Polypropylene composition for high stiffness stretched polypropylene film

Abstract

To provide a polypropylene composition imparting a polypropylene stretched film having heightened rigidity and stretchability.SOLUTION: There is provided a polypropylene composition for a stretched film comprising a propylene homopolymer or a propylene-ethylene copolymer containing units derived from 1.0 wt.% or less of ethylene, wherein the homopolymer or copolymer is a polymer manufactured by polymerizing a corresponding monomer with a catalyst containing a solid catalyst containing a succinate-based compound as an electron donating compound, and the homopolymer or the copolymer satisfy the following: 1) MFR (230°C, weight 2.16 kg) is 0.3 to 20 g / 10 minutes. 2) The xylene-insoluble content (XI) exceeds 97.5 wt.% and is 99.5 wt.% or less. 3) Stereoregularity (mmmm) of xylene-insoluble matter is 95.5 to 99%. 4) The molecular weight distribution (Mw / Mn) measured by GPC is 7.0-14.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polypropylene composition which provides a high stiffness stretched polypropylene film. [Background technology]

[0002] Biaxially stretched polypropylene films are used in a wide range of applications, and various techniques have been proposed to improve their performance. For example, Patent Document 1 discloses a polypropylene resin composition that is synthesized with a specific catalyst and has a xylene insoluble content of 92.5 to 97.5% by weight, a polydispersity index of 4.5 to 10, and a melt flow rate of 1 to 8 g / 10 min, as a polypropylene resin composition that provides a biaxially stretched film with excellent processability and rigidity. Patent Document 2 discloses a polypropylene resin composition that provides a stretched polypropylene film with excellent heat resistance and mechanical properties, the lower limit of the mesopentad fraction is 96%, the upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%, and the resin composition has a specific molecular weight distribution. Patent Document 3 discloses a polypropylene resin composition that provides a film with high rigidity with little stretching spots, the resin composition having an isotactic pentad index of 0.97 or more, and a specific hard component amount and MFR. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-000961 A [Patent Document 2] JP 2014-055276 A [Patent Document 3] JP 2004-315582 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, in recent years, from the viewpoint of protecting the global environment, biomass-derived resins are increasingly used instead of conventional petroleum-derived resins. Currently commercially available biomass-derived resins are polyethylene-based and have low rigidity, so it is necessary to blend a material with higher rigidity. In addition, the use of biomass-derived resins increases costs, and there is a demand for thinner films from the viewpoint of reducing packaging volume. However, thinning leads to a decrease in the rigidity of the film and a decrease in stretchability (film-forming ability). In order to improve these points, it is possible to blend a polypropylene resin with a biomass-derived resin, but the blended resin does not have sufficient stretchability, and the rigidity of the resulting film is not at a sufficient level. Therefore, the inventors came up with the idea that if polypropylene that gives a polypropylene film with higher rigidity and stretchability is blended with a biomass-derived resin, the rigidity of the film obtained from the blend can be improved and the stretchability can be prevented from decreasing. In view of such circumstances, the present invention aims to provide a polypropylene composition that gives a polypropylene stretched film with higher rigidity and stretchability. [Means for solving the problem]

[0005] The inventors have found that a specific polypropylene composition can solve the above problems. That is, the above problems are solved by the present invention described below. (Aspect 1) A polypropylene composition for stretched films comprising a propylene homopolymer or a propylene-ethylene copolymer containing 1.0% by weight or less of units derived from ethylene, The homopolymer or copolymer is (a) a solid catalyst comprising magnesium, titanium, a halogen, and a succinate-based compound as an electron donor compound; (b) organoaluminum compounds, and A polymer produced by polymerizing the corresponding monomer using a catalyst that optionally contains (c) an external electron donor compound; The homopolymer or copolymer satisfies the following: 1) MFR (230℃, load 2.16 kg) is 0.3 to 20 g / 10 min. 2) The xylene insoluble matter (XI) is greater than 97.5% by weight and is 99.5% by weight or less. 3) The stereoregularity (mmmm) of the xylene insoluble matter is 95.5 to 99%. 4) The molecular weight distribution (Mw / Mn) measured by GPC is 7.0 to 14. Polypropylene composition for oriented films. (Aspect 2) 2. The polypropylene composition for stretched films according to aspect 1, wherein the MFR is 5.0 to 20 g / 10 min. (Aspect 3) 3. The polypropylene composition for stretched films according to aspect 1 or 2, wherein the MFR is 9.0 to 20 g / 10 min. (Aspect 4) 4. The polypropylene composition for a stretched film according to any one of aspects 1 to 3, wherein the content of the units derived from ethylene in the copolymer is 0.2 to 0.8% by weight. (Aspect 5) The polypropylene composition for a stretched film according to any one of aspects 1 to 4, which is for a biaxially stretched film. (Aspect 6) The polypropylene composition for a stretched film according to any one of aspects 1 to 5, further comprising a nucleating agent. (Aspect 7) 7. The polypropylene composition for a stretched film according to aspect 6, comprising 0.01 to 0.2 parts by weight of the nucleating agent per 100 parts by weight in total of the homopolymer and copolymer. (Aspect 8) The polypropylene composition for stretched films according to aspect 6 or 7, wherein the nucleating agent is a nonitol-based nucleating agent or a phosphate-based nucleating agent. (Aspect 9) A stretched film produced from the polypropylene composition for a stretched film according to any one of aspects 1 to 8. Effect of the Invention

[0006] According to the present invention, there is provided a polypropylene composition which gives a polypropylene film having improved rigidity and stretchability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention will be described in detail below. In the present invention, "X to Y" includes the extreme values ​​X and Y.

[0008] I. Polypropylene Composition 1. Propylene homopolymer or propylene-ethylene copolymer The polypropylene composition contains a propylene homopolymer or a propylene-ethylene copolymer as a main component. That is, the polypropylene composition contains the homopolymer, the copolymer, or a combination thereof. Hereinafter, the homopolymer, the copolymer, or a combination thereof will be collectively referred to as "polypropylene". In one embodiment, the polypropylene composition is made of the polypropylene. That is, in the present invention, the polypropylene composition also includes an embodiment made of one type of polymer such as a propylene homopolymer. In another embodiment, the polypropylene composition contains the polypropylene and a component such as a nucleating agent.

[0009] The content of units derived from ethylene in the copolymer (also simply referred to as "ethylene content") is 1.0% by weight or less, preferably 0.8% by weight or less. If the ethylene content exceeds the upper limit, the rigidity of the film formed may decrease. The lower limit of the ethylene content is more than 0% by weight, but is preferably 0.1% by weight or more, more preferably 0.2% by weight or more. If the ethylene content is less than the lower limit, the film formability of the film formed may decrease.

