Unoriented films, sealant films, and multilayer sealant films

Abstract

To provide an unoriented polypropylene film that has a good balance of rigidity and low-temperature heat-sealing performance, or an unoriented polypropylene film with excellent rigidity, and that can be heat-sealed at low temperatures. [Solution] An unstretched film made of a propylene polymer composition containing, in a specific proportion, a specific propylene polymer (A) and a propylene-α-olefin copolymer (B) having an MFR of 0.1 to 30 g / 10 min, an intrinsic viscosity [η] measured at 135°C in tetralin solvent exceeding 1.5 dl / g and being 5.0 dl / g or less, and containing a specific amount of constituent units derived from α-olefins (excluding propylene).

Description

[Technical Field]

[0001] This invention relates to unoriented films, sealant films, and multilayer sealant films. [Background technology]

[0002] Propylene polymers are widely used as materials for various molded articles (see, for example, Patent Documents 1-4), and the required properties vary depending on the molding method and application. For example, films made from propylene polymers are widely used as packaging films for food and general merchandise, taking advantage of their excellent mechanical properties such as rigidity and optical properties such as gloss. Unoriented polypropylene films (see, for example, Patent Documents 5-7) are known to have an excellent balance of rigidity and heat resistance. Furthermore, Patent Document 8 discloses an unoriented polypropylene film with particularly excellent rigidity, using a specific propylene polymer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 1999 / 007752 [Patent Document 2] International Publication No. 2005 / 097842 [Patent Document 3] Japanese Patent Publication No. 2001-302858 [Patent Document 4] Japanese Patent Publication No. 2006-045446 [Patent Document 5] Japanese Patent Publication No. 2002-265712 [Patent Document 6] Japanese Patent Publication No. 2005-320359 [Patent Document 7] Japanese Patent Publication No. 2011-236357 [Patent Document 8] International Publication No. 2021 / 025142 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, when the unoriented polypropylene film described in Patent Document 8 was used as a sealant film, the sealing performance was poor (the sealing temperature was high).

[0005] Therefore, the object of the first aspect of the present invention is to provide an unoriented polypropylene film that is well balanced in rigidity and low-temperature heat-seal performance (hereinafter referred to as the "first object").

[0006] Furthermore, a second aspect of the present invention aims to provide an unoriented polypropylene film with excellent rigidity that can be heat-sealed at low temperatures (hereinafter referred to as the "second problem"). [Means for solving the problem]

[0007] As a result of diligent research, the inventors have found that an unstretched film made of the propylene polymer composition described below can solve the first problem, and have completed the first aspect of the present invention. The first aspect of the present invention relates, for example, to [1] below.

[0008] [1] A propylene polymer (A) containing 20-50% by mass of a propylene polymer (a1) having an intrinsic viscosity [η] in the range of 10-12 dl / g as measured at 135°C in tetralin solvent, and 50-80% by mass of a propylene polymer (a2) having an intrinsic viscosity [η] in the range of 0.5-1.5 dl / g as measured at 135°C in tetralin solvent [where the total amount of propylene polymer (a1) and propylene polymer (a2) is 100% by mass], It contains a propylene-α-olefin copolymer (B1) having a melt flow rate (230°C, 2.16 kg load) of 0.1 to 30 g / 10 min, an intrinsic viscosity [η] measured at 135°C in tetralin solvent exceeding 1.5 dl / g and being 5.0 dl / g or less, and containing 5.5 mol% or more of constituent units derived from α-olefins (excluding propylene). An unstretched film comprising a propylene polymer composition (X1) wherein, with a total of 100 parts by mass of the propylene polymer (A) and the propylene-α-olefin copolymer (B1), the content of the propylene polymer (A) is 1 to 10 parts by mass, and the content of the propylene-α-olefin copolymer (B1) is 90 to 99 parts by mass.

[0009] Furthermore, after diligent research, the inventors discovered that an unstretched film made of the propylene polymer composition described below can solve the second problem, and thus completed a second aspect of the present invention. The second aspect of the present invention relates, for example, to the following [2].

