JP2022148047A - polypropylene resin composition - Google Patents

Abstract

To provide a polypropylene resin composition that gives a drawn film having improved drawability and dimensional stability, and does not cause breakage even after long-term molding, contributing to stable production.SOLUTION: A propylene polymer of a specific structure and a propylene α-olefin copolymer of a specific structure are blended at a specific ratio, resulting in a drawn film having improved drawability and dimensional stability.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition. More specifically, the present invention relates to a polypropylene-based resin composition that improves the stretching processability, provides a stretched film with excellent dimensional stability, is resistant to breakage even after long-term molding, and contributes to production stability.

Polypropylene-based resin compositions are used in various fields such as daily necessities, kitchen utensils, packaging films, sheets, home electric appliances, electric parts, and automobile parts because of their excellent flexibility and heat resistance. Depending on its use, it has adequate dimensional stability.

In general, in order to improve the physical properties of stretched films, it is necessary to increase the stereoregularity of polypropylene. .

Patent Document 1 discloses 60 to 95% by weight of a propylene homopolymer having a melt flow index of 0.02 to 5 g/10 min, and a propylene homopolymer having a melt flow index of 50 to 1000 g/10 min. A stretching polypropylene resin composition containing 5 to 40% by weight of is described.

In Patent Document 2, 20 to 98 parts by weight of a propylene-based polymer A having an intrinsic viscosity [η] ^A of 1.8 to 8 (dl/g) and a melting point Tm of 140 to 165 (°C); [η] 2 to 80 parts by weight of a propylene-based polymer B having a ^B of 0.8 to 1.7 (dl/g) and a melting point Tm of 150 to 170 (°C), and 1<[η ] ^A /[η] ^B <10 for stretched films.

Patent Document 3 discloses a composition comprising 60 to 78% by weight of a propylene homopolymer and 22 to 40% by weight of a propylene-ethylene copolymer containing 25 to 55% by weight of ethylene polymerized units. 7 to 2.8 dl/g and the propylene-ethylene copolymer containing 80% or more by weight of xylene solubles is described.

However, any of the polypropylene-based compositions was broken when molded for a long period of time, making it difficult to carry out stable production.

JP-A-58-173141 Japanese Patent Application Laid-Open No. 2002-348423 Japanese Patent Application Laid-Open No. 2003-246900

An object of the present invention is to improve the stretching processability and obtain a stretched film having excellent dimensional stability, and to prevent breakage even after long-term molding, and to contribute to production stability. It is about providing things.

As a result of various investigations, the present inventors have found that by blending a propylene-based polymer having a specific structure and a propylene/α-olefin copolymer having a specific structure in a specific ratio, stretching processing can be achieved. The inventors have found that a stretched film having improved properties and excellent dimensional stability can be obtained, and have completed the present invention.

That is, the present invention includes the following aspects [1] to [3].
[1] 99.9 to 50 parts by mass of a propylene-based polymer (A) having a melt flow rate (MFR) of 0.5 to 10 g/10 min, and a melting point of 100 to 150° C., a melt flow rate ( 0.1 to 50 parts by mass of a propylene/α-olefin copolymer (B) having a MFR) of 10 to 1000 g/10 min (where the total of the propylene polymer (A) and the propylene polymer (B) is 100 parts by mass).
[2] An extruded sheet obtained from the polypropylene resin composition of [1].
[3] A uniaxially or biaxially stretched film obtained from the polypropylene resin composition according to [1].

The polypropylene-based resin composition according to the present invention has improved stretching processability, provides a stretched film with excellent dimensional stability, and is less likely to break even after long-term molding, contributing to production stability. It is possible to provide a molded article having good dimensional stability.

Hereinafter, each configuration of the polypropylene-based resin composition, extruded sheet, and uniaxially or biaxially stretched film according to one embodiment of the present invention will be specifically described.

[Polypropylene resin composition]
The polypropylene-based resin composition according to the present embodiment contains 50 to 99.9 parts by mass of the following propylene-based polymer (A) and 0.1 to 50 parts by mass of the propylene/α-olefin copolymer (B). . Here, the total amount of the propylene-based polymer (A) and the propylene/α-olefin copolymer (B) is 100 parts by mass.

[Propylene polymer (A)]
The propylene-based polymer (A) that can be used in the present embodiment has a structural unit derived from propylene and may have a structural unit derived from an α-olefin having 2 or 4 to 20 carbon atoms. The propylene-based polymer (A) has a content of 0 to 2% by mass of structural units derived from an α-olefin having 2 or 4 to 20 carbon atoms, and is preferably a propylene homopolymer. Examples of the α-olefins having 2 or 4 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1 -hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene and the like.

In addition, the propylene-based polymer (A) has a melt flow rate (MFR) measured under a load of 2.16 kg at 230° C. in accordance with ASTM D-1238 in the range of 0.5 to 10 g/10 minutes. , preferably in the range of 1.0 to 5 g/10 min. When the MFR is within this range, a composition having excellent mechanical strength and moldability can be obtained.

The propylene-based polymer (A) preferably has a melting point in the range of 155 to 168°C.
It is more preferably in the range of 157-165°C. When the melting point is within this range, a composition having excellent mechanical strength and moldability can be obtained.

