JP2000086833A - High density polyethylene resin composition for injection stretch blow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide resin compositions suitable for injection stretch blow molding at a high stretch ratio, capable of giving molded bottles high in rigidity and excellent in environmental stress resistance due to the absence of pinch-off and of satisfactorily responding to the need of dealing with lightweight of bottles in recent years. SOLUTION: Injection stretch blow molding resin compositions comprise (A) 100 pts.wt. metallocene ethylene polymer polymerized by a titanocene catalyst which has a melt index of 2-20 g/10 min and a density of not less than 0.950 g/cm3 and (B) 5-40 pts.wt. ethylene polymer polymerized by a chromium catalyst which has a melt index of 0.05-2 g/10 min and a density of not less than 0.95 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-density polyethylene resin composition suitable for injection stretch blow molding at a high stretching ratio. More specifically, the present invention relates to a high-density polyethylene resin composition for injection stretch blow molding comprising a specific ethylene polymer.

[0002]

2. Description of the Related Art Polyethylene resin is inexpensive and has excellent mechanical strength, and is therefore used as a material for various containers, and is particularly frequently used in direct blow bottles. However, at present, almost no polyethylene resin is used in an injection stretch blow bottle represented by polyethylene terephthalate or the like. Compared with the direct blow bottle, the injection stretch blow bottle of polyethylene resin has no pinch-off portion in the bottle, and therefore has excellent environmental stress crack resistance and impact characteristics, and can be expected to reduce the weight of the polyethylene resin bottle. One reason that polyethylene resin is hardly used in injection stretch blow molding is that it is difficult to release the bottomed parison formed in the injection stretch blow molding step of polyethylene resin at high temperatures. However, recent advances in molding technology and the like have made possible the high-temperature release of the bottomed parison formed in the injection stretch blow molding process, and it is now at the stage where it is practically used in injection stretch blow molding of polyethylene resin at a low draw ratio. It is getting.

In order to provide a polyethylene resin for injection stretch blow molding, for example, JP-A-59-1400
No. 33 and JP-A-9-194534 disclose polyethylene resins having a large flow ratio. However, when a bottomed parison is stretch-blow-molded at a high draw ratio using these polyethylene resins, the bottomed parison does not stretch uniformly and it is difficult to form a bottle. Japanese Patent Application Laid-Open No. 9-216915 discloses a low-density polyethylene resin. However, an injection-stretched blow-molded bottle molded using the polyethylene resin has insufficient buckling strength of the bottle. However, there is a problem that the bottomed parison cannot be stretched uniformly because the flow ratio is too small.

In the case of the polyethylene resin, it is impossible to satisfy both the melt viscosity required in the injection step and the melt viscosity required for stretch blow. Therefore, in the conventional injection stretch blow molding using a polyethylene resin, the range of molding conditions is extremely narrow, and it is possible to mold only an injection stretch blow molded bottle having a low stretching ratio.
Therefore, at present, a high-density polyethylene resin for injection stretch blow molding has not been provided which is satisfactory in terms of moldability at a high draw ratio, appearance such as surface gloss, and mechanical strength of a bottle.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention enables stretch blow molding at a high draw ratio, which cannot be achieved with conventional polyethylene resins, and provides the surface gloss of a molded bottle and An object of the present invention is to provide a high-density polyethylene resin composition for injection stretch blow molding having excellent buckling strength.

[0006]

Means for Solving the Problems The present inventors have made intensive studies on a high-density polyethylene resin composition for injection stretch blow molding, and as a result, have found that a specific polyethylene resin composition can solve the above-mentioned problems. Was completed. That is, the present invention is a high-density polyethylene resin composition for injection stretch blow molding under a high stretching ratio, comprising the following specific polyethylene resin composition. (A) 100 parts by weight of a metallocene ethylene polymer polymerized by a titanocene catalyst having a melt index of 2 to 20 g / 10 min and a density of 0.950 g / cm ³ or more;
(B) a melt index of 0.05 to 2 g / 10 minutes,
A high-density polyethylene resin composition for injection stretch blow molding, comprising 2 to 40 parts by weight of an ethylene polymer polymerized by a chromium catalyst having a density of 0.950 g / cm ³ or more.

