TECHNOLOGY FOCUS - POLYMERS - Preferred Properties: The ethylene- alpha -olefin copolymer composition (C) has melt flow rate of 10-27 g/10 minutes at 190 degrees C under the load of 2.16 kg, based on ASTM D1238. The ethylene- alpha -olefin copolymer composition (C) has density of 0.865-0.884 g/cm3, based on ASTM D1505, and Shore A hardness of 60-85, based on ASTM D2240. The ethylene- alpha -olefin copolymer (A) has melt flow rate of 11-50 g/10 minutes at 190 degrees C under the load of 2.16 kg based on ASTM D1238, density of 0.865-0.884 g/cm3, based on ASTM D1505, and Shore A hardness of 60-85 based on ASTM D2240. The ethylene- alpha -olefin copolymer (A) has melt flow rate of 0.5-11 g/10 minutes at 190 degrees C under the load of 2.16 kg based on ASTM D1238, density of 0.865-0.9 g/cm3, based on ASTM D1505, and Shore A hardness of 60-92 based on ASTM D2240. Preferred Composition: The ethylene- alpha -olefin copolymer composition (C) further comprises 80-90 mol% structural unit derived from ethylene, and 10-20 mol% structural unit derived from 3-20C alpha -olefin. The ethylene- alpha -olefin copolymer (A) comprises 80-90 mol% structural unit derived from ethylene, and 10-20 mol% structural unit derived from 3-20C alpha -olefin. The ethylene- alpha -olefin copolymer (B) comprises 80-92 mol% structural unit derived from ethylene, and 8-20 mol% structural unit derived from 3-20C alpha -olefin. The sealing material further contains 0.1-3 pts. wt. organic peroxide having 1-minute half life temperature of 100-170 degrees C with respect to 100 pts. wt. ethylene- alpha -olefin copolymer (c). The sealing material further comprises ethylene-based resin composition containing 0.1-5 pts. wt. silane coupling agent and 0.1-3 pts. wt. crosslinking agent with respect to 100 pts. wt. ethylene- alpha -olefin copolymer composition (C). The ethylene-based resin composition comprises 0.005-5 pts. wt. ultraviolet absorber, heat-resistant stabilizer and hindered-amine-type optical stabilizer and 0.05-5 pts. wt. crosslinking adjuvants with respect to 100 pts. wt. ethylene- alpha -olefin copolymer composition. Preferred Process: The sealing material is obtained by mixing ethylene- alpha -olefin copolymer composition (C) and additive, and extrusion-molding into sheet form.