PROPYLENE-ETHYLENE RANDOM BLOCK COPOLYMER AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a propylene-ethylene random block copolymer in which transparency and flexibility in a polyolefin-based elastomer are improved and the above properties and heat resistance are balanced and stickiness and bleedout are suppressed. SOLUTION: The propylene-ethylene random block copolymer is obtained by carrying out successive polymerization by using a metallocene catalyst. The propylene-ethylene random block copolymer is obtained by successive polymerization of 30-70 wt.% crystalline copolymer component (A) having 105-145°C melting peak temperature in the first step and 70-30 wt.% low (non-)crystalline copolymer component (B) containing an ethylene content larger by 6-15 wt.% than the ethylene content contained in the component (A) in a second step and satisfies the following conditions: (i) the block copolymer has a single peak at≤0°C in temperature-loss tangent curve; (ii) storage elastic modulus G' [MPa] at 23°C obtained by measurement of solid viscoelasticity is≤200; (iii) the temperature Tαat which G' becomes 2 MPA is 100 to 140°C and (iv) the difference between the melting peak temperature Tm and Tαis≤20°C. COPYRIGHT: (C)2005,JPO&NCIPI