JP2018188504A - Polypropylene resin composition for hollow molding, method for producing the same, and hollow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene resin composition for hollow molding excellent in rigidity and impact resistance (in particular, bottle impact strength) of an obtained hollow molding in addition to drawdown resistance during molding.SOLUTION: A polypropylene resin composition for hollow molding contains a polypropylene resin containing a matrix formed from a propylene polymer and an ethylene-propylene copolymer, where an MFR at 230°C and 2.16 kg is 0.1-5.0 g/10 min, an intrinsic viscosity of a xylene soluble content of the polypropylene resin is more than 2.0 dl/g and 4.0 dl/g or less, a ratio (Mw/Mn) of a weight average molecular weight Mand a number average molecular weight Mof the xylene insoluble content is 6-20, a content ratio of the ethylene-propylene copolymer is 15-30 mass%, a content ratio of an ethylene unit in the propylene polymer is 1.0 mass% or less, and a content ratio of a propylene unit in the ethylene-propylene copolymer is more than 40 mass% and 70 mass% or less.SELECTED DRAWING: None

Description

  The present invention relates to a polypropylene resin composition for hollow molding containing a polypropylene resin, a method for producing the same, and a hollow molded article.

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

Polypropylene is sometimes used as a film-like packaging material.
A polypropylene film can be produced, for example, by subjecting a polypropylene resin composition to inflation molding or T-die molding (Patent Documents 3 and 4).

JP-A-8-73673 JP 2003-342429 A International Publication No. 2014/054673 JP 2017-052906 A

In the polypropylene resin composition for hollow molding, a balance between the impact resistance and rigidity of the obtained molded product is required in addition to the drawdown resistance that prevents the resin melted during hollow molding from dripping down due to its own weight.
In Patent Document 1, a specific polypropylene homopolymer and a soft polypropylene resin are prepared to obtain a resin composition having an excellent balance between impact resistance and rigidity. In Patent Document 2, a propylene-based resin containing a copolymer component and an ethylene-based resin are melt-kneaded with an extruder to obtain a resin composition. Since these resin compositions are blended compositions that place importance on impact resistance, they have the disadvantage of low rigidity. In addition, it is necessary to provide an intermediate step such as blending of plural resins or melt kneading, and this is not preferable because the cost increases particularly when a large amount is produced.
Patent Documents 3 and 4 do not discuss hollow molding, but according to the study by the present inventors, the polypropylene resins described in Patent Documents 3 and 4 are designed with an emphasis on transparency. When the polypropylene resin composition is applied to hollow molding, the balance between the rigidity and impact resistance of the resulting molded product (hollow molded product) is not always sufficient. In particular, hollow molded products such as bottles that require higher impact resistance do not always satisfy market demands.

  The present invention relates to a polypropylene resin composition for hollow molding excellent in the rigidity and impact resistance (particularly bottle impact strength) of a hollow molded product obtained in addition to the drawdown resistance at the time of molding, a method for producing the same, and the hollow An object is to provide a hollow molded article using a polypropylene resin composition for molding.

The present invention has the following aspects.
[1] A polypropylene resin containing a matrix composed of a propylene polymer and an ethylene / propylene copolymer,
The melt mass flow rate at 230 ° C. and 2.16 kg is 0.1 to 5.0 g / 10 minutes,
The intrinsic viscosity of the polypropylene-based resin in xylene solubles in tetrahydronaphthalene at 135 ° C. is more than 2.0 dl / g and not more than 4.0 dl / g,
The ratio (M _w / M _n ) between the weight average molecular weight M _w and the number average molecular weight M _n of the xylene-insoluble portion of the polypropylene resin is 6 to 20,
The content ratio of the ethylene / propylene copolymer is 15 to 30% by mass with respect to the total mass of the polypropylene resin,
The ethylene unit content in the propylene polymer is 1.0 mass% or less with respect to the total mass of the propylene polymer,
A polypropylene-based resin composition for hollow molding, wherein a content ratio of propylene units in the ethylene / propylene copolymer is more than 40% by mass and 70% by mass or less based on a total mass of the ethylene / propylene copolymer.
[2] A process for producing a polypropylene resin composition for hollow molding as set forth in [1],
(A) a solid catalyst containing magnesium, titanium, halogen and an electron donor compound, wherein the electron donor compound is a succinate compound;
(B) an organoaluminum compound;
(C) an external electron donor compound that is a silicon compound;
A process for producing a polypropylene resin composition for hollow molding, comprising a step of polymerizing an ethylene monomer and a propylene monomer in the presence of the propylene polymer using a catalyst containing .
[3] A hollow molded article comprising the polypropylene resin composition for hollow molding according to [1].

The polypropylene resin composition for hollow molding of the present invention is excellent in the drawdown resistance during molding, and the rigidity and impact resistance (particularly bottle impact strength) of the resulting hollow molded product.
According to the method for producing a polypropylene resin composition for hollow molding of the present invention, a hollow molding polypropylene system excellent in drawdown resistance during molding, rigidity and impact resistance (particularly bottle impact strength) of the resulting molded product. A resin composition is obtained.
The hollow molded article of the present invention is excellent in rigidity and impact resistance (particularly bottle impact strength).

<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 melt mass flow rate (hereinafter also referred to as “MFR”) of the polypropylene resin composition of the present invention is 0.1 to 5.0 g / 10 min, preferably 0.1 to 2.0 g / 10 min. 0.3 to 1.8 g / 10 min is more preferable. If the MFR of the polypropylene resin composition is less than the lower limit, the fluidity at the time of molding may be too low to obtain a hollow molded product. When the MFR of the polypropylene resin composition exceeds the upper limit, the drawdown resistance is lowered, and it becomes difficult to stably produce a hollow molded product.
Here, MFR is a value measured under conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210-1.

(Polypropylene resin)
The polypropylene resin includes a matrix made of a propylene polymer and an ethylene / propylene copolymer. The ethylene / propylene copolymer is mainly composed of a rubber component.
The polypropylene resin may be a mixed resin in which a propylene polymer and an ethylene / propylene copolymer are mixed during polymerization, or a separately obtained propylene polymer and an ethylene / propylene copolymer are melt-kneaded. It may be a mixed resin mixed by. Since a material having excellent balance between rigidity and impact resistance (hereinafter also referred to as “balance of physical properties”) can be obtained at a lower cost, a mixture in which a propylene polymer and an ethylene / propylene copolymer are mixed during polymerization (polymerization) A mixture) is preferred.
In a polymerization mixture in which a propylene polymer and an ethylene / propylene copolymer are mixed by polymerization, the propylene polymer and the ethylene / propylene copolymer are mixed in a submicron order at the polymerization stage. Therefore, a composition based on a polymerization mixture in which a propylene polymer and an ethylene / propylene copolymer are mixed by polymerization exhibits an excellent balance of physical properties.
On the other hand, when a similar excellent physical property balance is obtained with a simple mechanical mixture obtained by melt-kneading a propylene polymer and an ethylene / propylene copolymer, there is a problem that the production cost is increased.
The reason why the polymer mixture and the mechanical mixture exhibit different physical properties is presumed to be because the dispersion state of the ethylene / propylene copolymer in the propylene polymer is different, but the propylene of the ethylene / propylene copolymer There is currently no known practical means for analyzing the dispersion state at the molecular level including the state of the interface with the polymer.
The method for producing the polypropylene resin will be described in detail later.

