JP6670130B2 - Polypropylene resin composition for hollow molding and hollow molded article - Google Patents

Description

  The present invention relates to a polypropylene-based resin composition for hollow molding containing a polypropylene-based resin and a hollow molded article.

Polypropylene is high in impact resistance, rigidity, transparency, chemical resistance, heat resistance, etc., and has excellent physical balance, so it is used as a container for filling beverages, foods, pharmaceuticals, cosmetics, detergents, etc. Sometimes.
A polypropylene container can be manufactured by, for example, hollow molding a polypropylene-based resin (Patent Documents 1 and 2).

JP 2011-513528 A JP 2003-342429 A

The polypropylene resin for hollow molding is required to have not only impact resistance, rigidity and transparency but also drawdown resistance to prevent the molten resin from dripping down by its own weight during the hollow molding.
However, the polypropylene resins for hollow molding described in Patent Literatures 1 and 2 sometimes have low impact resistance (particularly low-temperature impact resistance), rigidity, transparency, and drawdown resistance.
An object of the present invention is to provide a polypropylene-based resin composition for hollow molding having excellent impact resistance (particularly low-temperature impact resistance), rigidity, transparency, and drawdown resistance. Another object of the present invention is to provide a hollow molded article having high impact resistance (particularly low-temperature impact resistance), rigidity, transparency, and fluidity during production, and having excellent drawdown resistance.

The polypropylene resin composition for hollow molding of one embodiment of the present invention contains a polypropylene resin containing a matrix composed of a propylene copolymer and an ethylene-propylene copolymer, and has a temperature of 230 ° C. and a load of 21 according to JIS K7210. The melt flow rate measured under conditions of 0.18 N is 0.1 to 5.0 g / 10 min, and the polypropylene-based resin has an intrinsic viscosity of 0.77 in tetrahydronaphthalene at 135 ° C. of a xylene-soluble component. 2.0 to 2.0 dl / g, the ratio of the mass average molecular weight _Mw to the number average molecular weight _Mn ( _Mw / _Mn ) of the xylene-insoluble component is 6 or more, and the content ratio of the ethylene / propylene copolymer is 23 And the propylene copolymer contains 0.5 to 4.0% by mass of ethylene units and 96.0 to 99.5% by mass of propylene units. And the ethylene / propylene copolymer contains 60 to 85% by mass of ethylene units and 15 to 40% by mass of propylene units.
In the polypropylene resin composition for hollow molding of this embodiment, the polypropylene resin is preferably a polymerization mixture obtained by polymerizing an ethylene monomer and a propylene monomer in the presence of a propylene copolymer.
In the polypropylene resin composition for hollow molding of this embodiment, the nucleating agent is preferably contained in an amount of more than 0 parts by mass and 1.0 part by mass or less based on 100 parts by mass of the polypropylene resin.
The hollow molded article of one embodiment of the present invention contains the above-mentioned polypropylene-based resin composition.

The polypropylene resin composition for hollow molding of the present invention is excellent in impact resistance (particularly low-temperature impact resistance), rigidity, transparency and drawdown resistance.
Further, the hollow molded article of the present invention is excellent in impact resistance (particularly low-temperature impact resistance), rigidity, transparency, fluidity during production and drawdown resistance.

<Polypropylene resin composition>
The polypropylene resin composition for hollow molding of one embodiment of the present invention (hereinafter, abbreviated as “polypropylene resin composition”) contains a polypropylene resin.
The polypropylene resin composition has a melt flow rate (hereinafter, referred to as “MFR”) of 0.1 to 5.0 g / 10 minutes, and preferably 0.5 to 3.0 g / 10 minutes. Here, the MFR is a value measured under the conditions of a temperature of 230 ° C. and a load of 21.18 N according to JIS K7210.
If the MFR of the polypropylene resin composition is less than the lower limit, the molded product may not be obtained due to too low fluidity during molding. When the MFR of the polypropylene-based resin composition exceeds the above upper limit, impact resistance and drawdown resistance may be reduced.

(Polypropylene resin)
The polypropylene resin contains a matrix composed of a propylene copolymer and an ethylene / propylene copolymer mainly composed of a rubber component.
The polypropylene-based resin may be a mixed resin obtained by mixing a propylene copolymer and an ethylene / propylene copolymer at the time of polymerization, or a propylene copolymer and an ethylene / propylene copolymer obtained separately. It may be a mixed resin mixed by melt kneading. It is preferable that the propylene copolymer and the ethylene / propylene copolymer be a mixture (polymerized mixture) in which the propylene copolymer and the ethylene / propylene copolymer are mixed at the time of polymerization, since those having excellent physical property balance can be obtained at lower cost.
In the polymerization mixture in which the propylene copolymer and the ethylene / propylene copolymer are mixed by polymerization, the propylene copolymer and the ethylene / propylene copolymer are mixed in the submicron order at the polymerization stage. Therefore, a composition based on a polymerization mixture in which a propylene copolymer and an ethylene / propylene copolymer are mixed by polymerization exhibits an excellent balance of physical properties.
On the other hand, when a similar mechanical balance obtained by melt-kneading a propylene copolymer and an ethylene / propylene copolymer achieves the same excellent balance of physical properties, there is a problem that the production cost increases.
The polymerization mixture and the mechanical mixture exhibit different physical properties, which are presumed to be due to the different dispersion state of the ethylene / propylene copolymer in the propylene copolymer. At present, no practical means for analyzing the state of dispersion at the molecular level including the state of the interface with the propylene copolymer has been known.

A polypropylene-based resin in which a propylene copolymer and an ethylene / propylene copolymer are mixed at the time of polymerization can be produced by multi-stage polymerization. For example, in a first-stage polymerization reactor, an ethylene monomer and a propylene monomer are polymerized in the presence of a catalyst, and the obtained propylene copolymer is supplied to a second-stage polymerization reactor and a second-stage polymerization reaction is performed. A polypropylene-based resin can be obtained by copolymerizing an ethylene monomer and a propylene monomer in a vessel. In this method, in the second-stage polymerization reactor, an ethylene-propylene copolymer is produced in the presence of a propylene copolymer, and the produced ethylene-propylene copolymer is mixed with the propylene copolymer. .
By producing the ethylene-propylene copolymer in the presence of the propylene copolymer, the productivity is increased, and the dispersibility of the ethylene-propylene copolymer in the propylene copolymer is increased. Is improved.
Further, the multi-stage polymerization is not limited to the above method, the propylene copolymer may be polymerized in a plurality of polymerization reactors, or the ethylene / propylene copolymer may be polymerized in a plurality of polymerization reactors. . Further, as a method for obtaining a polypropylene-based resin, a method using a polymerization vessel having a gradient of a monomer concentration or a polymerization condition may be mentioned. In such a polymerization vessel, for example, one in which at least two polymerization regions are joined can be used, and the monomer can be polymerized by gas phase polymerization.
Specifically, in the presence of a catalyst, a monomer is supplied and polymerized in a polymerization region including a riser, and a monomer is supplied and polymerized in a downcomer connected to the riser. While recovering the polymer product. The method comprises means for completely or partially preventing the gas mixture present in the riser from entering the downcomer. Also, a gas and / or liquid mixture having a different composition than the gas mixture present in the riser is introduced into the downcomer. As the polymerization method, for example, a method described in JP-T-2002-520426 can be applied.
In the polymerization, a known catalyst for propylene polymerization is used, and if necessary, hydrogen may be added to adjust the molecular weight.