[0010] (1)Characteristics The polypropylene has the following characteristics: 1) MFR (230℃, load 2.16kg) The MFR of the polypropylene is 0.3 to 20 g / 10 min. If the MFR is less than the lower limit, it becomes difficult to produce the polypropylene itself. If the MFR exceeds the upper limit, the film formability when made into a film decreases. From this viewpoint, the lower limit of the MFR is preferably 0.5 g / 10 min or more, more preferably 2.0 g / 10 min or more, even more preferably 5.0 g / 10 min or more, and particularly preferably 9.0 g / 10 min or more. The upper limit is preferably 15 g / 10 min or less, more preferably 10 g / 10 min or less.

[0011] 2) Xylene insolubles (XI) The xylene insoluble content (XI) of the polypropylene is more than 97.5% by weight and not more than 99.5% by weight. XI is preferably 98.0 to 99.5% by weight. If XI is not more than the lower limit, the rigidity of the film formed is reduced. In the present invention, the xylene insoluble content is a component that is insoluble in xylene at 25° C. XI can be determined by a known method, but the following method can be preferably used. i) 2.5 g of polymer are dissolved in 250 ml of xylene at 135° C. with stirring. ii) After 20 minutes, the solution is cooled to 25° C. with stirring and then allowed to stand for 30 minutes. iii) The precipitate is filtered through filter paper, the solution is evaporated in a stream of nitrogen and the residue is dried under vacuum at 80° C. until a constant weight is reached. In this way, the weight percent of the polymer soluble in xylene at 25°C is calculated. The weight percent of the polymer insoluble in xylene at 25°C (100-weight percent of soluble polymer, also called xylene insoluble content (XI)) is considered to be the amount of isotactic components in the polymer. After thoroughly washing off residual xylene from the precipitate with methanol, the precipitate is dried at 80°C under vacuum to collect the xylene insoluble content.

[0012] 3) Stereoregularity of xylene insoluble matter (mmmm) The stereoregularity (mmmm) of the xylene insoluble matter of the polypropylene is 95.5 to 99%. If mmmm is below the lower limit, the rigidity of the film formed is reduced, and if it exceeds the upper limit, the film formability of the film formed is reduced. From this viewpoint, the lower limit of mmmm is preferably 96.0% or more, and the upper limit is preferably 98.5% or less. mmmm is measured by a known method, but is preferably measured by the following method. i) Prepare a xylene insoluble fraction by the method described above. ii) dissolving the insoluble matter in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene; 13 From the spectrum measured using the C resonance frequency (100 MHz), the ratio of the intensity of the peak corresponding to a pentad having four consecutive meso (m) bond sequences of propylene monomer is determined according to the method described in A. Zambelli, Macromolecules, 6, 925 (1973).

[0013] 4) Molecular weight distribution (Mw / Mn) The molecular weight distribution (Mw / Mn) of the polypropylene measured by GPC is 7.0 to 14. If the molecular weight distribution is below the lower limit, the rigidity of the film or the film formability of the film is reduced. If the molecular weight distribution exceeds the upper limit, the film formability is reduced. From this viewpoint, the lower limit of the molecular weight distribution is preferably 8.0 or more, 9.0 or more, or 10 or more, and the upper limit is preferably 12 or less.

[0014] 2. Polypropylene manufacturing method The polypropylene is produced by polymerizing the corresponding monomers using a catalyst comprising (a) a solid catalyst comprising magnesium, titanium, a halogen, and a succinate-based compound as an electron donor compound, (b) an organoaluminum compound, and, optionally, (c) an external electron donor compound.

[0015] (1) Solid catalyst (component (a)) A polymer polymerized using a catalyst containing a succinate-based compound as an internal electron donor compound (hereinafter also referred to as "Suc catalyst") has a wide molecular weight distribution and high and low molecular weight components are uniformly dispersed. The molecular weight distribution is a physical quantity and can be determined by measurement. However, this measured value cannot indicate the degree of dispersion of high and low molecular weight components. For example, it is possible to obtain a polymer having a molecular weight distribution (measured value) that is seemingly equivalent to that of a polymer obtained by polymerization using a Suc catalyst by melt-kneading high and low molecular weight components given in powder or pellet form using an extruder or the like, or by performing multi-stage polymerization of components with different molecular weights using a catalyst other than a Suc catalyst. However, the degree of dispersion of high and low molecular weight components differs between the polymer obtained in this way and the polymer obtained by polymerization using a Suc catalyst, with the latter achieving a uniform degree of dispersion. The difference is noticeable in performance such as rigidity, impact resistance, processability, or appearance.

[0016] Component (a) can be prepared by known methods, for example by contacting together a magnesium (Mg) compound, a titanium (Ti) compound and an electron donor compound.

[0017] The titanium compound used in the preparation of component (a) is represented by the general formula: Ti(OR) g X 4-g In the formula, R is a hydrocarbon group, X is a halogen, and 0≦g≦4. More specifically, the titanium compound is a titanium tetrahalide such as TiCl4, TiBr4, or TiI4; Ti(OCH3)Cl3, Ti(OC2H5)Cl3, or Ti(O n -C4H9)Cl3, Ti(OC2H5)Br3, Ti(OisoC4H9)Br3 and other alkoxytitanium trihalides; Ti(OCH3)2Cl2, Ti(OC2H5)2Cl2, Ti(O n -C4H9)2Cl2, Ti(OC2H5)2Br2, and other alkoxy titanium dihalides; Ti(OCH3)3Cl, Ti(OC2H5)3Cl, Ti(O n-C4H9)3Cl, Ti(OC2H5)3Br, etc.; monohalogenated trialkoxy titanium; Ti(OCH3)4, Ti(OC2H5)4, Ti(O n Among these, preferred are halogen-containing titanium compounds, particularly titanium tetrahalides, and particularly preferred is titanium tetrachloride.

[0018] Examples of magnesium compounds used in the preparation of component (a) include magnesium compounds having a magnesium-carbon bond or a magnesium-hydrogen bond, such as dimethylmagnesium, diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diamylmagnesium, dihexylmagnesium, didecylmagnesium, ethylmagnesium chloride, propylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, amylmagnesium chloride, butylethoxymagnesium, ethylbutylmagnesium, butylmagnesium hydride, etc. These magnesium compounds can be used in the form of a complex compound with, for example, organoaluminum, etc., and can be in either liquid or solid form. Further preferred examples of the magnesium compound include magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; alkoxymagnesium halides such as methoxymagnesium chloride, ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesium chloride, and octoxymagnesium chloride; aryloxymagnesium halides such as phenoxymagnesium chloride and methylphenoxymagnesium chloride; alkoxymagnesium such as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium, n-octoxymagnesium, and 2-ethylhexoxymagnesium; dialkoxymagnesium such as dimethoxymagnesium, diethoxymagnesium, dipropoxymagnesium, dibutoxymagnesium, and ethoxymethoxymagnesium; and aryloxymagnesium such as ethoxypropoxymagnesium, butoxyethoxymagnesium, phenoxymagnesium, and dimethylphenoxymagnesium.