Hereinafter, the present invention will be described in detail. The high-density polyethylene resin composition for injection stretch blow molding of the present invention is a composition of a specific ethylene polymer. That is, the melt viscosity required in the injection step and the uniform stretchability of the bottomed parison are imparted. (A) A specific metallocene ethylene polymer and the melt viscosity required in the stretch blow step are imparted. And a polyethylene resin composition comprising the obtained ethylene polymer.

Hereinafter, the specific metallocene ethylene polymer (A) will be described. The metallocene ethylene polymer used in the present invention is a specific range of an ethylene polymer polymerized by a titanocene catalyst. The ethylene polymer is an ethylene homopolymer or a copolymer with an α-olefin having 3 to 20 carbon atoms, preferably 4 to 20 carbon atoms. In particular, the metallocene ethylene polymer used in the present invention,
From the viewpoint of the buckling strength of the bottle obtained by injection stretch blow molding, ethylene homopolymer is preferred. Examples of the α-olefin having 3 to 20 carbon atoms as a comonomer of the ethylene copolymer include propylene, butene-1, pentene-1,
3-Methylbutene-1, hexene-1, 4-methylpentene-1, octene-1, decene-1, tetradecene-1, hexadecene-1, octadecene-1, eicosen-1 and the like can be used. Further, vinyl compounds such as vinylcyclohexane or styrene and derivatives thereof can also be used. If necessary, a tertiary random polymer containing a small amount of a non-conjugated polyene such as 1,5-hexadiene and 1,7-octadiene may be used. The density of these ethylene homopolymers or ethylene copolymers is 0.1.
950 g / cm ³ or more, preferably 0.955 g / cm ^3
3 or more, more preferably 0.960 g / cm ³ or more. The density here is determined by measuring the strand obtained at the time of melt index measurement in accordance with JIS-K-7112, and
Heat treatment was performed at 00 ° C. for 1 hour, and after cooling at room temperature for 1 hour, measurement was performed using a density gradient tube. When the density of the metallocene ethylene polymer is less than 0.950 g / cm ³ , the buckling strength of the bottle obtained by injection stretch blow molding is insufficient, and the gloss of the bottle surface is reduced.

The (A) metallocene ethylene polymer used in the present invention has a melt index (MI _2.16 ) at 190 ° C. under a load of 2.16 kg of 2 to 20 g / 10 g.
Min, preferably 3 to 15 g / 10 min, more preferably 4 to 10 g / 10 min. When the MI _2.16 is less than 2 g / 10 minutes, the fluidity of the polyethylene resin composition in the injection molding is insufficient, and as a result, residual distortion occurs in the molded bottomed parison, and the bottomed parison is released at high temperature. The bottomed parison deforms in some cases. In the case of a multi-cavity mold, problems such as the high-density polyethylene resin composition not being uniformly filled in each mold occur. On the other hand, if it exceeds 20 g / 10 minutes, melt mixing with (B) the ethylene polymer polymerized with the chromium catalyst becomes poor, and a large number of gels are generated on the surface of the stretch-blown bottle, and the bottomed parison Cannot be stretch blown uniformly.

Further, (A) the metallocene ethylene polymer imparts gloss to the surface of a bottle molded from the polyethylene resin composition. Particularly, when the molecular weight distribution of the metallocene ethylene polymer is set in the range of 3.5 to 5, the gloss of the injection-stretched blow-molded bottle is excellent. The molecular weight distribution was measured by gel permeation chromatography. The measuring device was Waters 150-C ALC / GPC, the columns were Shodex AT-807S and Tosoh TSK-gelGMH-H6 in series. It is measured at 140 ° C. using chlorobenzene.

