Method of production of ethylene-based polymer particles and stretch-molded article obtained from ethylene-based polymer particles

1. A method of production of ethylene-based polymer particles; wherein the method comprises the step of:

homopolymerizing ethylene or copolymerizing ethylene and a linear or branched α-olefin having 3 to 20 carbon atoms in the presence of an olefin polymerization catalyst comprising:

(A) fine particles having an average particle diameter greater than or equal to 1 nm and less than or equal to 300 nm obtained at least by the following two steps:

(Step 1) causing contact between a metal halide and an alcohol in a hydrocarbon solvent wherein the alcohol is a combination of two types of alcohols selected from alcohols having 1 to 25 carbon atoms and difference in carbon number of the two types of alcohols is greater than or equal to 4;

(Step 2) causing contact between a component obtained by (Step 1) and an organoaluminum compound and/or an organoaluminumoxy compound; and

(B) a transition metal compound represented in following General Formula (I) or (II):

wherein in Formula (I), M is a transition metal atom of Group 4 or 5 in the periodic table;

m is an integer ranging from 1 to 4;

R 1 to R 5 are the same or different and are a hydrogen atom, halogen atom, hydrocarbon group, heterocyclic compound residue, oxygen-containing group, nitrogen-containing group, boron-containing group, sulfur-containing group, phosphorous-containing group, silicon-containing group, germanium-containing group, or tin-containing group, wherein a ring is optionally formed by bonding together of at least 2 such groups;

R 6 is selected from the group consisting of a hydrogen atom, hydrocarbon groups having 1 to 4 carbon atoms and composed of only primary or secondary carbon atoms, aliphatic hydrocarbon groups having at least 4 carbon atoms, aryl group-substituted alkyl groups, monocyclic or bicyclic alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and halogen atoms;

n is a number satisfying valence number of M;

X is a hydrogen atom, halogen atom, hydrocarbon group, oxygen-containing group, sulfur-containing group, nitrogen-containing group, boron-containing group, aluminum-containing group, phosphorous-containing group, halogen-containing group, heterocyclic compound residue, silicon-containing group, germanium-containing group, or tin-containing group; wherein multiple groups indicated by X may be the same or different when n is greater than or equal to 2; and optionally multiple groups indicated by X form a ring by mutual bonding

wherein in Formula (II), M is titanium, zirconium, or hafnium;

R 11 to R 18 may be the same or different and are a hydrogen atom, halogen atom, hydrocarbon group, heterocyclic compound residue, oxygen-containing group, nitrogen-containing group, boron-containing group, sulfur-containing group, phosphorous-containing group, silicon-containing group, germanium-containing group, or tin-containing group, wherein two or more adjacent groups may be optionally bonded together to form a ring;

X 1 and X 2 are the same or different and are a hydrocarbon group, oxygen-containing group, sulfur-containing group, silicon-containing group, hydrogen atom, or halogen atom; and

Y is a divalent hydrocarbon group, divalent halogenated hydrocarbon group, divalent silicon-containing group, divalent germanium-containing group, divalent tin-containing group, —O—, —CO—, —S—, —SO—, —SO 2 —, —Ge—, —Sn—, —NR—, —P(R)—, —P(O)(R)—, —BR—, or —AlR— wherein R is the same or different and is a hydrogen atom, halogen atom, hydrocarbon group, halogenated hydrocarbon group, or alkoxy group; and

wherein an intrinsic viscosity [η] of the ethylene-based polymer particles, measured in decalin at 135° C., is from 5 to 50 dL/g.

2. The method of production of ethylene-based polymer particles according to claim 1 ; wherein the two types of alcohols are a combination of an alcohol having 2 to 12 carbon atoms and an alcohol having 13 to 25 carbon atoms.

3. The method of production of ethylene-based polymer particles according to claim 1 ; wherein the two types of alcohols are a combination of two types of alcohols selected from alcohols having 2 to 12 carbon atoms.

4. The method of production of ethylene-based polymer particles according to claim 1 ; wherein M in General Formula (I) of the transition metal compound (B) is a transition metal atom of Group 4 in the periodic table;

m is 2;

R 1 is a group selected from linear or branched hydrocarbon groups having 1 to 20 carbon atoms, alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and aromatic hydrocarbon groups having 6 to 20 carbon atoms;

R 2 to R 5 may be the same or different and are a hydrogen atom, halogen atom, or hydrocarbon group;

R 6 is selected from aliphatic hydrocarbon groups having at least 5 carbon atoms, aryl group-substituted alkyl groups, monocyclic or bicyclic alicyclic hydrocarbon groups, and aromatic hydrocarbon groups; and

X is a hydrogen atom, halogen atom, or hydrocarbon group.

5. The method of production of ethylene-based polymer particles according to claim 1 ; wherein the homopolymerization of ethylene, or the copolymerization of ethylene with a linear or branched α-olefin having 3 to 20 carbon atoms, is performed in a multi-stage polymerization.

6. Ethylene-based polymer particles obtained by the production method according to claim 1 ; wherein an average particle diameter of the ethylene-based polymer particles is within a range greater than or equal to 10 nm and less than 3,000 nm.

7. A method of production of a stretch-molded article comprising forming a stretch-molded article from ethylene-based polymer particles obtained by the production method according to claim 1 .

8. A method of production of a stretch-molded article according to claim 7 obtained by a solid-phase stretch-molding method.

9. A stretch-molded article obtained by the method according to claim 7 .