be formed by imagewise exposing a silver halide layer, converting the exposed silver halide to silver by development which silver is optionally bleached, and reducing the silver halide in the unexposed areas to catalytic silver nuclei with the physical developer solution. The silver halide layer or a layer adjacent thereto may comprise gelatine and copoly (styrene-methyl vinyl ketoneaminoguanidine) (see Example 9). The catalytic metal nuclei may be formed by imagewise exposing a photo-reducible ferric salt layer, and, if not already contained in the layer, treating the exposed layer with a metal salt, e.g. of silver, copper, gold, platinum or palladium, which is reducible by ferrous ions to form catalytic metal nuclei. The reducing agent (3) may be an amine borane, phosphine borane, arsine borane or stibine borane. Many examples of such reducing agents are given. The complexing agent (2) may contain a carboxylic acid group and is preferably gluconic acid, saccharic acid or quinic acid. The invention also comprises a physical developer composition which contains (1) a reducible water-soluble heavy metal (as hereinbefore defined) salt, (2) a complexing agent for the heavy metal ions, and (3) a phosphine borane, arsine borane or stibine borane reducing agent.