[0019] The electron donor compound used in the preparation of component (a) is generally called an “internal electron donor compound.” In the present invention, an internal electron donor compound selected from succinate-based compounds that provide a broad molecular weight distribution is used.

[0020] The succinate compound refers to a diester of succinic acid or a diester of a substituted succinic acid. The succinate compound preferably used in the present invention is represented by the following formula (I).

[0021] [ka]

[0022] in which the groups R1 and R2 are identical or different and are C1-C 20 R3 to R6 are the same or different and are each a C1 to C6 alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl group, optionally containing heteroatoms; 20 and R3 to R6 are linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl groups, and groups R3 to R6 bonded to the same carbon atom or different carbon atoms may be bonded together to form a ring.

[0023] R1 and R2 are preferably C1-C8 alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl groups. Particularly preferred are compounds in which R1 and R2 are selected from primary alkyls, especially branched primary alkyls. Examples of suitable R1 and R2 groups are C1-C8 alkyl groups, such as methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylhexyl groups. Particularly preferred are ethyl, isobutyl and neopentyl groups.

[0024] A preferred group of compounds represented by formula (I) are those in which R3-R5 are hydrogen and R6 is a branched alkyl, cycloalkyl, aryl, arylalkyl, and alkylaryl group having 3 to 10 carbon atoms. Preferred examples of such monosubstituted succinate compounds are diethyl-sec-butylsuccinate, diethyl thexylsuccinate, diethyl cyclopropylsuccinate, diethyl norbornylsuccinate, diethylperihydrosuccinate, diethyltrimethylsilylsuccinate, diethyl methoxysuccinate, diethyl-p-methoxyphenylsuccinate, diethyl-p-chlorophenylsuccinate, diethyl phenylsuccinate, diethyl cyclohexylsuccinate, diethyl phenyl ... Ethyl 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 thexyl succinate , diisobutyl cyclopropyl succinate, diisobutyl norbornyl succinate, diisobutyl perihydrosuccinate, diisobutyl trimethylsilyl succinate, diisobutyl methoxysuccinate, diisobutyl p-methoxyphenyl succinate, diisobutyl p-chlorophenyl succinate, diisobutyl cyclohexyl succinate, diisobutyl benzyl succinate, diisobutyl cyclohexyl methyl succinate, diisobutyl t-butyl succinate , diisobutyl isobutylsuccinate, diisobutyl isopropyl succinate, diisobutyl neopentyl succinate, diisobutyl isopentyl succinate, diisobutyl (1-trifluoromethylethyl) succinate, diisobutyl fluorenyl succinate, dineopentyl sec-butylsuccinate, dineopentyl thexyl succinate, dineopentyl cyclopropyl succinate, dineopentyl norbornyl succinate, dineopentyl perhydrosuccinate,Dineopentyl trimethylsilyl succinate, dineopentyl methoxysuccinate, dineopentyl-p-methoxyphenyl succinate, dineopentyl-p-chlorophenyl succinate, dineopentyl phenyl succinate, dineopentyl cyclohexyl succinate, dineopentyl benzyl succinate, dineopentyl cyclohexyl methyl succinate, dineopentyl-t-butyl succinate, dineopentyl isobutyl succinate, dineopentyl isopropyl succinate, dineopentyl neopentyl succinate, dineopentyl isopentyl succinate, dineopentyl (1-trifluoromethylethyl) succinate, dineopentyl fluorenyl succinate.

[0025] Another preferred group of compounds within the scope of formula (I) are C1-C aryl groups in which at least two radicals from R3 to R6 are different from hydrogen and optionally contain a heteroatom. 20The alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl groups are selected from the group consisting of linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, and alkylaryl groups. Compounds in which two groups different from hydrogen are bonded to the same carbon atom are particularly preferred. Specifically, compounds in which R3 and R4 are groups different from hydrogen, and R5 and R6 are hydrogen atoms. Preferred examples of such disubstituted succinates are diethyl-2,2-dimethylsuccinate, diethyl-2-ethyl-2-methylsuccinate, diethyl-2-benzyl-2-isopropylsuccinate, diethyl-2-cyclohexylmethyl-2-isobutylsuccinate, diethyl-2-cyclopentyl-2-n-butylsuccinate, diethyl-2,2-diisobutylsuccinate, diethyl-2-cyclohexyl-2-ethylsuccinate, diethyl-2-isopropyl-2-methylsuccinate, diethyl-2-tetradecyl-2-ethylsuccinate, diethyl-2-isobutyl-2-ethylsuccinate, 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-butylsuccinate, diisobutyl-2,2-diisobutylsuccinate, diisobutyl-2-cyclohexyl-2-ethylsuccinate, diisobutyl-2-isopropyl-2-methylsuccinate, diisobutyl-2-tetradecyl-2-ethylsuccinate, diisobutyl-2-isobutyl-2-ethylsuccinate, diisobutyl-2-(1-trifluoromethylethyl)-2-methylsuccinate, diisobutyl-2-isopentyl-2-isobutylsuccinate, diisobutyl-2-phenyl-2-n-butylsuccinate, dineopentyl-2,2-dimethylsuccinate, dineopentyl-2-ethyl-2-methylsuccinate, dineopentyl-2-benzyl-2-isopropylsuccinate, dineopentyl-2-cyclohexylmethyl-2-isobutylsuccinate, dineopentyl-2-cyclopentyl-2-n-butylsuccinate, dineopentyl-2,2-diisobutylsuccinate, dineopentyl-2-cyclohexyl-2-ethylsuccinate, dineopentyl-2-isopropyl-2-methylsuccinate, dineopentyl-2-tetradecyl-2-ethylsuccinate, dineopentyl-2-isobutyl-2-ethylsuccinate, dineopentyl-2-(1-trifluoromethylethyl)-2-methylsuccinate, dineopentyl-2-isopentyl-2-isobutylsuccinate, dineopentyl-2-phenyl-2-n-butylsuccinate. ,

