The present invention relates to a polyethylene copolymer which has excellent processability and long-term durability, and thus is useful for hollow molding of a pipe or the like.

The present invention relates to a novel ligand compound, a transition metal compound and a catalyst composition including the same. The novel ligand compound and the transition metal compound of the present invention may be useful as a catalyst of polymerization reaction for preparing an olefin-based polymer having a low density. In addition, an olefin polymer which is polymerized using the catalyst composition including the transition metal compound may be used for the manufacture of a product having low melt index (MI) and high molecular weight.

The present invention provides an ethylene/alpha-olefin copolymer having narrow molecular weight distribution together with a low density and an ultra low molecular weight, minimized number of unsaturated functional groups, and particularly a small amount of vinylidene among the unsaturated functional groups to show excellent physical properties, and a method for preparing the same.

The present invention relates to a transition metal compound for an olefin polymerization catalyst, the transition metal compound being represented by chemical formula 1. The description of chemical formula 1 is as defined in the specification.

The present invention relates to an ethylene/alpha-olefin copolymer and, more particularly, to an ethylene/alpha-olefin copolymer that exhibits excellent environmental stress crack resistance by appropriately controlling the ratio of crystal structure domain and amorphous domain, and the like. The ethylene/alpha-olefin copolymer comprises an ethylene repeating unit and an alpha-olefin repeating unit, and has a crystal structure including a crystalline domain containing lamellar crystals and an amorphous domain containing a tie molecule that mediates bonding between the lamellar crystals. The lamellar crystal thickness (dc) of the ethylene/alpha-olefin copolymer as calculated from the result of Small Angle X-ray Scattering (SAXS) analysis is between 12.0 and 16.0 nm, the amorphous domain thickness (da) is between 4.0 and 5.3 nm, and the thickness ratio da/dc is between 0.3 and 0.4.

The present invention relates to an olefin-based polymer, which has (1) a density (d) ranging from 0.85 to 0.90 g/cc, (2) a melt index (MI, 190 C., 2.16 kg load conditions) ranging from 0.1 g/10 min to 15 g/10 min, (3) a molecular weight distribution (MWD) in a range of 1.0 to 3.0, and (4) a number average molecular weight (Mn) and a Z+1 average molecular weight (Mz+1) satisfying the Equation 1, {Mn/(Mz+1)}100>15. The olefin-based polymer according to the present invention is a low-density olefin-based polymer and exhibits excellent tensile strength due to having improved molecular weight as compared to the flow index.

The present invention relates to a polypropylene-based resin composition which exhibits mechanical properties such as excellent strength and more improved impact strength, and a molded article comprising the same. The polypropylene-based resin composition comprises: a polypropylene-based resin; and an olefin-based copolymer, and shows two or more elution temperatures at a predetermined temperature range when analyzing the olefin-based copolymer by temperature rising elution fractionation (TREF).

The present invention relates to a method for evaluating an injection physical property of a plastic resin, and a polyethylene resin suitable for an injection molding process and, more particularly, to a novel method for evaluating an injection physical property of a plastic resin, which, when a particular plastic resin is processed by an injection process, can accurately derive injection suitability of the plastic resin and injection pressure in the injection process through a physical property value measured by using a resin specimen, and a polyethylene resin suitable for injection molding.

The present invention relates to a transition metal complex that exhibits high activity in the polymerization reaction of olefin monomers and improved copolymerization activity, thus enabling the preparation of a low density, high molecular weight polyolefin, a catalyst composition including the same, and a method for preparing a polyolefin using the composition.

The present invention relates to polyethylene resin having excellent impact strength, and more specifically, to polyethylene resin exhibiting excellent impact strength and flexural strength, when prepared into a molded product.