JP2016191023A - Propylene-based copolymer composition and film composed thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented film which is excellent in mechanical characteristics such as rigidity and transparency, can be heat-sealed at a low temperature and causes less deterioration in heat sealing strength even after heat treatment such as retort sterilization treatment.SOLUTION: There is provided a propylene-based copolymer composition which comprises 45 to 97 mass% of a propylene-ethylene block copolymer (A) or a propylene-α-olefin random copolymer (B) and 3 to 55 mass% of a syndiotactic propylene-based polymer composition (D) [where (A) or (B)+(D)=100 mass%].SELECTED DRAWING: None

Description

  The present invention is excellent in mechanical properties such as transparency and rigidity, and has little decrease in heat seal strength even after heat treatment such as pressurization and heat sterilization, and is suitable for packaging films such as heated and sterilized packages. The present invention relates to a propylene copolymer composition and a film comprising the same.

  Films having heat sealing properties are widely used for packaging applications such as food packaging and fiber packaging. In particular, food packaging applications are affected by social changes such as aging, nuclear families, single appointments, or increased working generations, resulting in diversification of food culture, shortening of cooking time, and demand for convenience. It is often used to purchase so-called retort foods that have undergone retort processing after filling, and to heat the retort foods in a bag of hot water when necessary and take out the contents for serving. It has become to. Such retort foods have begun to spread widely not only for general households but also for business use. For this reason, a packaging material capable of packaging a large amount of foods at once is required.

  Conventionally, for this application, a film having both sealing properties and heat resistance is required, and a polypropylene film or the like is used. However, such a film tends to have a reduced heat seal strength after retorting.

Furthermore, the packaging film for retort food as described above often has a problem of bag tearing during freezing storage or during freezing transportation, and there is a demand for improved pinhole resistance at low temperatures. Has been.
A number of proposals have been made as methods for solving the above-mentioned demand.

  As a method for preventing a decrease in heat seal strength after retorting, for example, a propylene / α-olefin block copolymer composed of 95 to 70% by mass of a polypropylene block and 5 to 30% by mass of an elastomer block is used as a heat seal layer. Has been proposed (Patent Document 1: Japanese Patent Laid-Open No. 2000-255012). Further, in order to improve the heat seal strength, heat resistance, etc. of the retort film, a polypropylene / ethylene block copolymer having an intrinsic viscosity [η] of the paraxylene-soluble part of 1.5 to 2.8 (dl / g). A composition in which 1 to 10% by mass of ethylene / α-olefin copolymer rubber is added to 90 to 99% by mass has been proposed (Patent Document 2: JP 2000-119480 A).

  Also, propylene polymer (A), propylene / α-olefin, which is suitably used for food packaging such as for retort food packaging materials, which are excellent in rigidity and heat seal strength and have a small decrease in heat seal strength after heat treatment A composition comprising a random copolymer component (B) and a random copolymer component (C) of ethylene and an α-olefin having 4 or more carbon atoms (Patent Document 3: Japanese Patent Application Laid-Open No. 2003-96251) is proposed. Has been.

  Furthermore, as a propylene polymer component, a method using a propylene random copolymer having a melting point of 140 to 155 ° C. polymerized by a metallocene catalyst system has been proposed (Patent Document 4: JP 2009-84379 A). Yes.

  However, when these films are used for the heat-sealing layer of the retort film, the thickness must be increased to 60 to 70 μm because of the need for maintaining heat seal strength after retort and bending resistance (pinhole resistance). It is the present condition that we do not get.

  On the other hand, as an example of obtaining a thin film by biaxial stretching, a crystalline polypropylene / ethylene random copolymer component containing 10 mol% or less of units derived from ethylene and 10 to 40 mol% of units derived from ethylene Use of a polypropylene / ethylene random block copolymer containing a low crystalline or amorphous polypropylene / ethylene random copolymer component for a heat seal layer of a biaxially oriented polypropylene film (for example, Patent Document 5: Japanese Patent Laid-Open No. Hei 9- No. 227757 and Patent Document 6: Japanese Patent Laid-Open No. 2005-305767), the biaxially stretched film has a heat seal strength of 440 to 780 g / 15 mm (4.3 to 7.6 N / 15 mm). It is weak and cannot be used as a heat-sealing layer for a retort film.

JP 2000-255012 A JP 2000-119480 A JP 2003-96251 A JP 2009-84379 A JP-A-9-227757 JP 2005-305767 A

  The present invention is a propylene-based copolymer that is excellent in mechanical properties such as rigidity and transparency, can be heat-sealed at low temperatures, and is suitable for obtaining a film with little decrease in heat-seal strength even after heat treatment such as retort sterilization. The object is to obtain a polymer composition and a film comprising it, preferably a biaxially stretched film.

  In the present invention, the propylene / ethylene block copolymer (A) or the propylene / α-olefin random copolymer (B) is 45 to 97% by mass, and the syndiotactic propylene polymer composition (D) is 3 to 3. Including 55% by mass [provided that (A) or (B) + (D) = 100% by mass. A propylene-based copolymer composition, a film or a biaxially stretched film comprising the composition, a multilayer film or a multilayer biaxially stretched film comprising the composition, and a use thereof.

  The film comprising the propylene-based copolymer composition of the present invention is excellent in mechanical properties such as transparency and rigidity, excellent in low temperature heat sealability, high in heat fusion strength, and heat treatment (pressurization / heat treatment). There is little decrease in the heat seal strength afterwards.

FIG. 1 shows a DSC curve of the syndiotactic propylene polymer composition (D-1) used in the examples of the present invention [first heating process (1st-run: 1st), first cooling process (cool)]. And a second temperature raising process (2nd-run: 2nd)]. FIG. 2 shows a DSC curve of the isotactic propylene-based polymer composition (H-1) used in the comparative example of the present invention [first heating process (1st-run: 1st), first cooling process (cool)]. And a second temperature raising process (2nd-run: 2nd)]. FIG. 3 shows a DSC curve of the isotactic propylene-based polymer composition (H-2) used in the comparative example of the present invention [first heating process (1st-run: 1st), first cooling process (cool)]. And a second temperature raising process (2nd-run: 2nd)].

<Propylene block copolymer (A)>
The propylene block copolymer (A), which is one of the polymer components contained in the propylene-based copolymer composition (G) of the present invention, is a propylene polymer component (a-1) and a propylene / α-olefin. It is a polymer composed of a random copolymer component (a-2).