The metallocene ethylene polymer (A) used in the present invention is polymerized using a titanocene catalyst comprising a titanocene compound and its cocatalyst. Examples of the metallocene catalyst include a zirconocene catalyst and a titanocene catalyst.When a zirconocene catalyst is used, the rate of crystallization of the ethylene polymer is particularly slow. Shrinkage does not occur, and it is difficult to release the bottomed parison at high temperature.

Titanocene catalysts are those substituted by at least one cyclopentadienyl group, substituted cyclopentadienyl group, hydrocarbyl silicon, etc., and those in which the cyclopentadienyl group is cross-linked by oxygen, nitrogen and phosphorus atoms. It consists of a known titanocene compound as a ligand and its cocatalyst. The cocatalyst is represented by the general formula C ⁺ A ⁻ , wherein C ⁺ is an oxidizing cation of an organic compound, an organometallic compound or an inorganic compound, or a Bronsted acid composed of a Lewis base and a protonic acid, and has titanocene coordination. Reacts with the anion of the child to form a cation of the titanocene compound. Examples of the titanocene compound used in the present invention include a titanium compound having a η bond with a cyclopentadienyl or substituted cyclopentadienyl group represented by the following general formula.

[0013]

Embedded image

Here, Ti is a titanium atom in an oxidation state of +2, +3, +4, Cp is a cyclopentadienyl or substituted cyclopentadienyl group which is η-bonded to titanium, X1 is an anionic ligand, X2 is a neutral conjugated diene compound. n + m is 1 or 2, Y is -O -, - S -, - NR- or a -PR-, Z is _{SiR 2, CR 2, SiR 2} -SiR 2, CR 2 C
R ₂ , CR = CR, CR ₂ SiR ₂ , GeR ₂ , BR ₂
R is hydrogen, hydrocarbyl in each case,
It is selected from silyl, germum, cyano, halo or combinations thereof and combinations thereof having up to 20 non-hydrogen atoms.

The substituted cyclopentadienyl group includes 1
Species or higher C1-C20 hydrocarbyl, C1-C20 halohydrocarbyl, Cyclopentadienyl substituted by halogen or C1-C20 hydrocarbyl-substituted Group 14 metalloid group , Indenyl, tetrahydroindenyl, fluorenyl or octafluorenyl, preferably having 1 to 1 carbon atoms.
6 is a cyclopentadienyl group substituted by an alkyl group.

As X1 and X2, for example, in the above formula, when n is 2, m is 0 and the oxidation number of titanium is +4, X1 is selected from methyl and benzyl, and n is 1 and m
Is 0 and the oxidation number of titanium is +3, X1 is 2- (N,
If N-dimethyl) aminobenzyl and the oxidation number of titanium are +4, X1 is 2-butene-1,4 diyl, and if n is 0, m is 1 and the oxidation number of titanium is +2, X2 is 1 , 4-diphenyl-1,3-butadiene or 1,3-pentadiene.

As the titanium compound, for example, [(Nt
-Butylamide) (tetramethyl-η ⁵ -cyclopentadienyl) -1,2-ethanediyl] titanium dimethyl, [(Nt-butylamide) (tetramethyl-η
⁵ - cyclopentadienyl) - dimethylsilane] titanium Niu arm dimethyl, [(N-methylamide) (tetramethyl-eta ⁵ - cyclopentadienyl) - dimethylsilane]
Titanium dimethyl, [(N-phenylamide) (tetramethyl-η ⁵ -cyclopentadienyl) -dimethylsilane] titanium dimethyl, [(N-benzylamide) (tetramethyl-η ⁵ -cyclopentadienyl)-
Dimethylsilane] titanium dimethyl, [(Nt-
Butylamide) (η ⁵ -cyclopentadienyl) -1,
2-ethanediyl] titanium dimethyl, [(Nt
-Butylamide) (η ⁵ -cyclopentadienyl) -dimethylsilane] titanium dimethyl,

