| 摘要 |
Radiation shielding material is provided to prevent oil leakage by sealing a neutron shielding layer between impermeable polyolefin resin layers. Radiation shielding material includes a first and a second impermeable resin layers(1) and a neutron shielding layer(2). The first and the second impermeable resin layers are made of polyolefin resin or polyolefin resin containing inorganic material. The neutron shielding layer is a sheet having minute air holes. The sheet is formed through mixing/extruding/foaming process of thermoplastic polyolefin with 100 weight part, foam agent with 0.1 to 10 weight part, foam making agent and bridge making agent with 0.5 to 50 weight part. The thermoplastic polyolefin contains UHMWPE(Ultra-High Molecular Weight Polyethylene) with 3 to 15 weight part. The sheet has a meshed air hole structure and is dipped into molten paraffin. The sheet is sealed up between impermeable resin layers. The sealed sheet is cooled at a melting point or less of the paraffin and the melting point is 47 to 65 °C. The porosity of the air hole is 30 to 90 %. |