  When the composition ratio of (a-1) and (a-2) in the propylene block copolymer (A) according to the present invention is expressed by mass ratio (a-1) / (a-2), 80 / 20-95 / 5 is preferable, More preferably, it exists in the range of 83 / 17-90 / 10.

  The propylene / α-olefin random copolymer component (a-2) constituting the propylene / block copolymer (A) according to the present invention is preferably a propylene / ethylene random copolymer, preferably an ethylene unit. The content of is preferably in the range of 10 to 20 mass%, more preferably 12 to 18 mass%.

  The propylene block copolymer (A) according to the present invention has a melt flow rate (MFR) of a propylene copolymer composition (D) and a syndiotactic propylene polymer composition (D) described later ( G) is not particularly limited as long as it has film-forming ability, but a value measured under a load of 230 ° C. and 2.16 kg in accordance with ASTM D-1238 is usually 2 to 10 (g / 10 minutes), preferably Is in the range of 2.5-8 (g / 10 min).

<Propylene polymer component (a-1)>
The propylene polymer (a-1), which is one of the components constituting the propylene block copolymer (A) according to the present invention, is a propylene homopolymer or 10% by mass or less, preferably 5% by mass with propylene. % Or less α-olefin copolymer. The α-olefin is an α-olefin having 2 to 10 carbon atoms other than propylene, such as ethylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4 -Methyl-1-pentene, 1-hexene, 1-octene can be mentioned. Among these polymers, a propylene homopolymer is preferably used because a film having excellent heat resistance can be obtained.

The propylene polymer (a-1) according to the present invention is usually a polymer having an isotactic structure and has a melting point (Tm1) in the range of 120 to 170 ° C.
The propylene polymer (a-1) according to the present invention can be produced using an olefin polymerization catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. As an example of a Ziegler-Natta catalyst, an active magnesium compound, a titanium compound, a halogen compound, and a solid titanium catalyst component having an internal electron donor as essential components are supported on an organic or inorganic carrier, and the periodic table groups I to 1 are included therein. Examples include a catalyst system in which an organometallic compound component of a Group III metal is added and an external electron donor is further added.

<Propylene / α-olefin random copolymer component (a-2)>
The propylene / α-olefin random copolymer component (a-2), which is one of the components constituting the propylene block copolymer (A) according to the present invention, has a carbon number other than propylene and the same polypropylene as described above. It is a copolymer with 2 to 10 α-olefin and has elastomeric properties. As the α-olefin, ethylene is particularly preferable.

  The propylene / α-olefin random copolymer component (a-2) according to the present invention usually has a propylene unit content of 70 to 85% by mass, preferably 75 to 83% by mass, and an α-olefin unit. Is in the range of 15 to 30% by mass, preferably 17 to 25% by mass (provided that the total of units derived from propylene and units derived from α-olefin is 100% by mass). When the content of the propylene unit is in the above range, the film made of the propylene-based copolymer composition (G) containing the copolymer component (a-2) has a low temperature impact resistance and a low temperature heat sealability. An excellent film that retains high sealing strength even after heat treatment can be obtained. In addition, content of a propylene unit can be measured by infrared absorption spectrum analysis.

  The propylene / α-olefin random copolymer component (a-2) according to the present invention is usually an amorphous or low-crystalline copolymer, and usually has no melting point or DSC (10 ° C. / Min) in the first temperature raising step and endothermic peak at 67 ± 3 ° C., and in the second temperature raising step, the copolymer does not have an endothermic peak at 67 ± 3 ° C.

The proportion of the copolymer (a-2) in the propylene block copolymer (A) is such that the copolymer (A) sample (a: gram) is completely dissolved in p-xylene, and then 23 After leaving at 24 ° C. for 24 hours, the precipitate (b: gram) is separated by centrifugation, and the p-xylene soluble part in the sample is calculated as the copolymer (a-2) by the following formula. it can.
Ratio of copolymer (a-2) = {(ab) / a} × 100 (mass%)

  The intrinsic viscosity [η] of the copolymer (a-2) is 2.0 to 10.0 dl / g, preferably 2.3 to 8.0 dl, when the intrinsic viscosity [η] measured at 135 ° C. is a decalin solvent. / G, more preferably 2.5 to 5.0 dl / g, even more preferably 2 to less than 3.5 (dl / g), and most preferably 2.5 to 3.3 (dl / g). When the intrinsic viscosity [η] is in the above range, the composition containing it has a good drop bag breaking strength at a low temperature after the retort treatment, and further prevents the occurrence of fish eyes and is resistant to blocking. A film excellent in properties or a biaxially stretched film can be produced.

  The intrinsic viscosity [η] is determined by adding excess acetone to the p-xylene-soluble part separated by the above fractionation operation to precipitate a dissolved product, and measuring the recovered precipitate in a decalin solvent at 135 ° C. Can be sought.

  The propylene / α-olefin random copolymer component (a-2) according to the present invention can be produced using an olefin polymerization catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. As an example of a Ziegler-Natta catalyst, an active magnesium compound, a titanium compound, a halogen compound, and a solid titanium catalyst component having an internal electron donor as essential components are supported on an organic or inorganic carrier, and the periodic table groups I to 1 are included therein. Examples include a catalyst system in which an organometallic compound component of a Group III metal is added and an external electron donor is further added.

<Ethylene / α-olefin random copolymer (C)>
The propylene-based copolymer composition (G) or the propylene / block copolymer (A) according to the present invention comprises the propylene-based polymer (a-1) and the propylene / α-olefin random copolymer component (a -2) In addition to the ethylene / α-olefin random copolymer (C), it is preferable from the viewpoint that a film or a biaxially stretched film excellent in low-temperature impact strength and drop impact strength can be obtained. .

  The ethylene / α-olefin random copolymer (C) according to the present invention is a random copolymer of ethylene and an α-olefin having 4 or more carbon atoms, preferably 4 to 10 carbon atoms. Specific examples of α-olefins include 1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-tetradecene and 1-octadecene. Can do. Among these, 1-butene, 1-hexene, and 1-octene are particularly preferable. These α-olefins may be contained alone or in combination of two or more. Further, it may be a mixture of different ethylene / α-olefin random copolymers.

  Preferable specific examples of the ethylene / α-olefin random copolymer (C) according to the present invention include an ethylene / 1-butene random copolymer, an ethylene / 1-hexene random copolymer, and an ethylene / 1-octene random copolymer. A polymer can be mentioned.

