| 摘要 |
An ethylene polymer which has a viscosity-average molecular weight (Mv) of 3,000,000-15,000,000 and which, after having undergone heating at 110°C for 6 hours in an environment having a reduced pressure of 0.1-0.5 kPa, has a quantity of heat of fusion (ΔH), as determined by differential scanning calorimetry, of 230-293 J/g, and in which the ratio of the 200/110 plane orientation index (a) of the ethylene polymer in an unprocessed state and the 200/100 plane orientation index (b) of a sheet obtained through pressing and rolling under the following conditions (1) to (3), (b)/(a), is 7 or greater. (1) Three grams of the ethylene polymer is pressed with a press-forming machine at 130°C and 11 MPa for 10 minutes. (2) The sheet is cooled at 25°C for 10 minutes while keeping the pressure at 11 MPa. (3) The obtained pressed sheet is heated at 140°C for 3 minutes and is compressed with a rolling machine having a temperature of 130°C and a let-off rate of 1 m/min, so as to result in a stretch ratio of 6. |
