Propylene-based resin composition and use thereof

Abstract

To provide: a stretched film having a satisfactory balance between stretchability and heat resistance, a sufficiently small value of thermal shrinkage (temperature of 150°C) and satisfactory printability; and a propylene-based polymer composition that can obtain the stretched film.SOLUTION: A propylene-based polymer composition includes satisfying following requirements 1) to 7); and an extruded sheet, a stretched film and a multilayer film are obtained from the composition. Requirement 1): a mesopentad fraction is 95% or more. Requirement 2): a content of a comonomer is 0.2 mol% or less. Requirement 3): MFR is 1 to 10 g / 10 min. Requirement 4): a ratio Mw / Mn of Mw which is mass-average molecular weight to Mn which is number-average molecular weight is 4.5 or smaller. Requirement 5): a ratio MZ+1 / Mn of MZ+1 which is Z+1 average molecular weight to Mn which is number-average molecular weight is 50 or smaller. Requirement 6): MZ+1 which is Z+1 average molecular weight is 2,500,000 or smaller. Requirement 7): a melting point is 150°C or higher.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a propylene-based resin composition and uses of a stretched film made thereof, etc. More specifically, the present invention relates to a propylene-based resin composition and a stretched film obtained therefrom that have a good balance between stretchability and heat resistance and good printability. [Background technology]

[0002] Biaxially oriented polypropylene film (OPP) is widely used as an industrial film and food film, and is in high demand. Furthermore, in order to further expand demand for OPP, efforts are being made to improve its performance. One such improvement is to reduce the heat shrinkage rate (a few tens of percent at 150°C). However, with OPP, whose main component is a unit derived from propylene, reducing the heat shrinkage rate (at 150°C) is not an easy task and is fraught with difficulties.

[0003] Patent Document 1 discloses an oriented polypropylene film, the mass average molecular weight (Mw) / number average molecular weight (Mn) of which is 5.5 or more and has a relatively wide molecular weight distribution. With this stretched film, the heat shrinkage rate (at 150° C.) does not become sufficiently small.

[0004] Patent Document 2 discloses an OPP made of a resin composition blended with random PP, which has a relatively small heat shrinkage rate (at 150°C), but has an increased amount of sticky components, resulting in poor printability.

[0005] Patent Document 3 discloses an OPP made of a propylene polymer with a low MFR (0.1 to 15) and a propylene polymer with a high MFR (20 to 500). Such an OPP does not have a good balance between stretchability and heat shrinkage, and stable production may be difficult. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2014-55276 [Patent Document 2] Patent Publication No. 2022-148047 [Patent Document 3] Patent Publication No. 2021-161381 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a stretched film having a good balance between stretchability and heat resistance, a sufficiently small heat shrinkage rate (at 150°C), and good printability, and a propylene-based polymer composition from which the same can be obtained. [Means for solving the problem]

[0008] The present invention includes any one of the following aspects [1] to [6]. [1] A propylene polymer composition characterized by satisfying the following requirements 1) to 7): Requirement 1) Mesopentad fraction is 95% or more Requirement 2) Comonomer content is 0.2 mol% or less Requirement 3) MFR is 1 to 10g / 10min Requirement 4) The ratio of mass average molecular weight Mw to number average molecular weight Mn, Mw / Mn, is 4.5 or less. Requirement 5) Z+1 average molecular weight M Z+1 and the ratio M Z+1 / Mn is 50 or less Requirement 6) Z+1 average molecular weight M Z+1 is 2,500,000 or less Requirement 7) Melting point is 150℃ or higher [2] The propylene polymer composition according to the above [1], characterized in that the cold xylene solubles (CXS) is 1.2 mass % or less. [3] The propylene-based polymer composition according to either of the above [1] and [2], characterized in that it contains the following propylene-based polymers, Polymer A and Polymer B, in the following ratios, respectively: Polymer A Mesopentad fraction 95% or more, MFR 1g / 10min or more, less than 6g / 10min, Melting point: over 150℃ 99~80% by mass Polymer B Mesopentad fraction 95% or more, MFR 6g / 10min or more, 100g / 10min or less, Mw / Mn 5.0 or less, Melting point: over 150℃ 1~20% by mass (The total of polymer A and polymer B is 100% by mass.) [4] An extruded sheet obtained from the propylene polymer composition according to any one of the above items [1] to [3]. [5] A uniaxially or biaxially stretched film obtained from the propylene polymer composition according to any one of the above [1] to [3]. [6] A multilayer film having at least one layer of the stretched film described in (5) above. Effect of the Invention