[(N-methylamide) (η^Five-Cyclope
Antadienyl) -1,2-ethanediyl] titanium
Dimethyl, [(N-methylamide) (η^Five-Cyclopen
Tadienyl) -dimethylsilane] titanium dimethyl
, [(N-benzylamide) (η^Five-Indenyl)-
Dimethylsilane] titanium dimethyl
Is located after the compound name in the titanocene compound
Compounds in which the dimethyl component is replaced with the following components:
Can be Dibenzyl, 2- (N, N-dimethylamino)
Benzyl, 2-butene-1,4-diyl, s-tran
s-η^Four-1,4-diphenyl-1,3-butadiene,
s-trans-η^Four-3-methyl-1,3-pentadi
En, s-trans-η^Four-1,4-dibenzyl-
1,3-butadiene, s-trans-η^Four−2,4-
Hexadiene, s-trans-η^Four-1,3-pentane
Diene, s-trans-η^Four-1,4-ditolyl-
1,3-butadiene, s-trans-η^Four-1,4-
Bis (trimethyl-silyl) -1,3-butadiene, s
0cis0η^Four01,4-diphenyl-1,3-butadi
En, s-cis-η^Four3-methyl-1,3-pentane
Diene, s-trans-η ^Four-2,4-hexadie
, S-cis-η^Four-1,3-pentadiene, sc
is-η^Four-1,4-ditolyl-1,3-butadiene,
s-cis-η^Four-1,4-bis (trimethylsilyl)
-1,3-butadiene and the like.

The cocatalyst of the titanocene compound includes a borate compound. Examples of the borate compound include triphenyl (hydroxyphenyl) borate, diphenyl-di (hydroxyphenyl) borate, triphenyl (2,4-dihydroxyphenyl) borate, tri (p-tolyl) (hydroxyphenyl) borate, and tris- (pentane). Fluorophenyl) (hydroxyphenyl) borate, tris (2,4-dimethylphenyl)
(Hydroxyphenyl) borate, tris- (3,5-
Dimethylphenyl) (hydroxyphenyl) borate,
Tris- (3,5-di-trifluoromethylphenyl)
(Hydroxyphenyl) borate, tris- (pentafluorophenyl) (2-hydroxyethyl) borate,
Tris- (pentafluorophenyl) (4-hydroxybutyl) borate, tris- (pentafluorophenyl) (4-hydroxy-cyclohexyl) borate, tris- (pentafluorophenyl) (4- (4′-hydroxyphenyl) phenyl) Borate, tris- (pentafluorophenyl) (6-hydroxy-2-naphthyl) borate, most preferably tris (pentafluorophenyl) (4-hydroxyphenyl) borate.

Examples of the counter cation of the borate compound include a carbonium cation, a tropylluium cation, an ammonium cation, an oxonium cation, a sulfonium cation, and a phosphonium cation. In addition, metal cations and organic metal cations whose self-confidence is easily reduced can also be mentioned. Specific examples of these cations include triphenylcarbonium ion, diphenylcarbonium ion, cycloheptatrinium, indenium, triethylammonium, tripropylammonium, tributylammonium,
Dimethyl ammonium, dipropyl ammonium,
Dicyclohexyl ammonium,

Trioctylammonium, N, N-dimethylammonium, diethylammonium, 2,
4,6-pentamethylammonium, N, N-dimethylbenzylammonium, di- (i-propyl) ammonium, dicyclohexylammonium, triphenylphosphonium, triphosphonium, tridimethylphenylphosphonium, tri (methylphenyl)
Phosphonium, triphenylphosphonium ion,
Triphenyl oxonium ion, triethyl oxonium ion, pyrium, silver ion, gold ion,
Platinum ions, copper ions, palladium ions, mercury ions, and ferrocenium ions. Of these, ammonium ions are particularly preferred. The polymerization method of the metallocene ethylene polymer (A) used in the present invention is not particularly limited, and examples thereof include a fluidized bed gas phase method, a slurry method, and a bulk polymerization method.