Such a propylene-based polymer (A) can be produced by polymerizing propylene in the presence of an α-olefin stereoregular polymerization catalyst, such as a Ziegler-Natta catalyst or a metallocene catalyst. An example of such a polymerization catalyst is a catalyst system comprising (a) a solid catalyst component containing magnesium, titanium, a halogen and an electron donor as essential components, (b) an organoaluminum compound, and (c) an electron donor. , which is described in detail below.

The magnesium component may be a reducing compound or a non-reducing compound. Examples of reducing compounds include magnesium compounds having magnesium-carbon bonds or magnesium-hydrogen bonds. Specific examples thereof include dimethylmagnesium, diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diamylmagnesium, dihexylmagnesium, didecylmagnesium, ethylmagnesium chloride, propylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, amylmagnesium chloride, Butylethoxymagnesium, ethylbutylmagnesium, butylmagnesium hydride may be mentioned.

Specific examples of non-reducing magnesium compounds include magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide, magnesium fluoride; magnesium methoxy chloride, magnesium ethoxy chloride, magnesium isopropoxy chloride, butoxy Alkoxy magnesium halides such as magnesium chloride, octoxy magnesium chloride; aryloxy magnesium halides such as phenoxy magnesium chloride, methylphenoxy magnesium chloride; ethoxy magnesium, isopropoxy magnesium, butoxy magnesium, n-octoxy magnesium, 2-ethyl Alkoxymagnesium such as hexoxymagnesium; aryloxymagnesium such as phenoxymagnesium and dimethylphenoxymagnesium; and magnesium carboxylates such as magnesium laurate and magnesium stearate.

These magnesium compounds may be used alone, or may form a complex compound with an organometallic compound to be described later. They may also be liquid or solid, may be derived by reacting magnesium metal with the corresponding compounds, and may be derived from magnesium metal in the manner described above during catalyst preparation. You can also Among these magnesium compounds, non-reducing magnesium compounds are preferred, halogen-containing magnesium compounds are more preferred, and magnesium chloride, alkoxy magnesium chloride, and aryloxy magnesium chloride are particularly preferred.
Examples of the titanium component include tetravalent titanium compounds represented by the following formula.
Ti(OR)nX4 _{- n}
(Wherein, R is a hydrocarbon group, X is a halogen atom, and n is 0≦n≦4)

Specific examples of such titanium compounds include titanium tetrahalides such as TiCl ₄ , TiBr ₄ and TiI ₄ ; Ti(OCH ₃ )Cl ₃ , Ti(OC ₂ H ₅ )Cl ₃ , Ti(On trihalogenated alkoxy titanium such as _-C4H9 )Cl3 _, Ti _{( OC2H5} ) _{Br3 ,} Ti(O _- iso _{- C4H9} ) _Br3 ; Ti ₍ OCH3) _2Cl2 , Ti _{Dialkoxytitanium} dihalides such as _{( OC2H5} ) _2Cl2 , Ti _{( On - C4H9} ) _{2Cl2 ,} Ti _{( OC2H5} ) _2Br2 ; Ti(OCH3) _3Cl , Ti(OC ₂ H ₅ ) ₃ Cl, Ti(On-C ₄ H ₉ ) ₃ Cl, Ti(OC ₂ H ₅ ) ₃ Br; Ti(OCH ₃ ) ₄ , tetraalkoxy titanium such as Ti(OC ₂ H ₅ ) ₄ , Ti(O-n-C ₄ H ₉ ) ₄ , Ti(O-iso-C ₄ H ₉ ) ₄ and Ti(O-2-ethylhexyl) ₄ ; can be exemplified.

Electron donors that can be used in preparing the solid catalyst component (a) include alcohols, phenols, ketones, aldehydes, carboxylic acids, organic acid halides, esters of organic or inorganic acids, ethers , acid amides, acid anhydrides, ammonia, amines, nitriles, isocyanates, nitrogen-containing cyclic compounds, oxygen-containing cyclic compounds, and the like. Among these, carboxylic acids, carboxylic acid anhydrides, carboxylic acid esters, carboxylic acid halides, alcohols, and ethers are preferably used.

Specific examples of the electron donor are given below.
(1) Alcohols: methanol, ethanol, propanol, butanol, pentanol, hexanol, 2-ethylhexanol, octanol, dodecanol, octadecyl alcohol, oleyl alcohol, benzyl alcohol, phenylethyl alcohol, cumyl alcohol, isopropyl alcohol, isopropylbenzyl alcohols having 1 to 18 carbon atoms such as alcohol; halogen-containing alcohols having 1 to 18 carbon atoms such as trichloromethanol, trichloroethanol and trichlorohexanol;

(2) Phenols: Phenols having 6 to 20 carbon atoms which may have a lower alkyl group as a substituent such as phenol, cresol, xylenol, ethylphenol, propylphenol, nonylphenol, cumylphenol and naphthol.

(3) Ketones: Ketones having 3 to 15 carbon atoms such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone and benzoquinone.

(4) aldehydes: aldehydes having 2 to 15 carbon atoms such as acetaldehyde, propionaldehyde, octylaldehyde, benzaldehyde, tolualdehyde and naphthaldehyde;

(5) Carboxylic acids: aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, pivalic acid, acrylic acid, methacrylic acid, crotonic acid; malonic acid, succinic acid, glutaric acid acids, adipic acid, sebacic acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids; tartaric acid and other aliphatic oxycarboxylic acids; cyclohexane monocarboxylic acid, cyclohexene monocarboxylic acid, cis-1,2-cyclohexanedicarboxylic acid, cis -alicyclic carboxylic acids such as 4-methylcyclohexene-1,2-dicarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, anisic acid, p-tert-butylbenzoic acid, naphthoic acid and cinnamic acid Acids; aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalic acid, trimellitic acid, hemimellitic acid, trimesic acid, pyromellitic acid, and mellitic acid. As the anhydrides of carboxylic acids, the acid anhydrides of the above carboxylic acids can be used.