[0026] Furthermore, compounds in which at least two groups different from hydrogen are bonded to different carbon atoms are also particularly preferred. Specifically, R3 and R5 are groups different from hydrogen. In this case, R4 and R6 may be hydrogen atoms or groups different from hydrogen, but it is preferable that one of them is a hydrogen atom (trisubstituted succinate). Preferred examples of such compounds include diethyl-2,3-bis(trimethylsilyl)succinate, diethyl-2,2-sec-butyl-3-methylsuccinate, diethyl-2-(3,3,3-trifluoropropyl)-3-methylsuccinate, diethyl-2,3-bis(2-ethylbutyl)succinate, diethyl-2,3-diethyl-2-isopropylsuccinate, diethyl-2,3-diisopropyl-2-methylsuccinate, diethyl-2,3 -Dicyclohexyl-2-methyldiethyl-2,3-dibenzylsuccinate, diethyl-2,3-diisopropylsuccinate, diethyl-2,3-bis(cyclohexylmethyl)succinate, diethyl-2,3-di-t-butylsuccinate, diethyl-2,3-diisobutylsuccinate, diethyl-2,3-dineopentylsuccinate, diethyl-2,3-diisopentylsuccinate, diethyl-2,3-(1-trifluoromethylethyl)succinate 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-cyclohexyl methyl succinate, diethyl-2 -Cyclohexyl-3-cyclopentyl 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, diisobutyl-2,3-diisopropyl succinate, 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-tetradecylsuccinate, diisobutyl-2,3-fluorenylsuccinate, diisobutyl-2-isopropyl-3-isobutylsuccinate, diisobutyl-2-te rt-Butyl-3-isopropyl succinate, diisobutyl-2-isopropyl-3-cyclohexyl succinate, diisobutyl-2-isopentyl-3-cyclohexyl succinate, diisobutyl-2-tetradecyl-3-cyclohexyl methyl succinate, diisobutyl-2-cyclohexyl-3-cyclopentyl succinate, dineopentyl-2,3-bis(trimethylsilyl) succinate, dineopentyl-2,2-sec-butyl-3-methyl succinate ester, dineopentyl-2-(3,3,3-trifluoropropyl)-3-methylsuccinate, dineopentyl-2,3-bis(2-ethylbutyl)succinate, dineopentyl-2,3-diethyl-2-isopropylsuccinate, dineopentyl-2,3-diisopropyl-2-methylsuccinate, dineopentyl-2,3-dicyclohexyl-2-methylsuccinate, dineopentyl-2,3-dibenzylsuccinate, dineopentyl-2,3-diisopropyl dineopentyl-2,3-bis(cyclohexylmethyl)succinate, dineopentyl-2,3-di-t-butylsuccinate, dineopentyl-2,3-diisobutylsuccinate, dineopentyl-2,3-dineopentylsuccinate, dineopentyl-2,3-diisopentylsuccinate, dineopentyl-2,3-(1-trifluoromethylethyl)succinate, dineopentyl-2,3-tetradecylsuccinate, 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-cyclohexyl methyl succinate, and dineopentyl-2-cyclohexyl-3-cyclopentyl succinate.

[0027] Among the compounds of formula (I), compounds in which some of the groups R3 to R6 are bonded together to form a ring can also be preferably used. Examples of such compounds include compounds listed in JP-A-2002-542347, such as 1-(ethoxycarbonyl)-1-(ethoxyacetyl)-2,6-dimethylcyclohexane, 1-(ethoxycarbonyl)-1-(ethoxyacetyl)-2,5-dimethylcyclopentane, 1-(ethoxycarbonyl)-1-(ethoxyacetylmethyl)-2-methylcyclohexane, and 1-(ethoxycarbonyl)-1-(ethoxy(cyclohexyl)acetyl)cyclohexane. In addition, cyclic succinate compounds such as 3,6-dimethylcyclohexane-1,2-dicarboxylate diisobutyl and cyclohexane-1,2-dicarboxylate diisobutyl, as disclosed in WO 2009 / 069483, can also be preferably used. Other preferred examples of the cyclic succinate compound include the compounds disclosed in WO 2009 / 057747.

[0028] In the compound of formula (I), when the groups R3 to R6 contain a heteroatom, the heteroatom is preferably a Group 15 atom including nitrogen and phosphorus atoms, or a Group 16 atom including oxygen and sulfur atoms. Examples of the compound in which the groups R3 to R6 contain a Group 15 atom include the compounds disclosed in JP-A-2005-306910. On the other hand, examples of the compound in which the groups R3 to R6 contain a Group 16 atom include the compounds disclosed in JP-A-2004-131537.

[0029] (2) Organoaluminum compounds (component (b)) Examples of the organoaluminum compound of component (b) include the following: Trialkylaluminum such as triethylaluminum and tributylaluminum; Trikenylaluminum such as triisoprenylaluminum: Dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide; Alkyl aluminum sesquialkoxides such as ethyl aluminum sesquiethoxide and butyl aluminum sesquibutoxide;

[0030] Partially halogenated alkylaluminums such as ethylaluminum dichloride, propylaluminum dichloride, butylaluminum dibromide, diethylaluminum chloride, dipropylaluminum chloride, dibutylaluminum chloride, and the like; Dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride; Partially hydrogenated alkylaluminums, such as alkylaluminum dihydrides, such as ethylaluminum dihydride, propylaluminum dihydride, etc.; Partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxy chloride, butylaluminum butoxy chloride, and ethylaluminum ethoxy bromide.

[0031] (3) Electron donor compound (component (c)) If necessary, the catalyst may contain an external electron donor compound as component (c). Such a compound is preferably an organosilicon compound, and specific examples thereof include the following compounds: Trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, bis-o-tolyldimethoxysilane, bis-m-tolyldimethoxysilane, bis-p-tolyldimethoxysilane, bis-p-tolyldiethoxysilane, bisethylphenyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, decyltrimethoxysilane, decyl aryltriethoxysilane, phenyltrimethoxysilane, gamma-chloropropyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, thexyltrimethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, phenyltriethoxysilane, gamma-aminopropyltriethoxysilane, chlortriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, 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, isobutylisopropyldimethoxysilane, n-propyltrimethoxysilane, di-n-propyldimethoxysilane, t-butylethyldimethoxysilane, t-butylpropyldimethoxysilane, t-butyl-t-butoxydimethoxysilane, isobutyltrimethoxysilane, cyclohexylisobutyldimethoxysilane, di-sec-butyldimethoxysilane, isobutylmethyldimethoxysilane, bis(decahydroisoquinolin-2-yl)dimethoxysilane, diethylaminotriethoxysilane, dicyclopentyl-bis(ethylamino)silane, tetraethoxysilane, tetramethoxysilane, isobutyltriethoxysilane. t-Butyltrimethoxysilane, i-Butyltrimethoxysilane, i-Butylsec-butyldimethoxysilane, Ethyl(perhydroisoquinolin2-yl)dimethoxysilane, Tri(isopropenyloxy)phenylsilane, i-Butyli-propyldimethoxysilane, Cyclohexyli-butyldimethoxysilane, Cyclopentyli-butyldimethoxysilane, Cyclopentylisopropyldimethoxysilane, Phenyltriethoxysilane, p-Tolylmethyldimethoxysilane,

