Patent ID: 6548570
Filing Date: 2003-04-15
Classification: B29B,C08K,C08L,G21F

Abstract:
Method for manufacturing a radiation shielding material from a polymer that is blended with a radiation-absorbing filler material, the polymer being an elastomer comprising a synthetic thermoplastic, vulcanizable elastomer, or a non-vulcanizing elastomer; wherein the vulcanizable elastomer is natural rubber (NR), polychloroprene (CR), nitrile-butadiene (NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), ethylene propylene terpolymer (EPM), ethylene propylene copolymer (EPM), polyurethane (PU), isobutylene-isoprene rubber, silicone rubber (VMO and MQ), ethylene vinyl acetate rubber (EVA) or blends thereof, wherein the non-vulcanizing elastomer is polypropylene/EPDM (PP/EPDM), styrene-ethylene-butylene-styrene (SEBS), polyvinyl-chloride-nitrile-butadiene (NBR/PVC), ethylene propylene copolymer (EPM), or blends thereof; the radiation absorbing filler material comprising a powder of an element with a high atomic number or compounds thereof selected from the group consisting of antimony, barium, bismuth, bromine, cadmium, cerium, cesium, gold, iodine, indium, iridium, lead, mercury, molybdenum, osminium, platinum, polonium, rhenium, rhodium, silver, strontium, tantalum, thorium, tin, tungsten, uranium, zirconium, elements from the lanthanide group and elements from the actinide group, represented by more than 80 weight percent, and having a grain size distribution in the range of 20 &mgr;m to 120 &mgr;m, the method including the steps of:A) mixing with the filler material a loading material in powdered form so as to improve wettability of the filler material with respect to the elastomer; the loading material comprising magnesium aluminum silicate, zinc stearate, silicone resin powder, strontium carbonate, barium carbonate, barium sulfate, calcium tungstate, gadolinium oxi-sulfide, barium sulfate doped with tin dioxide, zinc, antimony, elements from the lanthanide series or elements from the actinide series or mixtures thereof, wherein the loading material is a material that is different from the filler material; B) kneading the mixture of step A together with the elastomer inside a mixer while maintaining a temperature thereof below 180Â° C.; C) removing the kneaded mixture from the mixer and passing the kneaded mixture through cooled roll mills wherein the kneaded mixture is cooled and homogenized; D) cutting the cooled and homogenized mixture into strips on a strip cutting apparatus; E) passing the strips through a strainer having a mesh width of between 5 &mgr;m and 1000 &mgr;m; and F) forming the strained mixture into a foil.