(6) Organic acid halides: acid halides having 2 to 15 carbon atoms such as acetyl chloride, benzoyl chloride, toluyl chloride and anisyl chloride.

(7) Organic or inorganic acid esters: methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, methyl chloroacetate, dichloroacetic acid Ethyl, methyl methacrylate, ethyl crotonate, ethyl cyclohexanecarboxylate, dimethyl phthalate, diethyl phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-n-amyl phthalate, diisoamyl Phthalate, ethyl-n-butyl phthalate, ethyl isobutyl phthalate, ethyl-n-propyl phthalate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate, benzoic acid Carbons such as benzyl, methyl toluate, ethyl toluate, amyl toluate, ethyl ethyl benzoate, methyl anisate, ethyl anisate, ethyl ethoxybenzoate, γ-butyrolactone, δ-valerolactone, coumarin, phthalide, and ethyl carbonate organic or inorganic acid esters of numbers 2 to 30;

(8) Ethers: methyl ether, ethyl ether, isopropyl ether, butyl ether, amyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diamyl ether, diisoamyl ether, dineopentyl ether, dihexyl ether, dioctyl ether, methyl butyl ether, methyl isoamyl ether, ethyl isobutyl ether, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl) -1,3-dimethoxypropane, 2-isopropyl-3,7-dimethyloctyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclohexylmethyl-1, 3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2- Dipropyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclohexyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3- Dimethoxypropane, 2-heptyl-2-pentyl-1,3-dimethoxypropane.

Next, several examples of specific methods for producing the solid catalyst component (a) will be described.
(1) A method of contact-reacting a solution comprising a magnesium compound, an electron donor and a hydrocarbon solvent with an organometallic compound to precipitate a solid, or contacting the titanium compound while the solid is being precipitated.

(2) A method of contact-reacting a complex composed of a magnesium compound and an electron donor with an organometallic compound, and then contact-reacting a titanium compound.

(3) A method of contact-reacting a titanium compound and preferably an electron donor with a contact product of an inorganic carrier and an organomagnesium compound. At this time, the contact product may be contacted with the halogen-containing compound and/or the organometallic compound in advance.

(4) from a mixture of a solution containing a magnesium compound, an electron donor, and optionally a hydrocarbon solvent, and an inorganic or organic carrier, after obtaining an inorganic or organic carrier supporting a magnesium compound, then contacting with a titanium compound; how to let

(5) A method of obtaining a solid catalyst component supported by magnesium and titanium by contacting a solution containing a magnesium compound, a titanium compound, an electron donor and optionally a hydrocarbon solvent with an inorganic or organic carrier.

(6) A method of contact-reacting a liquid organomagnesium compound with a halogen-containing titanium compound. At this time, an electron donor is used once.

(7) A method of contacting a titanium compound after contacting a liquid organomagnesium compound with a halogen-containing compound. At this time, an electron donor is used once.

(8) A method of contact-reacting an alkoxy group-containing magnesium compound with a halogen-containing titanium compound. At this time, an electron donor is used once.

(9) A method of contact-reacting a complex comprising an alkoxy group-containing magnesium compound and an electron donor with a titanium compound.

(10) A method of contacting a complex composed of an alkoxy group-containing magnesium compound and an electron donor with an organometallic compound and then reacting it with a titanium compound.

(11) A method of contacting and reacting a magnesium compound, an electron donor and a titanium compound in any order. This reaction may involve pretreating each component with an electron donor and/or a reaction aid such as an organometallic compound or a halogen-containing silicon compound. In addition, in this method, it is preferable to use the electron donor at least once.

(12) A method of reacting a liquid magnesium compound having no reducing ability and a liquid titanium compound, preferably in the presence of an electron donor, to precipitate a solid magnesium-titanium composite.

In preparing the solid catalyst component, the electron donor is used in an amount of 0.01 to 5 mol, preferably 0.1 to 1 mol, and the titanium compound is used in an amount of 0.01 to 1,000 mol, preferably 0.01 to 1,000 mol, per 1 mol of the magnesium compound. It is used in an amount of 0.1 to 200 mol. Further, the halogen/titanium (atomic ratio) is about 2 to 200, preferably about 4 to 100, and the electron donor/titanium (molar ratio) is about 0.01 to 100, preferably about 0.2 to 10. It is desirable that the magnesium/titanium (atomic ratio) be about 1-100, preferably about 2-50.

Such a solid catalyst component can be used alone, but it is also possible to use it by supporting it on a porous substance such as an inorganic oxide or an organic polymer. Porous inorganic oxides used include SiO ₂ , Al ₂ O ₃ , MgO, TiO ₂ , ZrO ₂ , SiO ₂ -Al ₂ O ₃ composite oxides, MgO-Al ₂ O ₃ composite oxides, MgO-SiO. ₂ -Al ₂ O ₃ composite oxide and the like.