The ethylene / α-olefin random copolymer (C) according to the present invention preferably has a density of 865 to 910 kg / m ³ , preferably 875 to 900 kg / m ³ .
The density of the ethylene / α-olefin random copolymer (C) according to the present invention is measured using a press molding machine at Shinto Metal Industries, with a heating temperature of 190 ° C., a heating time of 2 minutes, and a heating pressure of 100 kg / cm ³ . A press sheet having a thickness of 0.5 mm formed by press molding is used as a measurement sample, and is obtained by measurement with a density gradient tube.

  The ethylene / α-olefin random copolymer (C) according to the present invention usually has an ethylene unit content of preferably 70 to 95 mol%, more preferably 80 to 93 mol%, and an α-olefin unit content. The amount is preferably in the range of 5 to 30 mol%, more preferably 7 to 20 mol% (provided that the total of units derived from ethylene and units derived from α-olefin is 100 mol%). .

  The ethylene / α-olefin random copolymer (C) according to the present invention usually has an MFR (load: 2160 g, temperature: 230 ° C.) of 0.5 to 10 g / 10 min, preferably 0.5 to 7. 0 g / 10 min.

  In the ethylene / α-olefin random copolymer (C) according to the present invention, the melting point is usually 100 ° C. or lower or does not exist, and when the melting point is present, the upper limit is preferably 90 ° C. Although there is no particular limitation, for example, 40 ° C., further 60 ° C. can be exemplified.

  The ethylene / α-olefin random copolymer (C) according to the present invention can be produced using an olefin polymerization catalyst such as a Ziegler-Natta catalyst (vanadium catalyst, etc.) or a metallocene catalyst.

  When the propylene block copolymer (A) according to the present invention contains an ethylene / α-olefin random copolymer (C), the propylene polymer component (a-1) and the propylene / α-olefin random copolymer 5 to 30% by mass, preferably 10 to 25% by mass, more preferably 12 to 20% by mass with respect to the total amount with the polymer component (a-2) (however, ethylene / α-olefin random) Copolymer (C) + propylene polymer component (a-1) + propylene / α-olefin random copolymer component (a-2) = 100 mass%).

<Producing method of propylene block copolymer (A)>
The propylene block copolymer (A) according to the present invention can be produced by various known production methods, specifically, for example, (a-1) and (a-2) by multistage polymerization. The multistage polymerization may be performed in one polymerization vessel, or each step may be performed using a plurality of polymerization vessels. The plurality of polymerization vessels may be used in parallel or in series.
The propylene block copolymer (A) according to the present invention may be produced by a method of melt-mixing according to a conventional method after producing the above (a-1) and (a-2).

  When the propylene block copolymer (A) according to the present invention contains an ethylene / α-olefin random copolymer (C), (a-1) and (a-2) were produced by multistage polymerization. Thereafter, a method of melt-mixing the ethylene / α-olefin random copolymer (C), or the propylene polymer (a-1) and the propylene / α-olefin random copolymer component (a -2) and an ethylene / α-olefin random copolymer (C) can be melt-mixed.

<Propylene / α-olefin random copolymer (B)>
The propylene-based copolymer composition (G) of the present invention may contain a propylene / α-olefin random copolymer (B) instead of the propylene / block copolymer (A).

  The propylene / α-olefin random copolymer (B) according to the present invention is usually a propylene / α-olefin random copolymer containing 90 to 98% by mass, preferably 92 to 98% by mass of units derived from propylene. is there.

  The α-olefin which is a copolymer component constituting the propylene / α-olefin random copolymer (B) according to the present invention is usually an α-olefin having 2 to 10 carbon atoms other than propylene, for example, Ethylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, ethylene and 1-butene Is preferable, and ethylene is particularly preferable.

  The propylene / α-olefin random copolymer (B) according to the present invention usually has an MFR (load: 2160 g, temperature: 230 ° C.) of 0.5 to 50 g / 10 minutes, preferably 2 to 50 g / 10 minutes. is there. When the MFR is in the above range, the resulting propylene polymer composition (G) can be easily formed into a film, and a film or a biaxially stretched film excellent in low-temperature impact strength can be obtained. For example, a material having an MFR in the range of 20 to 50 g / 10 minutes, particularly 20 to 40 g / 10 minutes may be used.

  The propylene / α-olefin random copolymer (B) according to the present invention is usually a polymer having an isotactic structure, and has a melting point (Tm2) of 105 to 150 ° C., preferably 120 to 150 ° C. Preferably it exists in the range of 130-147 degreeC. When the melting point is in the above range, a film or a biaxially stretched film having an excellent balance of heat seal strength, rigidity and bag drop impact strength can be obtained.

  The propylene / α-olefin random copolymer (B) according to the present invention can be produced using an olefin polymerization catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. As an example of a Ziegler-Natta catalyst, an active magnesium compound, a titanium compound, a halogen compound, and a solid titanium catalyst component having an internal electron donor as essential components are supported on an organic or inorganic carrier, and the periodic table groups I to 1 are included therein. Examples include a catalyst system in which an organometallic compound component of a Group III metal is added and an external electron donor is further added.

  The propylene / α-olefin random copolymer (B) according to the present invention is produced and sold as a random PP. For example, random PP: grade names PC630A, 5C37F, etc. From the company, random PP: trade name prime polypro grade name F327, F337 and the like can be mentioned.

<Syndiotactic propylene polymer composition (D)>
The syndiotactic propylene polymer composition (D), which is one of the polymer components contained in the propylene copolymer composition (G) of the present invention, is a propylene / α-olefin copolymer component (d- 1) and a syndiotactic propylene polymer component (d-2).

  Since the syndiotactic propylene-based polymer composition (D) according to the present invention contains the syndiotactic propylene-based polymer component (d-2), it has a feature that the crystallization rate is slow.

  For example, when the thermal melting property of the syndiotactic propylene polymer composition (D) is measured by DSC, the temperature is increased to 250 ° C. at a temperature increase rate of 10 ° C./min in the first temperature increase process (1st-run). When the syndiotactic propylene polymer composition (D) is melted and then cooled down to −50 ° C. at a temperature lowering rate of 10 ° C./min in the first temperature lowering process (cool), The polymer component (d-2) has a crystallization peak of 50 ± 3 ° C. when the temperature is raised to 250 ° C. at a temperature rising rate of 10 ° C./min in the second temperature raising step (2nd-run). After the syndiotactic propylene polymer component (d-2) crystallizes (exothermic peak), the syndiotactic propylene polymer component (d-2) melts (endothermic peak) at 155 ± 3 ° C. On the other hand, when the temperature is lowered to -50 ° C. at a rate of 1 ° C./min in the first temperature lowering process, the syndiotactic propylene polymer component (d-2) is crystallized at 70 ° C. ± 3 ° C. When the temperature was raised to 250 ° C. at 1 ° C./min again, the syndiotactic propylene polymer component (d-2) was not crystallized at 160 ° C. ± 3 ° C. Only the syndiotactic propylene polymer component (d-2) melts (endothermic peak).

