| 摘要 |
PURPOSE:To improve the properties of the frame body of a lead-acid battery against residual stress and shrinkage percentage so as to prevent generation of cracking for maintaining the sealing property of the battery over a long period of time by using a polyester of great stress cracking resistance as the frame body. CONSTITUTION:In a lead-acid battery, the circumference of a group of electrode plates comprising a positive electrode plate 1, a negative electrode plate 2 and a separator 3 is surrounded by a frame body 4 made of polyethylene. The frame body 4 is formed of thermoplastic resin made of a polyethylene resin of stress cracking resistance more than 10 [F50-hr] (ASTM test method D/693). Also, a polyethylene resin of melt index less than 5.0[g/10m in] (ASTM test method D/238) is used as the frame body 4. Besides, a polyester resin of density 0. 910 to 0. 955 [g/cm<2>] (ASTM test method D/505) is used. The properties of the frame body 4 against residual stress and against shrinkage percentage are both improved, and the sealing property of the battery is maintained over a long period of time while in use at temperatures not so high as to cause cracking. |