Examples of porous organic polymers include polystyrene, styrene-divinylbenzene copolymer, styrene-N,N'-alkylenedimethacrylamide copolymer, styrene-ethylene glycol dimethacrylate copolymer, polyethyl acrylate, acrylic methyl acid-divinylbenzene copolymer, ethyl acrylate-divinylbenzene copolymer, polymethyl methacrylate, methyl methacrylate-divinylbenzene copolymer, polyethylene glycol methyl dimethacrylate, polyacrylonitrile, acrylonitrile-divinylbenzene copolymer Polystyrene, polyacrylic ester, polyacrylonitrile typified by coalescence, polyvinyl chloride, polyvinylpyrrolidine, polyvinylpyridine, ethylvinylbenzene-divinylbenzene copolymer, polyethylene, ethylene-methyl acrylate copolymer, polypropylene, etc. Polyvinyl chloride-based, polyolefin-based polymers can be mentioned. Among these porous substances, SiO ₂ , Al ₂ O ₃ and styrene-divinylbenzene copolymers are preferably used.

The organoaluminum compound used with the solid catalyst component has at least one Al-carbon bond in the molecule. A representative example is shown below by a general formula.
R1m _AlY3 ^- _m
R ² R ³ Al—O—AlR ⁴ R ⁵
(Here, R ¹ to R ⁵ are hydrocarbon groups having 1 to 8 carbon atoms, which may be the same or different. Y represents halogen, hydrogen or an alkoxy group. m is 2≦m≦3.)

Specific examples of organoaluminum compounds include trialkylaluminum compounds such as triethylaluminum, triisobutylaluminum and trihexylaluminum; dialkylaluminum hydrides such as diethylaluminum hydride and diisobutylaluminum hydride; and mixtures of triethylaluminum and diethylaluminum chloride. Examples include mixtures of trialkylaluminum and dialkylaluminum halides, and alkylalumoxanes such as tetraethyldialumoxane and tetrabutyldialumoxane.

Of these organoaluminum compounds, trialkylaluminum, mixtures of trialkylaluminum and dialkylaluminum halides, alkylalumoxanes are preferred, especially triethylaluminum, triisobutylaluminum, mixtures of triethylaluminum and diethylaluminum chloride, or tetraethyldi Alumoxanes are preferred.

Specific examples of the electron donor used together with the solid catalyst component and organoaluminum compound include the following compounds.
(1) Compounds containing nitrogen atoms: 2,2,6,6-tetramethylpiperidine, 2,6-dimethylpiperidine, 2,6-diethylpiperidine, 2,6-diisopropylpiperidine, 2,6-diisobutyl-4- methylpiperidine, 1,2,2,6,6-pentamethylpiperidine, 2,2,5,5-tetramethylpyrrolidine, 2,5-dimethylpyrrolidine, 2,5-diethylpyrrolidine, 2,5-diisopropylpyrrolidine, 1,2,2,5,5-pentamethylpyrrolidine, 2,2,5-trimethylpyrrolidine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,6-diisopropylpyridine, 2,6-diisobutyl pyridine, 1,2,4-trimethylpiperidine, 2,5-dimethylpiperidine, methyl nicotinate, ethyl nicotinate, nicotinamide, benzoamide, 2-methylpyrrole, 2,5-dimethylpyrrole, imidazole, toluic acid Amide, benzonitrile, acetonitrile, aniline, paratoluidine, orthotoluidine, metatoluidine, triethylamine, diethylamine, dibutylamine, tetramethylenediamine, tributylamine.

(2) compounds containing a sulfur atom: thiophenol, thiophene, ethyl 2-thiophenecarboxylate, ethyl 3-thiophenecarboxylate, 2-methylthiophene, methylmercaptan, ethylmercaptan, isopropylmercaptan, butylmercaptan, diethylthioether, diphenylthioether , methyl benzenesulfonate, methyl sulfite, ethyl sulfite.

(3) compounds containing oxygen atoms: tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 2,2,5,5-tetraethyltetrahydrofuran, 2,2,5,5-tetramethyltetrahydrofuran, 2 , 2,6,6-tetraethyltetrahydropyran, 2,2,6,6-tetramethyltetrahydropyran, dioxane, dimethyl ether, diethyl ether, dibutyl ether diisoamyl ether, diphenyl ether, anisole, acetophenone, acetone, methyl ethyl ketone, acetylacetone, o -tolyl-t-butyl ketone, methyl-2,6-di-t-butylphenyl ketone, ethyl 2-furarate, isoamyl 2-furaate, methyl 2-furaate, propyl 2-furaate.

(4) Organosilicon compound: A compound represented by the general formula RnSi(OR')4-n is preferred, and specific examples are shown below. (Here, R and R' are hydrocarbon groups, and n is a numerical value of 0<n<4.)
Cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, bis o-tolyldimethoxysilane, bis m-tolyldimethoxysilane, bis-p-tolyldimethoxysilane, bis-p-tolyldiethoxysilane, bisethylphenyldimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyl trimethoxysilane, n-propyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, n -butyltriethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, ethyl silicate, butyl silicate, trimethylphenoxysilane, methyltriaryl roxysilane, vinyltris(β-methoxyethoxysilane), vinyltriacetoxysilane, dimethyltetraethoxydisiloxane.

The molar ratio of the organoaluminum compound per mol of Ti atoms in the solid catalyst component is in the range of 5 to 1000, and the molar ratio of the electron donor is in the range of 0.002 to 0.5 per mol of the organoaluminum compound. is preferred.