In the polymerization for obtaining the polymerization mixture, it is preferable to use a stereospecific Ziegler-Natta catalyst. More preferably, the catalyst contains (A) a solid catalyst component containing magnesium, titanium, halogen and an electron donor compound; (B) an organoaluminum compound; and (C) an external electron donor compound.
The properties of the obtained polymer differ depending on the type of the catalyst, but no practical means for analyzing all the differences in properties has been known.

As the titanium compound used for preparing the solid catalyst component (A), a tetravalent compound represented by a general formula: Ti (OR) _g X _4-g (R is a hydrocarbon group, X is a halogen, and 0 ≦ g ≦ 4) Are preferred. Examples of the hydrocarbon group include methyl, ethyl, propyl, and butyl, and examples of the halogen include Cl and Br.
More specific titanium _compounds, TiCl _4, TiBr 4, titanium tetrahalides such as _{TiI 4; Ti (OCH 3)} Cl 3, Ti (OC 2 H 5) Cl 3, Ti (O n -C 4 H _{9) Cl 3, Ti (OC} 2 H 5) Br 3, Ti (O-isoC 4 H 9) trihalide, alkoxy titanium such as _{Br 3; Ti (OCH 3)} 2 Cl 2, Ti (OC 2 H 5) _{2 Cl 2, Ti (O n} -C 4 H 9) 2 Cl 2, Ti (OC 2 H 5) 2 dihalogenated alkoxy titanium such as _{Br 2; Ti (OCH 3)} 3 Cl, Ti (OC 2 H 5) _{3 Cl, Ti (O n -C} 4 H 9) 3 Cl, Ti (OC 2 H 5) 3 monohalogenated trialkoxy titanium such as _{Br; Ti (OCH 3) 4} , Ti (OC 2 H 5 _{4, Ti (O n -C 4} H 9) 4 and the like tetraalkoxytitanium such. One of these titanium compounds may be used alone, or two or more thereof may be used in combination.
Preferred among the above titanium compounds are halogen-containing titanium compounds, particularly titanium tetrahalides, and particularly preferred is titanium tetrachloride (TiCl ₄ ).

As the magnesium compound used for preparing the solid catalyst component (A), a magnesium compound having a magnesium-carbon bond or a magnesium-hydrogen bond, for example, dimethylmagnesium, diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diamilmagnesium, dihexylmagnesium, Examples include didecyl magnesium, ethyl magnesium chloride, propyl magnesium chloride, butyl magnesium chloride, hexyl magnesium chloride, amyl magnesium chloride, butyl ethoxy magnesium, ethyl butyl magnesium, and butyl magnesium hydride.
These magnesium compounds can be used in the form of a complex compound with, for example, organoaluminum, and may be in a liquid state or a solid state.
Further preferred magnesium compounds include magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; and alkoxy such as methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride, and octoxy magnesium chloride. Magnesium halides; allyloxymagnesium halides such as phenoxymagnesium chloride and methylphenoxymagnesium chloride; alkoxymagnesiums such as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium, n-octoxymagnesium, 2-ethylhexoxymagnesium; phenoxymagnesium, dimethyl Allyloxymagnesium such as phenoxymagnesium; magnesium laurate , And the like carboxylates of magnesium such as magnesium stearate.
One of these magnesium compounds may be used alone, or two or more thereof may be used in combination.

Examples of the electron donor compound used for preparing the solid catalyst component (A) used in the production of the propylene resin composition described above include alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic or inorganic acids, ethers, Oxygen-containing electron donors such as acid amides and acid anhydrides, and nitrogen-containing electron donors such as ammonia, amines, nitriles, and isocyanates are known, but the electron donor compound in the present invention includes a dicarboxylic acid diester. Is preferred. Dicarboxylic acids are compounds having two carboxyl groups. The following are specific examples of dicarboxylic acid diesters.
Diethyl succinate, dibutyl succinate, diethyl methyl succinate, diethyl diisopropyl succinate, diallyl ethyl succinate, diisobutyl α-methylglutarate, dibutyl methyl malonate, diethyl malonate, diethyl ethyl malonate, isopropyl Diethyl malonate, diethyl butylmalonate, diethyl phenylmalonate, diethyl diethylmalonate, diethyl allylmalonate, diethyldiisobutylmalonate, diethyldinormalbutylmalonate, dimethylmaleate, monooctyl maleate, dioctyl maleate, maleic acid Dibutyl, dibutyl butyl maleate, diethyl butyl maleate, diisopropyl β-methylglutarate, di-2-ethylhexyl fumarate, diethyl itaconate, di itaconate Aliphatic polycarboxylic acid esters such as butyl, dioctyl citraconic acid and dimethyl citraconic acid;
Alicyclic polycarboxylates such as diethyl 1,2-cyclohexanecarboxylate, diisobutyl 1,2-cyclohexanecarboxylate, diethyl tetrahydrophthalate and diethyl nadiclate.

Monoethyl phthalate, dimethyl phthalate, methyl ethyl phthalate, monoisobutyl phthalate, mononormal butyl phthalate, diethyl phthalate, ethyl isobutyl phthalate, ethyl normal butyl phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, Di-n-heptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, dineopentyl phthalate, didecyl phthalate, benzyl butyl phthalate, diphenyl phthalate, diethyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, triethyl trimellitate, trimellitate Aromatic polycarboxylic acid esters such as dibutyl acid.
Heterocyclic polycarboxylic acid esters such as 3,4-furandicarboxylic acid.

Other examples of the polyvalent carboxylic acid diester that can be supported on the solid catalyst component include diethyl adipate, diisobutyl adipate, diisopropyl sebacate, di-n-butyl sebacate, di-n-octyl sebacate, and sebacic acid. Esters of long-chain dicarboxylic acids such as di-2-ethylhexyl can be mentioned.
Dicarboxylic acids also include succinic acid and substituted succinic acids having a substituent such as an alkyl group at the 1- or 2-position of the succinic acid. Among the dicarboxylic acid diesters, diesters of succinic acid, substituted succinic acid, phthalic acid, maleic acid, and substituted malonic acid are more preferable, and a succinate (succinate) -based electron donor compound can be suitably used.
Suitable succinate-based compounds are compounds having a succinate structure represented by the following chemical formula (I).
When a polymerization mixture obtained by polymerization using a catalyst containing a succinate-based compound as an electron donor is used, the _Mw / _Mn of the xylene-insoluble component can be easily adjusted to the following range, and the fluidity during molding and the resistance to drawdown can be improved. Properties can be easily improved. The fact that the xylene-insoluble matter M _w / M _n is large means that the molecular weight distribution of the propylene copolymer and the ethylene / propylene copolymer constituting the polypropylene resin is wide.