[0009] According to the present invention, there can be provided a stretched film which has a good balance between stretchability and heat resistance, a small heat shrinkage rate (at 150°C), and furthermore, is less sticky and has good printability, and a propylene-based polymer composition from which the same can be obtained. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the relationship between the value of Fm / Fy (-), which is an index of stretchability when forming biaxially stretched films, and the stretch ratio (times) in Examples 1 to 3 and Comparative Examples 1 to 5 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the respective configurations of the polypropylene resin composition of the present invention, the extruded sheet obtained from the composition, and the uniaxially or biaxially stretched film will be described.

[0012] <Propylene-Based Resin Composition> The propylene-based resin composition according to the present invention is characterized in that it satisfies the following requirements 1) to 7). Requirement 1) Mesopentad fraction is 95% or more Requirement 2) Comonomer content is 0.2 mol% or less Requirement 3) MFR is 1 to 10g / 10min Requirement 4) The ratio of mass average molecular weight Mw to number average molecular weight Mn, Mw / Mn, is 4.5 or less. Requirement 5) Z+1 average molecular weight M Z+1 and the ratio M Z+1 / Mn is 50 or less Requirement 6) Z+1 average molecular weight M Z+1 is 2,500,000 or less Requirement 7) Melting point is 150℃ or higher Each requirement is explained below.

[0013] Regarding requirement 1) The mesopentad fraction ([mmmm]%) of the propylene-based resin composition of the present invention is 95% or more, preferably 96% or more, and more preferably 97% or more. The upper limit is preferably 99.5% or less. The mesopentad fraction ([mmmm]%) is an index showing the stereoregularity of a propylene-based resin composition. Within this range, the composition exhibits high crystallinity and a small heat shrinkage rate (at 150° C.). The mesopentad fraction ([mmmm]%) is 13 The measurement is performed by C-NMR, and the details of the measurement are described in the Examples.

[0014] Regarding requirement 2) The comonomer content of the propylene polymer in the propylene resin composition of the present invention is 0.2 mol % or less. The propylene polymer in the propylene resin composition of the present invention is preferably a so-called homopolypropylene consisting only of units derived from propylene, but may be a copolymer with a comonomer, in which case the comonomer content is 0.2 mol% or less, preferably 0.1 mol% or less. Examples of the comonomer include ethylene and α-olefins having 4 to 8 carbon atoms, among which ethylene and 1-butene are preferred. Within this range, the heat shrinkage rate (at 150°C) is small.

[0015] Regarding requirement 3) The MFR (melt flow rate, 230°C, load 2.16 kgf) of the propylene-based polymer composition is 1 to 10 g / 10 min. The lower limit is preferably 2.0 g / 10 min, and more preferably 3.0 g / 10 min. The upper limit is preferably 9.0 g / 10 min or less, and more preferably 8.0 g / 10 min or less. By setting it in such a range, the heat shrinkage rate at high temperatures can be reduced.

[0016] Regarding requirement 4) The propylene-based resin composition of the present invention has a ratio of mass average molecular weight (Mw) to number average molecular weight (Mn), that is, Mw / Mn, of 4.5 or less. Mw and Mn are determined by gel permeation chromatography (GPC). The method of determination will be described in detail in the Examples. The upper limit of the Mw / Mn value is preferably 4.2 or less, and the lower limit is preferably 2.0 or more, and more preferably 2.5 or more. By setting the value in this range, the thermal shrinkage rate at high temperatures can be reduced.