The polymerization catalyst can also be used in the form of a prepolymerization catalyst obtained by prepolymerizing an olefin having 2 or more carbon atoms in advance. The following compounds can be exemplified as olefins that can be used for prepolymerization.

(1) Straight chains such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene shaped α-olefins.

(2) cycloolefins such as cyclopentene, cycloheptene, norbornene, 5-ethyl-2-norbornene, tetracyclododecene;

(3) 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1 - branched α-olefins such as hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene.

(4) Vinyl compounds such as allylnaphthalene, allylnorbornane, styrene, dimethylstyrenes, vinylnaphthalenes, allyltoluenes, allylbenzene, vinylcyclohexane, vinylcyclopentane, vinylcycloheptane, and allyltrialkylsilanes.

Propylene homopolymerization can be produced by polymerizing propylene using the above catalyst. The polymerization temperature is usually −50 to 100° C., preferably 0 to 90° C. in the case of suspension polymerization, and usually 0 to 250° C., preferably 20 to 150° C. in the case of solution polymerization. In the case of polymerization, the temperature is usually 0 to 120°C, preferably 20 to 100°C. The polymerization pressure is usually normal pressure to 150 (kg/cm ² ), preferably normal pressure to 100 (kg/cm ² ), and the polymerization reaction may be any of a batch system, a semi-continuous system and a continuous system. It can also be done in Furthermore, it is also possible to carry out the polymerization in two or more stages with different reaction conditions.

[Propylene/α-olefin copolymer (B)]
The propylene/α-olefin copolymer (B) as the second component constituting the polypropylene-based resin composition according to the present embodiment includes structural units derived from propylene and an α-olefin having 2 or 4 to 20 carbon atoms. and structural units derived from In the propylene/α-olefin copolymer (B), the content of structural units derived from an α-olefin having 2 or 4 to 20 carbon atoms is 0 to 20% by mass, preferably 1 to 10% by mass. .

Examples of α-olefins having 2 or 4 to 20 carbon atoms include ethylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene. As the propylene/α-olefin copolymer (B), binary random copolymerization of propylene and ethylene or terpolymerization of propylene, ethylene and 1-butene is particularly preferred. Such a polymer can be produced using a stereoregular polymerization catalyst similar to the stereoregular polymerization catalyst described above, and using polymerization conditions and a polymerization method similar to the polymerization conditions and polymerization method described above.

The propylene/α-olefin copolymer (B) has a melt flow rate (MFR) value measured under a load of 2.16 kg at 230° C. in accordance with ASTM D-1238 in the range of 10 to 1000 g/10 minutes. It is preferably in the range of 15 to 100 g/10 minutes, more preferably in the range of 30 to 100 g/10 minutes. When the MFR is within this range, a composition having excellent mechanical strength and moldability can be obtained.

The propylene/α-olefin copolymer (B) has a melting point in the range of 100 to 150°C, preferably in the range of 125 to 148°C. When the melting point is within this range, a composition having excellent mechanical strength and moldability can be obtained.

The polypropylene-based resin composition is prepared by polymerizing the propylene-based polymer (A) and the propylene/α-olefin copolymer (B) separately and then mixing them in predetermined proportions, followed by melt-kneading as necessary. can be manufactured by

By preparing a series of polymerization apparatuses, for example, by producing a propylene-based polymer (A) in the first stage and then producing a propylene/α-olefin copolymer (B) in the second stage, by a so-called multi-stage polymerization method. It may be produced by direct mixing.

This polypropylene-based resin composition may further contain an antioxidant, a heat stabilizer, a weather stabilizer, an antistatic agent, a slip agent, an antiblocking agent, and an antifogging agent, as long as the objects of the present invention are not impaired. Agents, lubricants, nucleating agents, dyes, pigments, natural oils, synthetic oils, waxes, fillers, and the like may be used.

As the antioxidant, hindered phenol-based, sulfur-based, lactone-based, organic phosphite-based, organic phosphonite-based antioxidants, or a combination of several of these antioxidants can be used.

As slip agents, amides of saturated or unsaturated fatty acids such as lauric acid, palmitic acid, oleic acid, stearic acid, erucic acid and hebenic acid, or bisamides of these saturated or unsaturated fatty acids can be used. Among these, erucic acid amide and ethylenebisstearic acid amide are preferred. The slip agent may be used in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polypropylene resin composition.

Antiblocking agents include fine powdered silica, finely powdered aluminum oxide, finely powdered clay, powdery or liquid silicone resins, polytetrafluoroethylene resins, and finely powdered crosslinked resins such as crosslinked acrylic resin and methacrylic resin powders. can be mentioned. Among these, finely divided silica and finely divided crosslinked resins may be used.

The polypropylene-based resin composition according to the present invention has improved stretching processability, provides a stretched film with excellent dimensional stability, and is less likely to break even after long-term molding, contributing to production stability. can do.

Various molded articles can be obtained by molding the polypropylene-based resin composition of the present invention according to known molding techniques. Molding techniques include T-die film molding, stretched film molding, inflation film molding, sheet molding, calendar molding, pressure molding, vacuum molding, pipe molding, profile extrusion molding, blow molding, laminate molding, injection molding, and injection stretch blow molding. Examples include molding, compression molding, injection compression molding, and the like.