In the formula (I), R ¹ and R ² are the same or different from each other, and may be a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl having 1 to 20 carbon atoms which may contain a heteroatom. Group. Desirable R ¹ and R ² are an alkyl, cycloalkyl, aryl, arylalkyl, and alkylaryl group having 1 to 8 carbon atoms. R ¹ and R ² are particularly preferably compounds selected from primary alkyls, especially branched primary alkyls. Specific examples of suitable R ¹ and R ² include methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl and 2-ethylhexyl, with ethyl, isobutyl and neopentyl being particularly preferred.
R ^{3 to} R ⁶ are the same or different from each other, and are hydrogen, or a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl group having 1 to 20 carbon atoms which may contain a hetero atom. It is. R ³ and R ⁴ , and R ⁵ and R ⁶ bonded to the same carbon atom may be bonded to each other to form a ring structure. Any two or more of R ^{3 to} R ⁶ bonded to different carbon atoms may be bonded to each other to form a ring structure.

One preferred group of compounds of formula (I) is that wherein R ³ -R ⁵ are hydrogen and R ⁶ has 3-10 carbon atoms, branched alkyl, cycloalkyl, aryl, arylalkyl And a monosubstituted succinate compound of an alkylaryl group.
Specific examples of suitable monosubstituted succinate compounds include diethyl-sec-butylsuccinate, diethyltexylsuccinate, diethylcyclopropylsuccinate, diethylnorbonylsuccinate, diethylperhydrosuccinate, diethyltrimethylsilyl Succinate, diethylmethoxysuccinate, diethyl-p-methoxyphenylsuccinate, diethyl-p-chlorophenylsuccinate, diethylphenylsuccinate, diethylcyclohexylsuccinate, diethylbenzylsuccinate, diethylcyclohexylmethyl Succinate, diethyl-t-butyl succinate, diethyl isobutyl succinate, diethyl isopropyl succinate, diethyl neopentyl succinate, diethyl isopentyl succinate Succinate, diethyl (1-trifluoromethylethyl) succinate, diethyl fluorenyl succinate, 1- (ethoxycarbodiisobutylphenyl) succinate, diisobutyl-sec-butyl succinate, diisobutyl texyl succinate, diisobutylcyclopropyl succinate Diisobutylnorbonyl succinate, diisobutyl perhydrosuccinate, diisobutyl trimethylsilyl succinate, diisobutyl methoxy succinate, diisobutyl-p-methoxyphenyl succinate, diisobutyl-p-chlorophenyl succinate, diisobutyl cyclohexyls Succinate, diisobutylbenzylsuccinate, diisobutylcyclohexylmethylsuccinate, diisobutyl-t-butylsuccinate Diisobutyl isobutyl succinate, diisobutyl isopropyl succinate, diisobutyl neopentyl succinate, diisobutyl isopentyl succinate, diisobutyl (1-trifluoromethylethyl) succinate, diisobutyl fluorenyl succinate, dineopentyl-sec-butyl Succinate, Dineopentyl Texyl Succinate, Dineopentyl Cyclopropyl Succinate, Dineopentyl Norbonyl Succinate, Dineopentyl Perihydrosuccinate, Dineopentyl Trimethylsilyl Succinate, Dineopentyl Methoxy succinate, Dineopentyl-p-methoxyphenyl succinate, Dineopentyl-p-chlorophenyl succinate, Dineopentylphenyl succinate, Dineo Pentyl cyclohexyl succinate, Dineopentyl benzyl succinate, Dineopentyl cyclohexyl methyl succinate, Dineopentyl-t-butyl succinate, Dineopentyl isobutyl succinate, Dineopentyl isopropyl succinate, Dineo Examples include pentyl neopentyl succinate, dineopentyl isopentyl succinate, dineopentyl (1-trifluoromethylethyl) succinate, and dineopentyl fluorenyl succinate.
One of these compounds may be used alone, or two or more of them may be used in combination.

Other preferred compounds of the formula (I) are those in which at least two groups of R ^{3 to} R ⁶ are not hydrogen but are linear or branched alkyl having 1 to 20 carbon atoms which may contain a heteroatom, Examples include disubstituted succinate compounds selected from alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl groups. Preferably, the two non-hydrogen groups are attached to the same carbon atom.
Specific examples of suitable disubstituted succinate compounds include diethyl-2,2-dimethylsuccinate, diethyl-2-ethyl-2-methylsuccinate, diethyl-2-benzyl-2-isopropylsuccinate, diethyl -2-cyclohexylmethyl-2-isobutylsuccinate, diethyl-2-cyclopentyl-2-n-propylsuccinate, diethyl-2-cyclopentyl-2-n-butylsuccinate, diethyl-2,2-diisobutyl Succinate, diethyl-2-cyclohexyl-2-ethylsuccinate, diethyl-2-isopropyl-2-methylsuccinate, diethyl-2-tetradecyl-2-ethylsuccinate, diethyl-2-isobutyl-2 -Ethyl succinate, diethyl-2- (1-trifluoromethylethyl -2-methylsuccinate, diethyl-2-isopentyl-2-isobutylsuccinate, diethyl-2-phenyl-2-n-butylsuccinate, diisobutyl-2,2-dimethylsuccinate, diisobutyl-2 -Ethyl-2-methylsuccinate, diisobutyl-2-benzyl-2-isopropylsuccinate, diisobutyl-2-cyclohexylmethyl-2-isobutylsuccinate, diisobutyl-2-cyclopentyl-2-n-propylsuccinate , Diisobutyl-2-cyclopentyl-2-n-butylsuccinate, diisobutyl-2,2-diisobutylsuccinate, diisobutyl-2-cyclohexyl-2-ethylsuccinate, diisobutyl-2-isopropyl-2-methyl Succinate, diisobutyl-2-tet Decyl-2-ethylsuccinate, diisobutyl-2-isobutyl-2-ethylsuccinate, diisobutyl-2- (1-trifluoromethylethyl) -2-methylsuccinate, diisobutyl-2-isopentyl-2- Isobutyl succinate, diisobutyl-2-phenyl-2-n-butyl succinate, diisobutyl-2,2-diisopropyl succinate, diisobutyl-2-phenyl-2-n-propyl succinate, dineopentyl-2, 2-dimethylsuccinate, dineopentyl-2-ethyl-2-methylsuccinate, dineopentyl-2-benzyl-2-isopropylsuccinate, dineopentyl-2-cyclohexylmethyl-2-isobutylsuccinate, dineopentyl-2 -Cyclopentyl-2-n-propyl Succinate, dineopentyl-2-cyclopentyl-2-n-butylsuccinate, dineopentyl-2,2-diisobutylsuccinate, dineopentyl-2-cyclohexyl-2-ethylsuccinate, dineopentyl-2-isopropyl-2-methyl Succinate, dineopentyl-2-tetradecyl-2-ethylsuccinate, dineopentyl-2-isobutyl-2-ethylsuccinate, dineopentyl-2- (1-trifluoromethylethyl) -2-methylsuccinate, Dineopentyl-2,2-diisopropylsuccinate, dineopentyl-2-isopentyl-2-isobutylsuccinate, and dineopentyl-2-phenyl-2-n-butylsuccinate are exemplified.
One of these compounds may be used alone, or two or more of them may be used in combination.