The intrinsic viscosity (hereinafter also referred to as “XSIV”) of the polypropylene-based resin in the polypropylene resin is 2.0 to 4.0 dl / g, and preferably 2.5 to 3.5 dl / g. When XSIV is less than the lower limit value or exceeds the upper limit value, the impact resistance of the composition and the hollow molded article may be lowered.
Here, XSIV is a measured value in tetrahydronaphthalene at 135 ° C. The xylene-soluble component was prepared by dissolving a polypropylene resin sample in o-xylene at 135 ° C and then cooling to 25 ° C. The cooled solution was filtered using filter paper, and the filtrate was evaporated to dryness. It is a component obtained.

The ratio ( _Mw / _Mn ) of the weight average molecular weight _Mw and the number average molecular weight _Mn of the xylene-insoluble matter (hereinafter also referred to as "XI") of the polypropylene resin is 6 to 20, 20 is preferred. When M _w / M _{n of} XI is less than the lower limit, the impact resistance (particularly bottle impact strength) of the hollow molded product may be lowered. When M _w / M _{n of} XI exceeds the above upper limit, stable production of the polypropylene resin composition becomes difficult, for example, the copolymer is poorly dispersed.
Here, the weight average molecular weight _Mw and the number average molecular weight _Mn of XI are values measured by gel permeation chromatography (GPC). In XI, a polypropylene resin sample was dissolved in o-xylene at 135 ° C. and then cooled to 25 ° C., and the cooled solution was filtered using filter paper, and what remained on the filter paper was collected. It is a component obtained.

In order to make M _w / M _n of XI within the above range, for example, when a polypropylene resin is produced by polymerizing an ethylene monomer and a propylene monomer in the presence of a propylene polymer, electron donation is performed. A catalyst containing succinate as the body compound may be used.
In the present invention, M _w / M _n of XI is a relatively large value. M _{w /} M _n of XI is large, the molecular weight distribution of the propylene polymer constituting the polypropylene resin means that wide. If the molecular weight distribution of the propylene polymer is wide, the molecular weight distribution of the ethylene / propylene copolymer tends to be wide. Therefore, it can be said that the larger the M _w / M _{n of} XI, the more the propylene polymer portion and the ethylene / propylene copolymer portion both contain relatively high molecular weight molecules. Due to the high molecular weight molecules, the polypropylene resin exhibits high strain hardening when stretched. Therefore, it is considered that the resin composition in a molten state is uniformly stretched and a molded product with good thickness accuracy and a small thickness difference can be obtained when hollow molding is performed. As the thickness accuracy is improved and the thickness difference is reduced, the thin portion is reduced, and stress concentration on the thin portion with weak strength is avoided. As a result, the impact resistance (bottle impact strength) of the hollow molded product is reduced. It is thought to improve.

  The content of the ethylene / propylene copolymer in the polypropylene resin (hereinafter also referred to as “BIPO”) is 15 to 30% by mass and 18 to 25% by mass with respect to the total mass of the polypropylene resin. It is preferable. When BIPO is less than the lower limit value, the impact resistance of the composition and the hollow molded article tends to decrease, and when the upper limit value is exceeded, the rigidity of the composition and the hollow molded article tends to decrease.

The content of ethylene units in the propylene polymer (hereinafter also referred to as “C2”) is 1.0% by mass or less based on the total mass of the propylene polymer. Therefore, the content ratio of the propylene unit in the propylene polymer is 99.0% by mass or more. When C2 exceeds the upper limit (that is, when the propylene unit content is less than the lower limit), the rigidity of the composition and the hollow molded article may be lowered.
The lower limit of C2 is not particularly limited, and may be 0% by mass.
Accordingly, the propylene polymer may be a homopolypropylene composed only of propylene units, and is composed of 99.0% by mass or more and less than 100% by mass of propylene units and 1.0% by mass or less of 0% by mass or more of ethylene units. A copolymer may also be used.
C2 is measured by ¹³ C-NMR method.

The ethylene / propylene copolymer is a copolymer having an ethylene unit and a propylene unit.
The content of propylene units in the ethylene / propylene copolymer (hereinafter also referred to as “Pc”) is more than 40% by mass and 70% by mass or less (that is, ethylene) with respect to the total mass of the ethylene / propylene copolymer. The unit content is more than 30% by mass and not more than 60% by mass, and preferably 45 to 65% by mass (that is, the ethylene unit content is 35 to 55% by mass). When Pc is not more than the lower limit value or exceeds the upper limit value, the impact resistance of the composition and the hollow molded article tends to be lowered.
Pc is measured by a ¹³ C-NMR method.

  The polypropylene resin composition of the present invention may be composed only of the polypropylene resin, or may further contain other components other than the polypropylene resin.

(Other ingredients)
The polypropylene resin composition of the present invention may contain a filler as long as it does not impair the effects of the present invention. The filler is added mainly for the purpose of improving the rigidity of the composition and the hollow molded article.
Examples of the filler include inorganic fillers such as talc, clay, calcium carbonate, magnesium hydroxide, and glass fiber, and organic fillers such as carbon fiber and cellulose fiber. These fillers may be used individually by 1 type, and may use 2 or more types together. In order to improve the dispersibility of the filler, surface treatment of the filler and preparation of a master batch of the filler and the resin may be performed as necessary.
Among the fillers, talc is preferable because it is easily mixed with the polypropylene resin and can easily improve the rigidity of the composition and the hollow molded article.
The addition amount of the filler may be a known amount. For example, it may be 0.1 to 40 parts by mass with respect to 100 parts by mass of the polypropylene resin.

The polypropylene resin composition of the present invention may contain a resin or rubber other than the polypropylene resin as needed, as long as the effects of the present invention are not impaired. Only one type of resin or rubber may be contained in the polypropylene resin composition, or two or more types may be used.
The polypropylene resin composition of the present invention is, as necessary, a chlorine absorbent, a heat-resistant stabilizer, a light stabilizer, an ultraviolet absorber, an internal lubricant, an external lubricant, and an anti-blocking agent as long as the effects of the present invention are not impaired. Antistatic agents, antifogging agents, flame retardants, dispersants, copper damage prevention agents, neutralizing agents, crystal nucleating agents, plasticizers, foaming agents, antifoaming agents, crosslinking agents, peroxides, oil-extended and pigments Other additives such as (organic or inorganic) may be contained. The addition amount of each additive may be a known amount.

  The polypropylene resin composition of the present invention contains the polypropylene resin and has an MFR of 0.1 to 5.0 g / 10 min. Excellent rigidity and impact resistance (particularly bottle impact strength).