[0010] [2] A propylene polymer (A) containing 20-50% by mass of a propylene polymer (a1) having an intrinsic viscosity [η] in the range of 10-12 dl / g as measured at 135°C in tetralin solvent, and 50-80% by mass of a propylene polymer (a2) having an intrinsic viscosity [η] in the range of 0.5-1.5 dl / g as measured at 135°C in tetralin solvent [where the total amount of propylene polymer (a1) and propylene polymer (a2) is 100% by mass], It contains a propylene-α-olefin copolymer (B2) having a melt flow rate (230°C, 2.16 kg load) of 0.1 to 30 g / 10 min, an intrinsic viscosity [η] measured at 135°C in tetralin solvent greater than 1.5 dl / g and less than or equal to 5.0 dl / g, and containing 1 mol% or more and less than 5.5 mol% of constituent units derived from α-olefins (excluding propylene). An unstretched film comprising a propylene-based polymer composition (X2) in which the content of the propylene-based polymer (A) is 1 to 18 parts by mass and the content of the propylene-α-olefin copolymer (B2) is 82 to 99 parts by mass with respect to a total of 100 parts by mass of the propylene-based polymer (A) and the propylene-α-olefin copolymer (B2).

[0011] The first and second aspects of the present invention further relate to the following [3] to [6].

[0012] [3] The unstretched film according to [1] or [2], wherein the melt flow rate (MFR) of the propylene-based polymer (A) measured at 230 °C under a load of 2.16 kg is 0.01 to 5 g / 10 min.

[0013] [4] The unstretched film according to any one of [1] to [3], wherein the area ratio of the high molecular weight region having a molecular weight of 1.5 million or more in the total area of the region surrounded by the molecular weight distribution curve measured by gel permeation chromatography (GPC) of the propylene-based polymer (A) is 7% or more.

[0014] [5] The unstretched film according to any one of [1] to [4], wherein the propylene-based polymer (A) has a molecular weight distribution curve measured by GPC having two peaks, and the ratio (MH / ML) of the peak molecular weight MH on the high molecular weight side to the peak molecular weight ML on the low molecular weight side is 50 or more.

[0015] [6] The unstretched film according to any one of [1] to [5], wherein the axial orientation degree of the PP(110) plane specified by wide-angle X-ray diffraction measurement is 0.85 or more.

[0016] The first aspect of the present invention further relates to the following [7].

[0017] [7] A sealant film comprising a laminate having a sealant film body and a surface layer in this order, wherein the surface layer is an unoriented film of any of the following [1] or [3] to [6] (provided that [1] is directly or indirectly referenced).

[0018] A second aspect of the present invention further relates to the following [8].

[0019] [8] A multilayer sealant film having an outer layer, an intermediate layer, and a sealant layer in that order, wherein the intermediate layer is an unoriented film of any of the [2] or [3] to [6] (with direct or indirect reference to [2]). [Effects of the Invention]

[0020] The unstretched film according to the first aspect of the present invention is excellent in its balance of rigidity and low-temperature heat-sealing performance (i.e., a low sealing start temperature, as described later).

[0021] The unstretched film according to the second aspect of the present invention exhibits excellent rigidity and excellent sealing performance (i.e., a low sealing start temperature, as described later). [Modes for carrying out the invention]

[0022] The following describes embodiments for carrying out the present invention.

[0023] [Unstretched film] The unstretched film according to the first aspect of the present invention comprises a propylene polymer composition (X1) containing a propylene polymer (A) and a propylene-α-olefin copolymer (B1), as described below.

[0024] Furthermore, the unstretched film according to the second aspect of the present invention comprises a propylene polymer composition (X2) containing a propylene polymer (A) and a propylene-α-olefin copolymer (B2), as described below.

[0025] Hereinafter, unless there is a need to distinguish between the propylene-α-olefin copolymer (B1) and the propylene-α-olefin copolymer (B2), they will be collectively referred to as "propylene-α-olefin copolymer (B)".

[0026] Furthermore, if there is no need to distinguish between the propylene polymer composition (X1) and the propylene polymer composition (X2), they may be collectively referred to as "propylene polymer composition (X)".

[0027] Details of the measurement conditions for each requirement are described in the Examples section.

[0028] [Propylene polymer (A)] The propylene polymer (A) contains 20 to 50% by mass of propylene polymer (a1) having an intrinsic viscosity [η] in the range of 10 to 12 dl / g as measured at 135°C in tetralin solvent, and 50 to 80% by mass of propylene polymer (a2) having an intrinsic viscosity [η] in the range of 0.5 to 1.5 dl / g as measured at 135°C in tetralin solvent [provided that the total amount of propylene polymer (a1) and propylene polymer (a2) is 100% by mass].