Particularly preferred as the compound represented by the formula (I) is a compound wherein at least two groups different from hydrogen, that is, R ³ and R ⁵ , or R ⁴ and R ⁶ are bonded to different carbon atoms. Are also mentioned.
Specific examples of this compound include diethyl-2,3-bis (trimethylsilyl) succinate, diethyl-2,2-sec-butyl-3-methylsuccinate, and diethyl-2- (3,3,3-trifluoro) Propyl) -3-methylsuccinate, diethyl-2,3-bis (2-ethylbutyl) succinate, diethyl-2,3-diethyl-2-isopropylsuccinate, diethyl-2,3-diisopropyl-2-methyl Succinate, diethyl-2,3-dicyclohexyl-2-methylsuccinate, diethyl-2,3-dibenzylsuccinate, diethyl-2,3-diisopropylsuccinate, diethyl-2,3-bis ( Cyclohexylmethyl) succinate, diethyl-2,3-di-t-butylsuccinate, diethyl-2,3-diethyl Butyl succinate, diethyl-2,3-dineopentyl succinate, diethyl-2,3-diisopentyl succinate, diethyl-2,3- (1-trifluoromethylethyl) succinate, diethyl-2 , 3-tetradecylsuccinate, diethyl-2,3-fluorenylsuccinate, diethyl-2-isopropyl-3-isobutylsuccinate, diethyl-2-tert-butyl-3-isopropylsuccinate, diethyl -2-isopropyl-3-cyclohexylsuccinate, diethyl-2-isopentyl-3-cyclohexylsuccinate, diethyl-2-tetradecyl-3-cyclohexylmethylsuccinate, diethyl-2-cyclohexyl-3-cyclopentylsuccinate Nate, diethyl-2,2,3,3-tetramethyl Succinate, diethyl-2,2,3,3-tetraethylsuccinate, diethyl-2,2,3,3-tetrapropylsuccinate, diethyl-2,3-diethyl-2,3-diisopropylsuccinate, Diisobutyl-2,3-bis (trimethylsilyl) succinate, diisobutyl-2,2-sec-butyl-3-methylsuccinate, diisobutyl-2- (3,3,3-trifluoropropyl) -3-methylsuccinate , Diisobutyl-2,3-bis (2-ethylbutyl) succinate, diisobutyl-2,3-diethyl-2-isopropylsuccinate, diisobutyl-2,3-diisopropyl-2-methylsuccinate, diisobutyl-2, 3-dicyclohexyl-2-methylsuccinate, diisobutyl-2,3-dibenzylsuccinate, Isobutyl-2,3-diisopropylsuccinate, diisobutyl-2,3-bis (cyclohexylmethyl) succinate, diisobutyl-2,3-di-t-butylsuccinate, diisobutyl-2,3-diisobutylsuccinate, Diisobutyl-2,3-dineopentylsuccinate, diisobutyl-2,3-diisopentylsuccinate, diisobutyl-2,3- (1-trifluoromethylethyl) succinate, diisobutyl-2,3-n-propyl Succinate, diisobutyl-2,3-tetradecylsuccinate, diisobutyl-2,3-fluorenylsuccinate, diisobutyl-2-isopropyl-3-isobutylsuccinate, diisobutyl-2-tert-butyl-3 -Isopropyl succinate, diisobutyl-2- Isopropyl-3-cyclohexylsuccinate, diisobutyl-2-isopentyl-3-cyclohexylsuccinate, diisobutyl-2-n-propyl-3- (cyclohexylmethyl) succinate, diisobutyl-2-tetradecyl-3-cyclohexylmethylsuccinate , Diisobutyl-2,2,3,3-tetramethylsuccinate, diisobutyl-2,2,3,3-tetraethylsuccinate, diisobutyl-2,2,3,3-tetrapropylsuccinate, diisobutyl -2,3-diethyl-2,3-diisopropylsuccinate, diisobutyl-2-cyclohexyl-3-cyclopentylsuccinate, dineopentyl-2,3-bis (trimethylsilyl) succinate, dineopentyl-2,2-sec-butyl -3-me Rusuccinate, Dineopentyl-2- (3,3,3-trifluoropropyl) -3-methylsuccinate, Dineopentyl-2,3-bis (2-ethylbutyl) succinate, Dineopentyl-2,3-diethyl-2-isopropyl Succinate, Dineopentyl-2,3-diisopropyl-2-methylsuccinate, Dineopentyl-2,3-dicyclohexyl-2-methylsuccinate, Dineopentyl-2,3-dibenzylsuccinate, Dineopentyl-2, 3-diisopropyl succinate, dineopentyl-2,3-bis (cyclohexylmethyl) succinate, dineopentyl-2,3-di-t-butylsuccinate, dineopentyl-2,3-diisobutylsuccinate, dineopentyl-2, 3-dineopentylsk , Dineopentyl-2,3-diisopentylsuccinate, dineopentyl-2,3- (1-trifluoromethylethyl) succinate, dineopentyl-2,3-dineopentylsuccinate, dineopentyl-2,3- Diisopentyl succinate, dineopentyl-2,3-tetradecylsuccinate, dineopentyl-2,3-fluorenylsuccinate, dineopentyl-2-isopropyl-3-isobutylsuccinate, dineopentyl-2-tert- Butyl-3-isopropylsuccinate, dineopentyl-2-isopropyl-3-cyclohexylsuccinate, dineopentyl-2-isopentyl-3-cyclohexylsuccinate, dineopentyl-2-tetradecyl-3-cyclohexylmethylsuccinate , Dineopentyl-2-n-propyl-3- (cyclohexylmethyl) succinate, Dineopentyl-2-cyclohexyl-3-cyclopentylsuccinate, Dineopentyl-2,2,3,3-tetraethylsuccinate, Dineopentyl-2,2 , 3,3-tetrapropyl succinate, and dineopentyl-2,3-diethyl-2,3-diisopropyl succinate.
One of these compounds may be used alone, or two or more of them may be used in combination.

Further, as the compound represented by the formula (I), a compound in which at least two or more of R ^{3 to} R ⁶ are bonded to form a ring is also preferable.
As such compounds, compounds described in JP-T-2002-542347, for example, 1- (ethoxycarbonyl) -1- (ethoxyacetyl) -2,6-dimethylcyclohexane, 1- (ethoxycarbonyl)- 1- (ethoxyacetyl) -2,5-dimethylcyclopentane, 1- (ethoxycarbonyl) -1- (ethoxyacetylmethyl) -2-methylcyclohexane, 1- (ethoxycarbonyl) -1- (ethoxy (cyclohexyl) acetyl ) Cyclohexane. Further, cyclic succinate compounds such as diisobutyl 3,6-dimethylcyclohexane-1,2-dicarboxylate disclosed in International Publication Nos. 2009/69483 and 2009/057774 can also be suitably used.