[0032] Among them, ethyl triethoxysilane, n-propyl triethoxysilane, n-propyl trimethoxysilane, t-butyl triethoxysilane, t-butyl methyl dimethoxysilane, t-butyl methyl diethoxysilane, t-butyl ethyl dimethoxysilane, t-butyl propyl dimethoxysilane, t-butyl t-butoxy dimethoxysilane, t-butyl trimethoxysilane, i-butyl trimethoxysilane, isobutyl methyl dimethoxysilane, i-butyl sec-butyl dimethoxysilane, ethyl (perhydroisoquinolin-2-yl) dimethoxysilane, bis (decahydroisoquinolin-2-yl) dimethoxysilane, tri (isopropenyloxy) phenyl silane, thexyl trimethoxysilane, vinyl triethoxysilane, phenyl triethoxysilane, phenyl trimethoxysilane, vinyl tributoxysilane, diphenyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane , i-butyl i-propyl dimethoxysilane, cyclopentyl t-butoxy dimethoxysilane, dicyclopentyl dimethoxysilane, cyclohexyl methyl dimethoxysilane, cyclohexyl i-butyl dimethoxysilane, cyclopentyl i-butyl dimethoxysilane, cyclopentyl isopropyl dimethoxysilane, di-sec-butyl dimethoxysilane, diethylamino triethoxysilane, tetraethoxysilane, tetramethoxysilane, isobutyl triethoxysilane, phenyl methyl dimethoxysilane, phenyl triethoxysilane, bis p-tolyl dimethoxysilane, p-tolyl methyl dimethoxysilane, dicyclohexyl dimethoxysilane, cyclohexyl ethyl dimethoxysilane, 2-norbornane triethoxysilane, 2-norbornane methyl dimethoxysilane, diphenyl diethoxysilane, methyl (3,3,3-trifluoro-n-propyl) dimethoxysilane, ethyl silicate, and the like are preferred.

[0033] (4) Polymerization The raw material monomer is polymerized by contacting it with the catalyst prepared as described above. At this time, it is preferable to first carry out prepolymerization using the catalyst. Prepolymerization is a process in which a polymer chain that serves as a foothold for the subsequent main polymerization of the raw material monomer is formed on a solid catalyst component. Prepolymerization can be carried out by a known method. Prepolymerization is usually carried out at 40°C or less, preferably 30°C or less, more preferably 20°C or less. Next, the prepolymerized catalyst (prepolymerization catalyst) is introduced into the polymerization reaction system to carry out the main polymerization of the raw material monomer. Polymerization may be carried out in a liquid phase, a gas phase, or a liquid-gas phase. The polymerization temperature is preferably from room temperature to 150°C, more preferably from 40°C to 100°C. The polymerization pressure is preferably in the range of 0.8 to 6.0 MPa when carried out in a liquid phase, and preferably in the range of 0.5 to 3.0 MPa when carried out in a gas phase. A conventional molecular weight regulator known in the art, such as a chain transfer agent (e.g., hydrogen or ZnEt2), may be used.

[0034] A polymerization vessel having a gradient of monomer concentration or polymerization conditions may also be used. In such a polymerization vessel, for example, one having at least two polymerization zones connected thereto is used, and a monomer can be polymerized by gas phase polymerization. Specifically, in the presence of a catalyst, a monomer is supplied and polymerized in a polymerization zone consisting of an uprising tube, and a monomer is supplied and polymerized in a downcomer connected to the uprising tube, and a polymer product is recovered while circulating between the uprising tube and the downcomer. This method includes a means for completely or partially preventing the gas mixture present in the uprising tube from entering the downcomer. Also, a gas or liquid mixture having a composition different from that of the gas mixture present in the uprising tube is introduced into the downcomer. As the above polymerization method, for example, the method described in JP-A-2002-520426 can be applied.

[0035] 3. Nucleating Agent The polypropylene composition preferably contains 0.01 to 0.2 parts by weight of a nucleating agent relative to 100 parts by weight of the polypropylene. By containing the nucleating agent, the rigidity of the obtained film is improved, but if the amount of the nucleating agent exceeds the upper limit, the film formability when the film is made is reduced. From this viewpoint, the lower limit of the amount of the nucleating agent is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, and the upper limit is preferably 0.1 parts by weight or less, more preferably 0.08 parts by weight or less.

[0036] A nucleating agent is an additive that promotes or controls the crystallization of a resin. For example, transparent nucleating agents are known that are used to control the size of the crystal components in a resin to be small and increase transparency, and rigid nucleating agents are known that are used to increase the amount of crystal components in a resin and increase rigidity. In the present invention, known nucleating agents can be used. From the viewpoint of availability, etc., the nucleating agent is preferably selected from nonitol-based nucleating agents, sorbitol-based nucleating agents, phosphate-based nucleating agents, triaminobenzene derivative nucleating agents, metal carboxylate nucleating agents, xylitol-based nucleating agents, and rosin-based nucleating agents, and more preferably nonitol-based nucleating agents or phosphate-based nucleating agents.

[0037] Examples of nucleating agents having a nonitol-based structure include 1,2,3-trideoxy-4,6:5,7-bis-[(4-propylphenyl)methylene]-nonitol; examples of nucleating agents having a xylitol-based structure include bis-1,3:2,4-(5',6',7',8'-tetrahydro-2-naphthaldehyde benzylidene)1-allyl xylitol, bis-1,3:2,4-(3',4'-dimethylbenzylidene)1-propyl xylitol; examples of nucleating agents having a sorbitol-based structure include bis-1,3:2,4-(4'-ethylbenzylidene)1-allyl sorbitol, bis-1,3:2,4-(3'-methyl-4'-fluoro-benzylidene)1-propyl sorbitol, bis-1,3:2,4-(3',4'-dimethyl benzylidene)1-propyl sorbitol, 2,4-(4'-ethylbenzylidene)-1-allyl sorbitol, mono 2,4-(3'-bromo-4'-ethylbenzylidene)-1-allyl sorbitol, bis-1,3:2,4-(4'-ethylbenzylidene)-1-allyl sorbitol, bis-1,3:2,4-(3',4'-dimethylbenzylidene)-1-methyl sorbitol, bis(p-methylbenzylidene)sorbitol, and 1,3:2,4-bis-o-(4-methylbenzylidene)-D-sorbitol.