[0029] Hereinafter, the intrinsic viscosity [η] measured at 135°C in tetralin solvent will also simply be referred to as "intrinsic viscosity [η]". The mass fractions of propylene polymer (a1) and propylene polymer (a2) are based on the total amount of (a1) and (a2).

[0030] <Propylene-based polymer (a1)> The intrinsic viscosity [η] of the propylene polymer (a1) is in the range of 10 to 12 dl / g, preferably in the range of 10.5 to 11.5 dl / g. Furthermore, the mass fraction of the propylene polymer (a1) in the propylene polymer (A) is in the range of 20 to 50 mass%, preferably in the range of 20 to 45 mass%, more preferably in the range of 20 to 40 mass%, and even more preferably in the range of 22 to 40 mass%.

[0031] Examples of propylene-based polymers (a1) include propylene homopolymers and copolymers of propylene and α-olefins having 2 to 8 carbon atoms (excluding propylene). Examples of α-olefins having 2 to 8 carbon atoms include ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Ethylene is preferred among these α-olefins. One or more α-olefins can be used.

[0032] In a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the content of constituent units derived from propylene is usually 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more, and the content of constituent units derived from the α-olefin having 2 to 8 carbon atoms (excluding propylene) is usually 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. The above content ratios are 13 It can be measured by 13C-NMR.

[0033] A propylene polymer (a1) with an intrinsic viscosity [η] in the range of 10 to 12 dl / g is preferable from the viewpoint of suppressing the number of fisheyes (FE) in the film obtained from the polymer composition.

[0034] On the other hand, when the intrinsic viscosity [η] of the propylene polymer (a1) exceeds 12 dl / g, the film moldability tends to deteriorate and the surface appearance of the film tends to worsen. Also, when the intrinsic viscosity [η] of the propylene polymer (a1) is less than 10 dl / g, the resulting film tends to have insufficient rigidity, heat resistance, and gas barrier properties.

[0035] When the mass fraction of the propylene polymer (a1) is less than 20% by mass, the resulting polymer composition tends to have insufficient melt tension, resulting in insufficient rigidity, heat resistance, and gas barrier properties of the resulting film. When it exceeds 50% by mass, it tends to cause defects in appearance during film formation.

[0036] One or more types of propylene polymers (a1) can be used.

[0037] <Propylene-based polymer (a2)> The intrinsic viscosity [η] of the propylene polymer (a2) is in the range of 0.5 to 1.5 dl / g, preferably in the range of 0.6 to 1.5 dl / g, and more preferably in the range of 0.8 to 1.5 dl / g. Furthermore, the mass fraction of the propylene polymer (a2) in the propylene polymer (A) is in the range of 50 to 80% by mass, preferably in the range of 55 to 80% by mass, more preferably in the range of 60 to 80% by mass, and even more preferably in the range of 60 to 78% by mass.

[0038] Examples of propylene-based polymers (a2) include propylene homopolymers and copolymers of propylene and α-olefins having 2 to 8 carbon atoms (excluding propylene). Examples of α-olefins having 2 to 8 carbon atoms include ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Ethylene is preferred among these α-olefins. One or more α-olefins can be used.

[0039] In a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the content of constituent units derived from propylene is usually 90% by mass or more, preferably 93% by mass or more, and more preferably 94% by mass or more, and the content of constituent units derived from the α-olefin having 2 to 8 carbon atoms (excluding propylene) is usually 10% by mass or less, preferably 7% by mass or less, and more preferably 6% by mass or less. The above content ratios are 13 It can be measured by 13C-NMR.

[0040] If the intrinsic viscosity [η] of the propylene polymer (a2) is less than 0.5 dl / g, the resulting polymer composition will have insufficient melt tension, and the fisheye pattern of the resulting film will tend to worsen. If the intrinsic viscosity [η] exceeds 1.5 dl / g, the viscosity will be high, and the film's moldability will tend to deteriorate.

