Patent Number: 054019710
Section: claims

1. A radiographic phosphor panel comprising a support, a luminescent layer overlaying said support, and an overcoat layer overlaying said luminescent layer, said luminescent layer including phosphor crystals, said luminescent layer being subject to iodine-associated yellowing, said overcoat layer being a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and second polymer selected from the group consisting of poly(methylmethacrylate) and poly(ethylmethacrylate), said poly(vinylidene fluoride-co-tetrafluoroethylene) and said second polymer having a ratio in parts by weight of from 70:30 to 10:90. 2. The radiographic phosphor panel of claim 1 wherein said overcoat layer is a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and poly(methylmethacrylate). 3. The radiographic phosphor panel of claim 1 wherein said overcoat layer is a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and poly(methylmethacrylate) in a ratio by weight of from 70:30 to 10:90. 4. The radiographic phosphor panel of claim 1 wherein said overcoat layer is a miscible blend of poly(vinylidene fluoride-cotetrafluoroethylene) and poly(methylmethacrylate) in a ratio by weight of from 70:30 to 50:50. 5. The radiographic phosphor panel of claim wherein said phosphor is selected from the group consisting of divalent alkaline earth metal fluorohalide phosphors containing iodine and alkali metal halide phosphors containing iodine. 6. The radiographic phosphor panel of claim 1 wherein said phosphor consisting essentially of the product of firing a combination of species characterized by the relationship: EQU MFX.sub.1-z I.sub.z.uM.sup.a X.sup.a :yA:tD M is selected from Mg, Ca, Sr, and Ba;  X is selected from Cl and Br;  M.sup.a is selected from Na, K, Rb, and Cs;  X.sup.a is selected from F, Cl, Br, and I;  A is selected from Eu, Ce, Sm, and Tb;  D is selected from V, Cr, Mn, Fe, Co, and Ni;  z is from 1.times.10.sup.-4 to 1;  u is from 0 to 1;  y is from 1.times.10.sup.-4 to 0.1; and  t is from 0 to 10.sup.-2 ;  oxide; and  oxosulfur reducing agent for iodine, said oxosulfur reducing agent being selected from the group consisting of inorganic and organic salts having anions having the general formula S.sub.j O.sub.k wherein 0.25&lt;j/k&lt;1.0, and Bunte compounds, said oxosulfur reducing agent being present prior to firing in a molar ratio of sulfur to alkaline earth metal of from 1.times.10.sup.-4 to 0.020.  X is selected from Cl and Br;  M.sup.a is selected from Na, K, Rb, and Cs;  X.sup.a is selected from F, Cl, Br, and I;  A is selected from Eu, Ce, Sm, and Tb;  a+b+c is from 0 to 0.4;  z is from 1.times.10.sup.-4 to 1;  r is from 10.sup.-6 to 0.1;  y is from 1.times.10.sup.-4 to 0.1;  oxide; and  said oxosulfur reducing agent. 7. The radiographic phosphor panel of claim 6 wherein said phosphor consists essentially of the product of firing a combination of species characterized by the relationship: EQU (Ba.sub.1-a-b-b Mg.sub.a Ca.sub.b Sr.sub.c)FX.sub.1-Z I.sub.z.rM.sup.a X.sup.a :yA 8. The radiographic phosphor panel of claim 1 wherein said support is substantially rigid. 9. The radiographic phosphor panel of claim 1 wherein said poly(vinylidene fluoride-co-tetrafluoroethylene) and said second polymer have a ratio in parts by weight of from 70:30 to 50:50. 10. The storage panel of claim 1 wherein said poly(vinylidene fluoride-co-tetrafluoroethylene) and said second polymer have relative concentrations that render said storage panel less subject to curl than an equivalent storage panel having a poly(methyl methacrylate) overcoat layer. 11. A storage phosphor panel comprising, in order: a support; a fluorescent layer including phosphor crystals capable of absorbing X-radiation and emitting longer wavelength electromagnetic radiation in response to stimulating radiation of a third wavelength, said phosphor including iodine and other halogen, said fluorescent layer being subject to yellowing upon exposure to ambient atmosphere; and an overcoat layer, said overcoat layer being a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and a second polymer selected from the group consisting of poly(methylmethacrylate) and poly(ethylmethacrylate), said poly(vinylidene fluoride-co-tetrafluoroethylene) and said second polymer having a ratio in parts by weight of from 70:30 to 10:90. 12. The storage panel of claim 11 wherein said overcoat layer is a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and poly(methylmethacrylate). 13. The storage panel of claim 11 wherein said overcoat layer is a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and poly(methylmethacrylate) in a ratio by weight of from 70:30 to 10:90. 14. The storage panel of claim 11 wherein said overcoat layer is a miscible blend of poly(vinylidene fluoride-co-tetrafluoroethylene) and poly(methylmethacrylate) in a ratio by weight of from 70:30 to 50:50. 15. The storage panel of claim 14 wherein said phosphor is selected from the group consisting of divalent alkaline earth metal fluorohalide phosphors containing iodine and alkali metal halide phosphors containing iodine. 16. The storage panel of claim 11 wherein said poly(vinylidene fluoride-co-tetrafluoroethylene) and said second polymer have a ratio in parts by weight of from 70:30 to 50:50. 17. The storage panel of claim 11 wherein said poly(vinylidene fluoride-co-tetrafluoroethylene) and said second polymer have relative concentrations that render said storage panel less subject to curl than an equivalent storage panel having a poly(methyl methacrylate) overcoat layer. 18. A method for preparing a radiographic phosphor panel comprising forming a luminescent layer on a support, making a solution of poly(vinylidene fluoride-co-tetrafluoroethylene) and a second polymer selected from the group consisting of poly(methylmethacrylate) and poly(ethylmethacrylate), and said poly(vinylidene fluoride-co-tetrafluoroethylene) said second polymer having a ratio in parts by weight of from 70:30 to 10:90, and coating said solution over said luminescent layer. 19. The method of claim 18 wherein said solution is in 2-butanone.