[0017] Requirement 5) The Z+1 average molecular weight M of the propylene-based resin composition of the present invention Z+1 and the ratio M Z+1 / Mn is not more than 50. The upper limit of this ratio is preferably not more than 40, and more preferably not more than 35. The lower limit is generally about 10 or more, and preferably 15 or more. In addition, M Z+1 is measured by GPC, and is defined as the sum of the weight fraction (Xi) of the molecular weight (Mi) at the elution position i of the GPC curve obtained via a molecular weight calibration curve, as follows: Z+1 average molecular weight M Z+1 =Σ(Xi·Mi 4 ) / Σ(Xi·Mi 3 ) (Each Σ means the sum of the values ​​at all elution positions. That is, the sum of the weight fractions Xi is ΣXi=1.) The details of the measurement will be described in the Examples. M Z+1 / Mw is the value that emphasizes the contribution of high molecular weight components in the molecular weight distribution, and is the Z-average molecular weight M defined by the following formula: Z Z average molecular weight Mz=Σ(Xi·Mi 3 ) / Σ(Xi·Mi 2 ) (Each Σ means the sum of the values ​​at all elution positions. That is, the sum of the weight fractions Xi is ΣXi=1.) and Mn ratio M Z This shows the molecular weight distribution value with more emphasis on the contribution of molecular weight than / Mn.

[0018] Regarding requirement 6) The Z+1 average molecular weight M of the propylene polymer composition Z+1 is 2,500,000 or less. The upper limit is preferably 2,000,000 or less. The lower limit is usually 800,000 or more, and preferably 1,000,000 or more. Within this range, the high molecular weight component is sufficient, and the effects of the present invention are easily obtained. In addition, stretch molding of the stretched film can be stably performed.

[0019] Regarding requirement 7) The melting point of the propylene polymer composition of the present invention is 150° C. or higher. In particular, the lower limit is particularly preferably 155° C. or higher. The upper limit is preferably 170° C. or lower, and more preferably 168° C. or lower.

[0020] The propylene-based polymer composition of the present invention preferably has a cold xylene solubles (CXS) of 1.2% by mass or less, more preferably 1.0% by mass or less. Of these, it is more preferably 0.8% by mass or less. The cold xylene solubles (CXS) are generally 0.1% by mass or more. The cold xylene solubles (CXS) can be determined by the following method.

[0021] Cold xylene solubles (CXS) (unit: mass%) 2 g of a sample made of a propylene-based polymer composition is dissolved in 300 mL of p-xylene (containing 0.5 mg / mL of BHT) at 13.0° C., and the resulting solution is allowed to stand at 25° C. After 48 hours, the precipitate and the filtrate are separated by filtration, and the p-xylene is evaporated from the filtrate. The filtrate is then dried under reduced pressure at 100° C. for 12 hours to recover the components dissolved in p-xylene. The ratio (mass %) of the mass (g) of the recovered components to 2 g of the sample is CXS. In order to set the CXS of the propylene polymer composition within the above range, the propylene polymer may be produced using a polymerization catalyst capable of producing a propylene polymer having high stereoregularity.

[0022] If CXS is within the above range, the crystallinity of the propylene-based polymer is sufficiently high, and the heat shrinkage rate at high temperatures (temperature 150° C.) of the stretched film obtained from the polymer can be made smaller. Furthermore, the film is less sticky and has good printability.

[0023] The propylene polymer composition of the present invention that satisfies the above requirements 1) to 7) can be produced by various methods. Propylene polymers having different molecular weights can be produced by multistage polymerization to form a composition, propylene polymers having different molecular weights can be produced by polymerization and then blended in a kneader to form a composition, or a propylene polymer can be polymerized using a plurality of polymerization catalysts having different performances to form a composition. The polymerization catalyst used may be a Ziegler-Natta catalyst or a metallocene catalyst, and the molecular weight of the propylene polymer may be adjusted by the amount of hydrogen present in the polymerization system. Two or more propylene polymers may be mixed or melt-kneaded simultaneously or sequentially using a mixing device such as a Banbury mixer, single-screw extruder, or twin-screw extruder.