[0038] Examples of commercially available nonitol-based crystal nucleating agents include Millad NX8000 (manufactured by Milliken Japan Co., Ltd.), Millad NX8000J (manufactured by Milliken Japan Co., Ltd.), and Millad NX8000K (manufactured by Milliken Japan Co., Ltd.); and examples of commercially available sorbitol-based crystal nucleating agents include RiKAFAST R-1 (manufactured by New Japan Chemical Co., Ltd.), Millad 3988 (manufactured by New Japan Chemical Co., Ltd.), Gelall E-200 (manufactured by New Japan Chemical Co., Ltd.), and Gelall MD (manufactured by New Japan Chemical Co., Ltd.).

[0039] Examples of the phosphate ester-based crystal nucleating agent include sodium 2,2-methylenebis(4,6-di-tert-butylphenyl) phosphate, aluminum 2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate, lithium 2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate, etc. Examples of commercially available phosphate ester-based crystal nucleating agents include Adeka STAB NA-11 (manufactured by ADEKA Corporation), Adeka STAB NA-21 (manufactured by ADEKA Corporation), Adeka STAB NA-71 (manufactured by ADEKA Corporation), etc.

[0040] Examples of triaminobenzene derivative nucleating agents include 1,3,5-tris(2,2-dimethylpropanamide)benzene, etc. Examples of commercially available triaminobenzene derivative crystal nucleating agents include IRGACLEAR XT386 (manufactured by BASF Japan Ltd.) and RIKACLEAR PC1 (manufactured by New Japan Chemical Co., Ltd.).

[0041] Examples of the metal carboxylate nucleating agent include calcium 1,2-cyclohexanedicarboxylate, etc. Examples of commercially available metal carboxylate nucleating agents include Hyperform HPN-20E (manufactured by Milliken Japan Co., Ltd.).

[0042] Examples of xylitol-based nucleating agents include bis-1,3:2,4-(5',6',7',8'-tetrahydro-2-naphthaldehyde benzylidene) 1-allyl xylitol and bis-1,3:2,4-(3',4'-dimethylbenzylidene) 1-propyl xylitol.

[0043] Examples of rosin-based nucleating agents include rosin acid metal salt compounds or rosin acid partial metal salt compounds (e.g., rosin acid partial calcium salts) obtained by reacting rosin acid with a metal such as calcium or magnesium. Examples of the rosin acid include pimaric acid, sandaracopimaric acid, palustric acid, isopimaric acid, abietic acid, dehydroabietic acid, neoabietic acid, dihydropimaric acid, dihydroabietic acid, and tetrahydroabietic acid.

[0044] 4.Other additives The polypropylene composition may further contain additives that are commonly used in olefin polymers, such as antioxidants, chlorine absorbers, heat stabilizers, light stabilizers, UV absorbers, antiblocking agents, antistatic agents, antifogging agents, flame retardants, dispersants, copper inhibitors, neutralizing agents, plasticizers, bubble inhibitors, crosslinking agents, peroxides, oil extenders, lubricants, and other organic and inorganic pigments. The amount of each additive may be a known amount. In the present invention, the polypropylene may be mixed with a master batch of a nucleating agent. When the matrix polymer of the master batch is different from the polypropylene, the polypropylene composition contains the matrix polymer as another component.

[0045] The polypropylene composition may contain a resin or elastomer other than the main component within a range that does not impair the effects of the present invention. The polypropylene composition may contain only one type of resin or elastomer, or two or more types. The content may be a known amount. When an elastomer is blended with the polypropylene composition of the present invention for the purpose of improving the impact resistance, it is preferable to use a copolymer of ethylene and an α-olefin having 3 or more carbon atoms in consideration of its affinity with polypropylene.

[0046] II. Film 1.Characteristics In the present invention, the term "film" is a general term for a film-like material, and in particular, a member having a thickness of less than 150 μm is called a film, and a member having a thickness of 150 μm or more is called a sheet. The film can be produced by extrusion molding the polypropylene composition. The molding temperature may be as known, but it is preferable to set the cylinder temperature to 180 to 250° C. The film obtained from the polypropylene composition is a stretched film, preferably a biaxially stretched film. The thickness of the stretched film is appropriately adjusted depending on the application, and is, for example, preferably 10 to 80 μm, more preferably 10 to 30 μm, and even more preferably 15 to 25 μm. If the thickness is less than the lower limit, the rigidity is likely to be insufficient. If the rigidity is insufficient, the film is not suitable as a film material used for food packaging, fiber packaging, etc. If the thickness exceeds the upper limit, the cost simply increases, and it is not practical to mass-produce the film at low cost in industry.

[0047] (1) Rigidity The tensile modulus of elasticity in the MD direction of the stretched film (JIS K7161) is preferably 1800 MPa or more, more preferably 1900 MPa or more, and even more preferably 2100 MPa or more. Although there is no upper limit for the tensile modulus, if the rigidity is too high, the film formability may decrease, so that the upper limit is preferably 2900 MPa or less, more preferably 2700 MPa or less.

[0048] (2) Impact resistance The impact strength (ASTM-D3420) of the stretched film at 23° C. is preferably 25 kJ / m or more, more preferably 30 kJ / m or more, and even more preferably 40 kJ / m or more.

[0049] (3)Applications The stretched film can be used for various purposes. For example, the film can be cut into a desired shape by die cutting, or the film can be subjected to secondary processing such as vacuum forming into containers. The stretched film is useful as a packaging material such as food containers and lids for lunch boxes, noodles, salads, side dishes, frozen foods, ice, ice cream, chilled drinks, etc. The polypropylene composition of the present invention is also suitable as a blend material for biomass-derived resins. The blend can be made into a stretched film with improved rigidity and stretchability. Examples of biomass-derived resins include biopolyethylene, biopolypropylene, biopolybutylene succinate, polylactic acid, PHBP, and thermoplasticized starch.

[0050] The stretched film may be subjected to secondary processing. The temperature in the secondary processing is not limited, but is preferably 140 to 170°C. The secondary processing refers to processing the stretched film, which is a primary processed molded product, and specifically refers to processing into a molded product having a different shape by compression molding, vacuum molding, pressure molding, vacuum pressure molding, etc., or fusing and joining films together. The molded product obtained by secondary processing is also called a secondary processed molded product.