  The syndiotactic propylene-based polymer composition (D) according to the present invention is prepared by using DSC in accordance with JIS K 7121 and K 7122, about 5 mg of a sample at a temperature rising rate of 10 ° C./min in the first temperature rising process. The heat of crystal fusion based on the syndiotactic propylene polymer component (d-2) determined from the DSC curve (1st-run) obtained by raising the temperature from room temperature to 250 ° C. is usually 8.0 to 15.0 J / g. In the range of 9.0 to 14.0 J / g, more preferably in the range of 10.0 to 13.0 J / g, and the crystal melting peak temperature in the range of 150 to 160 ° C., preferably 153 It is in the range of ~ 159 ° C. The heat of crystal fusion based on the propylene / α-olefin copolymer component (d-1) contained in the syndiotactic propylene polymer composition (D) is usually in the range of 2.0 to 12.0 J / g, Preferably, it is in the range of 2.5 to 11.0 J / g, and the crystal melting peak temperature is in the range of 45 to 55 ° C, preferably in the range of 47 to 53 ° C.

  The syndiotactic propylene polymer composition (D) according to the present invention is a DSC curve obtained by raising the temperature to 250 ° C. and then lowering the temperature to -50 ° C. at a temperature lowering rate of 10 ° C./min in the first temperature reduction process. No exothermic peak is observed in (cool), and the syndiotactic propylene polymer component (d-2) and the propylene / α-olefin copolymer component (d-1) are not crystallized in the first temperature-decreasing process. Think of it as something.

The syndiotactic propylene-based polymer composition (D) according to the present invention is cooled to −50 ° C. at the temperature rising rate of 10 ° C./min. The DSC curve (2nd-run) obtained by raising the temperature to ˜250 ° C. shows crystals of the syndiotactic propylene polymer component (d-2) that did not crystallize during the temperature reduction in the first temperature reduction process. The calorific value based on chemical conversion is usually in the range of 7.0 to 13.0 J / g, preferably in the range of 8.0 to 12.0 J / g, more preferably in the range of 9.0 to 11.0 J / g. is there. Crystallized syndiotactic propylene polymer component (d-2) having a crystallization peak temperature in the range of usually 45 to 55 ° C, preferably in the range of 47 to 53 ° C, more preferably in the range of 49 to 52 ° C. The amount of heat of crystal melting based on is usually in the range of 8.0-18.0 J / g, preferably in the range of 10.0-16.0 J / g, more preferably in the range of 12.0-14.0 J / g, The crystal melting peak temperature is in the range of 150 to 160 ° C, preferably 152 to 157 ° C, more preferably 153 to 155. In the DSC curve (2nd-run), the crystallization peak based on the propylene / α-olefin copolymer component (d-1) contained in the syndiotactic propylene polymer composition (D) is also melted. No peak is observed.

  In DSC (differential scanning calorimetry) based on JISK7122, in the range of 40-60 ° C in the second temperature raising step (10 ° C / min), the peak of crystallization heat is 20 J / g or less and in the range of 135-155 ° C, The heat of crystal fusion has a peak of 20 J / g or less. In this specification, DSC is measured according to JISK7122.

  As a composition similar to the syndiotactic propylene polymer composition (D) according to the present invention, an isotactic propylene polymer component (h-2) and a propylene / α-olefin copolymer component (h -1) is an isotactic propylene polymer composition (H), and the isotactic propylene polymer composition (H) is a syndiotactic propylene polymer composition (D) according to the present invention. Even if it is used instead of), the heat seal strength is not improved to the left.

  The isotactic propylene polymer composition (H) has a propylene / α-olefin copolymer component (h-1) in the DSC curve (1st-run) when the DSC curve is measured by the method described above. ) Based on the isotactic propylene polymer component (h-2) is 9.0 to 18 and the crystal melting heat based on the isotactic propylene polymer component (h-2) is 4 to 13 J / g. In the range of 0.0 J / g, the crystal melting peak is in the range of 160 to 162 ° C. In the DSC curve (cool) obtained by lowering the temperature, the amount of crystallization based on the isotactic propylene polymer component (h-2) is in the range of 11 to 17 J / g, and the crystallization peak is 76 to 90 ° C. It is in the range. In the DSC curve (2nd-run), the heat of crystal melting based on the isotactic propylene polymer component (h-2) is in the range of 10 to 17 J / g, and the crystal melting peak temperature is 161 to 163 ° C. It is in the range of the range.

The isotactic propylene polymer composition (H) according to the present invention is manufactured and sold by Mitsui Chemicals, Inc. under trade names such as Notio ^™ PN2060 and PN3560.

  The α-olefin constituting the propylene / α-olefin copolymer component (d-1), which is a component contained in the syndiotactic propylene polymer composition (D) according to the present invention, usually excludes propylene, 2-20 carbon atoms, preferably 2-10 carbon atoms, more preferably 2-6 carbon atoms, specifically, for example, ethylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3- Examples thereof include methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, and the like. Α-olefin is one type or two or more types.

  Specific examples of the propylene / α-olefin copolymer component (d-1) include, for example, propylene / ethylene copolymer, propylene / ethylene / 1-butene copolymer, propylene / 1-butene copolymer, and the like. Among them, a propylene / ethylene / 1-butene copolymer is preferable.

The syndiotactic propylene polymer composition (D) according to the present invention usually has an MFR (JIS K6721, 230 ° C., 2.16 kg load) of 0.01 to 200 g / 10 minutes, preferably 0.05 to 150 g. / 10 minutes, more preferably 0.05 to 100 g / 10 minutes.
The syndiotactic propylene-based polymer composition (D) according to the present invention is manufactured and sold by Mitsui Chemicals, Inc. under the trade name Notio ^™ SN0285, for example.