[0024] As the propylene-based polymer used in the present invention, a propylene homopolymer or a copolymer of propylene and ethylene or an α-olefin having 4 to 20 carbon atoms as a comonomer is used as long as the above requirements 1) to 7) are satisfied. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Among these comonomers, ethylene or an α-olefin having 4 to 10 carbon atoms is preferred, and ethylene is more preferred. The propylene-based polymer used in the present invention may contain propylene constituting the polymer, or further a comonomer such as ethylene, derived from biomass. For example, the propylene constituting the polymer may be only biomass-derived propylene, or may contain both biomass-derived propylene and fossil fuel-derived propylene. Biomass-derived propylene is propylene obtained from any renewable natural raw material, such as fungi, yeast, algae, and bacteria, or from plants or animals, and its residues, and contains propylene as carbon. 14 C isotope 10 ―12The biomass-derived propylene is contained in a ratio of about 100 (pMC) as measured in accordance with ASTM D 6866. Biomass-derived propylene is obtained by a conventionally known method. It is preferable that the propylene-based polymer used in the present invention contains biomass-derived propylene from the viewpoint of reducing the environmental load (mainly reducing greenhouse gases). If the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, even if the raw material propylene contains biomass-derived propylene, 14 C isotope 10 ―12 ~10 ―14 Other than the proportion of propylene in the polymer, its molecular structure is the same as that of propylene homopolymers made from fossil fuel-derived propylene, and therefore its performance is said to be the same. The propylene-based polymer (A) used in the present invention may contain propylene constituting the polymer, or further a comonomer such as ethylene, derived from chemical recycling. For example, the propylene constituting the polymer may be only propylene derived from chemical recycling, or may contain propylene derived from chemical recycling and propylene derived from fossil fuels and / or propylene derived from biomass. The propylene derived from chemical recycling is obtained by a conventionally known method. It is preferable that the propylene homopolymer (A) according to the present invention contains propylene derived from chemical recycling from the viewpoint of reducing the environmental load (mainly reducing waste). Even if the raw material monomer contains a monomer derived from chemical recycling, the monomer derived from chemical recycling is a monomer obtained by depolymerizing or pyrolyzing a polymer such as waste plastic back to a monomer unit such as propylene, and a monomer produced using the monomer as a raw material. Therefore, if the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, the molecular structure is the same as that of a propylene homopolymer made of a monomer derived from fossil fuels. Therefore, the performance is said to be the same.

[0025] The propylene polymer composition of the present invention is preferably produced by blending the following propylene polymers, Polymer A and Polymer B, in the ratios shown below. Polymer A Mesopentad fraction 95% or more, MFR 1g / 10min or more, less than 6g / 10min, Melting point: over 150℃ 99~80% by mass Polymer B Mesopentad fraction 95% or more, MFR 6g / 10min or more, 100g / 10min or less, Mw / Mn 5.0 or less, Melting point: over 150℃ 1~20% by mass (The total of polymer A and polymer B is 100% by mass.) Polymer A and Polymer B will be described below.

[0026] <Polymer A> Polymer A, which is a propylene-based polymer, has physical properties within the above-mentioned ranges. Among them, polymer A preferably has physical properties within the following ranges. That is, the mesopentad fraction ([mmmm]%) of polymer A is 95% or more, preferably 96% or more, and more preferably 97% or more. The upper limit is preferably 99.5% or less. The polymer A is preferably a so-called homopolypropylene consisting only of units derived from propylene, but may be a copolymer with a comonomer, in which case the content of the comonomer is preferably 0.2 mol% or less, more preferably 0.1 mol% or less. Examples of the comonomer include ethylene and α-olefins having 4 to 8 carbon atoms, and among these, ethylene and 1-butene are preferred. The MFR (melt flow rate, 230°C, load 2.16 kgf) of polymer A is 1 g / 10 min or more and less than 6 g / 10 min, and the lower limit is preferably 1.5 g / 10 min or more, more preferably 2.0 g / 10 min or more, and the upper limit is preferably 5.0 g / 10 min. The Mw / Mn of polymer A is preferably 5.0 or less. The lower limit is preferably 2.0 or more, and more preferably 2.5 or more. M of polymer AZ+1 / Mn is preferably 50 or less, and more preferably 40 or less. The lower limit is preferably 20 or more, and particularly preferably 25 or more. M of polymer A Z+1 is preferably 3,000,000 or less, more preferably 2,700,000 or less. The lower limit is usually 1,000,000 or more, and preferably 1,200,000 or more. Furthermore, the polymer A preferably has a cold xylene solubles (CXS) content of 1.2 mass % or less.

