Patent Number: 049838482
Section: summary

DESCRIPTION 1. Field of the Invention This invention relates to the field of X-ray intensifying screens. More particularly, this invention relates to X-ray intensifying screens which have an improved polyamide surface or topcoat layer which are used in conjunction with photographic films to produce an image thereon. 2. Background of the Invention It is known that various solution coated topcoats or surface films can be placed over an X-ray intensifying screen. These topcoats and films are designed to improve and protect the phosphor-binder layer and assist in the processability of the X-ray intensifying screen in various ways. To produce an image, film is placed in contact with screens. The mechanism for doing this varies with the equipment used. These X-ray intensifying screen surfaces do not always provide long-term protection in book cassettes, and are particularly short-lived when used within the modern, automatic systems now found in the busier radiographic sections of modern hospitals. For example, screens and magazines of X-ray films are loaded by hospital staff personnel in an automatic changer, and from that point on, work can be done in ordinary, white light. The appropriate screen matched with the appropriate photographic film elements present in the changer are then exposed as required. Then, the magazine of exposed X-ray film is removed for film processing and a magazine of unexposed X-ray film is put back into the system. A disadvantage with this automatic system, particularly since the X-ray intensifying screen is an expensive part of the overall system, is that considerable stress is placed on the screen and it is required that the surface thereof be tough and durable to survive automatic handling (e.g. X-ray photographic films rubbing over the screen surface, mechanical parts, etc.) and not develop imageable artifacts. Additionally, there is a need to reduce the static which can build up within this automatic equipment as films slide against screens during the handling. As is well known any static produced can cause unwanted film exposure and subsequent handling problems. Thus, there is a pressing need to develop X-ray intensifying screens that can survive multiple uses within the modern, automatic changers, for example. It has been found that the above disadvantages can be overcome and an improved X-ray intensifying screen provided by bonding a thin, clear, transparent, tough, flexible film of the invention to the surface of a supported phosphor containing layer. SUMMARY OF THE INVENTION In accordance with this invention there is provided an X-ray intensifying screen comprising a support having thereon a phosphor-binder layer, and a polymeric film adhered to the phosphor-binder layer, the improvement wherein bonded to the phosphor-binder layer is a clear, transparent, flexible, tough, dimensionally stable polyamide film having a thickness of no greater than about 15.2 .mu.m, the X-ray intensifying screen having an average dynamic coefficient of friction in the range of 0.15 to 0.25 and low static susceptibility when the screen is used within a book cassette or an automatic changer therefor.