Abstract: An object of the invention is to provide an ethylene-based polymer excellent in moldability and durability, and also excellent in the balance of stiffness and durability, and to provide a molded product of hollow plastic using the ethylene-based polymer. The ethylene-based polymer according to the invention is an ethylene-based polymer having specific characteristics and manufactured by a homopolymerization of ethylene or a copolymerization of ethylene and ?-olefin using a chromium catalyst.

Abstract: The object of the present invention is to provide a production method for a polyolefin, in which catalyst activity is improved, and a polyolefin such as a linear low density polyethylene can advantageously be industrially produced. The present invention relates to a production method for a polyolefin, in which in producing a polyolefin by the polymerization reaction of an olefin using a catalyst, an organohalide is present in the reaction system in an amount of from 0.05 to 10 ppm by weight in terms of the halogen atom as a concentration in a raw material olefin, and 1-hexene for linear low density polyethylene production raw material, containing an organohalide in an amount of from 0.05 to 10 ppm by weight in terms of the halogen atom.

Abstract: A polyethylene based resin exhibiting excellent moldability and durability and having an excellent balance between impact resistance and stiffness; and a hollow plastic molded article using the foregoing resin, which exhibits excellent moldability, durability and barrier properties and has an excellent balance between impact resistance and stiffness, are provided. The polyethylene based resin satisfies the following requirements (1) to (4): (1) a high-load melt flow rate (HLMFR) is from 1 to 100 g/10 min; (2) a density is from 0.940 to 0.960 g/cm3; (3) a strain hardening parameter ?max of elongational viscosity is from 1.05 to 1.50; and (4) a rupture time in a full notch tensile creep test and a density satisfy the following relational expression (A): log(rupture time)??355×(density)+337.6(A).

Abstract: A sliding door device which a sliding door is inserted into the guide portion in one direction of the sliding direction as an insertion direction upon assembling. A rack gear includes a plurality of standard teeth arranged along the sliding door, and a thick tooth having a larger width, along the sliding door, than those of the standard teeth and being disposed in a left/right symmetrical position with respect to a center in the sliding door. A pinion gear includes a single large tooth groove engaged with the thick tooth, and a short tooth having a length shorter than those of the other teeth while abutting onto a tooth tip of the thick tooth positioned at a rear side of the insertion direction, from among the respective thick teeth.

Abstract: An object of the invention is to provide an ethylene-based polymer excellent in moldability and durability, and also excellent in the balance of stiffness and durability, and to provide a molded product of hollow plastic using the ethylene-based polymer. The ethylene-based polymer according to the invention is an ethylene-based polymer having specific characteristics and manufactured by a homopolymerization of ethylene or a copolymerization of ethylene and ?-olefin using a chromium catalyst.

Abstract: The polyethylene of the invention is polymerized using a chromium catalyst, and has a weight average molecular weight (Mw) of 30,000 or more at the maximum value in a branching degree distribution curve that shows a molecular weight dependency of short chain branches having 4 or more carbon atoms.

Abstract: A polyethylene based resin exhibiting excellent moldability and durability and having an excellent balance between impact resistance and stiffness; and a hollow plastic molded article using the foregoing resin, which exhibits excellent moldability, durability and barrier properties and has an excellent balance between impact resistance and stiffness, are provided. The polyethylene based resin satisfies the following requirements (1) to (4): (1) a high-load melt flow rate (HLMFR) is from 1 to 100 g/10 min; (2) a density is from 0.940 to 0.960 g/cm3; (3) a strain hardening parameter ?max of elongational viscosity is from 1.05 to 1.50; and (4) a rupture time in a full notch tensile creep test and a density satisfy the following relational expression (A): log (rupture time)??355×(density)+337.6 (A).

Abstract: A sliding door device which a sliding door is inserted into the guide portion in one direction of the sliding direction as an insertion direction upon assembling. A rack gear includes a plurality of standard teeth arranged along the sliding door, and a thick tooth having a larger width, along the sliding door, than those of the standard teeth and being disposed in a left/right symmetrical position with respect to a center in the sliding door. A pinion gear includes a single large tooth groove engaged with the thick tooth, and a short tooth having a length shorter than those of the other teeth while abutting onto a tooth tip of the thick tooth positioned at a rear side of the insertion direction, from among the respective thick teeth.