<Propylene-based copolymer composition (G)>
The propylene-based copolymer composition (G) of the present invention comprises the propylene / block copolymer (A) or the propylene / α-olefin random copolymer (B) in an amount of 45 to 97% by mass, preferably 50 to 92% by mass, more preferably 55-90% by mass and the syndiotactic propylene polymer composition (D) in an amount of 3-55% by mass, preferably 8-50% by mass, more preferably 10-45 [ However, (A) + (D) or (B) + (D) = 100 mass%. It is a composition containing.

  A composition having a syndiotactic propylene copolymer composition (D) content of less than 3% by mass does not improve the low-temperature heat seal strength of the resulting film or biaxially stretched film, and the film is heat treated. After the heat treatment, the heat seal strength is greatly reduced. On the other hand, a composition in which the content of the syndiotactic propylene-based polymer (D) exceeds 55% by mass may lower the moldability of the resulting film or biaxially stretched film.

  As the propylene-based copolymer composition (G) of the present invention, the composition containing the propylene block copolymer (A) is superior in pinhole resistance of the resulting film, and the film or biaxial There is less reduction in heat seal strength after heat treating the stretched film.

<Additives>
In the propylene-based copolymer composition (G) of the present invention, the propylene block copolymer (A) or the propylene / α-olefin random copolymer (B), and the syndiotactic are optionally included. In addition to tick propylene polymer composition (D), propylene / α-olefin random copolymer component (a-2), ethylene / α-olefin random copolymer (C), and syndiotactic propylene polymer An elastomer component other than the composition (D) can be added. Examples of such elastomer components include ethylene / propylene / diene copolymer rubber, ethylene / 1-butene / diene copolymer rubber, propylene / 1-butene copolymer rubber, styrene / butadiene block copolymer or styrene / isoprene block. Mention may be made of hydrogenated products of copolymers.

  Moreover, in the polymer which comprises the propylene-type copolymer composition (G) of this invention, or the propylene-type copolymer composition (G) of this invention, in the range which does not impair the objective of this invention, Antioxidants, heat stabilizers, lubricants, antistatic agents, hydrochloric acid absorbents, antiblocking agents, slip agents, nucleating agents, pigments, dyes, or various polymers may be blended.

  Examples of the antioxidant include a phenolic antioxidant, an organic phosphite antioxidant, a thioether antioxidant, a hindered amine antioxidant, and the like. Examples of the antiblocking agent include aluminum oxide, fine powder silica, polymethyl methacrylate powder, and silicon resin.

  Examples of the slip agent include bisamides such as ethylene bisstearamide, higher fatty acid amides such as oleic acid amide and erucic acid amide. Examples of the lubricant include higher fatty acid metal salts such as calcium stearate, zinc stearate, and metal montanate, and polyolefin waxes such as polyethylene wax and polypropylene wax. Examples of the nucleating agent include rosin nucleating agents such as dibenzylidene sorbitol and partial metal salts of rosin acid, aluminum nucleating agents, and talc.

  The propylene-based copolymer composition (G) of the present invention can be used by being molded by various known molding methods, by various molding methods such as a film, a biaxially stretched film, a sheet, a hollow body, and melt molding. .

<Film>
The film of the present invention is a film comprising the propylene-based copolymer composition (G), and is produced by various known film forming methods, specifically, a T-die cast film forming method and an inflation film forming method. obtain.

  The film of the present invention is usually not stretched and has a thickness of 5 μm or more, preferably 5 to 55 μm, more preferably 10 to 50 μm. A film having a thickness of less than 5 μm may be a packaging material having insufficient bag drop strength when used for a heat-sealing layer.

The upper limit of the thickness of the film of the present invention is not particularly limited, but a film exceeding 50 μm may maintain its heat sealing performance and bag breaking strength performance, and the cost advantage of being thin may be reduced. is there.
The film of the present invention can be a film having a thickness of 50 to 100 μm depending on the application.

<Biaxially stretched film>
The biaxially stretched film of the present invention is a film formed by biaxially stretching the above film, and the mechanical properties are further improved by biaxially stretching.

  The biaxially stretched film of the present invention usually has a thickness of 5 μm or more, preferably 5 to 55 μm, more preferably 10 to 50 μm. A film having a thickness of less than 5 μm may be a packaging material having insufficient bag drop strength when used for a heat-sealing layer.

  The upper limit of the thickness of the biaxially stretched film of the present invention is not particularly limited, but a film exceeding 50 μm has the cost advantage of maintaining its heat seal performance and bag breaking strength performance and being thin. May fade.

The biaxially stretched film of the present invention can be a film having a thickness of 50 to 100 μm depending on the use.
The film of the present invention and the biaxially stretched film (hereinafter sometimes collectively referred to as “biaxially stretched film etc.”) are monolayers as long as they are composed of the propylene-based copolymer composition (G). Alternatively, it may be a multilayer of two or more layers. For example, when the biaxially stretched film or the like has a three-layer structure, the thickness of the inner layer is usually 50 to 99 percent of the total thickness, and the thickness of both surface layers is 0.5 to 25 percent of the total, respectively. Of thickness. The thickness of the surface layer is preferably 0.5 to 15 μm, particularly 1 to 10 μm. As described above, when the biaxially stretched film or the like is a multilayer, quality control is easy, the final yield is increased, and there is a merit in cost.
Further, the surface of the biaxially stretched film or the like of the present invention may be subjected to surface treatment such as corona treatment or flame treatment on one side or both sides as necessary in order to improve the adhesion to the base material layer.

  The biaxially stretched film of the present invention has transparency, rigidity and other mechanical strength, low temperature heat sealability, heat fusion strength (heat seal strength), and heat seal strength retention after heat treatment (pressurization / heat treatment). The balance between the physical properties such as, and the bag breaking strength at a low temperature after heat treatment when it is made into a bag is excellent. Further, it tends to be excellent in blocking resistance. Furthermore, the biaxially stretched film of the present invention has a small thermal shrinkage rate, that is, excellent dimensional stability during heating.

<Method for producing biaxially stretched film>
The biaxially stretched film of the present invention can be molded from the propylene-based copolymer composition (G) using a known biaxially stretched film molding method.

For biaxial stretching, methods such as sequential biaxial stretching, simultaneous biaxial stretching, and multistage stretching are appropriately employed.
As conditions for biaxial stretching, known biaxially stretched film production conditions, for example, in the sequential biaxial stretching method, the longitudinal stretching temperature ranges from 100 ° C. to 145 ° C., the stretching ratio ranges from 4 to 7 times, and the transverse stretching temperature. Of 150 to 190 ° C. and a draw ratio of 8 to 11 times.

