The present invention relates to a process for the preparation of a procatalyst suitable for preparing a catalyst composition for olefin polymerization, said process comprising the steps of: Step A) providing or preparing a Grignard compound; Step B) contacting the Grignard compound with a silane compound to give a solid support; Step C) activating said solid support, comprising two sub steps: Step C1) contacting the solid support obtained in step B) with at least one first activating compound and a second activating compound; and Step C2) a second activation step by contacting the partly activated solid support obtained in step C1) with an activating electron donor; to obtain an activated solid support; Step D) reacting the activated solid support obtained in step C) with a halogen-containing Ti compound, optionally an activator and at least one internal electron donor in several sub steps to obtain said procatalyst. The invention moreover relates to a procatalyst, a catalytic system comprising said procatalyst and to a process to prepare polyolefins using said catalyst system and the polyolefins obtained therewith.

A process for preparing ethylene polymers including the step of polymerizing ethylene or copolymerizing ethylene and one or more comonomers at a temperature from 100° C. to 350° C. and a pressure of from 110 MPa to 350 MPa in a continuously operated tubular polymerization reactor, thereby yielding a reaction mixture, wherein the tubular polymerization reactor has a reactor cooling jacket for removing the heat of the reaction and a pressure control valve, the reaction mixture leaves the reactor through the pressure control valve, the reaction mixture then passes a post-reactor cooler equipped with a post-reactor cooling jacket, the reactor cooling jacket is provided with a reactor coolant having an inlet temperature and the post-reactor cooling jacket is provided with a post-reactor coolant having an inlet temperature, and the inlet temperature of the post-reactor coolant is independently controlled from the inlet temperature of the reactant coolant.

A process for preparing ethylene polymers including the step of polymerizing ethylene or copolymerizing ethylene and one or more comonomers at a temperature from 100° C. to 350° C. and a pressure of from 110 MPa to 350 MPa in a continuously operated tubular polymerization reactor, thereby yielding a reaction mixture, wherein the tubular polymerization reactor has a reactor cooling jacket for removing the heat of the reaction and a pressure control valve, the reaction mixture leaves the reactor through the pressure control valve, the reaction mixture then passes a post-reactor cooler equipped with a post-reactor cooling jacket, the reactor cooling jacket is provided with a reactor coolant having an inlet temperature and the post-reactor cooling jacket is provided with a post-reactor coolant having an inlet temperature, and the inlet temperature of the post-reactor coolant is independently controlled from the inlet temperature of the reactant coolant.

In some embodiments, a polyethylene composition includes has 80 wt % to 99.9 wt % ethylene content and 20 wt % to 0.1 wt % a C3 to C40 α-olefin comonomer content, based on ethylene content plus comonomer content. The composition has a Mw/Mn of 15 to 45, a density of 0.93 g/cm.sup.3 to 0.97 g/cm.sup.3, a complex viscosity (at 628 rad/s, 190° C.) of 600 Pa*s or less, a zero shear viscosity by Cross model of 150,000 Pa*s to 350,000 Pa*s. It may also have a V index of less than 7. In some embodiments, an article includes the polyethylene composition. In some embodiments, the article is a pipe.

In some embodiments, a polyethylene composition includes has 80 wt % to 99.9 wt % ethylene content and 20 wt % to 0.1 wt % a C3 to C40 α-olefin comonomer content, based on ethylene content plus comonomer content. The composition has a Mw/Mn of 15 to 45, a density of 0.93 g/cm.sup.3 to 0.97 g/cm.sup.3, a complex viscosity (at 628 rad/s, 190° C.) of 600 Pa*s or less, a zero shear viscosity by Cross model of 150,000 Pa*s to 350,000 Pa*s. It may also have a V index of less than 7. In some embodiments, an article includes the polyethylene composition. In some embodiments, the article is a pipe.

Disclosed is a method for preparing an EVA copolymer with a high ethylene content by solution polymerization under a low to a medium pressure. The method comprises the following steps: initiating with a free radical initiator(s), a copolymerization reaction between ethylene and vinyl acetate in a solvent in a reactor under a low to a medium pressure to obtain the EVA copolymer; and continuing to add ethylene during the reaction to maintain the low to medium pressure, wherein the low to medium pressure is 1-101 MPa, and a ratio of a mass of the vinyl acetate to a mass of the initially added ethylene is (1:1) to (1:20). The amount of ethylene incorporated in the EVA copolymer prepared according to the method is ≥ 50 wt%, and the EVA copolymer has properties equivalent to those of an EVA copolymer obtained by bulk polymerization at high temperature under high pressure.

Disclosed is a method for preparing an EVA copolymer with a high ethylene content by solution polymerization under a low to a medium pressure. The method comprises the following steps: initiating with a free radical initiator(s), a copolymerization reaction between ethylene and vinyl acetate in a solvent in a reactor under a low to a medium pressure to obtain the EVA copolymer; and continuing to add ethylene during the reaction to maintain the low to medium pressure, wherein the low to medium pressure is 1-101 MPa, and a ratio of a mass of the vinyl acetate to a mass of the initially added ethylene is (1:1) to (1:20). The amount of ethylene incorporated in the EVA copolymer prepared according to the method is ≥ 50 wt%, and the EVA copolymer has properties equivalent to those of an EVA copolymer obtained by bulk polymerization at high temperature under high pressure.

A method of preparing a catalyst support comprising contacting an acid-soluble titanium-containing compound with an acid to form a first mixture; contacting the first mixture with an alkali metal silicate to form a hydrogel which has a silica content of from about 18 wt. % to about 35 wt. % based on the total weight of the hydrogel; contacting the hydrogel with an alkaline solution to form an aged hydrogel; washing the aged hydrogel to form a washed hydrogel; and drying the washed hydrogel to produce a titanium-containing-silica support wherein the support has a pore volume equal to or greater than about 1.4 cm.sup.3/g.

A method of preparing a catalyst support comprising contacting an acid-soluble titanium-containing compound with an acid to form a first mixture; contacting the first mixture with an alkali metal silicate to form a hydrogel which has a silica content of from about 18 wt. % to about 35 wt. % based on the total weight of the hydrogel; contacting the hydrogel with an alkaline solution to form an aged hydrogel; washing the aged hydrogel to form a washed hydrogel; and drying the washed hydrogel to produce a titanium-containing-silica support wherein the support has a pore volume equal to or greater than about 1.4 cm.sup.3/g.

A method for evaluating long-term durability of a resin for piping is provided. Unlike the conventional FNCT evaluation method requiring a long period of time, the method disclosed herein is capable of predicting long-term durability of a resin for piping in a short time, by a simple calculation using a content of tie molecules, an entanglement molecular weight (M.sub.e) and a content of ultrahigh molecular weight components. In addition, the olefinic polymer is configured to have a predetermined relationship in relation to the content of tie molecules, the entanglement molecular weight (M.sub.e) and the content of ultrahigh molecular weight components, whereby the polymer of the present application can be used in the manufacture of a heating pipe requiring excellent long-term durability.