[Extruded sheet, uniaxially or biaxially stretched film]
The extruded sheet according to the present invention is obtained by extruding the polypropylene-based resin composition according to the present invention. Further, the extruded sheet can be uniaxially or biaxially oriented into a uniaxially or biaxially oriented film.

The manufacturing method generally includes the following steps. First, a polypropylene-based resin composition is melted with an extruder, extruded into a sheet form from a T-die, and cooled and solidified with a cooling roll. Then, the obtained sheet is passed through a number of heating rolls and stretched in the machine direction to obtain a uniaxially stretched film. Subsequently, the film is transversely stretched through a heating furnace composed of a preheating section, a stretching section, and a heat treatment section to obtain a biaxially stretched film. After that, if necessary, the film is subjected to a corona discharge treatment or the like, and then wound up. The melting temperature of polypropylene varies depending on its molecular weight, but the resin temperature in the extruder is usually adjusted within the range of 200°C to 290°C. The longitudinal stretching is usually adjusted to 130 to 160°C, and the transverse stretching is usually carried out at 145 to 165°C. The draw ratios for longitudinal stretching and transverse stretching may be appropriately set according to the properties of the polypropylene-based resin composition to be used, and can be set to 4 to 10 times each. The area ratio of biaxial stretching (longitudinal stretching ratio×lateral stretching ratio) can be 16 times or more.

Films stretched in this way exhibit excellent mechanical strength, stiffness and optical properties and have a good appearance. Therefore, the stretched film can be used for industrial applications including electrical material applications such as film capacitors, secondary battery separator films, process paper, protective films, and optical films, or general-purpose applications such as food packaging, tobacco packaging, filling packaging, and fiber packaging. It can be suitably used as a packaging material.

Next, the present invention will be described in more detail through Examples and Comparative Examples, but the present invention is not limited by those Examples.
The method for producing the propylene homopolymer and the propylene/ethylene random copolymer used in Examples and Comparative Examples will be described.

(Production example 1)
<Production of propylene homopolymer>
[Preparation of solid titanium catalyst component]
7.14 kg (75 mol) of anhydrous magnesium chloride, 37.5 liters of decane and 35.1 liters (225 mol) of 2-ethylhexyl alcohol were heated at 130° C. for 2 hours to form a homogeneous solution. Thereafter, 1.67 kg (11.3 mol) of phthalic anhydride was added to this solution, and the mixture was stirred and mixed at 130° C. for an additional hour to dissolve the phthalic anhydride in the uniform solution. After cooling the homogeneous solution thus obtained to room temperature, the entire amount was added dropwise to 200 liters (1800 mol) of titanium tetrachloride kept at -20° C. over 1 hour. After the dropwise addition, the temperature of the resulting solution was raised to 110°C over 4 hours, and when the temperature reached 110°C, 5.03 liters (18.8 mol) of diisobutyl phthalate was added. Stirring was further continued at 110° C. for 2 hours, after which the solid portion was collected by hot filtration. This solid portion was resuspended in 275 liters of TiCl ₄ and heat-reacted again at 110° C. for 2 hours. After completion of the reaction, the solid portion was collected again by hot filtration and washed with 110° C. decane and hexane. This washing operation was continued until no titanium compound was detected in the washing liquid.

The synthesized solid titanium catalyst component was then slurried in hexane. A portion of this catalyst was sampled and dried, and the composition of the dried product was analyzed and found to be 2.5% by mass of titanium, 58% by mass of chlorine, 18% by mass of magnesium and 13.8% by mass of diisobutyl phthalate.

[Preliminary polymerization]
In a 500-liter reactor equipped with a stirrer, 3.5 kg of the solid titanium catalyst component obtained above and 300 liters of n-heptane were charged under a nitrogen gas atmosphere and cooled to -5°C while stirring. Next, 6 liters of an n-heptane solution of triethylaluminum (2.0 mol/liter) and an n-heptane solution of cyclohexylmethyldimethoxysilane (0.01 mol/liter) were added at 60 (mmol/liter) and 10 (mmol/liter), respectively. liter) and continued stirring for 5 minutes.

Then, after reducing the pressure in the system, propylene was continuously supplied and propylene was polymerized for 4 hours. After the polymerization was completed, the propylene was purged with nitrogen gas and the solid phase was washed three times with 10 liters of n-hexane each at room temperature. Further, the solid phase portion was dried under reduced pressure at room temperature for 1 hour to prepare a catalyst component. As a result of measuring the amount of magnesium contained in the catalyst component, the prepolymerized amount was 1.8 g per gram of the solid titanium catalyst component.

[Main polymerization]
In a 500-liter stainless steel autoclave equipped with a stirrer, 6 liters of an n-heptane solution of triisobutylaluminum (0.1 mol/liter) and an n-heptane solution of cyclohexylmethyldimethoxysilane (0.01 mol) were placed under a nitrogen gas atmosphere. /liter) was mixed and held for 5 minutes. Then, after injecting 100 liters of hydrogen gas and 300 liters of liquid propylene as molecular weight control agents, the temperature of the reaction system was raised to 70°C. After 4.2 g of the catalyst component obtained above was introduced into the reaction system, propylene was polymerized for 1 hour. After the polymerization was completed, unreacted propylene was purged to obtain 50.5 kg of white polypropylene powder. The amount of propylene homopolymer produced per gram of solid titanium catalyst component was 33.5 kg. The MFR of this propylene homopolymer was 3.0 g/10 minutes.