When R ^{3 to} R ^{6 of the} compound represented by the formula (I) include a hetero atom, the hetero atom is a Group 15 atom such as a nitrogen atom or a phosphorus atom, or a Group 16 atom such as an oxygen atom or a sulfur atom. It is preferably a group atom. Examples of the compound in which R ^{3 to} R ⁶ contain a Group 15 atom include the compounds disclosed in JP-A-2005-306910. Examples of the compound in which R ^{3 to} R ⁶ contain a Group 16 atom include the compounds disclosed in JP-A-2004-131537.
Examples of the halogen atom constituting the solid catalyst component (A) include fluorine, chlorine, bromine, iodine and a mixture thereof, and chlorine is particularly preferable.

Examples of the organoaluminum compound (B) include trialkylaluminums such as triethylaluminum and tributylaluminum, trialkenylaluminums such as triisoprenylaluminum, dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide, and ethylaluminum sesquiethoxy. , Aluminum sesquialkoxides such as butylaluminum sesquibutoxide, and R ⁷ _2.5 Al (OR ⁸ ) _0.5 (R ⁷ and R ⁸ may be the same or different hydrocarbon groups. Partially alkoxylated alkylaluminum, diethylaluminum chloride, dibutylaluminum chloride, diethylaluminum having an average composition represented by the formula: Alkyl aluminum sesquihalogenides such as dialkylaluminum halogenides such as mubromide, ethyl aluminum sesquichloride, butyl aluminum sesquichloride, ethyl aluminum sesquibromide, alkyl aluminum dihalogenides such as ethyl aluminum dichloride, propyl aluminum dichloride, butyl aluminum dibromide, etc. Partially halogenated alkylaluminums, such as dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride, and partially hydrogenated alkylaluminums such as an alkylaluminum dihydride such as ethylaluminum dihydride and propylaluminum dihydride , Ethyl aluminum ethoxy cyclolide, butyl aluminum butoki Chlorides, alkylaluminum, and the like which are partially alkoxylated and halogenated, such as ethylaluminum ethoxy bromide.
As the organoaluminum compound (B), one type may be used alone, or two or more types may be used in combination.

The external electron donor compound (C) includes an organosilicon compound.
Preferred organic silicon compounds include, for example, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane Silane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, bis-tolyldimethoxysilane, bism-tolyldimethoxysilane, bisp-tolyldimethoxysilane, bisp-tolyldiethoxysilane, bisethylphenyldimethoxysilane , Dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysila , Ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane , Methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, texyltrimethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, phenyltriethoxysilane, γ- Aminopropyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane Orchid, 2-norbornanetrimethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, ethyl silicate, butyl silicate, trimethylphenoxysilane, methyltriallyloxysilane, vinyltris (β-methoxyethoxysilane ), Vinyltriacetoxysilane, dimethyltetraethoxydisiloxane, and the like.
Among them, ethyltriethoxysilane, n-propyltriethoxysilane, t-butyltriethoxysilane, texyltrimethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, vinyltributoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane Silane, dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane, phenylmethyldimethoxysilane, bis p-tolyldimethoxysilane, p-tolylmethyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, 2-nonebornanetriethoxysilane, 2 -Norbornanemethyldimethoxysilane, diphenyldiethoxysilane, ethyl silicate are preferred.
One kind of the external electron donor compound (C) may be used alone, or two or more kinds may be used in combination.

  Among the above catalysts, the solid catalyst component (A) contains magnesium, titanium, halogen, and an electron donor compound containing a phthalate or succinate compound, and the organoaluminum compound (B) contains triethylaluminum, tributylaluminum. Preferably, the trialkylaluminum and the external electron donor compound (C) are organosilicon compounds such as dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane and diisopropyldimethoxysilane.

  The polypropylene resin has an intrinsic viscosity of 0.7 to 2.0 dl / g, preferably 0.8 to 1.8 dl / g, in xylene-soluble components in tetrahydronaphthalene at 135 ° C. When the intrinsic viscosity of the polypropylene-based resin is less than the lower limit, production of the polypropylene-based resin may be difficult, and when the intrinsic viscosity exceeds the upper limit, transparency of a molded product obtained from the resin composition is reduced. There is a tendency.

In the polypropylene resin, the ratio ( _Mw / _Mn ) of the mass average molecular weight _Mw to the number average molecular weight _Mn of the xylene-insoluble component is 6 or more, and preferably 8 or more. Here, the mass average molecular weight _Mw and the number average molecular weight _Mn of the xylene-insoluble portion of the polypropylene-based resin are values measured using gel permeation chromatography. The xylene-insoluble matter was obtained by dissolving a sample of a polypropylene resin in o-xylene at 135 ° C., cooling to 25 ° C., filtering the cooled solution using a filter paper, and removing what remained on the filter paper. It is a component obtained by sampling.
If the _Mw / _{Mn of the} polypropylene resin is less than the lower limit, fluidity and drawdown resistance during hollow molding may be reduced.
In order to keep the _Mw / _Mn of the polypropylene resin within the above range, a polymerization catalyst containing succinate as an electron donor compound may be used.

  The content ratio of the ethylene / propylene copolymer in the polypropylene-based resin is 23 to 35% by mass, and preferably 25 to 33% by mass. When the content of the ethylene / propylene copolymer in the polypropylene resin is less than the lower limit, the impact resistance of a molded article obtained from the resin composition tends to decrease. The rigidity of a molded article obtained from the resin composition tends to decrease.

The propylene copolymer is a copolymer containing 0.5 to 4.0% by mass of ethylene units and 96.0 to 99.5% by mass of propylene units. If the content of the ethylene unit in the propylene copolymer is less than the lower limit (that is, if the content of the propylene unit exceeds the upper limit), the balance between impact resistance and transparency may be impaired. On the other hand, when the content ratio of the ethylene unit in the propylene copolymer exceeds the upper limit (that is, when the content ratio of the propylene unit is less than the lower limit), the rigidity may decrease.
In the propylene copolymer, the content ratio of the ethylene unit is preferably 1.0 to 3.0% by mass, and the content ratio of the propylene unit is preferably 97.0 to 99.0% by mass.

  The ethylene / propylene copolymer is a copolymer having an ethylene unit and a propylene unit. In the ethylene / propylene copolymer, the propylene unit content is 15 to 40% by mass (that is, the ethylene unit content is 60 to 85% by mass), and the propylene unit content is 18 to 36% by mass (that is, the ethylene unit content is 64%). -82% by mass). When the propylene unit content in the ethylene-propylene copolymer is less than the lower limit, the impact resistance of a molded article obtained from the resin composition tends to decrease. There is a tendency that the transparency of a molded article obtained from the product is reduced.

