A method capable of stably performing continuous production of a propylene polymer with high productivity while reducing generation of agglomerates is described. In the method, a monomer(s) containing propylene is/are (co)polymerized in a presence of an olefin polymerization catalyst with a polymerization system containing two or more gas phase polymerization reactors or a polymerization system containing a liquid phase polymerization reactor(s) and a gas phase polymerization reactor(s) such that that the total number of liquid phase polymerization reactor(s) and gas phase polymerization reactor(s) is three or more. In at least one gas phase polymerization reactor, an average retention time τ.sub.G [hour] in the gas phase polymerization, an average particle diameter D.sub.pi [μm] of fed powder, and a total amount C.sub.o [wt %] of an ethylene-derived structural unit and C4-C12 α-olefin-derived structural units in a polymer in discharged powder are in a predetermined relationship.

To provide a solid catalyst component for olefin polymerization having a small amount of fine powder. A solid catalyst component for olefin polymerization containing a titanium atom, a magnesium atom, a halogen atom, and an internal electron donor. The solid catalyst component has an absolute difference in binding energy of 73.50 to 75.35 eV between a peak (1) with the binding energy of 457.00 to 459.00 eV and a peak (2) with the binding energy of 532.50 to 534.50 eV. The peak (1) and the peak (2) are within peak components measured by X-ray photoelectron spectroscopy, the peak (1) is obtained by waveform separation of peaks assigned to the 2p orbitals of the titanium atom, and the peak (2) is obtained by waveform separation of peaks assigned to the is orbital of an oxygen atom.

To provide a solid catalyst component for olefin polymerization having a small amount of fine powder. A solid catalyst component for olefin polymerization containing a titanium atom, a magnesium atom, a halogen atom, and an internal electron donor. The solid catalyst component has an absolute difference in binding energy of 73.50 to 75.35 eV between a peak (1) with the binding energy of 457.00 to 459.00 eV and a peak (2) with the binding energy of 532.50 to 534.50 eV. The peak (1) and the peak (2) are within peak components measured by X-ray photoelectron spectroscopy, the peak (1) is obtained by waveform separation of peaks assigned to the 2p orbitals of the titanium atom, and the peak (2) is obtained by waveform separation of peaks assigned to the is orbital of an oxygen atom.

A polypropylene comprising a xylene soluble fraction of 1.5 wt % by weight of the polymer and soluble fraction or less, wherein the polypropylene has a melt flow rate within a range from 50 g/10 min to 500 g/10 min and a flexural modulus within a range from 1780 MPa to 2200 MPa. The polypropylene is preferably made from contacting propylene with a solid magnesium/titanium catalyst component that has been washed at least once with a solvent having a desirable solubility parameter.

A polypropylene comprising a xylene soluble fraction of 1.5 wt % by weight of the polymer and soluble fraction or less, wherein the polypropylene has a melt flow rate within a range from 50 g/10 min to 500 g/10 min and a flexural modulus within a range from 1780 MPa to 2200 MPa. The polypropylene is preferably made from contacting propylene with a solid magnesium/titanium catalyst component that has been washed at least once with a solvent having a desirable solubility parameter.

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′).

Disclosed is a method for preparing a solid catalyst for propylene polymerization, and more specifically, a method for preparing a solid catalyst for propylene polymerization including (1) first reacting dialkoxy magnesium and titanium halide compound under the presence of an organic solvent; (2) adding two kinds of non-aromatic internal electron donors to a product of the step (1) and reacting the mixture; and (3) second reacting the product of the step (2) with a titanium halide compound and washing a reaction product. The catalyst prepared according to the method as described in the present disclosure not only may provide high catalytic activity, but also may provide a propylene polymer having excellent stereoregularity.

Disclosed is a method for preparing a solid catalyst for propylene polymerization, and more specifically, a method for preparing a solid catalyst for propylene polymerization including (1) first reacting dialkoxy magnesium and titanium halide compound under the presence of an organic solvent; (2) adding two kinds of non-aromatic internal electron donors to a product of the step (1) and reacting the mixture; and (3) second reacting the product of the step (2) with a titanium halide compound and washing a reaction product. The catalyst prepared according to the method as described in the present disclosure not only may provide high catalytic activity, but also may provide a propylene polymer having excellent stereoregularity.

Provided is a solid catalyst component for olefin polymerization comprising an electron-donating compound other than a phthalate, the solid catalyst component being equal in the olefin-polymerizing activity and in the primary physical properties of the resulting polymer such as stereoregularity and molecular weight distribution to those with use of a phthalate as an electron-donating compound. A solid catalyst component for olefin polymerization comprises a magnesium atom, a titanium atom, a halogen atom, an ester compound (A) represented by a general formula (1) and a diester compound (B) represented by a general formula (2), wherein

a ratio represented by the following expression:

(content (mass %) of ester compound (A)/content (mass %) of diester compound (B))

is 0.05 to 50.