Improvements in or relating to method for preparing copy

Abstract

Abstract 722,023. Photographic processes. DICK CO., A. B. Oct. 24, 1951 [Nov. 1, 1950], No. 24843/51. Class 98 (2). [Also in Groups XV and XVI] A method of producing copy from an original in which the letter outlines contain a radiationabsorbing heat-generating material comprises arranging the original in contact with a transfer sheet having a coloured coating and arranging a copy sheet in contact with the coated side of the transfer sheet, and directing radiations on to the original to generate heat in the letter outlines and cause corresponding areas of the coating composition to be reduced to molten condition and transferred to the copy sheet. The sheets may be urged together by vacuum or pressure. The dark design areas of the original should contain activators or substances capable of converting light rays into heat. The radiation may be by radiations rich in infra-red, of wave-length 8000-40,000 Angstroms, and may be produced by a photographer's flash bulb, tungsten filament lamp, carbon arc lamp or infra-red ray lamp. The heat should be produced rapidly and the exposure be short, and for this purpose the source of radiation may be a capacitor device similar to that used in industrial spot-welding, or a hot wire or tubular tungsten filament lamp with the use of lenses or reflectors. The radiation source may traverse the original at a constant speed so that exposure of each part is of short duration. An assembly suitable for use in carrying out the invention comprises a housing 15 with a glass lid 17, and a flexible blanket 18 sealed all round its edge to the housing. The original 10, transfer sheet 12 and copy sheet 14 are placed on a plate 16, on the blanket, and pressure is produced in the housing or a vacuum generated in the space above the blanket so as to compress the assembly against the lid 17, through which the radiations are directed. The coating composition of the transfer sheet should be substantially solid and non-tacky at room temperature and become molten at some temperature between 125‹ and )5000 F. The coating may be formed of wax, paraffin, bitumen, or hydrocarbons or fatty acids or their derivatives, with or without oils or plasticizers. Dyes and pigments may be added to produce desired colours. Other low-melting point solids may be used, such as the natural gums and resins which include rosin, shellac, gum elemi, copal, dammar, sandarac, colophony, or amber, or thermoplastic synthetic resinous materials such as ethyl cellulose, nitrocellulose, polyacrylates, polyalkylacrylates, polyethylene, polystyrene, or polyvinyl acetates, with or without plasticizers. Examples of coating compositions are:-(1) (violet-coloured coating), methyl violet 5 parts, oleic acid 10, montan wax-crude 60, petrolatum 90; (2) (black), carnauba wax 9, montan wax 6, methyl violet 7, mineral oil 63, lampblack 15; (3) (blue), carnauba wax 4, paraffin wax 4, ozaokerite 1, octadecyl alcohol 2, cottonseed oil 2, Prussian blue 2.

Inventors

No inventors recorded.

Bibliographic Details