A polyethylene composition includes a first polyethylene which is an ethylene copolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, a second polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 15,000 to 100,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, and a third polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of >2.3, where the first polyethylene has more short chain branching than the second polyethylene or the third polyethylene. The polyethylene composition has a soluble fraction in a CEF analysis of at least 10 weight percent. Film made from the polyethylene composition may have a machine direction 1% secant modulus of 190 MPa (at a film thickness of about 1 mil), a seal initiation temperature (SIT) of 100 C. (at a film thickness of about 2 mil), an area of hot tack window (AHTW) of 160 Newtons.Math.C (at a film thickness of about 2 mil) and an oxygen transmission rate (OTR) of 650 cm.sup.3 per 100 inch.sup.2 (at a film thickness of about 1 mil).

A polyethylene composition comprises a first polyethylene which is an ethylene copolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, a second polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of less than 75,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, and a third polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 100,000 to 300,000 and a molecular weight distribution M.sub.w/M.sub.n of >2.3, where the first polyethylene has more short chain branching than the second polyethylene or the third polyethylene. The polyethylene composition has a soluble fraction in a CEF analysis of at least 15 weight percent. Film made from the polyethylene composition may have a machine direction 1% secant modulus of 200 MPa (at a film thickness of about 1 mil) and an oxygen transmission rate (OTR) of 700 cm.sup.3 per 100 inch.sup.2 (at a film thickness of about 1 mil). Film made from the polyethylene composition retains much of its dart impact performance on downgauging from a thickness of 1 mil to a thickness of 0.75 mil.

In some embodiments disclosed herein are polyethylene composition including a first polyethylene which is an ethylene copolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, a second polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of less than 75,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, a third polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of less than 75,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, and a fourth polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 100,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of >2.3, where the first polyethylene has more short chain branching than the second polyethylene or the third polyethylene. The polyethylene composition may have a soluble fraction in a CEF analysis of at least 7.5 weight percent. Film made from the polyethylene composition may have a machine direction 1% secant modulus of 200 MPa (at a film thickness of about 1 mil) and an oxygen transmission rate (OTR) of 550 cm.sup.3 per 100 inch.sup.2 (at a film thickness of about 1 mil). Film made from the polyethylene composition retains much of its dart impact performance on downgauging from a thickness of 1 mil to a thickness of 0.75 mil.

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 process for continuously producing an ultra-high molecular weight polyethylene by the ethylene slurry polymerization, wherein raw materials containing ethylene and optionally at least one comonomer are subjected to a continuous slurry polymerization in a hydrogen free atmosphere in the ethylene slurry polymerization condition by using 2-6 ethylene slurry polymerization reaction tanks connected in series, and the deviations of the polymerization temperatures, the polymerization pressures, and the gas phase compositions between the tanks each other are controlled to certain ranges. The ultra-high molecular weight polyethylene having the viscosity-average molecular weight of 150-800?10.sup.4 g/mol can be continuously produced. This process has flexible polymerization manner, large room for adjusting and controlling, and stable polymer performance. Moreover, the obtained ultra-high molecular weight polyethylene has low metal content, low ash content, and excellent mechanical properties.

A triblock polymer of formula B-A-B is provided. According to the formula, the symbol A represents a central block which is a statistical copolymer comprising units of a 1,3-diene and more than 50 mol % of ethylene units. The symbols B each represent an end block which is a polyethylene with a melting point of greater than 90 C. and a number-average molar mass of greater than or equal to 2000 g/mol and less than or equal to 10 000 g/mol. The polymer has improved rheological properties relative to a statistical copolymer based on ethylene and 1,3-diene of the same microstructure without changing its mechanical and dynamic or thermal properties.

A method of preparing a supported metallocene catalyst capable of more effectively preparing a polyolefin which may be preferably used for blow molding, etc., because its molecular weight distribution is such that polymer elasticity is increased to improve swell, is provided.

The present invention provides a polypropylene-based composite material capable of exhibiting excellent strength properties and impact strength properties, particularly, markedly improved impact strength properties at a low temperature without using a separate additive by including (A) polypropylene, and (B) an olefin-based polymer which satisfies the conditions of the following (b1) to (b4): (b1) density (d): from 0.850 to 0.910 g/cc, (b2) melt index (MI, 190 C., 2.16 kg load conditions): from 0.1 g/10 min to 100 g/10 min, (b3) molecular weight distribution (MWD): from 1.5 to 3.0, and (b4) i) two peaks are shown in a temperature range of 20 C. to 120 C. when taking measurements of temperature rising elution fractionation, and ii) a relation of T(90)T(50)60 C. is satisfied (where T(90) is a temperature at which 90 wt % of the olefin-based polymer is eluted, and T(50) is a temperature at which 50 wt % of the olefin-based polymer is eluted).

A metal complex of the formula (1) CyLMZ.sub.p(A).sub.n (1), wherein M is a group 4 metal Z is an anionic ligand, p is number of 1 to 2, preferably 2, Cy is a cyclopentadienyl-type ligand substituted with at least one aliphatic C.sub.3-C.sub.20 hydrocarbyl group, which is bonded to the cyclopentadienyl-type ligand, in particular to its cyclopentadienyl ring, via a secondary, a tertiary or quaternary carbon atom and, L is an amidinate ligand of the formula (2), wherein the amidine-containing ligand is covalently bonded to the metal M via the imine nitrogen atom, and Sub1 is a substituent comprising a group 14 atom through which Sub1 is bonded to the imine carbon atom and Sub2 is a substituent comprising a heteroatom of group 15, through which Sub2 is bonded to the imine carbon atom and A is a neutral Lewis base ligand selected from the list consisting of ether, thioether, amine, tertiary phosphane, imine, nitrile and isonitrile, wherein the number of said metal ligands n is in the range of 0 to the amount that specifies the 18-electron rule. ##STR00001##

Organometallic complexes are described which are useful as pre-polymerization catalysts which may form part of olefin polymerization catalyst systems. The catalyst systems find use in the polymerization of ethylene, optionally with one or more C.sub.3-12 alpha-olefin comonomers. The organometallic complexes are broadly represented by formula I:

##STR00001##

wherein L is a bridging group containing a contiguous chain of atoms connecting P with Cy, wherein the contiguous chain contains 2 or 3 atoms and wherein Cy is a cyclopentadienyl-type ligand. The olefin polymerization catalyst system is effective at polymerizing ethylene with alpha-olefins in a solution phase polymerization process at high temperatures and produces ethylene copolymers with high molecular weight and high degrees of alpha-olefin incorporation. Pre-metallation compounds, metallation processes and synthetic methods to make the organometallic complexes as well as polymerization processes are also described.