[0027] <Polymer B> Polymer B, which is a propylene-based polymer, has physical properties within the above-mentioned ranges. Among them, polymer B preferably has physical properties within the following ranges. That is, the mesopentad fraction ([mmmm]%) of polymer B is preferably 95% or more, more preferably 96% or more, and further preferably 97% or more. The upper limit is preferably 99.5% or less. Polymer B may be a so-called homopolypropylene consisting only of units derived from propylene, or may be a copolymer with a comonomer. In that case, the comonomer content is preferably 0.2 mol % or less, and more preferably 0.1 mol % or less. Examples of the comonomer include ethylene and α-olefins having 4 to 8 carbon atoms, with ethylene being preferred. The MFR (melt flow rate, 230° C., load 2.16 kgf) of polymer B is 8 g / 10 min or more and 100 g / 10 min or less, and the upper limit is preferably 80 g / 10 min or less. The Mw / Mn of the polymer B is 5.0 or less, preferably 4.5 or less, and the lower limit is generally 2.0 or more, preferably 2.5 or more. M of polymer B Z+1 / Mn is preferably 50 or less, and more preferably 40 or less. The lower limit is generally 5 or more. M of polymer B Z+1is preferably 3,000,000 or less, more preferably 2,700,000 or less, and most preferably 2,000,000 or less. The lower limit is usually 300,000 or more, and preferably 400,000 or more. The melting point of the polymer B is 150° C. or higher, and preferably 155° C. or higher. The upper limit is preferably 170° C. or lower, and more preferably 168° C. or lower.

[0028] Furthermore, the polymer B preferably has a cold xylene solubles (CXS) content of 1.2 mass % or less.

[0029] The propylene polymer composition of the present invention is preferably prepared from 80 to 99% by mass of the above-mentioned polymer A and 1 to 20% by mass of the polymer B, and more preferably prepared from 85 to 95% by mass of the above-mentioned polymer A and 15 to 5% by mass of the polymer B. (The total of the polymer A and the polymer B is taken as 100% by mass.)

[0030] To the propylene polymer composition of the present invention, various additives such as a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slipping agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent, a pigment, a dye, and an inorganic or organic filler may be added as necessary within the range not impairing the object of the present invention.

[0031] Examples of the antioxidant include phenol-based antioxidants, organic phosphite-based antioxidants, thioether-based antioxidants, hindered amine-based antioxidants, etc. Examples of the antiblocking agent include aluminum oxide, finely divided silica, polymethyl methacrylate powder, silicone resin, etc. Examples of slip agents include bisamides such as ethylene bisstearamide, higher fatty acid amides such as oleic acid amide and erucic acid amide.

[0032] Examples of the lubricant include calcium stearate, zinc stearate, metal salts of higher fatty acids such as metal montanic acid salts, and polyolefin waxes such as polyethylene wax and polypropylene wax. Examples of the nucleating agent include rosin-based nucleating agents such as dibenzylidene sorbitol and partial metal salts of rosin acid, aluminum-based nucleating agents, and talc.

[0033] <Extruded sheet, uniaxially or biaxially stretched film> The propylene polymer composition of the present invention can be molded into a sheet, an unstretched film, a uniaxially or biaxially stretched film, etc., by various known molding methods for use. Examples of the molding methods include a molding method by extrusion, such as sheet molding, T-die film molding, stretched film molding, calendar molding, inflation molding, etc. The extruded sheet usually has a thickness of 250 to 3000 μm. The unstretched film generally has a thickness of 3 μm or more, preferably 5 to 250 μm, and more preferably 10 to 200 μm.

[0034] A uniaxially or biaxially stretched film can be formed by stretching an extruded sheet or an unstretched film in one or two directions. For biaxial stretching, a method such as sequential biaxial stretching, simultaneous biaxial stretching, or multistage stretching is appropriately used. The stretching ratio is usually 1.5 to 10 times for a uniaxially stretched film, and 1.5 to 7 times in the longitudinal direction and 2 to 10 times in the transverse direction for a sequentially biaxially stretched film. The stretching temperature is usually 100 to 140° C. in uniaxial stretching and simultaneous biaxial stretching, and in sequential biaxial stretching, the stretching temperature in the longitudinal direction is usually 100 to 140° C. and the stretching temperature in the transverse direction is usually 140 to 180° C. The uniaxially or biaxially stretched film has a thickness of 5 μm or more, preferably 5 to 100 μm.

[0035] The uniaxially or biaxially stretched film of the present invention is obtained from a characteristic propylene-based polymer composition, and not only has excellent mechanical strength, rigidity characteristics and optical characteristics but also has a small heat shrinkage rate (at 150°C). It is expected that the use of the film in a wide range of applications such as industrial packaging materials, food packaging and textile packaging will expand, further increasing demand.