<Method for Producing Polypropylene Resin Composition>
The polypropylene resin composition of the present invention may be produced by any production method as long as it satisfies the above characteristics.
For example, a propylene polymer and an ethylene / propylene copolymer are mixed during polymerization to obtain a polypropylene resin, and if necessary, other components are mixed into the polypropylene resin to obtain a polypropylene resin composition. Also good. Separately produced propylene polymer and ethylene / propylene copolymer are mixed by melt kneading to obtain a polypropylene resin, and if necessary, other components are mixed into the polypropylene resin to form a polypropylene resin composition You may get things.
There are no particular limitations on the method of mixing the polypropylene-based resin and other components in the case of containing other components, and examples thereof include a method using a mixer such as a Henschel mixer or a tumbler mixer.
After mixing, the obtained 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.

As described above, the polypropylene resin is preferably a polymerization mixture in which a propylene polymer and an ethylene / propylene copolymer are mixed during polymerization.
Such a polymerization mixture is obtained by polymerizing an ethylene monomer and a propylene monomer in the presence of a propylene polymer. In this method, since the ethylene / propylene copolymer is produced in the presence of the propylene polymer, the productivity is increased and the dispersibility of the ethylene / propylene copolymer in the propylene polymer is increased. Improved physical property balance.

As the method for producing the polymerization mixture, a multistage polymerization method is typically used. For example, in a first stage polymerization reactor having a two-stage polymerization reactor, a propylene monomer and, if necessary, an ethylene monomer are polymerized to obtain a propylene polymer, and the obtained propylene While supplying the polymer to the second stage polymerization reactor, the polymerization mixture can be obtained by polymerizing the ethylene monomer and the propylene monomer in the second stage polymerization reactor.
The polymerization conditions may be the same as known polymerization conditions. For example, the first stage polymerization conditions include a slurry polymerization method in which propylene is in a liquid phase and the monomer density and productivity are high. As the second stage polymerization conditions, there is generally a gas phase polymerization method that makes it easy to produce a copolymer having high solubility in propylene.
The polymerization temperature is preferably 50 to 90 ° C, more preferably 60 to 90 ° C, and further preferably 70 to 90 ° C. When the polymerization temperature is at least the lower limit of the above range, the productivity and the stereoregularity of the obtained polypropylene are more excellent.
The polymerization pressure is preferably from 25 to 60 bar (2.5 to 6.0 MPa), more preferably from 33 to 45 bar (3.3 to 4.5 MPa) when carried out in the liquid phase. When performed in the gas phase, 5 to 30 bar (0.5 to 3.0 MPa) is preferable, and 8 to 30 bar (0.8 to 3.0 MPa) is more preferable.
The polymerization (polymerization of propylene monomer, polymerization of ethylene monomer and propylene monomer) is usually performed using a catalyst. During the polymerization, hydrogen may be added as necessary to adjust the molecular weight. By adjusting the molecular weight of the propylene polymer or ethylene / propylene copolymer, it is possible to adjust the MFR of the polypropylene resin, and thus the MFR of the polypropylene resin composition.
Before polymerization in the first stage polymerization reactor, prepolymerization of propylene may be performed in order to form a polymer chain as a foothold for the subsequent main polymerization in the solid catalyst component. The prepolymerization is usually performed at 40 ° C. or lower, preferably 30 ° C. or lower, more preferably 20 ° C. or lower.

A known olefin polymerization catalyst can be used as the catalyst.
As the catalyst for polymerizing the ethylene monomer and the propylene monomer in the presence of the propylene polymer, a stereospecific Ziegler-Natta catalyst is preferable, and the following components (A), (B) and ( A catalyst containing C) (hereinafter also referred to as “catalyst (I)”) is particularly preferable.
(A) A solid catalyst containing magnesium, titanium, halogen and an electron donor compound, wherein the electron donor compound is a succinate compound.
(B) Organoaluminum compound.
(C) An external electron donor compound which is a silicon compound.
Therefore, a preferred embodiment of the method for producing a polypropylene resin composition of the present invention is that the catalyst (I) is used to polymerize an ethylene monomer and a propylene monomer in the presence of the propylene polymer. It is a manufacturing method which has the process of obtaining a polypropylene resin.
By using the catalyst (I), a polypropylene resin in which M _w / M _{n of} XI is within the above range can be easily obtained. When a catalyst in which the electron donor compound of the catalyst (I) is another compound (for example, a phthalate compound) is used instead of the catalyst (I), M _w / M _{n of} XI tends to be relatively narrow. .
In addition, although the property of the polymer obtained differs according to the kind of catalyst, the realistic means to analyze all the difference in property is not known.

Component (A) is prepared using, for example, a titanium compound, a magnesium compound, and an electron donor compound.
As a titanium compound used for the component (A), a tetravalent titanium compound represented by the general formula: Ti (OR) _g X _4-g (R is a hydrocarbon group, X is a halogen, 0 ≦ g ≦ 4) is used. Is preferred. Examples of the hydrocarbon group include methyl, ethyl, propyl, butyl and the like, and examples of the halogen include Cl, Br and the like.
More specific titanium _compounds, TiCl _4, TiBr 4, titanium tetrahalides of TiI _{4 such; 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 Br _{3 such; 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 Br ₂ or the _{like; 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} ) tetraalkoxy titanium such as _4. These titanium compounds may be used individually by 1 type, and may use 2 or more types together.
Among the above titanium compounds, preferred are halogen-containing titanium compounds, more preferred are titanium tetrahalides, and particularly preferred is titanium tetrachloride (TiCl ₄ ).

As the magnesium compound used in component (A), a magnesium compound having a magnesium-carbon bond or a magnesium-hydrogen bond, such as dimethyl magnesium, diethyl magnesium, dipropyl magnesium, dibutyl magnesium, diamyl magnesium, dihexyl magnesium, didecyl magnesium, Examples include ethyl magnesium chloride, propyl magnesium chloride, butyl magnesium chloride, hexyl magnesium chloride, amyl magnesium chloride, butyl ethoxy magnesium, ethyl butyl magnesium, butyl magnesium hydride and the like.
These magnesium compounds can be used, for example, in the form of a complex compound with organic aluminum or the like, 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; alkoxy such as methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride and octoxy magnesium chloride. Magnesium halides; aryloxymagnesium halides such as phenoxymagnesium chloride and methylphenoxymagnesium chloride; alkoxymagnesiums such as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium, n-octoxymagnesium and 2-ethylhexoxymagnesium; phenoxymagnesium and dimethyl Allyloxymagnesium such as phenoxymagnesium; Magnesium laurate , Carboxylic acid salts of magnesium such as magnesium stearate. These magnesium compounds may be used individually by 1 type, and may use 2 or more types together.