(Production example 2)
<Production of propylene/ethylene random copolymer>
Using dicyclopentyldimethoxysilane in place of the cyclohexylmethyldimethoxysilane described in Preparation Example 1, and replacing 300 liters of liquid propylene in the autoclave with 300 liters of hydrogen gas as a molecular weight control agent, 300 liters of liquid propylene and 0.5 liters of ethylene. A copolymer was produced in the same manner as in Production Example 1, except that 6 kg was injected. The obtained propylene/ethylene random copolymer had an MFR of 60 g/10 min and an ethylene content of 3.0% by mass.

(Production example 3)
<Production of propylene/ethylene random copolymer>
In the main polymerization described in Production Example 1, the procedure is the same as in Production Example 1, except that instead of 300 liters of liquid propylene, 150 liters of hydrogen gas as a molecular weight control agent, 300 liters of liquid propylene, and 0.8 kg of ethylene are injected into the autoclave. to produce a copolymer. The obtained propylene/ethylene random copolymer had an MFR of 20 g/10 min and an ethylene content of 4.0% by mass.

(Production example 4)
<Production of propylene/ethylene random copolymer>
In the main polymerization described in Production Example 1, the procedure is the same as in Production Example 1, except that instead of 300 liters of liquid propylene, 60 liters of hydrogen gas as a molecular weight control agent, 300 liters of liquid propylene, and 0.8 kg of ethylene are injected into the autoclave. to produce a copolymer. The obtained propylene/ethylene random copolymer had an MFR of 0.5 g/10 min and an ethylene content of 4.5% by mass.

(Production example 5)
<Production of propylene/ethylene random copolymer>
Using dicyclopentyldimethoxysilane in place of the cyclohexylmethyldimethoxysilane noted in Preparation Example 1, and replacing 300 liters of liquid propylene in the autoclave with 100 liters of hydrogen gas as a molecular weight control agent, 300 liters of liquid propylene and 0.2 liters of ethylene. A copolymer was produced in the same manner as in Production Example 1, except that 6 kg was injected. The obtained propylene/ethylene random copolymer had an MFR of 2.5 g/10 min and an ethylene content of 3.0% by mass.
The physical properties of the propylene homopolymers and propylene/ethylene random copolymers obtained in the above production examples were determined by the following measuring methods. Table 1 shows the results.

・MFR
It was measured according to ASTM D-1238 (measurement temperature 230°C, load 2.16 kg).
• Content of structural units derived from ethylene The content of structural units derived from ethylene contained in the propylene/ethylene random copolymer (ethylene content) was measured by the ¹³ C-NMR method under the following conditions.

( ¹³ C-NMR measurement conditions)
Measurement device: JEOL LA400 type nuclear magnetic resonance device Measurement mode: BCM (Bilevel Complete decoupling)
Observation frequency: 100.4MHz
Observation range: 17006.8Hz
Pulse width: C nucleus 45° (7.8 μs)
Pulse repetition time: 5 seconds Sample tube: 5 mmφ
Sample tube rotation speed: 12Hz
Accumulation times: 20000 times Measurement temperature: 125°C
Solvent: 1,2,4-trichlorobenzene: 0.35 ml/heavy benzene: 0.2 ml
Sample amount: about 40 mg

• Melting point The melting points of the propylene homopolymer and the propylene/ethylene random copolymer were measured by differential scanning calorimetry (DSC).
The measurement was performed using a Diamond DSC manufactured by Perkin Elmer.

The temperature at the maximum peak position in the endothermic curve was obtained by the following method.
The obtained polypropylene-based resin composition was heated at 230° C. using a press molding machine and processed into a sheet. A sample cut out therefrom was placed in an aluminum pan with a flat bottom, heated to 230° C. in a nitrogen atmosphere, and held for 10 minutes. After that, the temperature was lowered from 230° C. to −30° C. at 10° C./min, held for 1 minute, and then raised to 230° C. at 10° C./min. The apex of the endothermic peak during the temperature rise was defined as the melting point, and when there were multiple endothermic peaks, the apex of the maximum endothermic peak was defined as the melting point.

・Mesopentad fraction (mmmm) (noise removal method)
The mesopentad fraction (mmmm) was determined according to the following measurement conditions and calculation method.
1. Measurement conditions Apparatus: AVANCE III cryo-500 type nuclear magnetic resonance apparatus manufactured by Bruker Biospin Measurement nuclei: 13C (125 MHz)
Measurement mode: Single pulse proton broadband decoupling Pulse width: 45° (5.00 microseconds)
Repeat time: 5.5 seconds Accumulation times: 256 times Measurement solvent: o-dichlorobenzene/heavy benzene (80/20% by volume) mixed solvent Sample concentration: 50 mg/0.6 mL
Measurement temperature: 120°C
Chemical shift standard: 21.59 ppm (mesopentad methyl peak
shifts)

2. Calculation method The mesopentad fraction (mmmm, %), which is one of the indicators of the stereoregularity of a polymer and used to examine its microtacticity, is the peak intensity ratio of the C-NMR spectrum obtained under the measurement conditions of 1 above. calculated from

Here, in the case of polypropylene having an unprecedentedly high level of stereoregularity, such as the object to be measured in the present invention, if the rmmr, mmrm, rmrr, rmrm, and mrrr regions are included in the integral value, the integral of "noise" It is considered that there is a problem that the degree of influence on the value increases, and S2 in the general calculation method is overestimated, that is, mmmm (%) is underestimated. Prog. Polym. Sci. 26 (2001), 443-533 also, in the case of polypropylene having a stereoregularity of 95% or more, if certain requirements are satisfied, the integral values of the rmmr, mmrm, rmrr, rmrm, and mrrr regions are , is theoretically reported to be 0.1% or less in total, suggesting that it leads to overestimation of S2 in a general calculation method.