<Multilayer film / Multilayer biaxially stretched film>
The multilayer film and multilayer biaxially stretched film of the present invention (hereinafter sometimes referred to as “multilayer biaxially stretched film”) are formed by laminating a base material layer on one side of the film or the biaxially stretched film. It is a film.

  The substrate layer is not particularly limited as long as it can be used as a packaging material in the form of a sheet, film, tray or container. Examples of the base material layer include polyethylene terephthalate, a film made of polyester represented by polyethylene naphthalate, a polycarbonate film, a polyamide film made of nylon 6, nylon 66, etc., an ethylene / vinyl alcohol copolymer film, a polyvinyl alcohol film, a poly Thermoplastic resin films such as vinyl chloride films, polyvinylidene chloride films, and films made of polyolefins such as polypropylene, or sheets made of these thermoplastic resins, as well as trays or cup-shaped containers thermoformed from sheets, aluminum foil, Examples of those shapes are paper.

  The base material layer made of a thermoplastic resin film may be an unstretched film or a uniaxially or biaxially stretched film. Of course, the base material layer may be one layer or two or more layers. The thermoplastic resin film may be a film in which a metal such as aluminum, zinc or silica, an inorganic material, or an oxide thereof is deposited.

  As a method of laminating the biaxially stretched film or the like of the present invention and the base material layer, a generally performed laminating method can be employed as it is, and in that case, between the biaxially stretched film or the like and the base material layer. An adhesive layer can be provided. For example, a urethane-based or isocyanate-based anchor coating agent is applied to the base material layer, and the biaxially stretched film of the present invention is dry laminated thereon, or the thermoplastic that becomes the base material layer on the biaxially stretched film, etc. The resin can also be produced by extrusion lamination or extrusion coating.

  Moreover, the multilayer biaxially stretched film of the present invention is remarkably excellent in drop bag breaking strength at low temperatures after heat treatment. In other words, the multilayer biaxially stretched film of the present invention retains the heat seal strength of the film layer (peel strength of the heat seal portion) and the heat seal strength after heat treatment (pressurization / heat treatment) when used as a packaging material. The balance between the physical properties such as mechanical properties and rigidity, and the strength of dropped bags at low temperatures after heat treatment when formed into a bag is excellent. Further, it tends to be excellent in blocking resistance.

  The multilayer biaxially stretched film and the like of the present invention has mechanical strength such as heat resistance, high heat seal strength, and rigidity by using the biaxially stretched film or the like for a heat-sealing layer (heat seal layer). Depending on the type of the base material layer, high gas barrier properties, mechanical strength, and the like are imparted, and therefore it is suitable as a medicine for heat sterilization or pressure / heat sterilization, or as a film for packaging retort food. The multilayer biaxially stretched film of the present invention can be used as a packaging material in a film state, or can be used as a packaging material after changing to the shape of a tray or a container.

<Packaging for heat sterilization>
The package for heat sterilization according to the present invention uses a packaging material made of the biaxially stretched film or the like of the present invention or a multilayer biaxially stretched film. The contents are sealed and packaged by packaging (filling) the contents, such as medicines or foods (materials to be wrapped), and heat-sealing layers such as biaxially stretched films.

  The packaging material may be a biaxially stretched film or the like, but is preferable because the above-described multilayer biaxially stretched film or the like can utilize the characteristics of the base material layer. Moreover, when using as a package for heat sterilization, the said base material layer is normally laminated | stacked on single side | surfaces, such as a biaxially stretched film. Examples of the multilayer biaxially stretched film include the following combinations.

  Polyester layer / biaxially stretched film, etc., polyamide layer / biaxially stretched film, etc., polyester layer / polyamide layer / biaxially stretched film, etc., polyester layer / aluminum foil / biaxially stretched film, etc., polyester layer / polyamide layer / aluminum foil Examples thereof include: / biaxially stretched film, polyamide layer / polyvinylidene chloride layer / polyester layer / biaxially stretched film, and the like.

  Since the layers such as the biaxially stretched film are arranged in the innermost layer in this way to form the heat seal part, the package is firmly heat sealed, and heat sterilization, pressure / heat sterilization treatment Even later, the drop bag breaking strength at low temperatures is excellent, and high heat seal strength is maintained. Therefore, such a package for heat sterilization is less likely to cause leakage of food contents, for example, when transported at low temperatures or handled in stores or at home, etc., and at room temperature or under refrigeration / freezing. Even if it is stored for a long period of time, the contents can be kept almost unchanged.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.
The polypropylene used in the examples of the present invention and comparative examples is shown below.
(1) Propylene block copolymer (A-1)
86% by mass of propylene homopolymer component (a-1-1) and 14% by weight of propylene / ethylene random copolymer component (a-2-1) (ethylene content 26.6 mol%, intrinsic viscosity [η] 3 0.1 dl / g) of propylene block polymer (A-1-1) 86% by mass and ethylene / α-olefin random copolymer (D-1) 14% by mass (melting point: 68 ° C., density 885 kg / m) ³ , a composition obtained by melt-kneading MFR 0.5 g / 10 min (JIS K7210, temperature 190 ° C.) (melting point 164 ° C., MFR 2.5 g / min (JIS K 7210 temperature 230 ° C.))
(2) Propylene block copolymer (A-1-1)
86% by mass of propylene homopolymer component (a-1-1) and 14% by weight of propylene / ethylene random copolymer component (a-2-1) (ethylene content 26.6 mol%, intrinsic viscosity [η] 3 0.1 dl / g) propylene block polymer (A-1-1) (melting point: 164 ° C., MFR: 3 g / 10 min (JIS K7210 temperature: 230 ° C.))
(3) Propylene / ethylene random copolymer (B-1) having an ethylene content of 4% by mass
Melting point: 143.5 ° C., MFR (230 ° C., 2.16 kg); 7.5 g / min (manufactured by Sun Aroma Co., Ltd., grade PC630A)
(3) Propylene homopolymer (F-1)
Melting point: 165 ° C., MFR: 3/10 min, trade name: Prime Polypro F113A manufactured by Prime Polymer Co., Ltd.
(4) Syndiotactic propylene polymer composition (D-1)
MFR: 1.4 g / 10 min, heat of crystal fusion based on propylene / α-olefin copolymer component (d-1-1) measured by DSC curve (1st-run) measured by the above method: 7.5 J / g, Crystal melting peak temperature: 52.4 ° C., Crystal melting heat amount based on syndiotactic propylene polymer component (d-2-1): 8.7 J / g, Crystal melting peak temperature: 155 ° C. The resulting DSC curve (cool) does not contain the syndiotactic propylene polymer component (d-2-1) and the propylene / α-olefin copolymer component (d-1-1). Crystallization peak temperature based on syndiotactic propylene polymer component (d-2-1) measured by DSC curve (2nd-run): 50.6 ° C., crystallization heat quantity: 10.3 J / g, crystal melting peak Temperature: 155 ° C., heat of crystal melting: 13.3 J / g, MFR: 1.4 g / 10 minutes, trade name Notio ^™ SN0285, manufactured by Mitsui Chemicals, Inc.
The DSC curve is shown in FIG.