The ethylene polymer polymerized by the (B) chromium catalyst used in the present invention has a specific density and a specific melt index. The ethylene polymer polymerized with the chromium catalyst used in the present invention has a long chain branch, and the polyethylene resin composition of the present invention has a melt viscosity suitable for stretch blow molding under a high draw ratio. To be given. As the ethylene polymer polymerized with the chromium catalyst, an ethylene homopolymer, or ethylene and a carbon atom 3
To 20 and preferably 4 to 20 α-olefins. In particular, the ethylene polymer polymerized with the chromium catalyst used in the present invention is preferably an ethylene homopolymer from the buckling strength of a bottle obtained by injection stretch blow molding. C3 to C3 as a comonomer of the ethylene copolymer
As the α-olefin of No. 20, propylene, butene-
1, pentene-1, 3-methylbutene-1, hexene
1,4-methylpentene-1, octene-1, decene-
1, tetradecene-1, hexadecene-1, octadecene-1, eicosene-1 and the like can be used. Further, vinyl compounds such as vinylcyclohexane or styrene and derivatives thereof can also be used. If necessary, a ternary random polymer containing a small amount of a non-conjugated polyene such as 1,5-hexadiene and 1,7-octadiene may be used.

The density of the ethylene homopolymer or ethylene copolymer polymerized with these chromium catalysts is 0.950 g.
/ Cm ³ or more, preferably 0.955 g / cm ³ or more,
More preferably, it is 0.960 g / cm ³ or more. The density here is measured by a density gradient tube after heat-treating the strand obtained at the time of melt index measurement at 100 ° C. for 1 hour and further cooling at room temperature for 1 hour in accordance with JIS-K-7112. . When the density of the ethylene polymer polymerized by the chromium catalyst is less than 0.950 g / cm ³ , the buckling strength of the bottle obtained by injection stretch blow molding is insufficient, and the gloss of the bottle surface is reduced.

The ethylene polymer polymerized with the chromium catalyst (B) used in the present invention has a melt flow index (MI _2.16 ) at 190 ° C. under a load of 2.16 kg of 0.05 to 2 g / 10 min. , Preferably 0.1 to 1 g / 10 min, more preferably 0.2 to 1 g / 10 min.
0.8 g / 10 min. MI _2.16 is 0.05g / 10
If it is less than minutes, the fluidity of the polyethylene resin composition will be insufficient during injection molding, the melt mixing with the metallocene ethylene polymer will be poor, and many gels will be generated on the surface of the molded bottle. On the other hand, when it exceeds 2 g / 10 minutes, the melt viscosity of the polyethylene resin composition is insufficient,
Stretch blow molding under a high draw ratio, which is the object of the present invention, becomes difficult.

The chromium catalyst used in the process for producing the ethylene polymer (B) used in the present invention is a known Philips catalyst. The chromium catalyst is a chromium oxide or a compound that forms chromium oxide at least partially by calcination, such as chromium halide, oxyhalide, nitrate, acetate, sulfate, oxalate, and alcoholate. Specific examples thereof include chromium trioxide, chromium chloride, potassium dichromate, and chromate achromate. Of these, chromium trioxide, chromium acetate and chromium acetylacenate are preferred.

In the present invention, (A) 2 to 40 parts by weight, preferably 5 to 35 parts by weight, more preferably 7 parts by weight of an ethylene polymer polymerized with a chromium catalyst per 100 parts by weight of a metallocene ethylene polymer. And 30 parts by weight of the polyethylene resin composition. When the weight of the ethylene polymer polymerized by the chromium catalyst is less than 2 parts by weight, the melt viscosity required for the stretch blow molding of the polyethylene resin composition is insufficient. Uniform stretch blow of parison becomes difficult. As a guide of the melt viscosity required for stretch blow molding of the polyethylene resin composition, the melt viscosity at 190 ° C. and 100 rad / s is set to 3000 to 14000 Pa.s. It is preferable to set the range of s. The melt viscosity is measured using an ARES manufactured by Rheometrics Scientific, Inc., with a polyethylene resin composition sandwiched between a flat plate having a diameter of 25 mm and a flat plate gap of 3 mm, and the melt viscosity at a shear rate of 100 rad / s is measured.