Abstract: The object of the present invention is to provide a production method for a polyolefin, in which catalyst activity is improved, and a polyolefin such as a linear low density polyethylene can advantageously be industrially produced. The present invention relates to a production method for a polyolefin, in which in producing a polyolefin by the polymerization reaction of an olefin using a catalyst, an organohalide is present in the reaction system in an amount of from 0.05 to 10 ppm by weight in terms of the halogen atom as a concentration in a raw material olefin, and 1-hexene for linear low density polyethylene production raw material, containing an organohalide in an amount of from 0.05 to 10 ppm by weight in terms of the halogen atom.

Abstract: A method for producing an ethylene polymer which comprises continuously polymerizing ethylene alone or copolymerizing ethylene and a C3-C8 ?-olefin by multistage polymerization in a plurality of polymerization reactors connected in series in the presence of a chromium catalyst having at least a part of chromium atoms converted to hexavalent chromium carried on an inorganic oxide carrier by calcination-activating in a non-reducing atmosphere, wherein an organoaluminum compound of the formula (1): (R1)xAl(OR2)y(OSiR3R4R5)z??(1) (in the above formula, R1 and R2 may be the same or different, each represents a C1-C18 alkyl group or a C6-C18 aryl group, R3, R4 and R5 may be the same or different, each represents a C1-C18 alkyl group or a C6-C18 aryl group, R1, OR2 and OSiR3R4R5 respectively may be the same or different when each has a plurality of kinds, and x, y and z are respectively 0?x?3, 0?y<3, 0?z<3, and x+y+z=3) is introduced at least one or all of the polymerization reactors.

Abstract: A method for producing an ethylene polymer which comprises continuously polymerizing ethylene alone or copolymerizing ethylene and a C3-C8 ?-olefin by multistage polymerization in a plurality of polymerization reactors connected in series in the presence of a chromium catalyst having at least a part of chromium atoms converted to hexavalent chromium carried on an inorganic oxide carrier by calcination-activating in a non-reducing atmosphere, wherein an organoaluminum compound of the formula (1): (R1)xAl(OR2)y(OSiR3R4R5)z??(1) (in the above formula, R1 and R2 may be the same or different, each represents a C1-C18 alkyl group or a C6-C18 aryl group, R3, R4 and R5 may be the same or different, each represents a C1-C18 alkyl group or a C6-C18 aryl group, R1, OR2 and OSiR3R4R5 respectively may be the same or different when each has a plurality of kinds, and x, y and z are respectively 0?x?3, 0?y<3, 0?z<3, and x+y+z=3) is introduced at least one or all of the polymerization reactors.

Abstract: The invention relates to a method for producing an ethylene polymer, comprising performing polymerization of ethylene in co-presence of hydrogen using a trialkylaluminum compound-carried chromium catalyst, wherein the chromium catalyst is obtained by calcination-activating a chromium compound that is carried on an inorganic oxide carrier in a non-reducing atmosphere to convert chromium atoms in the chromium compound into hexavalent chromium atoms for at least a portion thereof, and treating with a trialkylaluminum compound in an inert hydrocarbon solvent to carry thereon and removing to dry the solvent so that the chromium atoms are not over-reduced by the trialkylaluminum compound, and to an ethylene polymer suitable for blow molded articles obtained by the production method. The ethylene polymer of the invention have improved environment stress crack resistance (ESCR) and impact resistance in a good balance and are suitable for molded blow articles, in particular large size blow molded articles.

Abstract: A catalyst for the production of an ethylene polymer comprising a specific trivalent alkyl chromium compound, an inorganic oxide solid and optionally an organoaluminum compound (first catalyst), a catalyst for the production of an ethylene polymer comprising the specific trivalent alkyl chromium compound, a specific tetravalent alkyl chromium compound and an inorganic oxide solid (second catalyst) and a process for producing an ethylene polymer using those catalysts. The first catalyst of the present invention does not cause deterioration with the passage of time, is stable to heat and light, has greatly improved activity and can efficiently produce an ethylene copolymer with &agr;-olefin.