(5) Isotactic propylene polymer composition (H)
(5-1) Isotactic propylene polymer composition (H-1)
MFR: 6 g / 10 min, heat of crystal fusion based on propylene / α-olefin copolymer component (h-1-1) measured by DSC curve (1st-run) measured by the above method: 12.5 J / g, Crystal melting peak temperature: 50.6 ° C., heat of crystal melting based on isotactic propylene polymer component (h-2-1): 9.8 J / g, crystal melting peak temperature: 161 ° C. Heat of crystallization based on isotactic propylene polymer component (h-2-1) measured by DSC curve: 11.5 J / g, crystallization peak temperature: 77.0 ° C., DSC curve (2nd-run) Crystal melting peak temperature based on measured isotactic propylene polymer component (h-2-1): 162 ° C., heat of crystal melting: 10.6 J / g, propylene / α-olefin copolymerization No crystal melting peak based on body component (h-1-1), trade name Notio ^™ PN2060 manufactured by Mitsui Chemicals.
The DSC curve is shown in FIG.

(5-2) Isotactic propylene polymer composition (H-2)
MFR: 6 g / 10 min, heat of crystal fusion based on propylene / α-olefin copolymer component (h-1-2) measured by DSC curve (1st-run) measured by the above method: 4.4 J / g, Crystal melting peak temperature: 44.2 ° C., heat of crystal melting based on isotactic propylene polymer component (h-2-2): 17.1 J / g, crystal melting peak temperature: 161 ° C. Heat of crystallization based on isotactic propylene polymer component (h-2-2) measured by DSC curve: 16.4 J / g, crystallization peak temperature: 89.8 ° C., DSC curve (2nd-run) Crystal melting peak temperature based on measured isotactic propylene-based polymer component (h-2-2): 162.0 ° C., heat of crystal melting: 16.5 J / g, both propylene / α-olefin No crystal melting peak based on polymer component (h-1-2), MFR: 6 g / 10 min, trade name Notio ^™ PN3560 manufactured by Mitsui Chemicals, Inc.
The DSC curve is shown in FIG.
The physical properties of the biaxially stretched film and the multilayer biaxially stretched film in the present invention were measured by the following methods.

(1) Biaxially stretched film physical property measuring method (1-1) Haze The haze (HZ) of a biaxially stretched film was measured using the Nippon Denshoku Industries Co., Ltd. haze meter 300A.

(1-2) Tensile test A strip test piece (length: 50 or 150 mm, width: 15 mm) is taken from the biaxially stretched film in the flow direction (MD) and the width direction (TD), respectively, and a tensile tester. Using a Tensilon universal testing machine RTC-1225 (Orientec Co., Ltd.), a tensile test was performed with a chuck distance of 100 mm and a crosshead speed of 300 mm / min (however, Young's modulus was measured at 5 mm / min). Tensile strength (MPa) and Young's modulus (MPa) were determined.

(1-3) Thermal Shrinkage A test piece having a width of 100 mm and a length of 100 mm was cut out so that the length direction of the biaxially stretched film was the film flow direction (MD) and the width direction (TD), and this was cut at 120 ° C. The sample was allowed to stand in the oven for 15 minutes and then taken out and allowed to cool to room temperature, the dimensional change of the test piece was measured, and the thermal shrinkage was measured.

(1-4) Bending resistance Using a tester industry gelboflex tester, a test piece having a width of 210 mm and a length of 297 mm was cut out from a biaxially stretched film, with a bending angle of 440 degrees and a bending speed of 40 times / minute, After performing 3000 bend tests in each atmosphere of 0 ° C. and −30 ° C., a bag was made with the test piece after the bend test, and the number of pinholes (pieces / m ² ) was checked with an ageless seal check made by Mitsubishi Gas Chemical. ) Was measured.

(2) Physical properties of multilayer biaxially stretched film (2-1) Heat seal strength Biaxially stretched polyamide film (thickness: 15 μm) and propylene copolymer composition as multilayer biaxially stretched film used for heat seal strength measurement The biaxially stretched film was prepared, and the biaxially stretched polyamide film and the biaxially stretched film were bonded together with a laminating machine to obtain a multilayer biaxially stretched film. The anchor agent used was Takelac A310 and Takenate A3 (Mitsui Chemicals) mixed with ethyl acetate (Makishima Wako Pure Chemicals) as a solvent. Using a Toyo Seiki heat seal tester, cut out a test piece of 100 mm width and 150 mm length from a multilayer biaxially stretched film, fold it in half, a heater at 180 ° C. to 230 ° C., a pressure of 0.2 MPa, and a sealing time After performing heat sealing in 1 second, it cut out to the test piece which sealed, and heat seal intensity | strength was measured using the Tensilon universal testing machine RTC-1225 by Orientec.

  On the other hand, the heat seal strength after retort sterilization was measured by the following method. That is, the test piece prepared by the above method was placed in a hot water shower type high-pressure and high-temperature sterilization treatment apparatus, treated at 121 ° C. for 30 minutes, and then cooled. Next, the heat seal strength (N / 15 mm) was measured by the same method as described above.

[Example 1]
As a propylene copolymer composition, propylene / ethylene block copolymer (A-1): syndiotactic propylene polymer composition (D-1) was weighed at 60:40 (mass ratio), and Bruckner Company A sheet having a thickness of about 1.5 mm was formed with a T-die sheet molding machine using a single screw extruder (screw diameter: 60 mm, screw length: L / D = 27, barrier flight screw). The sheet was heated at 120 ° C. and stretched 5 times in the sheet flow direction (longitudinal direction). The sheet stretched 5 times was heated at 160 ° C. and stretched 10 times in the direction perpendicular to the flow direction (lateral direction) to obtain a 40 μm heat-sealing film. One side of the heat-sealing film was subjected to corona treatment.