The electron donor compound used for the component (A) is a succinate compound. When the catalyst (I) containing a succinate compound as an electron donor is used, a polypropylene resin in which M _w / M _{n of} XI is within the above range can be easily obtained.
The succinate compound may be an ester of succinic acid, or may be an ester of substituted succinic acid having a substituent such as an alkyl group at the 1-position or 2-position of succinic acid. Specific examples include diethyl succinate, dibutyl succinate, diethyl methyl succinate, diethyl diisopropyl succinate, diallyl ethyl succinate and the like.
Suitable succinate compounds include compounds having a succinate structure represented by the following chemical formula (I).

In 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 that may contain a hetero atom. It is a group.
R ^{3 to} R ⁶ are the same as or different from each other, hydrogen, or a linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl group having 1 to 20 carbon atoms that may contain a hetero atom. It is. R ³ and R ⁴ , 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.

Preferred R ¹ and R ² are alkyl, cycloalkyl, aryl, arylalkyl, and alkylaryl groups 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.

One preferred group of compounds of formula (I) are branched alkyl, cycloalkyl, aryl, arylalkyl, wherein R ^{3 to} R ⁵ are hydrogen and R ⁶ has 3 to 10 carbon atoms. And monosubstituted succinate compounds of alkylaryl groups.
Specific examples of suitable mono-substituted succinate compounds include diethyl-sec-butyl succinate, diethyl texyl succinate, diethyl cyclopropyl succinate, diethyl norbornyl succinate, diethyl perhydrosuccinate, diethyl trimethylsilyl Succinate, diethyl methoxy succinate, diethyl-p-methoxyphenyl succinate, diethyl-p-chlorophenyl succinate, diethyl phenyl succinate, diethyl cyclohexyl succinate, diethyl benzyl succinate, diethyl cyclohexyl methyl Succinate, diethyl-t-butyl succinate, diethyl isobutyl succinate, diethyl isopropyl succinate, diethyl neopentyl succinate, diethyl isopentyl succinate , Diethyl (1-trifluoromethylethyl) succinate, diethyl fluorenyl succinate, 1- (ethoxycarbodiisobutylphenyl) succinate, diisobutyl-sec-butyl succinate, diisobutyl hexyl succinate, diisobutylcyclopropyl succinate , Diisobutyl norbornyl succinate, diisobutyl perhydrosuccinate, diisobutyltrimethylsilyl succinate, diisobutyl methoxy succinate, diisobutyl-p-methoxyphenyl succinate, diisobutyl-p-chlorophenyl succinate, diisobutyl cyclohexyls Succinate, diisobutylbenzyl succinate, diisobutylcyclohexylmethyl succinate, diisobutyl-t-butyl succinate , 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 norbornyl succinate, dineopentyl perhydrosuccinate, dineopentyl trimethylsilyl succinate, dineopentyl Methoxy succinate, dineopentyl-p-methoxyphenyl succinate, dineopentyl-p-chlorophenyl succinate, dineopentyl phenyl succinate, dineo Pentylcyclohexyl 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. These compounds may be used individually by 1 type, and may use 2 or more types together.

As another preferred compound of the compound represented by formula (I), at least two groups of R ^{3 to} R ⁶ are not hydrogen, but linear or branched alkyl having 1 to 20 carbon atoms which may contain a hetero atom, And disubstituted succinate compounds selected from alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl groups. Two groups that are not hydrogen are preferably bonded to the same carbon atom.
Specific examples of suitable disubstituted succinate compounds include diethyl-2,2-dimethyl succinate, diethyl-2-ethyl-2-methyl succinate, diethyl-2-benzyl-2-isopropyl succinate, diethyl -2-cyclohexylmethyl-2-isobutyl succinate, diethyl-2-cyclopentyl-2-n-propyl succinate, diethyl-2-cyclopentyl-2-n-butyl succinate, 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-methyl succinate, diethyl-2-isopentyl-2-isobutyl succinate, diethyl-2-phenyl-2-n-butyl succinate, diisobutyl-2,2-dimethyl succinate, diisobutyl-2 -Ethyl-2-methyl succinate, diisobutyl-2-benzyl-2-isopropyl succinate, diisobutyl-2-cyclohexylmethyl-2-isobutyl succinate, diisobutyl-2-cyclopentyl-2-n-propyl succinate Diisobutyl-2-cyclopentyl-2-n-butyl succinate, diisobutyl-2,2-diisobutyl succinate, diisobutyl-2-cyclohexyl-2-ethyl succinate, diisobutyl-2-isopropyl-2-methyl Succinate, diisobutyl-2-teto 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-dimethyl succinate, dineopentyl-2-ethyl-2-methyl succinate, dineopentyl-2-benzyl-2-isopropyl succinate, dineopentyl-2-cyclohexylmethyl-2-isobutyl succinate, dineopentyl-2 -Cyclopentyl-2-n-propyl Xinate, dineopentyl-2-cyclopentyl-2-n-butyl succinate, dineopentyl-2,2-diisobutyl succinate, dineopentyl-2-cyclohexyl-2-ethyl succinate, dineopentyl-2-isopropyl-2-methyl Succinate, dineopentyl-2-tetradecyl-2-ethyl succinate, dineopentyl-2-isobutyl-2-ethyl succinate, dineopentyl-2- (1-trifluoromethylethyl) -2-methyl succinate, Examples include dineopentyl-2,2-diisopropyl succinate, dineopentyl-2-isopentyl-2-isobutyl succinate, and dineopentyl-2-phenyl-2-n-butyl succinate. These compounds may be used individually by 1 type, and may use 2 or more types together.