[0041] When the mass fraction of the propylene polymer (a2) is less than 50% by mass, it tends to cause defects in the appearance during film formation. When it exceeds 80% by mass, the melt tension of the resulting polymer composition tends to be insufficient, and the rigidity, heat resistance, and gas barrier properties of the resulting film tend to be insufficient.

[0042] One or more types of propylene polymers (a2) can be used.

[0043] <Additives> The propylene polymer (A) may contain additives such as antioxidants, neutralizing agents, flame retardants, and nucleating agents as needed. One or more additives may be used. The proportion of additives is not particularly limited and can be adjusted as appropriate.

[0044] <Physical properties of propylene polymer (A)> The propylene polymer (A) has a melt flow rate (MFR), measured at 230°C and a 2.16 kg load, preferably in the range of 0.01 to 5 g / 10 min, more preferably 0.05 to 4 g / 10 min, and even more preferably 0.1 to 3 g / 10 min. When the MFR of the propylene polymer (A) is within the above range, it exhibits excellent film moldability.

[0045] The propylene polymer (A) has a melt tension (MT) measured at 230°C preferably in the range of 5 to 30 g, more preferably 7 to 25 g, and even more preferably 10 to 20 g. When the MT of the propylene polymer (A) is within the above range, it exhibits excellent film moldability.

[0046] The melt tension (MT) can be measured using the following equipment and conditions.

[0047] • Equipment: Capillograph 1C manufactured by Toyo Seiki Co., Ltd. (product name) ·Temperature: 230℃ Orifice: L=8mm, D=2.095mm • Extrusion speed: 15 mm / min • Pickup speed: 15m / min The propylene polymer (A) has a high molecular weight region of 1.5 million or more in proportion to the total area of ​​the region enclosed by the molecular weight distribution curve measured by gel permeation chromatography (GPC). This high molecular weight region (corresponding to the mass ratio of high molecular weight components with a molecular weight of 1.5 million or more) is preferably 7% or more, more preferably 10% or more, and even more preferably 12% or more. The upper limit of this area ratio is, for example, 30%, preferably 25%. The fact that the area ratio of the high molecular weight region occupies a specific proportion or more means that the propylene polymer (A) contains high molecular weight components with a molecular weight of 1.5 million or more. At least a portion of these high molecular weight components is a high molecular weight component with an intrinsic viscosity [η] of 10 to 12 dl / g. Therefore, if the proportion of the high molecular weight components is within the above range, the melt tension of the polymer composition will be superior.

[0048] The propylene polymer (A) preferably has two peaks in its molecular weight distribution curve, as measured by GPC. Here, the ratio (MH / ML) of the peak molecular weight MH on the high molecular weight side to the peak molecular weight ML on the low molecular weight side is preferably 50 or more, more preferably 70 or more, and even more preferably 90 or more. The upper limit of the ratio (MH / ML) is, for example, 500, preferably 300. The presence of two peaks in the molecular weight distribution curve and an MH / ML ratio above a specific value indicates a high content of high molecular weight components in the polymer and a high intrinsic viscosity [η]. Therefore, a propylene polymer (A) in this form contributes to improved melt tension, rigidity when formed into a film, and improved heat resistance.

[0049] The propylene polymer (A) has a peak molecular weight ML on the low molecular weight side of the molecular weight distribution curve measured by GPC, which is preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 50,000 or less, from the viewpoint of viscosity and film moldability.

[0050] <Method for producing propylene polymer (A)> Various known methods can be used to produce the propylene polymer (A), including, for example, the method described in sections

[0038] to

[0075] of International Publication No. 2021 / 025142.

[0051] [Propylene-α-olefin copolymer (B)] The propylene-α-olefin copolymer (B1) has a melt flow rate (MFR) of 0.1 to 30 g / 10 min measured at 230°C and a 2.16 kg load, an intrinsic viscosity [η] greater than 1.5 dl / g and less than or equal to 5.0 dl / g measured at 135°C in tetralin solvent, and contains 5.5 mol% or more of structural units derived from α-olefins (excluding propylene).

[0052] Propylene-α-olefin copolymer (B2) is a copolymer having a melt flow rate (MFR) of 0.1 to 30 g / 10 min measured at 230°C and a 2.16 kg load, an intrinsic viscosity [η] greater than 1.5 dl / g and less than or equal to 5.0 dl / g measured at 135°C in tetralin solvent, and containing 1 mol% to less than 5.5 mol% of structural units derived from α-olefins (excluding propylene).