[0036] <Multilayer film> The multilayer film of the present invention is obtained by laminating at least one other layer on one side of the above-mentioned uniaxially or biaxially stretched film. Other layers include films made of polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate films, polyamide films made of nylon 6, nylon 66, etc., ethylene-vinyl alcohol copolymer films, polyvinyl alcohol films, polyvinyl chloride films, polyvinylidene chloride films, etc., or sheets made of these films, aluminum foil, paper, etc.

[0037] As a method for laminating the uniaxially or biaxially stretched film of the present invention with the other layer, a lamination method generally used can be adopted, and in addition to forming these multilayer films by multilayer coextrusion, an adhesive layer can be provided between the uniaxially or biaxially stretched film and the other layer. For example, a method of applying a urethane-based or isocyanate-based anchor coating agent to the other layer and dry laminating the uniaxially or biaxially stretched film of the present invention, or a method of extrusion laminating or extrusion coating the other layer on the uniaxially or biaxially stretched film can be adopted.

[0038] Examples of the multilayer film of the present invention include polyester layer / biaxially oriented film, polyamide layer / biaxially oriented film, polyester layer / polyamide layer / biaxially oriented film, polyester layer / aluminum foil / biaxially oriented film, polyester layer / polyamide layer / aluminum foil / biaxially oriented film, polyamide layer / polyvinylidene chloride layer / polyester layer / biaxially oriented film, and the like.

[0039] The multilayer film of the present invention has excellent sealing strength (peel strength) and blocking resistance when the film portion is used for uniaxial or biaxial stretching in a heat-sealed portion. In addition, the multilayer film has functions such as mechanical strength and gas barrier properties due to the other layers of the multilayer film, and is expected to be used in a wider range of applications as a packaging material. EXAMPLES

[0040] Next, the present invention will be described more specifically through examples and comparative examples, but the present invention is not limited to these examples in any way.

[0041] <Mesopentad fraction (unit: %)> The mesopentad fraction (mmmm fraction) is a value determined by the assignment given in Macromolecules, 8, 687 (1975) by A. Zambelli et al. 13 The measurement was performed by C-NMR under the following conditions. The mesopentad fraction is a value expressed by the following formula. Mesopentad fraction = ((peak area at 21.7 ppm) / (peak area at 19-23 ppm)) x 100

[0042] <Measurement conditions> Equipment JNM-Lambada400 (product name, manufactured by JEOL Ltd.) Resolution 400MHz Measurement temperature 125℃ Solvent: 1,2,4-trichlorobenzene / deuterated benzene = 7 / 4 (mass ratio) Pulse width 7.8μsec Pulse interval: 5 seconds Accumulation count: 2000 times Shift standard TMS=0ppm Mode Single pulse broadband decoupling.

[0043] <Content of ethylene as a comonomer in propylene polymer (unit: mol%)> When the propylene-based polymer contains ethylene as a comonomer, the content of ethylene is 13 It is measured using Fourier transform infrared spectroscopy (FTIR) calibrated with C-NMR. The area of ​​the -CH2- absorption peak of the film used as the sample (approximately 300 μm thick, multiple films may be used in layers if necessary) is 775-670 cm -1 (0.2-3% ethylene) or 758-702 cm -1 The absorption peak was measured from 3-33% ethylene.

[0044] <MFR (unit: g / 10min)> The MFR (melt flow rate) of the propylene-based polymer was measured at 230 °C under a load of 2.16 kgf in accordance with JIS K7210.

[0045] <mw mn><M Z+1 > <M Z+1 / Mn> Measurement was performed under the following conditions, and the obtained chromatogram was analyzed by a known method to determine the Mn, Mw, and M Z、 M Z+1 Calculate Mw / Mn and M Z+1 , M Z+1 / Mn was obtained. Equipment: HLC-8321GPC / HT (detector: RI) Column: TSKgel guard column H HR (30) HT (7.5mm I.D. x 7.5cm) x 1 and TSKgel GMH HR -H(20)HT(7.8mmI.D.×30cm)×3 pieces connected together (made by Tosoh) Eluent: 1,2,4-trichlorobenzene (Fujifilm Wako Pure Chemical GPC grade) + BHT (0.05%) ·Flow rate: 1.0mL / min. Detection conditions: polarity=(-) ·Injection volume: 0.3mL Column temperature: 140℃ System temperature: 40℃ Sample concentration: 1mg / mL Pretreatment: The sample was weighed, TCB (without BHT) was added, and the sample was dissolved by shaking at 140°C for 1 hour. After that, the sample was filtered by heating using a sintered filter with a pore size of 0.5 μm (visually confirming that there was no insoluble matter). Calibration curve: A quintic approximation curve using standard polystyrene from Tosoh. However, the molecular weight was converted to PP equivalent molecular weight using the Q factor.