Particularly preferred compounds of formula (I) also include compounds in which at least two groups different from hydrogen, ie R ³ and R ⁵ , or R ⁴ and R ⁶ are bonded to different carbon atoms. .
Specific examples of this compound include diethyl-2,3-bis (trimethylsilyl) succinate, diethyl-2,2-sec-butyl-3-methylsuccinate, 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-dii Butyl succinate, diethyl-2,3-dineopentyl succinate, diethyl-2,3-diisopentyl succinate, diethyl-2,3- (1-trifluoromethylethyl) succinate, diethyl-2 , 3-tetradecyl succinate, diethyl-2,3-fluorenyl succinate, diethyl-2-isopropyl-3-isobutyl succinate, diethyl-2-tert-butyl-3-isopropyl succinate, diethyl 2-isopropyl-3-cyclohexyl succinate, diethyl-2-isopentyl-3-cyclohexyl succinate, diethyl-2-tetradecyl-3-cyclohexylmethyl succinate, diethyl-2-cyclohexyl-3-cyclopentyl succinate 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-isopropyl succinate, diisobutyl-2,3-diisopropyl-2-methyl succinate, diisobutyl-2, 3-dicyclohexyl-2-methyl succinate, diisobutyl-2,3-dibenzyl succinate, Isobutyl-2,3-diisopropyl succinate, diisobutyl-2,3-bis (cyclohexylmethyl) succinate, diisobutyl-2,3-di-t-butyl succinate, diisobutyl-2,3-diisobutyl succinate, Diisobutyl-2,3-dineopentyl succinate, diisobutyl-2,3-diisopentyl succinate, diisobutyl-2,3- (1-trifluoromethylethyl) succinate, diisobutyl-2,3-n-propyl Succinate, diisobutyl-2,3-tetradecyl succinate, diisobutyl-2,3-fluorenyl succinate, diisobutyl-2-isopropyl-3-isobutyl succinate, diisobutyl-2-tert-butyl-3 -Isopropyl succinate, diisobutyl-2- Isopropyl-3-cyclohexyl succinate, diisobutyl-2-isopentyl-3-cyclohexyl succinate, diisobutyl-2-n-propyl-3- (cyclohexylmethyl) succinate, diisobutyl-2-tetradecyl-3-cyclohexylmethyl succinate , Diisobutyl-2,2,3,3-tetramethyl succinate, diisobutyl-2,2,3,3-tetraethyl succinate, diisobutyl-2,2,3,3-tetrapropyl succinate, diisobutyl -2,3-diethyl-2,3-diisopropyl succinate, diisobutyl-2-cyclohexyl-3-cyclopentyl succinate, dineopentyl-2,3-bis (trimethylsilyl) succinate, dineopentyl-2,2-sec-butyl -3-Me Rusuccinate, dineopentyl-2- (3,3,3-trifluoropropyl) -3-methyl succinate, dineopentyl-2,3-bis (2-ethylbutyl) succinate, dineopentyl-2,3-diethyl-2-isopropyl Succinate, dineopentyl-2,3-diisopropyl-2-methyl succinate, dineopentyl-2,3-dicyclohexyl-2-methyl succinate, dineopentyl-2,3-dibenzyl succinate, dineopentyl-2, 3-diisopropyl succinate, dineopentyl-2,3-bis (cyclohexylmethyl) succinate, dineopentyl-2,3-di-t-butyl succinate, dineopentyl-2,3-diisobutyl succinate, dineopentyl-2, 3-Dineopentylsk Dynepentyl-2,3-diisopentyl succinate, dineopentyl-2,3- (1-trifluoromethylethyl) succinate, dineopentyl-2,3-dineopentyl succinate, dineopentyl-2,3- Diisopentyl succinate, dineopentyl-2,3-tetradecyl succinate, dineopentyl-2,3-fluorenyl succinate, dineopentyl-2-isopropyl-3-isobutyl succinate, dineopentyl-2-tert- Butyl-3-isopropyl succinate, dineopentyl-2-isopropyl-3-cyclohexyl succinate, dineopentyl-2-isopentyl-3-cyclohexyl succinate, dineopentyl-2-tetradecyl-3-cyclohexylmethyl succinate Dineopentyl-2-n-propyl-3- (cyclohexylmethyl) succinate, dineopentyl-2-cyclohexyl-3-cyclopentyl succinate, dineopentyl-2,2,3,3-tetraethylsuccinate, dineopentyl-2,2 3,3-tetrapropyl succinate, dineopentyl-2,3-diethyl-2,3-diisopropyl succinate. These compounds may be used individually by 1 type, and may use 2 or more types together.

As the compound represented by the formula (I), those in which at least two of R ^{3 to} R ⁶ are bonded to form a ring are 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. In addition, cyclic succinate compounds such as diisobutyl 3,6-dimethylcyclohexane-1,2-dicarboxylate disclosed in International Publication No. 2009/069483 and International Publication No. 2009/057747 can also be suitably used.

Among the compounds represented by formula (I), when R ^{3 to} R ⁶ contain 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. A group atom is preferred. Examples of the compound in which R ^{3 to} R ⁶ include a Group 15 atom include compounds disclosed in JP-A-2005-306910. Examples of the compound in which R ^{3 to} R ⁶ include a group 16 atom include compounds disclosed in JP-A-2004-131537.
Examples of the halogen atom constituting the component (A) include fluorine, chlorine, bromine, iodine or a mixture thereof, and chlorine is particularly preferable.

Examples of the organic aluminum compound of component (B) include trialkylaluminum such as triethylaluminum and tributylaluminum, trialkenylaluminum such as triisoprenylaluminum, dialkylaluminum alkoxide such as diethylaluminum ethoxide and dibutylaluminum butoxide, and ethylaluminum. Alkyl aluminum sesquialkoxides such as sesquiethoxide and butylaluminum sesquibutoxide, R ⁷ _2.5 Al (OR ⁸ ) _0.5 (R ⁷ and R ⁸ are each a hydrocarbon group that may be different or the same. .) Partially alkoxylated alkylaluminum, diethylaluminum chloride, dibutylaluminum chloride, diethylaluminum having an average composition represented by Dialkylaluminum halides such as bromide, alkylaluminum sesquichloride, ethylaluminum sesquichloride, alkylaluminum sesquihalides such as ethylaluminum sesquibromide, alkylaluminum dihalogenides such as ethylaluminum dichloride, propylaluminum dichloride, butylaluminum dibromide Partially hydrogenated alkylaluminums such as dialkylaluminum hydrides such as partially halogenated alkylaluminum, diethylaluminum hydride and dibutylaluminum hydride, and alkylaluminum dihydrides such as ethylaluminum dihydride and propylaluminum dihydride , Ethylaluminum ethoxy chloride, butylaluminum butoxycyclo De, partially alkyl aluminum or the like which is alkoxylated and halogenated, such as ethylaluminum ethoxy bromide and the like. The said component (B) may be used individually by 1 type, and may use 2 or more types together.

As the external electron donor compound of component (C), an organosilicon compound is used.
Preferred organosilicon compounds include, for example, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, and t-amylmethyldiethoxy. Silane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, bis-o-tolyldimethoxysilane, bism-tolyldimethoxysilane, bisp-tolyldimethoxysilane, bisp-tolyldiethoxysilane, bisethylphenyldimethoxysilane , Dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane , 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 Lan, 2-norbornanetrimethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, ethyl silicate, butyl silicate, trimethylphenoxysilane, methyltriallyloxysilane, vinyltris (β-methoxyethoxysilane) ), Vinyltriacetoxysilane, dimethyltetraethoxydisiloxane, methyl (3,3,3-trifluoro-n-propyl) dimethoxysilane, cyclohexylethyldimethoxysilane, cyclopentyl-t-butoxydimethoxysilane, diisobutyldimethoxysilane, isobutylisopropyl Dimethoxysilane, n-propyltrimethoxysilane, di-n-propyldimethoxysilane, texyltrimethoxysilane, t-butylethyldimethoxysilane, t-butyl Rupropyldimethoxysilane, t-butyl-t-butoxydimethoxysilane, isobutyltrimethoxysilane, cyclohexylisobutyldimethoxysilane, di-sec-butyldimethoxysilane, isobutylmethyldimethoxysilane, bis (decahydroisoquinolin-2-yl) dimethoxysilane , Diethylaminotriethoxysilane, dicyclopentyl-bis (ethylamino) silane, tetraethoxysilane, tetramethoxysilane, isobutyltriethoxysilane and the like.
Among these, ethyltriethoxysilane, n-propyltriethoxysilane, t-butyltriethoxysilane, texyltrimethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, vinyltributoxysilane, diphenyldimethoxysilane, diisopropyldimethoxy Silane, dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane, phenylmethyldimethoxysilane, bis p-tolyldimethoxysilane, p-tolylmethyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, 2-nonebornanetriethoxysilane, 2 -Norbornanemethyldimethoxysilane, diphenyldiethoxysilane, ethyl silicate are preferred. The said component (C) may be used individually by 1 type, and may use 2 or more types together.

