13 results about "Natta" patented technology

A solution-phase polymerization process using a metallocene catalyst in the first reactor and a Ziegler-Natta catalyst in the second reactor yielded 0.942 g / cm³. 3 A high-density polyethylene composition is obtained having a density and a melt index I2 exceeding 5.0 g / 10 min. When prepared into plaque, the high-density polyethylene resin has an environmental stress crack resistance (ESCR) exceeding 1000 hours (determined by ASTM D1693 in 100% IGEPAL CO-630 under condition B) and an IZOD impact strength of 10 feed-pounds / inch or more. The polyethylene composition containing the first and second ethylene copolymers is relatively easy to process and can be used in the manufacture of molded articles.

The invention relates to a gas-phase olefin polymerisation process comprising the steps of: (a) operating the process in the presence of a Ziegler-Natta catalyst system (ZN1) in a continuous way, wherein stream (10), comprising unreacted and inert materials, is (partially) circulated back into the reactor; (b) discontinuing the circulation of stream (10) back into the reactor; (c) gradually discontinuing the introduction of ZN1 while at the same time gradually introducing a Ziegler-Natta catalyst system (ZN2) into the reactor so that the polymer production rate is kept at a rate not less than 30% below the production rate as in step (a); and (d) after the introduction of ZN1 is discontinued and the feed of ZN2 is at its full rate, resuming (partially) recirculation of stream (10) back into the reactor; wherein ZN1 comprises an internal electron donor moiety that reduces the polymerization activity of ZN2.

According to the silicon-magnesium composite Ziegler-Natta catalyst carrier and the preparation method thereof provided by the invention, a spherical silica gel carrier is prepared by using a spray drying method, then porous silicon spheres with good morphology and pore structure are obtained after high-temperature activation, and then magnesium source loading is carried out, so that the silicon-magnesium composite Ziegler-Natta catalyst carrier is obtained. The finally prepared silicon-magnesium composite Ziegler-Natta catalyst carrier successfully overcomes the defects of the existing preparation technology in morphology perfection and particle size uniformity. The method provided by the invention is simple in process, easy to operate, low in cost and easy for industrial production, and the prepared porous silicon spheres have the advantages of large specific surface area, controllable pore structure, high mechanical strength and the like; the prepared silicon-magnesium composite Ziegler-Natta catalyst carrier is used for olefin polymerization reaction, and has the advantages of high effective titanium loading rate, good polymerization product perfectness, good other properties and the like.

The present invention relates to a process for preparing a heterophasic polypropylene composition by a multi-stage polymerization process using a Ziegler-Natta catalyst. The prepared heterophasic polypropylene composition comprises ethylene and 1-butene comonomer units. The method is characterized in that the 1-butene comonomer is effectively utilized in the process of preparing the heterophasic polypropylene composition.

The invention relates to the technical field of olefin polymerization, discloses a method for improving gas-phase copolymerization activity of propylene and alpha-olefin and a polymer, and aims to solve the problems of low polymerization activity and non-uniform rubber phase distribution caused by residual inhibitory activity center of an external electron donor in a copolymerization stage of a conventional Ziegler-Natta catalyst. The preparation method comprises the following steps: pre-complexing, pre-polymerizing, carrying out two-stage polymerization and post-treating, firstly, pre-complexing and pre-polymerizing a titanium Z-N catalyst, triethyl aluminum and cyclohexylmethyldimethoxysilane, and then carrying out first-stage propylene homopolymerization to obtain a high-isotacticity intermediate; after transition treatment, a mixture of a compound activity accelerant and triethyl aluminum is added into the second-stage gas-phase reactor, gas-phase copolymerization is performed under certain conditions, the compound activity accelerant and alkyl aluminum synergistically peel off an external electron donor and release an inhibited active center, so that the activity in the copolymerization stage is improved by 50% or above, and the method is adaptive to an existing industrial device and has a wide application prospect. The method is suitable for the fields of high-end automobile parts, household appliance shells and the like.

The invention relates to a powdery ethylene homopolymer with a high melt index, which has a melt index of 600-2500g / 10min, a molecular mass distribution of 3.0-10.0, a melting point of 115-135 DEG C, a true density of 0.950-0.980 g / cm < 3 >, a crystallinity of 70-95%, a bulk density of 0.30-0.55 g / cm < 3 > and an average particle size of 50-500mm under a load of 2.16 kg and a temperature of 190 DEG C, and under an ethylene kettle slurry polymerization condition, a Ziegler type catalyst and a Ziegler-Natta type catalyst are used as main catalysts, according to the preparation method, ethylene is subjected to kettle type slurry homopolymerization under the conditions that the polymerization temperature of ethylene and hydrogen is 70-100 DEG C, the polymerization pressure is 1.0-4.2 MPa and the molar ratio of hydrogen to ethylene in a gas phase of a reaction kettle is (2.0-7.0): 1 by taking ethylene as a raw material, alkyl aluminum or halogenated alkyl aluminum as a cocatalyst and straight-chain alkane, branched-chain-containing alkane, cycloalkane and branched-chain-containing cycloalkane as a polymerization solvent, the preparation method is simple and easy to control, and the obtained ethylene homopolymer has high melt index, true density, melting point and crystallinity and narrow particle size distribution.