[0046] <Cold xylene solubles (CXS) (unit: mass%)> 2 g of a sample made of a propylene-based polymer is dissolved in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 13.0° C., and the resulting solution is allowed to stand at 25° C. After 48 hours, the precipitate and filtrate are separated by filtration, and the p-xylene is evaporated from the filtrate. The filtrate is then dried under reduced pressure at 100° C. for 12 hours to recover the components dissolved in p-xylene. The ratio (mass %) of the mass (g) of the recovered components to 2 g of the sample is CXS.

[0047] Properties of biaxially stretched films <Tensile modulus (unit: MPa)> The tensile modulus (MPa) of the biaxially stretched film was measured in accordance with JIS K7127 under the following conditions. (Measurement conditions) A sample biaxially stretched film was cut into a strip of 10 mm width and 150 mm length, and pulled in a tensile test at a crosshead speed of 500 mm / min, with the machine direction being MD and the direction perpendicular to MD being TD.

[0048] <Heat shrinkage rate (temperature 150℃) (unit: %)> The sample biaxially stretched film was placed in a hot air oven and heated at 150°C for 15 minutes. The heat shrinkage rate was the ratio of the length that had shrunk to the dimension before heating. The longitudinal stretching direction was defined as MD, and the transverse stretching direction was defined as TD.

[0049] <Stretchability>(Fm / Fy) The evaluation was carried out using the following method, with reference to Satoshi Tamura, Kuramoto Masataka, Toshitaka Kanai, Proceedings of the 17th Autumn Meeting of the Society of Plastics Processing (November 6-7, 2009, Nagasaki). A 30mmφ sheet forming machine (GM Engineering) was used to prepare an unstretched raw material approximately 150mm wide. This was then cut to 90mm length x 90mm width. The raw material was then stretched 5 times in the machine direction (MD) at a preheating temperature of 153°C for 90 seconds in a table tenter biaxial stretching machine (Bruckner) at a stretching temperature of 153°C. The stretched material was then stretched 8 times in the transverse direction (TD) at the same stretching temperature. The yield force Fy (N) and maximum force Fm (N) were determined from the stretching force-stretch ratio curve measured with a load cell, and the stretching force ratio Fm / Fy was calculated as an index of stretchability. The Fm / Fy value is an index showing the stretchability when the film is stretched, and a larger value indicates better stretchability.

[0050] Example 1 In Example 1, a propylene-based polymer composition was used containing polymer A (main resin) and polymer B (low molecular weight component) shown in Table 2 in the ratios shown in Table 2. The physical properties of this composition are shown in Tables 1 and 2. Using the propylene-based polymer composition of Example 1, an unstretched raw sheet was prepared by a sheet forming machine, and cut into a size of 90 mm length x 90 mm width. The cut sheet was stretched 5 times in the machine direction (MD) at a stretching temperature of 153°C with a preheating time of 90 sec in a table tenter biaxial stretching machine, and then stretched 8 times in the transverse direction (TD) at the same stretching temperature (stretching speed of 286% / sec for both machine and transverse stretching), and relaxed at a heat setting temperature of 150°C (machine direction: 5% and transverse direction: 5%) to obtain a sequentially biaxially stretched film having a thickness of 20 microns (μm).

[0051] Example 2 and Example 4 Using the propylene polymer compositions of Examples 2 and 4 shown in Table 1, axially stretched films were obtained under the same conditions as in Example 1. The physical properties were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0052] Comparative Examples 1 to 5 A biaxially stretched film was formed in the same manner as in Example 1 using the propylene-based polymer composition shown in Table 1. The physical properties of the obtained biaxially stretched film are shown in Table 1.