(Nucleating agent)
The polypropylene resin composition of the present invention may contain a nucleating agent. The nucleating agent promotes the formation of polypropylene crystal nuclei. By forming a crystal nucleus, rigidity and transparency can be further improved.
Specific examples of the nucleating agent include a nonitol compound, a sorbitol compound, a metal salt of a carboxylic acid, an aromatic phosphate compound, and a triaminobenzene derivative nucleating agent. In terms of high rigidity and low odor, an aromatic phosphate compound and a triaminobenzene derivative nucleating agent are preferred.
Examples of the nonitol-based compound include 1,2,3-trideoxy-4,6-5,7-bis-o-[(4-propylphenyl) methylene] nonitol.
Examples of the sorbitol compound include dibenzylidene sorbitol, 1,3,2,4-di- (methylbenzylidene) sorbitol, 1,3,2,4- (ethylbenzylidene) sorbitol, 1,3,2,4- (Methoxybenzylidene) sorbitol, 1,3,2,4- (ethoxybenzylidene) sorbitol and the like.
Examples of the metal salt of a carboxylic acid include sodium adipate, potassium adipate, aluminum adipate, sodium sebacate, potassium sebacate, aluminum sebacate, sodium benzoate, aluminum benzoate, and di-para-t-butylbenzoate. Aluminum oxide, titanium di-para-t-butylbenzoate, chromium di-para-t-butylbenzoate, aluminum hydroxy-di-t-butylbenzoate and the like.
Examples of the aromatic phosphate ester-based nucleating agent include 2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate sodium salt-based nucleating agent and phosphoric acid-2,2′-methylenebis (4 , 6-di-tert-butylphenyl) aluminum salt nucleating agent and lithium 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate nucleating agent.
Examples of the triaminobenzene derivative-based nucleating agent include 1,3,5-tris (2,2-dimethylpropanamide) benzene.
One of the above nucleating agents may be used alone, or two or more may be used in combination.

  The content of the nucleating agent is preferably more than 0 parts by mass and 1.0 part by mass or less, more preferably 0.05 to 0.5 parts by mass, per 100 parts by mass of the polypropylene resin. When the nucleating agent is included in the above range, the rigidity and transparency of a molded product obtained from the resin composition can be further increased. However, even if the nucleating agent is contained in excess of the upper limit, the effect of promoting the formation of crystal nuclei will level off and the production cost will simply increase, so that it is not practical in the case of industrially mass production at low cost.

Examples of a method for producing a polypropylene resin composition containing a nucleating agent include a method in which the polypropylene resin and the nucleating agent are mixed and melt-kneaded. If necessary, other resins or rubbers other than the polypropylene-based resin, additives, and the like may be further mixed. The order of addition of each component is not limited.
The mixing method is not particularly limited, and examples thereof include a method using a mixer such as a Henschel mixer or a tumbler mixer.
After mixing, the resulting mixture may be melt-kneaded and further pelletized. As the melt kneading apparatus, a single screw extruder, a twin screw extruder, a Banbury mixer, a kneader, a roll mill, or the like can be used.

The polypropylene-based resin composition may contain a resin or rubber other than the polypropylene-based resin as long as the effects of the present invention are not impaired. The polypropylene resin composition may contain only one type of resin or rubber, or two or more types.
In addition, the polypropylene resin composition of the present invention may contain, as optional components, for example, chlorine absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, internal lubricants, external lubricants, antiblocking agents, antistatic agents, antistatic agents, Other additives such as clouding agents, flame retardants, dispersants, copper damage inhibitors, neutralizers, plasticizers, foaming agents, foam inhibitors, crosslinking agents, peroxides, oil extensions and pigments (organic or inorganic) May be included. The amount of each additive may be a known amount.

The polypropylene resin composition of the present invention having an MFR, a melt viscosity and a composition in the above-mentioned ranges is excellent in impact resistance, particularly low-temperature impact resistance, rigidity and transparency.
In addition, the polypropylene resin composition of the present invention has high drawdown resistance, and can prevent the molten resin composition from dropping down due to its own weight during hollow molding.

<Hollow molded product>
The hollow molded article of the present invention contains the above-mentioned polypropylene-based resin composition.
As a method of manufacturing a hollow molded product, for example, a step of melt-kneading a polypropylene-based resin composition using an extruder, extruding to form a tubular parison, sandwiching the parison in a mold, and To form a molded article by blowing air into the mold and bringing the molten resin into close contact with the inner surface of the mold, and a step of cooling the molded article.
The hollow molded article can be used, for example, as a container for filling beverages, foods, pharmaceuticals, cosmetics, detergents, and the like. Further, the hollow molded article can be used for a lid, a container, and the like.

Hereinafter, Examples and Comparative Examples are shown, but the present invention is not limited to the following Examples.
In each example, the content ratio of the propylene unit in the ethylene / propylene copolymer, the intrinsic viscosity of the xylene-soluble portion of the polypropylene resin, _Mw / _Mn of the xylene-insoluble portion of the polypropylene resin, and the MFR of the polypropylene resin composition Was measured as follows.
1) Propylene unit content of the ethylene / propylene copolymer:
The content ratio of the propylene unit of the ethylene / propylene copolymer was determined by measuring a sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene using JNM LA-400 ( ¹³ C resonance frequency, manufactured by JEOL Ltd.). 100 MHz) and measured by ¹³ C-NMR method.
2) Intrinsic viscosity of xylene-soluble component of polypropylene resin:
The xylene-soluble component of the polypropylene resin was obtained by the following method.
2.5 g of a sample is placed in a flask containing 250 ml of o-xylene (solvent) and stirred at 135 ° C. for 30 minutes using a hot plate and a reflux device while purging with nitrogen to completely dissolve the polypropylene resin. Then, the mixture was cooled at 25 ° C. for 1 hour. The resulting solution was filtered using filter paper. 100 ml of the filtrate after filtration was collected, transferred to an aluminum cup or the like, evaporated to dryness at 140 ° C. while purging with nitrogen, and allowed to stand at room temperature for 30 minutes to obtain a xylene-soluble matter.
Using the obtained xylene-soluble component as a sample, intrinsic viscosity was measured in tetrahydronaphthalene at 135 ° C. using a capillary automatic viscosity measuring device (SS-780-H1, manufactured by Shibayama Scientific Instruments Co., Ltd.).
3) _Mw / _Mn of xylene-insoluble content of the polypropylene resin:
The mass average molecular weight _Mw and the number average molecular weight _Mn of the xylene-insoluble portion of the polypropylene resin were measured using gel permeation chromatography (PL-GPC220 manufactured by Polymer Laboratories Co., Ltd.).
As a method for collecting the xylene-insoluble component, acetone is added to the residue (mixture of xylene-insoluble component and solvent) remaining on the filter paper when the xylene-soluble component is filtered as described above, and then filtered. The resulting components were evaporated to dryness in a vacuum drying oven set at 80 ° C. to obtain xylene-insoluble components.
4) MFR:
The MFR of the polypropylene-based resin composition was measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K7210.

