Patent ID: 6063871
Filing Date: 2000-05-16
Classification: C08F,C08L

Abstract:
An ethylene polymer composition comprising:(A) a first ethylene polymer in an amount of 20 to 90% by weight, said first ethylene polymer being an ethylene polymer or a copolymer of ethylene and an .alpha.-olefin of 3 to 20 carbon atoms and having the following properties:(A-1) the density (d.sub.A) is in the range of 0.96 to 0.98 g/cm.sup.3 ; and(A-2) the intrinsic viscosity (.eta.), as measured in decalin at 135.degree. C., is in the range of 0.5 to 3.0 dl/g; and(B) a second ethylene polymer in an amount of 80 to 10% by weight, said second ethylene polymer being an ethylene polymer or a copolymer of ethylene and an .alpha.-olefin of 3 to 20 carbon atoms and having the following properties:(B-1) the density (d.sub.B) is in the range of 0.91 to 0.965 g/cm.sup.3, and(B-2) the intrinsic viscosity (.eta.), as measured in decalin at 135.degree. C., is in the range of 3.0 to 10 dl/g;at least one of said first ethylene polymer (A) and said second ethylene polymer (B) being an ethylene polymer prepared by the use of a metallocene catalystwherein said ethylene polymer composition has the following properties:(1) a ratio (d.sub.A /d.sub.B) of the density (d.sub.A) of the first ethylene polymer (A) to the density (d.sub.B) of the second ethylene polymer (B) is larger than 1;(2) the density is in the range of 0.940 to 0.970 g/cm.sup.3 ;(3) the melt flow rate (MFR, measured at 190.degree. C. under a load of 2.16 kg) is in the range of 0.005 to 20 g/10 min;(4) the melt flow rate (MFR) and the melt tension (MT) satisfy the following relationlog(MT).gtoreq.-0.4 log(MFR)+0.7; and(5) the diametrical swell ratio exceeds 1.35, wherein the diametrical swell ratio is measured in the following manner:Capillograph--1B (barrel diameter: 10 mm, manufactured by Toyo Seiki Seisakusho) is equipped with a tubular nozzle (inner diameter (D.sub.o): 3 mm, outer diameter: 4 mm, length: 10 mm) and a barrel (to be charged with a sample) is heated to 200.degree. C. and maintained at that temperature; the barrel is charged with 10 g of a sample; then, a piston is fitted, and degassing is performed, followed by preheating for 6 minutes; after the preheating, the sample is extruded at each piston speed of 10, 20, 30, 50 and 75 mm/min; the diameter (D.sub.i) of the strands thus extruded are measured at a position 15 mm downward from the nozzle tip; a ratio (D.sub.i /D.sub.o) of the strand diameter (D.sub.i) measured at each piston speed to the tubular nozzle diameter (D.sub.o) is plotted against the piston speed on semi-logarithmic paper to obtain a curve; from this curve, a ratio corresponding to the piston speed of 50 mm/min is read out, and this value is taken as the diametrical swell ratio.