  As the catalyst (I), the component (B) is a trialkylaluminum such as triethylaluminum or triisobutylaluminum, and the component (C) is an organic silicon such as dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane or diisopropyldimethoxysilane. What is a compound is preferable.

In addition, the method of obtaining the said polymerization mixture by a multistage polymerization method is not limited to said method, A propylene polymer may be superposed | polymerized in a some polymerization reactor, and an ethylene-propylene copolymer is made into a some polymerization reaction. The polymerization may be carried out in a vessel.
Examples of a method for obtaining the polymerization mixture include a method using a polymerization vessel having a gradient of monomer concentration and polymerization conditions. In such a polymerization vessel, for example, a monomer 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. The polymerization product is recovered while circulating. This 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 from the gas mixture present in the riser is introduced into the downcomer. As this polymerization method, for example, the method described in JP-T-2002-520426 can be applied.

<Hollow molding>
The hollow molded article of the present invention is composed of the above polypropylene resin composition.
As a method for producing a hollow molded article, for example, a process of melt-kneading a polypropylene resin composition using an extruder, extrusion molding to produce a tubular parison, and sandwiching the parison with a mold and the inside of the parison There is a method including a step of blowing air into the mold and bringing the melted resin into close contact with the inner surface of the mold and shaping to obtain a shaped product, and a step of cooling the shaped product.
The hollow molded article can be used as a container for filling beverages, foods, pharmaceuticals, cosmetics, detergents and the like, for example. The hollow molded article can also be used for a lid, a container, and the like.

Examples and Comparative Examples are shown below, but the present invention is not limited to the following Examples.
The measurement method used in this example is shown below.

〔Measuring method〕
<Content of ethylene unit in propylene polymer (C2) and content of propylene unit in ethylene / propylene copolymer (Pc)>
A sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene was measured by ¹³ C-NMR method using JNM LA-400 ( ¹³ C resonance frequency 100 MHz) manufactured by JEOL Ltd.

<Intrinsic Viscosity of Polypropylene Resin in Xylene (XSIV)>
The xylene-soluble content of the polypropylene resin was obtained by the following method, and the intrinsic viscosity (XSIV) of the xylene-soluble content was measured.
A polypropylene sample (2.5 g) was placed in a flask containing 250 mL of o-xylene (solvent), and stirred for 30 minutes at 135 ° C. while purging with nitrogen using a hot plate and a reflux apparatus, to obtain a resin composition. After complete dissolution, the mixture was cooled at 25 ° C. for 1 hour. The solution thus obtained was filtered using filter paper. 100 mL of the filtrate after filtration was collected, transferred to an aluminum cup or the like, evaporated and dried at 140 ° C. while purging with nitrogen, and allowed to stand at room temperature for 30 minutes to obtain a xylene-soluble component.
The intrinsic viscosity was measured in tetrahydronaphthalene at 135 ° C. using a capillary automatic viscometer (SS-780-H1, manufactured by Shibayama Scientific Instruments).

< _Mw / _Mn of xylene insoluble matter (XI) of polypropylene resin>
After filtration for obtaining xylene solubles in the above XSIV measurement, acetone was added to the residue (mixture of xylene insoluble components and solvent) remaining on the filter paper, followed by filtration. Thereafter, the components that were not filtered and remained on the filter paper were evaporated to dryness in a vacuum drying oven set at 80 ° C. to obtain xylene-insoluble matter (XI).
The above XI as a sample, as follows, divided by the number average molecular weight (M _n) and weight average molecular weight was measured of (M _w), weight average molecular weight number average molecular weight (M _w) (M _n) The molecular weight distribution ( _Mw / _Mn ) was determined.
PL GPC220 manufactured by Polymer Laboratories is used as an apparatus, 1,2,4-trichlorobenzene containing an antioxidant is used as a mobile phase, and UT-G (1), UT-807 (Showa Denko KK) is used as a column. 1) and UT-806M (2) connected in series were used, and a differential refractometer was used as a detector. Moreover, the same solvent as the mobile phase was used as a solvent for the sample solution of xylene-insoluble matter, and a measurement sample was prepared by dissolving at a sample concentration of 1 mg / mL for 2 hours while shaking at a temperature of 150 ° C. 500 μL of the sample solution thus obtained was injected into the column and measured at a flow rate of 1.0 mL / min, a temperature of 145 ° C., and a data acquisition interval of 1 second. For column calibration, a polystyrene standard sample (shodex STANDARD, manufactured by Showa Denko KK) having a molecular weight of 580 to 7.45 million was used and approximated by a cubic equation. The Mark-Houwink-Sakurada coefficients are K = 1.21 × 10 ⁻⁴ and α = 0.707 for polystyrene standard samples, and K = 1.37 × 10 ⁻⁴ and α = for propylene-based polymers. 0.75 was used.

<MFR>
The MFR (total MFR) of the polypropylene resin composition was measured under conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K 7210-1.

[Example 1]
(Manufacture of polypropylene resin)
In this example, a succinate-based (indicated in the table as “Suc”) Ziegler-Natta catalyst is used as the polypropylene resin, and propylene is polymerized in the first stage to form a propylene polymer. In the stage, a polymerization mixture obtained by copolymerizing ethylene and propylene in the presence of the propylene polymer to form an ethylene / propylene copolymer was used. Specifically, the polymerization mixture was produced as follows.

A solid catalyst was prepared according to the following procedure according to the preparation method described in the examples of JP-T-2011-500907.
In a 500 mL 4-neck round bottom flask purged with nitrogen, 250 mL of TiCl ₄ was introduced at 0 ° C. While stirring, 10.0 g of fine spherical MgCl ₂ .1.8 C ₂ H ₅ OH (produced 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, stirring was stopped, the solid product was allowed to settle, and the supernatant liquid was siphoned off. The following procedure was then repeated twice: 250 mL of fresh TiCl ₄ was added and the mixture was allowed to react at 120 ° C. for 60 minutes and the supernatant was siphoned off. The solid was washed 6 times with anhydrous hexane (6 × 100 mL) at 60 ° C.