(Example 1)
Nonitol nucleating agent containing 100 parts by mass of polypropylene resin and 1,2,3-trideoxy-4,6: 5,7-bis-[(4-propylphenyl) methylene] -nonitol (manufactured by Milliken Japan Co., Ltd.) , Millad NX8000J) 0.25 parts by mass, an antioxidant (B225 manufactured by BASF, 1: 1 mixture of Irganox 1010 and Irgafos 168) 0.2 parts by mass, a neutralizing agent (Calcium Steer manufactured by Tannan Chemical Industry Co., Ltd.) (Rate) of 0.05 parts by mass was stirred and mixed with a Henschel mixer for 1 minute to obtain a mixture for melt-kneading.
In this example, a succinate-based (indicated as “Suc” in the table) Ziegler-Natta catalyst is used as the polypropylene-based resin, and in the first stage, ethylene and propylene are copolymerized to form a propylene copolymer. In the second stage, a polymerization mixture obtained by copolymerizing ethylene and propylene in the presence of the propylene copolymer to form an ethylene / propylene copolymer was used. Specifically, the polymerization mixture was produced as follows.
According to the preparation method described in the example of JP-A-2011-500907, the solid catalyst component was prepared as follows.
250 mL of TiCl ₄ was introduced at 0 ° C. into a 500 mL four-necked round bottom flask purged with nitrogen. While stirring, 10.0 g of fine spherical MgCl ₂ .1.8C ₂ H ₅ OH (prepared according to the method described in Example 2 of USP-4,399,054, but operating at 3000 rpm instead of 10000 rpm) And 9.1 mmol of diethyl-2,3- (diisopropyl) succinate. The temperature was raised to 100 ° C. and held for 120 minutes. Next, the stirring was stopped, the solid product was allowed to settle, and the supernatant was drawn off. The following procedure was then repeated twice: 250 mL of fresh TiCl ₄ was added, the mixture was allowed to react at 120 ° C. for 60 minutes, and the supernatant was drawn off. The solid was washed six times at 60 ° C. with anhydrous hexane (6 × 100 mL).
The solid catalyst was mixed with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) in an amount such that the mass ratio of TEAL to the solid catalyst was 18 and the mass ratio of TEAL / DCPMS was 10, and 5 Minutes of contact. Preliminary polymerization was performed by holding the obtained catalyst system in liquid propylene in a suspended state at 20 ° C. for 5 minutes. The obtained prepolymer was introduced into a first polymerization reactor of a polymerization apparatus having a two-stage polymerization reactor in series, and a propylene copolymer was produced in a propylene liquid phase state. Was used to produce an ethylene-propylene copolymer. At the time of polymerization, the polymerization temperature, polymerization pressure, catalyst addition amount, first stage ethylene supply amount, second stage ethylene supply amount and propylene supply amount were adjusted, and hydrogen was used as a molecular weight regulator, and polypropylene was used. The supply amounts of the first stage and the second stage were adjusted so that the intrinsic viscosity of the xylene-soluble component of the polypropylene resin and the MFR of the resin composition became a predetermined amount. In addition, the residence time distributions of the first and second stages were adjusted so that the copolymer component had a predetermined amount.
Polypropylene resin comprising the obtained polymerization mixture, ethylene unit content in the propylene copolymer, ethylene-propylene copolymer content in the polypropylene-based resin, propylene unit content in the ethylene-propylene copolymer, Table 1 shows the intrinsic viscosity of the xylene-soluble portion of the polypropylene-based resin and the _Mw / _Mn of the xylene-insoluble portion of the polypropylene-based resin.
Next, the mixture for melt-kneading was melt-kneaded using a single-screw extruder (NVC-50, manufactured by Nakatanani Machine Co., Ltd.) set at a screw temperature of 230 ° C. and a screw rotation speed of 90 rpm, and pelletized to obtain an MFR of 1 A polypropylene-based resin composition of 0.4 g / 10 minutes was obtained.

(Examples 2 to 8)
As shown in Table 1, the ethylene unit content in the propylene copolymer, the ethylene / propylene copolymer content in the polypropylene resin, the intrinsic viscosity of the xylene-soluble portion of the polypropylene resin, the ethylene / propylene copolymer The polymerization conditions were adjusted so that the propylene unit content in the mixture was adjusted to obtain a polymerization mixture of a propylene copolymer and an ethylene / propylene copolymer.
An MFR polypropylene resin composition shown in Table 1 was obtained in the same manner as in Example 1 except that the polymerization mixture was used as a polypropylene resin.

(Example 9)
An MFR polypropylene resin composition shown in Table 1 was obtained in the same manner as in Example 1 except that the nucleating agent was not mixed with the polypropylene resin.

(Comparative Example 1)
In a first stage, ethylene and propylene are copolymerized to form a propylene copolymer using a phthalate-based (indicated as “Pht” in the table) Ziegler-Natta catalyst, and in a second stage, In the presence of the propylene copolymer, ethylene and propylene were copolymerized to form an ethylene / propylene copolymer, thereby obtaining a polymerization mixture. Specifically, the polymerization mixture was produced as follows.
A solid catalyst comprising MgCl ₂ and Ti and diisobutyl phthalate as an internal donor was prepared by the method described in Example 5 of EP 728,769. Next, using the solid catalyst, triethylaluminum (TEAL) as an organoaluminum compound, and dicyclopentyldimethoxysilane (DCPMS) as an external electron donor compound, the weight ratio of TEAL to the solid catalyst was 20, and the weight ratio of TEAL / DCPMS was 20 Was contacted at 12 ° C. for 24 minutes in such an amount as to give 10. Preliminary polymerization was performed by maintaining the obtained catalyst system in liquid propylene in a suspended state at 20 ° C. for 5 minutes. The obtained prepolymer was introduced into a first polymerization reactor of a polymerization apparatus having a two-stage polymerization reactor in series, and a propylene copolymer was produced in a propylene liquid phase state. Was used to produce an ethylene-propylene copolymer. At the time of polymerization, the polymerization temperature, polymerization pressure, catalyst addition amount, first stage ethylene supply amount, second stage ethylene supply amount and propylene supply amount were adjusted, and hydrogen was used as a molecular weight regulator, and polypropylene was used. The supply amounts of the first stage and the second stage were adjusted so that the intrinsic viscosity of the xylene-soluble component of the polypropylene resin and the MFR of the resin composition became a predetermined amount. In addition, the residence time distributions of the first and second stages were adjusted so that the copolymer component had a predetermined amount.
The resulting polymerization mixture has an ethylene unit content in the propylene copolymer, an ethylene / propylene copolymer content in the polypropylene resin, an intrinsic viscosity of the xylene-soluble portion of the polypropylene resin, and an ethylene / propylene copolymer. Table 1 shows the content ratio of the propylene units.
An MFR polypropylene resin composition shown in Table 2 was obtained in the same manner as in Example 1 except that this polymerization mixture was used as a polypropylene resin.