[0053] However, for Polymer A, Polymer B, and Polymer C, the following were used. Polymer A Commercially available propylene polymer (Prime Polymer Co., Ltd., product name F133A) Polymer B (1) Polymer B-1 Commercially available propylene polymer (Prime Polymer Co., Ltd., product name S119) (2) Polymer B-2 Commercially available propylene polymer (Prime Polymer Co., Ltd., product name Y-2000GV) (3) Polymer B-3 Commercially available propylene polymer (Prime Polymer Co., Ltd., product name S135) (4) Polymer B-4 Commercially available propylene polymer (Prime Polymer Co., Ltd., product name S229R) (5) Polymer B-5 Commercially available propylene polymer (Prime Polymer Co., Ltd., product name Y-2045GP) (6) Polymer B-6 Commercially available propylene polymer (Prime Polymer Co., Ltd., product name S235WC) Polymer C (1) Polymer C The polymer used was that obtained in the following Reference Example (Polymer C).

[0054] Reference example (polymer C) Polymer C was obtained by the following: A propylene-based polymer was used as the support with dicyclopentyldimethoxysilane as the electron donor. Using a supported titanium catalyst (high stereoregularity catalyst), random copolymerization with an ethylene unit content of 0.6 mol% was performed in two stages to obtain a propylene-ethylene copolymer with a broadened molecular weight distribution, with the amounts of 52 wt% high molecular weight copolymer with an intrinsic viscosity [η] of 4.3 dl / g and 48 wt% low molecular weight copolymer with an intrinsic viscosity [η] of 2.1 dl / g being adjusted. For 100% by weight of the copolymer, 0.1 parts by weight of tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (manufactured by BASF Ltd.), a phenol-based antioxidant, 0.1 parts by weight of 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite (manufactured by ADEKA Corp.), a phosphorus-based antioxidant, and 0.1 parts by weight of calcium stearate (manufactured by Nippon Oil & Fats Co., Ltd.) as a neutralizing agent were blended, and the mixture was melt-kneaded at a resin temperature of 230°C using a single-screw extruder and granulated into pellets.

[0055] For Examples 1 to 3 and Comparative Examples 1 to 5, the relationship between the stretchability indicated by the value of Fm / Fy and the shrinkage rate (%) in the TD direction is shown in FIG. As shown in FIG. 1, in Examples 1, 2, and 3, the stretchability is well maintained and the shrinkage rate (%) in the TD direction is small. On the other hand, in Comparative Examples 1 and 2, the stretchability is poor. Also, in Comparative Examples 3, 4, and 5, the stretchability was excellent, but the thermal shrinkage rate (%) in the TD direction was larger than that in each of the Examples.

[0056] [Table 1-1]

[0057] [Table 1-2]

[0058] [Table 2]

[0059] [Table 3]

[0060] [Table 4]

[0061] [Table 5]

[0062] [Table 6]

[0063] [Table 7]

[0064]

Table 8

[0065]

Table 9

Claims

1. A propylene-based polymer composition satisfying the following requirements 1) to 7): Requirement 1) Mesopentad fraction is 95% or more Requirement 2) The comonomer content is 0.2 mol% or less. Requirement 3) MFR is 1 to 10 g / 10 min. Requirement 4) The ratio Mw / Mn of the mass average molecular weight Mw to the number average molecular weight Mn is 4.5 or less. Requirement 5) Z+1 average molecular weight M Ｚ＋１ and the ratio M Ｚ＋１ / Mn is 50 or less Requirement 6) Z+1 average molecular weight M Ｚ＋１ is 2,500,000 or less Requirement 7) Melting point is 150°C or higher

2. 2. The propylene-based polymer composition according to claim 1, wherein the propylene-based polymer composition has a cold xylene solubles (CXS) content of 1.2 mass% or less.

3. 3. The propylene-based polymer composition according to claim 1, comprising the following propylene-based polymers, Polymer A and Polymer B, in the following ratios: Polymer A Mesopentad fraction: 95% or more MFR: 1g / 10min or more, less than 6g / 10min, Melting point: over 150°C 99-80% by mass Polymer B Mesopentad fraction: 95% or more MFR 6g / 10min or more, 100g / 10min or less, Mw / Mn 5.0 or less, Melting point: over 150°C 1-20% by mass (The total of polymer A and polymer B is 100% by mass.)

4. An extruded sheet obtained from the propylene polymer composition according to claim 1 or 2.

5. A uniaxially or biaxially stretched film obtained from the propylene polymer composition according to claim 1 or 2.

6. A multilayer film having at least one layer of the stretched film according to claim 5.

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