[0051] 2. Manufacturing method of stretched film The method for producing the stretched film is not particularly limited. For example, an unstretched film or sheet made of the polypropylene composition is prepared, and the unstretched film or sheet is stretched by a known method to obtain a stretched sheet. The unstretched film or sheet can be produced by winding a resin molten in an extruder with a cooling roll. The melt extrusion method is preferably a T-die extrusion method. The cooling step includes widely known cooling methods such as water cooling, air cooling, rolls and belts, but it is preferable that the molten resin is quenched uniformly and efficiently, and the belt method (Patent No. 4237275), sleeve rubber roll method (Patent No. 4472018), swing roll method (Patent No. 4701067), etc. can also be used in combination. The molten resin temperature in the extruder is preferably 200 to 250 ° C, and the cooling roll temperature is preferably 20 to 90 ° C. The molding temperature when stretching the unstretched sheet or film is preferably 140 to 170 ° C, more preferably 150 to 165 ° C, and even more preferably 155 to 160 ° C. EXAMPLES

[0052] The polymer was prepared as follows. [Polymer 1] (1) Preparation of solid catalyst component A solid catalyst component was prepared according to the preparation method described in the examples of JP 2011-500907 A. Specifically, the method is as follows: In a 500 mL four-neck round-bottom flask purged with nitrogen, 250 mL of TiCl4 was introduced at 0°C. With stirring, 10.0 g of finely spherical MgCl2·1.8C2H5OH and 9.1 mmol of diethyl-2,3-(diisopropyl)succinate were added. The finely spherical MgCl2·1.8C2H5OH was prepared according to the method described in Example 2 of US Patent 4,399,054, but operating at 3000 rpm instead of 10000 rpm. The temperature was raised to 100°C and held for 120 minutes. Then, the stirring was stopped, the solid product was allowed to settle, and the supernatant liquid was siphoned off. The following operation was then repeated twice: 250 mL of fresh TiCl4 was added, the mixture was reacted at 120° C. for 60 min, and the supernatant liquid was siphoned off. The solid was washed six times with anhydrous hexane (6×100 mL) at 60° C.

[0053] (2) Preparation of Polymer 1 The solid catalyst was contacted with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) in amounts such that the weight ratio of TEAL to the solid catalyst was 11 and the molar ratio of DCPMS / TEAL was 0.03 at 12°C for 24 minutes. The obtained catalyst system was prepolymerized by keeping it in a suspended state in liquid propylene at 20°C for 5 minutes. The obtained prepolymer was introduced into a polymerization reactor and polymerized with propylene and ethylene under the conditions shown in Table 1 to produce polymer 1. The MFR, ethylene-derived unit content, xylene insoluble content (XI), stereoregularity of xylene insoluble content (mmmm), and molecular weight distribution (Mw / Mn) of the obtained polymer are shown in Table 1 (same below).

[0054] [Polymer 2] The solid catalyst used in the production of polymer 1 was contacted with TEAL and diisopropyldimethoxysilane (DIPMS) in amounts such that the mass ratio of TEAL to the solid catalyst was 11 and the molar ratio of DIPMS / TEAL was 0.20 for 24 minutes at 12°C. The obtained catalyst system was suspended in liquid propylene and held at 20°C for 5 minutes to carry out prepolymerization. The obtained prepolymer was introduced into a polymerization reactor and propylene was polymerized under the conditions shown in Table 1 to produce polymer 2.

[0055] [Polymer 3] A multi-stage polymerization method was carried out using a two-stage polymerization reactor under the conditions shown in Table 1. The prepolymer used in the production of polymer 2, propylene, and hydrogen were supplied to the first-stage polymerization reactor to prepare a polymer. The obtained polymer was transferred to the second-stage reactor, where propylene and hydrogen were supplied to carry out polymerization, to obtain polymer 3, which is composed of polymers with different MFRs.

[0056] [Polymer 4] Polymer 4 was obtained in the same manner as in the production of Polymer 2, except that the hydrogen concentration was changed to the value shown in Table 1.

[0057] [Polymer 5] Polymer 5 was produced in the same manner as Polymer 2, except that propylene and ethylene were polymerized under the conditions shown in Table 1.

[0058] [Polymer 6] Polymer 6 was produced in the same manner as Polymer 2, except that propylene and ethylene were polymerized under the conditions shown in Table 1.

[0059] [Polymer 7] (1) Preparation of solid catalyst component A solid catalyst component was prepared by the method described in Example 1 of EP 674991. The solid catalyst was prepared by supporting Ti and diisobutyl phthalate as an internal donor on MgCl2 by the method described in the above patent publication. Note that a catalyst containing a phthalate-based compound as an internal electron donor compound is also called a "Pht catalyst."

[0060] (2) Preparation of Polymer 7 The solid catalyst obtained above was contacted with TEAL and cyclohexylmethyldimethoxysilane (CHMMS) in amounts such that the weight ratio of TEAL to the solid catalyst was 8 and the molar ratio of CHMMS / TEAL was 0.02 at -5°C for 5 minutes. The obtained catalyst system was prepolymerized by maintaining it in a suspended state in liquid propylene at 20°C for 5 minutes. The obtained prepolymer was introduced into a polymerization reactor and propylene was polymerized under the conditions shown in Table 1 to produce polymer 7.

[0061] [Polymer 8] The solid catalyst used in the production of polymer 7, TEAL, and DIPMS were contacted for 24 minutes at 12° C. in amounts such that the weight ratio of TEAL to the solid catalyst was 11 and the molar ratio of DIPMS / TEAL was 0.20. The obtained catalyst system was prepolymerized by maintaining it in a suspended state in liquid propylene at 20° C. for 5 minutes. The obtained prepolymer was introduced into a polymerization reactor, and propylene was polymerized under the conditions shown in Table 1 to produce polymer 8.

[0062] [Polymer 9] Polymer 9 was produced in the same manner as in Polymer 7, except that propylene and ethylene were polymerized under the conditions shown in Table 1.

[0063] [Example 1] Based on polymer 1, 0.05% by weight of nucleating agent 1 (ADEKA STAB NA-11 (phosphate ester nucleating agent) manufactured by ADEKA CORPORATION), 0.2% by weight of antioxidant (BASF Japan Ltd. B225), and 0.05% by weight of neutralizing agent (calcium stearate) were added, and the mixture was stirred and mixed for 1 minute with a Henschel mixer. The mixture was extruded at a cylinder temperature of 230°C using an NVC φ50mm single screw extruder manufactured by Nakatani Machinery Co., Ltd., and the strand was cooled in water and then cut with a pelletizer to obtain a pellet-shaped polypropylene composition. A biaxially stretched film was produced from the obtained polypropylene composition by the method described below, and evaluated.

[0064] [Examples 2 and 3] Except for using polymers 2 and 3 instead of polymer 1 and adjusting the amount of nucleating agent 1 as shown in Table 2, biaxially stretched films were produced and evaluated in the same manner as in Example 1.

[0065] [Example 4] A biaxially stretched film was produced and evaluated in the same manner as in Example 1, except that Polymer 4 was used instead of Polymer 1 and no nucleating agent was used.