<Manufacture of multilayer biaxially stretched film>
A biaxially stretched polyamide film (thickness: 15 μm) and a biaxially stretched film (heat fusion layer) made of the propylene copolymer composition are prepared, and the biaxially stretched polyamide film and the biaxially stretched film are laminated with a laminator. Bonding was performed to obtain a multilayer biaxially stretched film. The anchor agent used was Takelac A310 and Takenate A3 (Mitsui Chemicals) mixed with ethyl acetate (Makishima Wako Pure Chemicals) as a solvent.
The physical properties of the obtained biaxially stretched film (heat fusion layer) and multilayer biaxially stretched film were measured by the above methods. The results are shown in Table 1.

[Example 2]
Propylene copolymer having propylene / ethylene block copolymer (A-1): syndiotactic propylene polymer composition (D-1) as 80:20 (mass ratio) as propylene copolymer composition A biaxially stretched film (heat fusion layer) and a multilayer biaxially stretched film were obtained in the same manner as in Example 1 except that the combined composition was used. The measurement results are shown in Table 1.

Example 3
Propylene copolymer having propylene / ethylene block copolymer (A-1): syndiotactic propylene polymer composition (D-1) as 90:10 (mass ratio) as propylene copolymer composition A biaxially stretched film (heat fusion layer) and a multilayer biaxially stretched film were obtained in the same manner as in Example 1 except that the combined composition was used. The measurement results are shown in Table 1.

Example 4
Propylene copolymer having propylene / ethylene block copolymer (A-1): syndiotactic propylene polymer composition (D-1) as 95: 5 (mass ratio) as propylene copolymer composition A biaxially stretched film (heat fusion layer) and a multilayer biaxially stretched film were obtained in the same manner as in Example 1 except that the combined composition was used. The measurement results are shown in Table 1.

Example 5
Propylene-based copolymer composition: Propylene-ethylene block copolymer (A-1-1): Syndiotactic propylene-based polymer composition (D-1) in 80:20 (mass ratio) Except using the copolymer composition, it carried out similarly to Example 1, and obtained the biaxially stretched film (heat-fusion layer) and the multilayer biaxially stretched film. The measurement results are shown in Table 1.

[Comparative Example 1]
As a propylene-type copolymer composition, it replaces with the propylene-type copolymer composition used in Example 1, and is the same as Example 1 except using a propylene ethylene block copolymer (A-1) independently. The biaxially stretched film (heat fusion layer) and the multilayer biaxially stretched film were obtained. The measurement results are shown in Table 1.

[Comparative Example 2]
Example 1 except that the propylene-based copolymer composition (A-1-1) was used alone as the propylene-based copolymer composition in place of the propylene-based copolymer composition used in Example 1. In the same manner as above, a biaxially stretched film (heat fusion layer) and a multilayer biaxially stretched film were obtained. The measurement results are shown in Table 1.

Example 6
Except using the propylene-type copolymer composition using the propylene-ethylene random copolymer (B-1) instead of the propylene-ethylene block copolymer (A-1) used in Example 2, it implemented. It carried out similarly to Example 2 and obtained the biaxially stretched film (heat-fusion layer) and the multilayer biaxially stretched film. The measurement results are shown in Table 2.

Example 7
Except using the propylene-type copolymer composition using the propylene-ethylene random copolymer (B-1) instead of the propylene-ethylene block copolymer (A-1) used in Example 4, it implemented. It carried out similarly to Example 2 and obtained the biaxially stretched film (heat-fusion layer) and the multilayer biaxially stretched film. The measurement results are shown in Table 2.

[Comparative Example 3]
The same procedure as in Example 2 was performed except that a composition using a propylene homopolymer (F-1) was used instead of the propylene / ethylene block copolymer (A-1) used in Example 2, and two An axially stretched film (heat fusion layer) and a multilayer biaxially stretched film were obtained. The measurement results are shown in Table 2.

[Comparative Example 4]
The same procedure as in Example 4 was performed except that a composition using a propylene homopolymer (F-1) was used instead of the propylene / ethylene block copolymer (A-1) used in Example 4, and two An axially stretched film (heat fusion layer) and a multilayer biaxially stretched film were obtained. The measurement results are shown in Table 2.

[Comparative Example 5]
A biaxially stretched film (heat fusion) was carried out in the same manner as in Example 5 except that the propylene / ethylene random copolymer (B-1) used in Example 5 alone was used as the propylene copolymer composition. Layer) and a multilayer biaxially stretched film. The measurement results are shown in Table 2.

[Comparative Example 6]
The same procedure as in Example 2 was performed except that the isotactic propylene polymer composition (H-1) was used instead of the syndiotactic propylene polymer composition (D-1) used in Example 2. A biaxially stretched film (heat-sealing layer) and a multilayer biaxially stretched film were obtained. The measurement results are shown in Table 2.

[Comparative Example 7]
The same procedure as in Example 2 was performed except that the isotactic propylene polymer composition (H-2) was used instead of the syndiotactic propylene polymer composition (D-1) used in Example 2. A biaxially stretched film (heat-sealing layer) and a multilayer biaxially stretched film were obtained. The measurement results are shown in Table 2.

  The biaxially stretched film obtained from the propylene-based copolymer composition of the present invention is excellent in low temperature heat sealability and can be widely used as a packaging film.

Claims (5)

  45 to 97% by mass of propylene / ethylene block copolymer (A) or propylene / α-olefin random copolymer (B) and 3 to 55% by mass of syndiotactic propylene polymer composition (D). [However, (A) or (B) + (D) = 100% by mass) A propylene-based copolymer composition characterized by that.   A film or a biaxially stretched film comprising the propylene-based copolymer composition according to claim 1.   The multilayer film or multilayer biaxially stretched film by which a base material layer is laminated | stacked on the single side | surface of the film or biaxially stretched film of Claim 2.   The base material layer is a base material layer selected from aluminum, paper, polyester resin film, polycarbonate film, polyamide film, ethylene / vinyl alcohol copolymer film, polyvinyl alcohol film, polyvinyl chloride film, and polyvinylidene chloride film. The multilayer film or multilayer biaxially stretched film of Claim 3.   A packaging film for a heated and sterilized package comprising the multilayer film, the multilayer biaxially stretched film, or the biaxially stretched film according to claim 3 or 4 as a heat-sealing layer.