(Comparative Examples 2 to 8)
As shown in Table 2, the ethylene unit content in the propylene copolymer, the ethylene / propylene copolymer content in the polymerization mixture, the intrinsic viscosity of the xylene-soluble portion of the polypropylene resin, the ethylene / propylene copolymer The polymerization conditions were adjusted so that the propylene unit content ratio was adjusted to obtain a polymerization mixture of a propylene copolymer and an ethylene / propylene copolymer.
An MFR polypropylene-based resin composition shown in Table 2 was obtained in the same manner as in Example 1 except that the polymerization mixture was used as a polypropylene-based resin.

<Evaluation>
The Izod impact strength, flexural modulus, and haze of the polypropylene resin composition of each example were measured by the following methods, and the resin pressure during molding (index of fluidity) and the drawdown resistance were evaluated. Tables 1 and 2 show the measurement results and evaluation results.

[Izod impact strength]
The polypropylene-based resin composition was subjected to injection molding at a cylinder temperature of 255 ° C., a mold temperature of 40 ° C., an average injection speed of 200 mm / sec, and a cooling time of 20 seconds using an injection molding machine (FANUC ROBOSHOT S2000i injection molding machine manufactured by FANUC CORPORATION). It was molded to obtain a test specimen having a width of 10.0 mm, a thickness of 4.0 mm, and a length of 80 mm.
Izod impact strength was measured at a temperature of 0 ° C. using a digital impact tester (DG-UB2) manufactured by Toyo Seiki Seisaku-Sho, Ltd. in accordance with JIS K7110 using the test specimen for measurement. The higher the Izod impact strength, the better the impact resistance.

[Flexural modulus]
In accordance with JIS K7151, a polypropylene resin composition was molded from an injection molding machine (FANUC ROBOSHOT S2000i injection molding machine manufactured by FANUC) at a cylinder temperature of 255 ° C, a mold temperature of 40 ° C, an average injection speed of 200 mm / sec, and a cooling time of 20. Molding was performed under the conditions of seconds to obtain a test specimen having a width of 10.0 mm, a thickness of 4.0 mm, and a length of 80 mm.
Based on JIS K7171 and using a fully automatic testing machine (AG-X10 kN) manufactured by Shimadzu Corporation, the test piece for measurement was used at a temperature of 23 ° C., a relative humidity of 50%, a span of 64 mm, and a bending speed of 2.0 mm / min. The flexural modulus was measured under the conditions. The higher the value of the flexural modulus, the better the rigidity.

[transparency]
The polypropylene resin composition was press-molded under the conditions of a molding temperature of 210 ° C., a pressure of 10 MPa and a molding time of 60 seconds, and then cooled at a cooling temperature of 30 ° C. and a cooling time of 60 seconds. A sheet-shaped test piece having a thickness of 0.5 mm was prepared. Using this test piece, the haze was measured by a haze measuring device (Model HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K7136. The smaller the haze value, the better the transparency.

[Resin pressure during molding]
Using a hollow molding machine (manufactured by Nippon Steel Works Co., Ltd., extruder screw diameter: 50 mm), the extruder was used to extrude the polypropylene resin composition at a molding temperature of 230 ° C. and a screw rotation speed of 15 rotations / minute. The resin pressure (MPa) was measured.

[Drawdown resistance]
Using a hollow molding machine (manufactured by Nippon Steel Works, screw diameter of extruder: 50 mm), the polypropylene resin composition is extruded vertically downward at a molding temperature of 230 ° C. and a screw rotation speed of 15 rotations / minute. Molding produced a tubular parison. The prepared parison was visually observed to evaluate drawdown resistance. Those that maintained the shape of the parison after molding were evaluated as good, and those that were deformed by their own weight and could not maintain the shape of the parison after molding were evaluated as poor.

The polypropylene-based resin compositions of Examples 1 to 9 had a large Izod impact strength at 0 ° C. and a large flexural modulus, and were excellent in low-temperature impact resistance and rigidity. Moreover, the haze was small and the polypropylene resin composition of Examples 1-9 was excellent in transparency. Moreover, the polypropylene resin compositions of Examples 1 to 9 were also excellent in fluidity and drawdown resistance.
The polypropylene-based resin composition of Comparative Example 1 in which the xylene-insoluble portion of the polypropylene-based resin had an _Mw / _Mn of less than 6 had a high resin pressure during molding and a low drawdown resistance.
The polypropylene resin composition of Comparative Example 2 in which the propylene copolymer contained less than 0.5% by mass of ethylene units had a low Izod impact strength at 0 ° C. and a large haze.
The polypropylene resin composition of Comparative Example 3 in which the content of the ethylene / propylene copolymer in the polypropylene resin was less than 20% by mass had a low Izod impact strength at 0 ° C.
The polypropylene resin composition of Comparative Example 4 in which the content of the ethylene / propylene copolymer in the polypropylene resin exceeded 35% by mass had a low flexural modulus.
The polypropylene resin composition of Comparative Example 5, in which the content of propylene units in the ethylene / propylene copolymer was less than 15% by mass, had a low Izod impact strength at 0 ° C.
The polypropylene resin composition of Comparative Example 6 in which the content ratio of propylene units in the ethylene / propylene copolymer exceeded 40% by mass had a large haze.
The haze was large in the polypropylene resin composition of Comparative Example 7 in which the intrinsic viscosity of the xylene-soluble component in the polypropylene resin exceeded 2.0 dl / g.
The polypropylene-based resin composition of Comparative Example 8 having an MFR of more than 5 g / 10 minutes had a low Izod impact strength at 0 ° C. and low drawdown resistance.

Claims (4)

It contains a polypropylene resin containing a matrix composed of a propylene copolymer and an ethylene-propylene copolymer, and has a melt flow rate of 0.1 to 5 measured at 230 ° C. under a load of 21.18 N according to JIS K7210. 0.0 g / 10 minutes,
The polypropylene-based resin has an intrinsic viscosity of 0.7 to 2.0 dl / g in tetrahydronaphthalene at 135 ° C. of a xylene-soluble component, and a mass average molecular weight _Mw and a number average molecular weight _Mn of a xylene-insoluble component. The ratio ( _Mw / _Mn ) is 6 or more, and the content ratio of the ethylene / propylene copolymer is 23 to 35% by mass;
The propylene copolymer contains 0.5 to 4.0% by mass of ethylene units and 96.0 to 99.5% by mass of propylene units,
The polypropylene resin for hollow molding, wherein the ethylene / propylene copolymer contains 60 to 85% by mass of ethylene units and 15 to 40% by mass of propylene units.   The polypropylene resin composition for hollow molding according to claim 1, wherein the polypropylene resin is a polymerization mixture obtained by polymerizing an ethylene monomer and a propylene monomer in the presence of a propylene copolymer. The polypropylene resin for hollow molding according to any one of claims 1 to 2 , wherein the nucleating agent is contained in an amount of more than 0 part by mass and 1.0 part by mass or less based on 100 parts by mass of the polypropylene resin. Composition. A hollow molded article containing the polypropylene resin composition for hollow molding according to any one of claims 1 to 3 .