Abstract: The invention relates to a method for producing an ethylene polymer, comprising performing polymerization of ethylene in co-presence of hydrogen using a trialkylaluminum compound-carried chromium catalyst, wherein the chromium catalyst is obtained by calcination-activating a chromium compound that is carried on an inorganic oxide carrier in a non-reducing atmosphere to convert chromium atoms in the chromium compound into hexavalent chromium atoms for at least a portion thereof, and treating with a trialkylaluminum compound in an inert hydrocarbon solvent to carry thereon and removing to dry the solvent so that the chromium atoms are not over-reduced by the trialkylaluminum compound, and to an ethylene polymer suitable for blow molded articles obtained by the production method. The ethylene polymer of the invention have improved environment stress crack resistance (ESCR) and impact resistance in a good balance and are suitable for molded blow articles, in particular large size blow molded articles.

Abstract: A polymerization catalyst which exhibits a high activity and a good hydrogen response and thus is suitable for the production of an ethylene polymer having a wide molecular weight range can be obtained by a method using a chromium compound, an organic aluminum compound and a carrier and comprising the following steps (a) to (d): (a) contacting a chromium compound with a carrier in the presence or absence of a solvent; (b) adding an organic aluminum compound to said contacted substances at a temperature of not higher than 60° C. in an amount such that the mixing ratio of said organic aluminum compound to said chromium compound falls within the range of from 0.5/1 to 100/1 as calculated in terms of the ratio of aluminum atom/chromium atom (Al/Cr molar ratio) and that the following relationship (1) is satisfied: log10t≦0.33log10C+0.

Abstract: A blow-moldable or extrudable ethylene polymer having an excellent moldability which gives a molded product free of roughened surface, having: a number-average molecular weight Mn (V1) as determined from the amount of a terminal vinyl group by .sup.13 C-NMR measurement with respect to a fraction having a number-average molecular weight Mn of 100,000 according to GPC; and a number-average molecular weight Mn (V2) as determined from the amount of a terminal vinyl group by .sup.13 C-NMR measurement with respect to a fraction having a number-average molecular weight Mn of 10,000 according to GPC, Mn(V1) and Mn(V2) satisfying the following relationship:1.01.ltoreq.log.sub.10 {Mn(V1)/Mn(V2)}.ltoreq.3.0and having a melt flow rate (HLMFR) of from 0.1 to 70 g/10 min.

Abstract: An ethylene base polymer and a preparation method of an ethylene base polymer characterized in use of a catalyst comprising a chromium amide compound, a solid inroganic oxide calcined at 100 to 500.degree. C. and alumoxane. According to the present invention, an ethylene base polymer with a wide molecular weight distribution, excellent shock and environmental stress cracking resistances, causing no melt fracture, and suitable for film forming and blow molding can be effectively prepared.

Abstract: A process for the production of ethylenic polymers is disclosed in which an ethylenic monomer is polymerized in the presence of a catalyst comprising a chromium compound, an alumoxane and an organometallic alkoxide and/or organometallic siloxide and a carrier supporting thereon these compounds. The resultant polymer has a balanced proportion of rigidity and environmental stress cracking resistance (ESCR) and an excellent moldability property.

Abstract: An ethylenic polymerization catalyst comprising (A) a chromium compound, (B) a carrier, (C) aluminoxane, and (D) a transition metal compound comprising a group having conjugated .pi. electron as a ligand, wherein said chromium compound (A) is not calcined; and a process for producing an ethylenic polymer comprising a step of polymerizing a monomer comprising ethylene in the presence of the ethylenic polymerization catalyst.

Abstract: A metallocene having an asymmetric ligand which is represented by the formula below and its enantiomer: ##STR1## and a process for producing a polyolefin using the same as a catalyst component. The metallocene and its enantiomer are particularly effective in the production of highly stereospecific polyolefins.