A process for preparing a procatalyst for polymerization of olefins, comprising contacting a magnesium-containing support with a halogen-containing titanium compound, and an internal electron donor according to Formula (I), said process comprising the steps of: i) contacting a compound R4zMgX42-z with an alkoxy- or aryloxy-containing silane compound to give a first intermediate reaction product, being a solid Mg(OR1)xX12-x, ii) optionally contacting the solid Mg(OR1)xX1 2-x obtained in step ii) with at least one activating compound selected from the group formed by activating electron donors and metal alkoxide compounds of formula M1(OR2)v-w(OR3)w or M2(OR2)v-w(R3)w, to obtain a second intermediate product; iii) contacting the first or second intermediate reaction product, obtained respectively in step i) or ii), with a halogen-containing Ti-compound and said compound represented Formula (I), as the internal electron donor.

The present invention provides a method for transitioning between a Ziegler-Natta catalyst and a single-site catalyst during the production of a polypropylene homopolymer or copolymer in a continuous multi-stage polymerization reaction, comprising: 1. A process for transitioning between a Ziegler-Natta catalyst and a single-site catalyst during the production of a polypropylene homopolymer or copolymer in a continuous multi-stage polymerization reaction, comprising: a) polymerizing propylene and optionally a comonomer in the presence of a Ziegler-Natta catalyst in a first reactor and thereafter in a second reactor; b) ceasing the supply of the Ziegler-Natta catalyst into the first reactor; c) ceasing the supply of external donor to the Ziegler-Natta catalyst and reducing the supply of Ziegler-Natta cocatalyst into the first reactor, wherein step c) is carried out at least 5 minutes, preferably 5 to 60 minutes, after step b); d) reducing the solids content of the second reactor from the first operating level to a transition level in the range of 40 to 80% relative to the first operating level prior to step d); e) introducing the single-site catalyst into the first reactor, wherein step e) occurs at least 30 minutes, preferably 30 minutes to 2 hours, after step d); and f) increasing the solids content of said second reactor to a second operating level, preferably to the same level as before step d). The present invention relates to the above method, which comprises the steps of:

A process for producing a cap or closure comprising obtaining a polypropylene composition by sequential polymerization comprising the steps: A) polymerizing in a first reactor, preferably a slurry reactor, in the presence of a Ziegler-Natta catalyst monomers comprising propylene and optionally one or more comonomers selected from ethylene and C4-C10 alpha-olefins, to obtain a first propylene polymer fraction having a comonomer content in the range of 0.0 to 1.8 wt %, and a MFR2 in the range of from 12.0 to 40.0 g / 10 min, as measured according to ISO 1133 at 230° C. under a load of 2.16 kg; B) polymerizing in a second reactor, preferably a first gas-phase reactor, monomers comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins, in the presence of the first propylene polymer fraction, to obtain a second propylene polymer fraction, wherein the polypropylene composition comprising said first and second propylene polymer fractions has an MFR2 in the range of from 12.0 to 60.0 g / 10 min, as measured according to ISO 1133 at 230° C. under a load of 2.16 kg, has a comonomer content in the range of from 2.2 to 5.0 wt % and wherein the ratio of the comonomer content of component A) to the comonomer content of the polypropylene composition is 0.35 or less, C) melting, extruding and moulding the polypropylene composition in the presence of at least one nucleating agent to prepare a cap or closure; and D) exposing the cap or closure obtained in step (C) to a cooling rate of 50 K / s or more.

The application belongs to the technical field of polymer preparation, and discloses a preparation method of butene-1 polymer, which comprises the following steps: under the action of a Ziegler-Natta catalyst system, 1-butene and optional C2-C 10 α-olefin monomers are subjected to a polymerization reaction; the polymer solution is fully contacted with a deactivator, and is subjected to pressurization and temperature increase to obtain a supercritical polymer solution; 3) devolatilization treatment is performed to obtain a polymer melt; the Ziegler-Natta catalyst system comprises component A, component B and component C; component A is a solid catalyst component containing Ti and an internal electron donor and loaded with protected alkoxy magnesium particles; component B is a mixture of organic aluminum and an antioxidant, and the molar ratio of the organic aluminum and the antioxidant is 1:(1-100); and component C is an external electron donor. The method has low cost and low energy consumption, and the polymer has excellent performance and good antioxidant performance.

This invention discloses a method for controlling the molecular weight distribution in the production of low-pressure high-density polyethylene, which relates to the field of polymer material polymerization production technology, including the following steps: (1) Catalyst pre-activation: Select Ziegler-Natta catalyst or chromium-based catalyst and activate it at 90-110℃ for 2-4 hours under an inert atmosphere; (2) Preparation of composite molecular weight regulator: It is prepared by compounding α-methylstyrene dimer and thiol compounds at a weight ratio of 80-90:10-20; (3) Two-stage polymerization: The temperature of the first stage is 70-80℃, and the hydrogen concentration is 0.5-1.0 mol%, generating high molecular weight segments; the temperature of the second stage is 85-95℃, and the hydrogen concentration is 1.5-2.5 mol%, and the composite regulator is added online to generate low molecular weight segments; (4) Post-treatment: After degassing, drying and granulation, HDPE products with controllable molecular weight distribution are obtained, which solves the problems of low control precision, large fluctuation and poor compatibility of traditional processes.