Polymerization process control methods for making polyethylene are provided. The process control methods include performing a polymerization reaction in a polymerization reactor to produce the polyethylene, where ethylene, and optionally one or more comonomers, in the polymerization reaction is catalyzed by an electron donor-free Ziegler-Natta catalyst and an alkyl aluminum co-catalyst. A melt flow ratio (I.sub.21/I.sub.2) of the polyethylene removed from the polymerization reactor is measured and an amount of long chain branching (LCB) of the polyethylene from the polymerization reactor is controlled by adjusting a weight concentration of the alkyl aluminum co-catalyst present in the polymerization reactor. In addition, an electron donor-free Ziegler-Natta catalyst productivity of the polyethylene being produced in the polymerization reactor is measured from which the amount of LCB of the polyethylene from the polymerization reactor is determined using the measured electron donor-free Ziegler-Natta catalyst productivity and a predetermined relationship between the electron donor-free Ziegler-Natta catalyst productivity and the LCB.

The present invention relates to an olefin coordination polymerization catalyst and a preparation method and application thereof. The olefin polymerization catalyst consists of a primary catalyst mainly prepared from a magnesium compound, a transition metal halide, a C.sub.2-C.sub.15 alcohol and an electron donor in a molar ratio of 1:1-40:0.01-10:0.001-10, and a co-catalyst which is an organoaluminum compound; and the molar ratio of the transition metal halide to the co-catalyst is 1:10-500. The catalyst of the present invention has a good particle morphology, and a spherical shape, and the catalyst particles do not stick to the vessel wall; the catalyst has high activity and excellent hydrogen regulation performance, and the melt index MFR of polyethylene may be adjusted within 0.01 g/10 min-550 g/10 min; and the catalyst is applicable in slurry polymerization process, loop reactor polymerization process, gas phase polymerization process or combined polymerization process.

The present invention relates to an olefin coordination polymerization catalyst and a preparation method and application thereof. The olefin polymerization catalyst consists of a primary catalyst mainly prepared from a magnesium compound, a transition metal halide, a C.sub.2-C.sub.15 alcohol and an electron donor in a molar ratio of 1:1-40:0.01-10:0.001-10, and a co-catalyst which is an organoaluminum compound; and the molar ratio of the transition metal halide to the co-catalyst is 1:10-500. The catalyst of the present invention has a good particle morphology, and a spherical shape, and the catalyst particles do not stick to the vessel wall; the catalyst has high activity and excellent hydrogen regulation performance, and the melt index MFR of polyethylene may be adjusted within 0.01 g/10 min-550 g/10 min; and the catalyst is applicable in slurry polymerization process, loop reactor polymerization process, gas phase polymerization process or combined polymerization process.

The invention relates to a biaxially oriented polypropylene (BOPP) film comprising a propylene homopolymer or propylene-ethylene copolymer having an ethylene content of at most 1.0 wt % based on the propylene-ethylene copolymer having an Mw/Mn in the range from 5.0 to 12, wherein Mw stands for the weight average molecular weight and Mn stands for the number average weight and wherein Mw and Mn are measured according to ASTM D6474-12, an XS in the range from 1.0 to 6.0 wt %, wherein XS stands for the amount of xylene solubles which are measured according to ASTM D 5492-10, a melt flow rate in the range of 1 to 10 dg/min as measured according to IS01133 (2.16 kg/230° C.) and a crystal size distribution as indicated by a height/width ratio of the highest peak of the first cooling curve of at least 0.70 W/g° C. as determined by ASTM D3418-08 using a heating and cooling rate of 10° C./min.

The invention relates to a biaxially oriented polypropylene (BOPP) film comprising a propylene homopolymer or propylene-ethylene copolymer having an ethylene content of at most 1.0 wt % based on the propylene-ethylene copolymer having an Mw/Mn in the range from 5.0 to 12, wherein Mw stands for the weight average molecular weight and Mn stands for the number average weight and wherein Mw and Mn are measured according to ASTM D6474-12, an XS in the range from 1.0 to 6.0 wt %, wherein XS stands for the amount of xylene solubles which are measured according to ASTM D 5492-10, a melt flow rate in the range of 1 to 10 dg/min as measured according to IS01133 (2.16 kg/230° C.) and a crystal size distribution as indicated by a height/width ratio of the highest peak of the first cooling curve of at least 0.70 W/g° C. as determined by ASTM D3418-08 using a heating and cooling rate of 10° C./min.