The polyethylene resin composition of the present invention comprises:
(A) The metallocene ethylene polymer and (B) the ethylene polymer polymerized by the chromium catalyst are heated at 150 to 300 ° C. using a known kneading device such as a uniaxial or biaxial extruder, a Banbury mixer, a kneader, or a roll. Knead. The polyethylene resin composition of the present invention comprises a phenol stabilizer and / or an organic phosphite stabilizer, and / or
Or organic thioether-based stabilizers and / or stabilizers such as metals of higher fatty acids, pigments, dyes, nucleating agents, lubricants, inorganic fillers or reinforcing materials such as carbon black, talc, glass fibers, flame retardants, neutron blocking agents And the like can be added to the polyolefin within a range that does not impair the purpose of the present invention.

Examples of the phenol-based stabilizer include 2,6-di-t-butyl-4-methylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-Di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl -6-t-butylphenol, 2-t-
Butyl-2-ethyl-6-t-octylphenol, 2
-Isobutyl-4-ethyl-6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrocinnamate )
Methane, 2,2'-methylenebis (4-methyl-6-t
-Butylphenol), 4,4′-butylidenebis (3
-Methyl-6-t-butylphenol), 4,4′-thiobis (3-methyl-6-t-butylphenol),

2,2'-thiobis (4-methyl-6-t
-Butylphenol), 1,3,5-trimethyl-2,
4,6-tris (3,5-di-t-butyl-4-hydroxyphenyl) benzylbenzene, 1,3,5-tris (2-methyl-4-hydroxy-5-t-butylphenol) methane, tetrakis ( Methylene (3,5-di-butyl-4-hydroxyphenyl) propionate) methane, β- (3,5-di-tert-butyl-4-hydroxylphenol) propionic acid alkyl ester, 2,
2'-oxamidobis (ethyl-3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionate,
Tetrakis (methylene (2,4-di-t-butyl-4-
Hydroxyl) propionate), n-octadecyl-
3- (4'-hydroxy-3,5-di-t-butylphenyl) propionate,

2,6-di-t-butyl-p-cresol, 2,4,6-tris (3 ', 5'-di-t-butyl-4'-hydroxybenzylthiono-1,3,5 -Triazine, 2,2′-methylenebis (4-methyl-6-t
-Butylphenol), 4.4′-methylenebis (2,
6-di-t-butylphenol), 2,2′-methylenebis (6- (1-methylcyclohexyl) -p-cresol), bis (3,5-bis (4-hydroxy-3-t)
-Butylphenyl) butyric acid) glycol ester, 4,4′-butylidenebis (6-t-butyl-m
-Cresol), 1,1,3-tris (2-methyl-4)
-Hydroxy-5-t-butylphenyl) butane, 1,
3,5 tris (2,6-dimethyl-3-hydroxy-
4-t-butylbenzyl) isocyanurate,

1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, 1,3,5-tris (3,5-di- t-
Butyl-4-hydroxybenzyl) isocyanate,
1,3,5-tris ((3,5-di-t-butyl-4-
(Hydroxyphenyl) propionyloxyethyl) isocyanurate, 2-octylthio-4,6-di (4-
(Hydroxy-3,5-di-t-butyl) phenoxy-
1,3,5-triazine, 4,4′-thiobis (6-t
-Butyl-m-cresol) and the like.

As the organic phosphite-based stabilizer, trioctyl phosphite, trilauryl phosphite,
Tridecyl phosphite, octyl diphosphite,
Tris (2,4-di-t-butylphenyl) phosphite, triphenylphosphite, tris (butoxyethyl) phosphite, tris (nonylphenyl) phosphite, distearylpentaerythritol diphosphite, tetra (tridecyl)- 1,1,3-Tris (2-
Methyl-5-t-butyl-4-hydroxyphenyl) butanediphosphite, tetra (tridecyl) -4,4 '
-Butylidenebis (3-methyl-6-tert-butylphenol) diphosphite, tris (3,5-di-tert-butyl-4-hydroxyphenyl) phosphite,