The above solid catalyst, triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) are mixed in an amount such that the mass ratio of TEAL to the solid catalyst is 18 and the mass ratio of TEAL / DCPMS is 10 at room temperature. Touched for a minute. The resulting catalyst system was prepolymerized by holding it in liquid propylene in suspension for 5 minutes at 20 ° C. The obtained prepolymer was introduced into a first stage polymerization reactor of a polymerization apparatus equipped with a two-stage polymerization reactor in series to produce a propylene polymer in a propylene liquid phase state. An ethylene-propylene copolymer was produced in a gas phase polymerization reactor. During the polymerization, the polymerization temperature is set to 70 ° C., the polymerization pressure and the amount of the catalyst added are adjusted, and the propylene unit content in the ethylene / propylene copolymer is adjusted to a predetermined amount. The ethylene supply amount and the propylene supply amount were adjusted to obtain C2 / (C2 + C3) shown in Table 1. C2 / (C2 + C3) indicates the ratio (molar ratio) of ethylene to the total of ethylene and propylene. In addition, by using hydrogen as a molecular weight regulator, the supply amounts of the first and second stages are adjusted so that the intrinsic viscosity of the MFR of the polypropylene resin composition and the xylene solubles of the polypropylene resin becomes a predetermined value. The hydrogen concentration shown in Table 1 was adjusted. Further, the residence time distributions of the first stage and the second stage were adjusted so that the content ratio of the ethylene / propylene copolymer in the polypropylene resin was a predetermined amount.
The polypropylene resin comprising the obtained polymerization mixture is composed of the ethylene / propylene copolymer content (BIPO) in the polypropylene resin, the propylene unit content (Pc) in the ethylene / propylene copolymer, and the xylene of the polypropylene resin. Table 1 shows the intrinsic viscosity (XSIV) of the soluble component and _Mw / _Mn of the xylene-insoluble component of the polypropylene resin.

(Production of polypropylene resin composition)
Henschel mixer containing 100 parts by mass of the polypropylene resin, 0.2 parts by mass of an antioxidant (B225 manufactured by BASF) and 0.05 parts by mass of a neutralizer (calcium stearate manufactured by Tamnan Chemical Industry Co., Ltd.) And stirred for 1 minute to obtain a mixture for melt kneading.
Next, the mixture for melt kneading was melt kneaded using a single screw extruder (NVC-50 manufactured by Nakatani Machinery Co., Ltd.) set at a screw temperature of 230 ° C. and a screw rotation speed of 90 rpm, and pelletized. A 5 g / 10 min polypropylene resin composition was obtained.

(Evaluation)
About the obtained polypropylene resin composition, bending elastic modulus (rigidity), Charpy impact strength (0 ° C.) (low temperature impact resistance), bottle thickness accuracy, bottle thickness difference, bottle impact strength (5 ° C.) ) (Low temperature impact resistance of the molded product). The results are shown in Table 1.

<Bending elastic modulus>
In accordance with JIS K6921-2, the polypropylene resin composition was injected into an injection molding machine (FANUC ROBOSHOT S2000i manufactured by FANUC CORPORATION), and the molten resin temperature was 230 ° C. for a material having an MFR of 1.5 g / 10 min or more. Specified in JIS K7139 for materials with an MFR of less than 1.5 g / 10 min under the conditions of 255 ° C., mold temperature 40 ° C., average injection speed 200 mm / sec, pressure holding time 40 seconds, and total cycle time 60 seconds A multipurpose test piece (type A1) to be measured was molded and processed into a width of 10 mm, a thickness of 4 mm, and a length of 80 mm to obtain a measurement test piece (type B2). Using a test specimen for type B2 measurement, using a fully automatic testing machine (AG-X10kN) manufactured by Shimadzu Corporation, the bending elastic modulus was measured at a temperature of 23 ° C., a relative humidity of 50%, a distance between fulcrums of 64 mm, and a test speed of 2 mm / min. It was measured.
The higher the value of the flexural modulus, the better the rigidity. The flexural modulus is preferably 1000 MPa or more.

<Charpy impact strength (0 ° C)>
In accordance with JIS K6921-2, the polypropylene resin composition was injected into an injection molding machine (FANUC ROBOSHOT S2000i manufactured by FANUC CORPORATION), and the molten resin temperature was 230 ° C. for a material having an MFR of 1.5 g / 10 min or more. Multi-purpose as defined in JIS K7139 for a material having a surface temperature of less than 1.5 g / 10 min under the conditions of 255 ° C., mold temperature 40 ° C., average injection speed 200 mm / second, pressure holding time 40 seconds, and total cycle time 60 seconds. A test piece (type A1) was molded. In accordance with JIS K7111-1, this multipurpose test piece was processed into a width of 10 mm, a thickness of 4 mm, and a length of 80 mm using a notching tool A-3 manufactured by Toyo Seiki Co., Ltd. A test piece for measurement was obtained. About the test piece for the measurement, Charpy impact strength (edgewise impact, 1eA method) was measured at a temperature of 0 ° C. using a fully automatic impact tester (No. 258-ZA) with a cryogenic bath manufactured by Yasuda Seiki Seisakusho Co., Ltd. did.

<Bottle thickness accuracy and bottle thickness difference>
Using a hollow molding machine (manufactured by Nippon Steel Co., Ltd., screw diameter of extruder: 50 mm), the polypropylene resin composition is extruded downward in the vertical direction at a molding temperature of 230 ° C. and a screw rotational speed of 15 revolutions / minute. After forming a tubular parison by molding, a 500 mL cylindrical bottle having an average wall thickness of 0.8 mm was hollow-molded at a die / core = φ18.6 mm / φ16 mm and a mold temperature of 25 ° C. The obtained cylindrical bottle was divided into four vertically. The obtained divided pieces were used as measurement test pieces.
Using a bench-type offline sheet thickness measuring device TOF-4R05 manufactured by Yamabun Denki Co., Ltd., continuously measure the thickness within the range of ± 30mm from the center in the longitudinal direction (height direction of the cylindrical bottle) of each measurement specimen. The thickness standard deviation, the average thickness, and the difference between the maximum value and the minimum value of the thickness were determined.
The ratio of the thickness standard deviation to the average thickness (100 × thickness standard deviation / average thickness) was calculated, and the average value (%) of the thickness standard deviation / average thickness value of each of the four test specimens for measurement was defined as the bottle thickness accuracy. .
The average value (mm) of the difference between the maximum value and the minimum value of each of the four test specimens for measurement was taken as the bottle thickness difference.
The smaller the bottle thickness accuracy or the bottle thickness difference, the better the thickness accuracy of the hollow molded product. The bottle thickness accuracy is preferably 6% or less, and more preferably 5% or less. The difference in bottle thickness is preferably 0.15 mm or less, and more preferably 0.1 mm or less.