Therefore, in the present invention, it is calculated according to the following (Equation 1). The rmmr, mmrm, rmrr, rmrm, mrrr regions were excluded from the calculations as suggested in Prog. Polym. Sci. 26 (2001), 443-533. Hereinafter, the calculation method in this specification is referred to as the "noise removal method".

mmmm (noise removal method) (%) = S1/S2*100 (Formula 1)
S1 = (peak containing mmmm, mmmr)-(n-propyl end)-(n-butyl end)-mrrm*2
S2 = S1 + mmmr + mmrr + mrrm + rrrr
= S1 + 5 * mrrm + rrrr

In calculating with the above (Equation 1), as an example, assignments were made as follows. The mmmm peak overlaps the mmmr, (n-propyl end) and (n-butyl end) peaks.
Peak including mmmm and mmmr: Peak area from 21.2 to 22.0 ppm mmmr = mrrm * 2
mmrr = mrrm * 2
mrrm: peak area from 19.5 to 19.7 ppm rrrr: peak area from 20.0 to 20.2 ppm n-propyl end: (A1 + A3)/2
A1: peak area of 14.2 ppm A3: peak area of 39.4 ppm n-butyl end: peak area of 36.7 ppm

(Example 1)
90 parts by mass of the propylene homopolymer obtained in Production Example 1 and 10 parts by mass of the propylene/ethylene random copolymer obtained in Production Example 2 were blended, and tetrakis [methylene- 3-(3',5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane 500 ppm, phosphorus antioxidant [tris (2,4-di-t-butylphenyl) phosphite] 1000 ppm calcium stearate was mixed in a 1000 ppm Henschel mixer. After that, the mixture was put into a twin-screw extruder (30 mmφ) and kneaded at a die temperature of 230° C. and a screw rotation speed of 200 rpm to obtain pellets of the polypropylene-based resin composition.

An extruded sheet (original sheet) was formed as follows using the pellets of the polypropylene resin composition.

(raw sheet production)
Using a GM Engineering T-die molding machine, a raw sheet having a thickness of 0.8 mm was produced under conditions of a die temperature of 250° C., a chill roll temperature of 30° C., and a take-up speed of 0.8 m/min.

The following physical properties were evaluated using the obtained pellets and raw sheets of the polypropylene-based resin composition. The results are shown in Table 2.

(Examples 2 and 3)
A resin composition was prepared in the same manner as in Example 1, except that the propylene homopolymer obtained in Production Example 1 and the propylene/ethylene random copolymer obtained in Production Example 2 or 3 were blended in the proportions shown in Table 1. was prepared and an extruded sheet was formed. The physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Comparative example 1)
A resin composition was prepared and an extruded sheet was formed in the same manner as in Example 1, except that 100 parts by mass of the propylene homopolymer obtained in Production Example 1 was used and the propylene/ethylene random copolymer was not used. rice field. The physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Examples 2-4)
A resin composition was prepared in the same manner as in Example 1, except that the propylene homopolymer obtained in Production Example 1 and the propylene/ethylene random copolymer obtained in Production Example 4 or 5 were blended in the proportions shown in Table 1. Preparation of products and molding of extruded sheets were performed. The physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 2.

- Haze The haze was measured according to JIS K7136 using the stretched film produced in the following evaluation of stretching load.

- Shrinkage rate The original sheet was placed in a hot air oven and heated in an atmosphere of 120°C for 15 minutes. The thermal shrinkage ratio was defined as the ratio of the length that shrunk to the size before heating. In addition, the longitudinal stretching direction was MD, and the transverse stretching direction was TD.

-Young's Modulus Based on ISO 178, the Young's modulus (MPa) in the machine direction (MD) and the transverse direction (TD) was measured under the following conditions.
Ambient temperature: 23°C
Test piece: JISK-6781
Tensile speed: 50 mm/min Between chucks: 80 mm

- Stretching load Using the obtained original sheet, a stretched film of 24 to 27 µm was produced under the following conditions with a biaxial stretching machine (KAROIV manufactured by Bruckner).
・Preheating temperature: 145℃
・Stretch ratio: MD/TD = 5 times/8 times (sequential stretching)
・ Stretching speed: 143%/s,
The stretching load was expressed as a measured value of yield point strength (stretching strength) when stretching in the MD direction.

Claims (3)

99.9 to 50 parts by mass of a propylene-based polymer (A) having a melt flow rate (MFR) of 0.5 to 10 g/10 minutes, and a melting point of 100 to 150 ° C. and a melt flow rate (MFR) of 0.1 to 50 parts by mass of propylene/α-olefin copolymer (B) at 10 to 1000 g/10 minutes (provided that the total of propylene polymer (A) and propylene polymer (B) is 100 parts by mass) A polypropylene-based resin composition containing). An extruded sheet obtained from the polypropylene resin composition according to claim 1. A uniaxially or biaxially stretched film obtained from the polypropylene resin composition according to claim 1 .