The invention relates to a process for the preparation of a heterophasic propylene copolymer consisting of a propylene-based matrix and a dispersed ethylene-a-olefin copolymer, comprising the steps of a) preparing the propylene-based matrix from propylene and optionally a C2 or C4-C12 α-olefin by contacting at least propylene and optionally C2 or C4-C12 a-olefin with a catalyst in a first gas-phase reactor at a temperature T1 and a pressure P1, b) subsequently preparing the dispersed ethylene-α-olefin copolymer from ethylene and a C3-C12 α-olefin by contacting the ethylene and the C3-C12 α-olefin with a catalyst in a second gas-phase reactor at a temperature T2 and a pressure P2, wherein T1-T2 is in the range from 6 to 25° C., wherein T1>T2, wherein PI and P2 are in the range from 22 to 30 bar to prepare a heterophasic propylene copolymer (A′).

The invention relates to a process for the preparation of a heterophasic propylene copolymer consisting of a propylene-based matrix and a dispersed ethylene-a-olefin copolymer, comprising the steps of a) preparing the propylene-based matrix from propylene and optionally a C2 or C4-C12 α-olefin by contacting at least propylene and optionally C2 or C4-C12 a-olefin with a catalyst in a first gas-phase reactor at a temperature T1 and a pressure P1, b) subsequently preparing the dispersed ethylene-α-olefin copolymer from ethylene and a C3-C12 α-olefin by contacting the ethylene and the C3-C12 α-olefin with a catalyst in a second gas-phase reactor at a temperature T2 and a pressure P2, wherein T1-T2 is in the range from 6 to 25° C., wherein T1>T2, wherein PI and P2 are in the range from 22 to 30 bar to prepare a heterophasic propylene copolymer (A′).

A process of producing a composition comprising a copolymer of ethylene and one or more C4-C8 α-olefins, may include copolymerizing the ethylene and the one or more C4-C8 α-olefins in the presence of a procatalyst and an alkylaluminum cocatalyst. The procatalyst may be a Ti-containing Ziegler Natta procatalyst and the polymerization may include the procatalyst and the alkylaluminum cocatalyst in amounts such that a molar ratio of Al:Ti ranges from about 0.5 to about 50.0.

A process of producing a composition comprising a copolymer of ethylene and one or more C4-C8 α-olefins, may include copolymerizing the ethylene and the one or more C4-C8 α-olefins in the presence of a procatalyst and an alkylaluminum cocatalyst. The procatalyst may be a Ti-containing Ziegler Natta procatalyst and the polymerization may include the procatalyst and the alkylaluminum cocatalyst in amounts such that a molar ratio of Al:Ti ranges from about 0.5 to about 50.0.

A polyethylene powder, wherein, when a free induction decay curve obtained by the Carr-Purcell-Meiboom-Gill method in pulsed NMR is subjected to three-component approximation, the relaxation time T of each component and the abundance R of each component satisfy the following <requirement (1)> and <requirement (2)>:

<Requirement (1)>

An entanglement index at 180 C. determined by (formula I) is 12 to 25 ms:

(entanglement index)=T.sub.R.sub./(R.sub.+R.sub.)+T.sub.R.sub./(R.sub.+R.sub.) (formula I) T.sub.: relaxation time (ms) of low-mobility component R.sub.: abundance (%) of low-mobility component T.sub.: relaxation time (ms) of intermediate component R.sub.: abundance (%) of intermediate component
<Requirement (2)>

An intermediate component ratio at 180 C. determined by (formula II) is 0.25 to 0.5:

(intermediate component ratio)=R.sub./(R.sub.+R)(formula II).