<Bottle impact strength (5 ° C)>
Two cylindrical bottles molded under the same conditions as those for evaluating the bottle thickness accuracy and the bottle thickness difference were vertically divided into two pieces to obtain a total of four divided pieces. The obtained divided pieces were used as measurement test pieces.
Using a hydroshot HIPS-P10 manufactured by Shimadzu Corporation, a test specimen for measurement was fixed to a support with a hole with an inner diameter of 40 mmφ in a layer adjusted to 5 ° C., and then a diameter of 12 having a hemispherical impact surface. A test specimen for measurement was hit with a 0.7 mmφ striker at an impact speed of 1 m / s, and puncture energy (J) was determined according to JIS K7211-2. The average value of the puncture energy of each of the four test specimens for measurement was taken as the bottle impact strength.
The higher the bottle impact strength value, the better the low-temperature impact resistance of the molded product. The bottle impact strength is preferably 3.5 J or more, and more preferably 4.0 J or more.

(Examples 2-3, Comparative Examples 2-6)
In the same manner as in Example 1 except that the polymerization conditions were adjusted to the values shown in Table 1 so that the ethylene unit content ratio (C2), BIPO, Pc, and XSIV in the propylene polymer were the values shown in Table 1. A polymerization mixture of a propylene polymer and an ethylene / propylene copolymer was obtained. In Example 2 and Comparative Example 2, ethylene was supplied to the first stage polymerization reactor so that the ethylene concentration shown in Table 1 was reached, and ethylene and propylene were copolymerized to form a propylene copolymer. It was.
MFR polypropylene resin compositions shown in Table 1 were obtained in the same manner as in Example 1 except that the polymerization mixture was used as a polypropylene resin.
About the obtained polypropylene resin composition, evaluation similar to Example 1 was performed. The results are shown in Table 1.

(Comparative Example 1)
In this example, a phthalate-based (shown as “Pht” in the table) Ziegler-Natta catalyst is used as the polypropylene resin, and propylene is polymerized in the first stage to form a propylene polymer. In the stage, a polymerization mixture obtained by copolymerizing ethylene and propylene in the presence of the propylene polymer to form an ethylene / propylene copolymer was used. Specifically, the polymerization mixture was produced as follows.
A solid catalyst in which Ti and diisobutyl phthalate as an internal donor were supported on MgCl ₂ was prepared by the method described in Example 5 of European Patent No. 728769.
Next, using the above solid catalyst, triethylaluminum (TEAL) as the organoaluminum compound and dicyclopentyldimethoxysilane (DCPMS) as the external electron donor compound, the weight ratio of TEAL to the solid catalyst is 20, and the weight ratio of TEAL / DCPMS. Was contacted at 12 ° C. for 24 minutes. The resulting catalyst system was preliminarily polymerized by keeping it in suspension in liquid propylene at 20 ° C. for 5 minutes. The obtained prepolymer was introduced into a first stage polymerization reactor of a polymerization apparatus equipped with a two-stage polymerization reactor in series to produce a propylene polymer in a propylene liquid phase state. An ethylene-propylene copolymer was produced in a gas phase polymerization reactor. During the polymerization, the polymerization temperature is set to 70 ° C., the polymerization pressure and the amount of the catalyst added are adjusted, and the propylene unit content in the ethylene / propylene copolymer is adjusted to a predetermined amount. The ethylene supply amount and the propylene supply amount were adjusted to obtain C2 / (C2 + C3) shown in Table 1. In addition, by using hydrogen as a molecular weight regulator, the supply amounts of the first and second stages are adjusted so that the intrinsic viscosity of the MFR of the polypropylene resin composition and the xylene solubles of the polypropylene resin becomes a predetermined value. The hydrogen concentration shown in Table 1 was adjusted. Further, the residence time distributions of the first stage and the second stage were adjusted so that the content ratio of the ethylene / propylene copolymer in the polypropylene resin was a predetermined amount. A MFR polypropylene resin composition shown in Table 1 was obtained in the same manner as in Example 1 except that this polymerization mixture was used as a polypropylene resin, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

The polypropylene resin compositions of Examples 1 to 3 were excellent in drawdown resistance during hollow molding and had a high flexural modulus. Moreover, the thickness accuracy of the obtained molded product was good, the thickness difference was small, and the bottle impact strength (5 ° C.) was excellent.
The polypropylene resin composition of Comparative Example 1 in which the _Mw / _Mn of the xylene insoluble matter (XI) of the polypropylene resin is less than 6 was carried out even though the Charpy impact strength (0 ° C.) was high. Compared with the composition of Example 1, the thickness accuracy of the molded product was poor, the thickness difference was large, and the bottle impact strength (5 ° C.) was inferior.
The polypropylene resin composition of Comparative Example 2 in which the ethylene unit content ratio (C2) in the propylene polymer was more than 1.0% by mass had a low flexural modulus and poor rigidity.
The polypropylene resin composition of Comparative Example 3 in which the content (BIPO) of the ethylene / propylene copolymer in the polypropylene resin is less than 15% by mass is inferior in Charpy impact strength (0 ° C.). The impact strength (5 ° C.) of the molded product was also inferior.
The polypropylene resin compositions of Comparative Examples 4 to 5 in which the content (Pc) of propylene units in the ethylene-propylene copolymer of the polypropylene resin is 40% by mass or less or more than 70% by mass have Charpy impact strength (0 ° C) and bottle impact strength (5 ° C).
The polypropylene resin composition of Comparative Example 6 in which the intrinsic viscosity (XSIV) of the xylene solubles of the polypropylene resin is less than 2.0% by mass is inferior in Charpy impact strength (0 ° C.) and bottle impact strength (5 ° C.). It was.

Claims (3)

A polypropylene resin containing a matrix made of a propylene polymer and an ethylene / propylene copolymer;
The melt mass flow rate at 230 ° C. and 2.16 kg is 0.1 to 5.0 g / 10 minutes,
The intrinsic viscosity of the polypropylene-based resin in xylene solubles in tetrahydronaphthalene at 135 ° C. is more than 2.0 dl / g and not more than 4.0 dl / g,
The ratio (M _w / M _n ) between the weight average molecular weight M _w and the number average molecular weight M _n of the xylene-insoluble portion of the polypropylene resin is 6 to 20,
The content ratio of the ethylene / propylene copolymer is 15 to 30% by mass with respect to the total mass of the polypropylene resin,
The ethylene unit content in the propylene polymer is 1.0 mass% or less with respect to the total mass of the propylene polymer,
A polypropylene-based resin composition for hollow molding, wherein a content ratio of propylene units in the ethylene / propylene copolymer is more than 40% by mass and 70% by mass or less based on a total mass of the ethylene / propylene copolymer. It is a manufacturing method of the polypropylene-type resin composition for hollow molding of Claim 1, Comprising:
(A) a solid catalyst containing magnesium, titanium, halogen and an electron donor compound, wherein the electron donor compound is a succinate compound;
(B) an organoaluminum compound;
(C) an external electron donor compound that is a silicon compound;
A process for producing a polypropylene resin composition for hollow molding, comprising a step of polymerizing an ethylene monomer and a propylene monomer in the presence of the propylene polymer using a catalyst containing .   A hollow molded article comprising the polypropylene resin composition for hollow molding according to claim 1.