Tris (mono- or dinonylphenyl) phosphite, hydrogenated-4,4'-isopropylidenediphenol polyphosphide, bis (octylphenyl) bis (4,4'-butylidenebis (3-methyl-6- t-
Butylphenol)) 1,6-hexaneoldiphosphide, phenyl-4,4'-isopropylidenediphenolpentaerythritol diphosphide, bis (
2,4-di-tert-butylphenyl) pentaerythritol diphosphide, bis (2,6-di-tert-butyl-4)
Methylphenyl) pentaerythritol diphosphide, tris ((4,4′-isopropylidenebis (2-
t-butylphenol)) phosphide, di (nonylphenyl) pentaerythritol diphosphide, tris (1,3-di-stearoyloxyisopropyl) phosphite, 4,4′-isopropylidenebis (2-t-
(Butylphenol) di (nonylphenyl) phosphide, 9,10-di-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakis (2,4-di-t-butylphenyl) -4,4 '-Biphenylenediphosphide and the like.

Examples of the organic thioether-based stabilizers include dialkylthiopropionates such as dilauryl-, dimyristyl- and distearyl- and butyl-, octyl-, and the like.
Esters of polyhydric alcohols of alkylthiopropionic acids such as lauryl-, stearyl-, etc. (eg glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, trishydroxyethyl isocyanurate) (eg pentaerythitol tetralaurylthiopropionate) ). More specifically, dilauryl thiopropionate, dimyristyl thiopropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, distearyl thiodibutyrate and the like can be mentioned.

Examples of the metal salt of a higher fatty acid include alkaline earth metal salts such as magnesium, calcium and barium salts of higher fatty acids such as stearic acid, oleic acid, lauric acid, caprylic acid, arachidic acid, palmitic acid and behenic acid. , Cadmium salts, zinc salts, lead salts, sodium salts, potassium salts, lithium salts and the like. Magnesium stearate, magnesium laurate, magnesium palmitate, calcium stearate calcium oleate, barium stearate, barium laurate, barium laurate, magnesium, zinc stearate, zinc calcium oleate, zinc stearate, zinc laurate, Lithium stearate, sodium stearate, sodium palmitate, sodium laurate, potassium stearate, potassium laurate, calcium 12-hydroxystearate, etc.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to examples and the like, but these do not limit the scope of the present invention. MI _2.16 ; 190 according to ASTM-D-1238.
This is a value measured at a temperature of 2.degree. Density: The strand obtained at the time of the melt index measurement was measured at 100 ° C. for 1 strand in accordance with JIS-K-7112.
After a heat treatment for an hour, and then left to cool for 1 hour at room temperature, it was measured with a density gradient tube. Injection stretch blow molding: Using an injection stretch blow molding machine (SBIII-250P-50) manufactured by Aoki Solid Laboratory Co., Ltd., the bottomed parison is stretched 5 times vertically and 3 times horizontally to obtain a basis weight of 80.
g, a 20 mm-diameter square bottle with an internal volume of 800 ml was molded. The surface gloss of the molded bottle is measured with a gloss meter manufactured by Nippon Denshoku Industries Co., Ltd. The thickness unevenness is measured by measuring the thickness of the side of the bottle, and the ratio of the thickness of the thickest part to the thickness of the thinnest part Was used to evaluate the uniform stretchability of the bottle. Further, the load when the bottle was deformed by 4 mm at a compression speed of 10 mm / min was determined using a compression tester, and the buckling strength of the bottle was determined.

(A) Metallocene polymer polymerized by titanocene catalyst Triethylammonium tris (pentafluorophenyl) (4-hydroxyphenyl) borate and [(Nt-butylamide) (tetramethyl-η ^5-
Cyclopentadienyl) - dimethylsilane] Chitanyuumu s-trans -η ⁴ -1,3- pentadiene using a supported titanocene catalyst on silica, hexanes 75 ° C.
And ethylene and hydrogen were supplied to the reactor to prepare the metallocene ethylene polymer shown in Table 1.