[0066] [Examples 5 and 6] Biaxially stretched films were produced and evaluated in the same manner as in Example 4, except that the amount of nucleating agent shown in Table 2 was used. In Example 5, nucleating agent 1 (ADEKA STAB NA-11 (phosphate ester-based nucleating agent) manufactured by ADEKA CORPORATION) was used, and in Example 6, nucleating agent 2 (NX8000J (nonitol-based nucleating agent) manufactured by Milliken Japan) was used.

[0067] [Example 7] A biaxially stretched film was produced and evaluated in the same manner as in Example 1, except that Polymer 5 was used instead of Polymer 1 and no nucleating agent was used.

[0068] [Example 8] A biaxially stretched film was produced and evaluated in the same manner as in Example 7, except that the amount of nucleating agent 2 shown in Table 2 was used.

[0069] [Example 9] A biaxially stretched film was produced and evaluated in the same manner as in Example 1, except that Polymer 6 was used instead of Polymer 1 and no nucleating agent was used.

[0070] [Example 10] A biaxially stretched film was produced and evaluated in the same manner as in Example 9, except that the amount of nucleating agent 2 shown in Table 2 was used.

[0071] [Comparative Examples 1 to 3] Biaxially stretched films were produced and evaluated in the same manner as in Example 1, except that the polymers and nucleating agents (types and amounts) shown in Table 2 were used.

[0072] [Table 1]

[0073] [Table 2]

[0074] [MFR] The measurement was performed under conditions of a temperature of 230° C. and a load of 2.16 kg according to JIS K6921-2. The MFR measurement of the polymer was performed after adding 0.05 g of H-BHT manufactured by Honshu Chemical Industry Co., Ltd. to 5 g of the sample and homogenizing the mixture by dry blending.

[0075] [Xylene insolubles] 2.5 g of polymer was dissolved in 250 ml of xylene at 135° C. with stirring. After 20 minutes, the solution was cooled to 25° C. with stirring and then allowed to stand for 30 minutes. The precipitate was filtered through filter paper, the solution was evaporated in a nitrogen stream, and the residue was dried under vacuum at 80° C. until a constant weight was reached. Thus, the weight percent of polymer soluble in xylene at 25° C. was calculated. The weight percent of polymer insoluble in xylene at 25° C. (weight percent of 100-soluble polymer, also called xylene insoluble (XI)) is considered to be the amount of isotactic components of the polymer. The xylene insolubles were collected by thoroughly washing the precipitate with methanol to remove residual xylene, and then drying under vacuum at 80° C.

[0076] [Ethylene content (C2)] A sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene was analyzed using a JNM LA-400 (13C resonance frequency 100 MHz) manufactured by JEOL Ltd. 13 It was calculated from the value measured by C-NMR method.

[0077] [Manufacturing of biaxially oriented films] Preparation of raw sheet: Using a Thermoplastics Industries Co., Ltd. three-type three-layer film molding machine (φ25 mm x 3), the molten resin film extruded from a T-die at a cylinder and die temperature of 250°C was cooled with a metal roll and air knife air adjusted to 30°C, and taken up at a speed of 0.6 m / min to obtain a raw sheet approximately 230 mm wide and 800 μm thick. Preparation of biaxially stretched film: A sheet for stretching 100 mm long and 100 mm wide was cut out from the center of the width direction of the raw sheet, and set on the sample mounting part of Bruckner's KARO IV, and the sample gripping part was gripped with an air chuck. After preheating at 150-165 ° C for 60 seconds in the stretching section of the device, it was stretched 5 times in the MD direction (machine axis direction), and then stretched 9 times in the TD direction (direction perpendicular to the machine axis). While maintaining the stretched state, it was moved to the stretch relaxation section, where it was heated and stress relaxed at 100 ° C for 30 seconds, and then the sample was returned to the sample setting position, the air chuck was released, and the stretched film was taken out to obtain a sample.

[0078] [Tensile modulus of biaxially stretched film] According to JIS K7161, a sample cut from the center of the stretched film was pulled at a pulling speed of 5 mm / min using a Tensilon Autocom manufactured by TSE, and a stress-strain curve was obtained. A tangent was drawn from the zero point of the curve, and the load at an elongation of 2% was divided by the cross-sectional area of ​​the sample (x100) to obtain the tensile modulus. The test was carried out at 23°C, with the pulling direction parallel to the MD direction of the film.

[0079] [Impact resistance] A sample with a width of 100 mm and a length of 550 mm was cut out from the center of the stretched film in the TD direction according to ASTM-D3420. The impact strength of the sample was measured using a thermostatic chamber-equipped impact tester manufactured by Toyo Seiki Seisakusho, and the obtained value was divided by the thickness of the sample to calculate the film impact strength.

[0080] [Thickness and thinness accuracy] Three samples measuring 80 mm wide and 550 mm long were cut out from the stretched film. The thickness of the sample was measured at 1 mm intervals using a Yamabun Denki continuous thickness meter, and the average, maximum, minimum, and standard deviation (σ) of the three continuous thicknesses were calculated as indexes of thickness precision.

[0081] [Film forming property] The obtained film was visually inspected and evaluated according to the following criteria. 1: The film is uniform 2: The film is not torn but is uneven 3: The film is torn

[0082] The polypropylene composition of the present invention has excellent film-forming properties and can give a stretched film having excellent rigidity.

Claims

1. A polypropylene composition for oriented films comprising a propylene-ethylene copolymer containing 1.0% by weight or less of units derived from ethylene, and containing no nucleating agent, The copolymer is (a) a solid catalyst comprising magnesium, titanium, a halogen, and a succinate-based compound as an electron donor compound; (b) an organoaluminum compound, and (c) a polymer prepared by polymerizing the corresponding monomer using a catalyst that optionally contains an external electron donor compound; The copolymer satisfies the following: 1) MFR (230° C., load 2.16 kg) is 0.3 to 20 g / 10 min. 2) The xylene insoluble matter (XI) is more than 97.5% by weight and not more than 99.5% by weight. 3) The stereoregularity (mmmm) of the xylene insoluble matter is 95.5 to 99%. 4) The molecular weight distribution (Mw / Mn) measured by GPC is 7.0 to 14. Polypropylene composition for oriented films.

2. The polypropylene composition for stretched films according to claim 1, wherein the MFR is 5.0 to 20 g / 10 min.

3. The polypropylene composition for stretched films according to claim 1 or 2, wherein the MFR is 9.0 to 20 g / 10 min.

4. The polypropylene composition for stretched films according to any one of claims 1 to 3, wherein the content of the units derived from ethylene in the copolymer is 0.2 to 0.8% by weight.

5. The polypropylene composition for stretched films according to any one of claims 1 to 4, which is for use in biaxially stretched films.

6. A stretched film produced from the polypropylene composition for stretched films according to any one of claims 1 to 5.

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