(B) Ethylene polymer polymerized with a chromium catalyst An ethylene polymer polymerized with a chromium catalyst as shown in Table 1 was produced according to the polymerization method described in Example 1 of JP-A-4-249502. . The ethylene polymers of (A) and (B) were weighed at the compounding ratio shown in Table 1 and 100 p
pm Irganox 1076 (trade name, manufactured by Ciba Geigy) and mixed for 2 minutes with a Hensiel mixer.
Using a twin screw extruder (PCM-45, manufactured by Ikegai Iron & Steel Co., Ltd.), screw rotation speed 80 rpm, barrel setting temperature 20
The mixture was melt-kneaded at 0 ° C. and pelletized to obtain a polyethylene resin composition. The obtained polyethylene resin composition was subjected to injection stretch blow molding.

[0039]

Examples 1 to 5 The polyethylene resin compositions of Examples 1 to 5 have no problem in both the injection and stretching blow steps, and the resulting bottle has no gel and is excellent in surface gloss.
In addition, the bottle has a uniform thickness, and the buckling strength of the bottle is excellent.

Comparative Example 1 Since the melt flow index of the metallocene ethylene polymer is low, the melt viscosity in the injection process is insufficient, and when the bottomed parison is released at high temperature, the bottomed parison is deformed due to residual strain. Even when blown, the bottomed parison did not grow evenly.

[0040]

Comparative Example 2 Due to the high melt flow index of the metallocene ethylene polymer, the viscosity of the bottomed parison was insufficient,
Uniform stretch blow cannot be performed. In addition, the melt mixing property with the ethylene polymer polymerized by the chromium catalyst was poor, and many gels were observed on the bottle surface.

Comparative Example 3 The amount of the ethylene polymer polymerized by the chromium catalyst was too small, and when the bottomed parison was stretch blown, the bottomed parison melt viscosity was low and the side of the bottomed parison burst.

[0041]

Comparative Example 4 The amount of the ethylene polymer polymerized by the chromium catalyst was too large, and when the bottomed parison was stretch blown, the melt viscosity of the bottomed parison was so high that the bottomed parison was not stretched uniformly.

Comparative Example 5 Since the density of each of the ethylene polymers is low, the buckling strength of the bottle is reduced and the gloss is also reduced.

[0042]

COMPARATIVE EXAMPLE 6 Using a zirconocene catalyst in which alumoxane and bis (n-butylcyclopentadienyl) zirconium dichloride were supported on silica, 75
At 0 ° C, ethylene and hydrogen were supplied to the reactor to prepare a zirconocene ethylene polymer described in Table 1. Although it is presumed that the crystallization rate of the polyethylene resin composition using this ethylene polymer is low, the bottomed parison did not shrink appropriately, and the bottomed parison could not be released at a high temperature.

[0043]

[Table 1]

[0044]

The high-density polyethylene resin composition of the present invention is suitable for injection stretch blow molding at a high stretch ratio,
The molded bottle also had high rigidity and no pinch-off, so it was also excellent in environmental stress crack resistance, and was a resin composition that could sufficiently cope with the demand for lighter bottles in recent years.

Claims (4)

[Claims] (A) a melt index of 2 to 20 g;
Metallocene ethylene polymer 10 polymerized with a titanocene catalyst having a density of 0.950 g / cm ³ or more
0 parts by weight, (B) melt index is 0.05 to 2 g
/ 10 minutes, and 2 to 40 parts by weight of an ethylene polymer polymerized with a chromium catalyst having a density of 0.950 g / cm ³ or more, comprising a high-density polyethylene resin composition for injection stretch blow molding. 2. The high-density polyethylene resin composition for injection stretch blow molding according to claim 1, wherein the metallocene ethylene polymer is an ethylene homopolymer. 3. The high-density polyethylene resin composition for injection stretch blow molding according to claim 1, wherein a metallocene ethylene polymer having a molecular weight distribution of 3.5 to 5 is used. 4. A melt viscosity at 190 ° C. and a shear rate of 0.1 rad / s of 3000-14000 Pa.s. The high-density polyethylene resin composition for injection stretch blow molding according to any one of claims 1 to 3, which is s.