[0053] The intrinsic viscosity [η] of the propylene-α-olefin copolymer (B) is greater than 1.5 dl / g and less than or equal to 5.0 dl / g, preferably greater than 1.5 dl / g and less than or equal to 4.5 dl / g, more preferably greater than 1.5 dl / g and less than or equal to 4.0 dl / g, and even more preferably greater than 1.5 dl / g and less than or equal to 2.5 dl / g. When a propylene-α-olefin copolymer (B) with an intrinsic viscosity [η] within the above range is used, the productivity during film molding is good, and the resulting film has good impact resistance.

[0054] The melt flow rate (MFR) of the propylene-α-olefin copolymer (B), measured at 230°C and a 2.16 kg load, is 0.1 to 30 g / 10 min, preferably 0.3 to 10 g / 10 min, and more preferably 0.5 to 10 g / 10 min. Using a propylene-α-olefin copolymer (B) with an MFR within the above range results in good productivity during film molding and good impact resistance of the resulting film.

[0055] The melting point (Tm) of the propylene-α-olefin copolymer (B1), specifically the melting point (Tm) measured using a differential scanning calorimeter (DSC) under the conditions adopted in the examples described later, is preferably 120 to 170°C, more preferably 125 to 170°C, and even more preferably 125 to 135°C. The melting point (Tm) is preferably within this range from the viewpoint of moldability and heat resistance.

[0056] The melting point (Tm) of the propylene-α-olefin copolymer (B2), specifically the melting point (Tm) measured using a differential scanning calorimeter (DSC) under the conditions adopted in the examples described later, is preferably 120 to 170°C, more preferably 125 to 170°C, even more preferably 130 to 170°C, and particularly preferably 130 to 155°C. The melting point (Tm) is preferably within this range from the viewpoint of moldability and heat resistance.

[0057] The molecular weight distribution (Mw / Mn) of the propylene-α-olefin copolymer (B), as measured by gel permeation chromatography (GPC), is preferably 4.0 or higher, more preferably 4.0 to 6.5, and even more preferably 4.0 to 6.0. Here, Mn is the number-average molecular weight and Mw is the weight-average molecular weight.

[0058] Examples of propylene-α-olefin copolymers (B) include propylene-α-olefin random copolymers, block-type propylene copolymers (a mixture of propylene homopolymer or propylene-α-olefin random copolymer and amorphous or low-crystallinity propylene-α-olefin random copolymer), and random block polypropylene.

[0059] Examples of α-olefins include α-olefins having 2 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 4-methyl-1-pentene, and 3-methyl-1-pentene. Among these α-olefins, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene are preferred. One or more types of α-olefins can be used.

[0060] In the propylene-α-olefin copolymer (B1), the content of constituent units derived from α-olefins (excluding propylene) is 5.5 mol% or more, preferably 5.5 to 9.0 mol%, and more preferably 5.5 to 7.0 mol%, when the total content of constituent units derived from propylene and constituent units derived from α-olefins is taken as 100 mol%.

[0061] In the propylene-α-olefin copolymer (B2), the content of constituent units derived from α-olefins (excluding propylene) is 1 mol% or more and less than 5.5 mol%, preferably 1.5 to 4.5 mol%, and more preferably 2.0 to 4.0 mol%.

[0062] The aforementioned content ratio is, 13 It can be measured by 13C-NMR.

[0063] Propylene-α-olefin copolymer (B) can be produced by copolymerizing propylene with another α-olefin using a catalyst, or commercially available polypropylene resins can be used. Examples of catalysts include those described in International Publication No. 2021 / 025142

[0050] to

[0075] , which are formed from a solid catalyst component having magnesium, titanium, and halogen as essential components, an organometallic compound catalyst component such as an organoaluminum compound, and an electron-donating compound catalyst component such as an organosilicon compound; and metallocene catalysts that use a metallocene compound as one component of the catalyst.

[0064] The propylene polymer (A) and the propylene-α-olefin copolymer (B) may each contain at least one constituent unit derived from biomass monomers (propylene). The monomers of the same type that constitute the polymer may consist only of biomass monomers, only of fossil fuel monomers, or both biomass monomers and fossil fuel monomers. Biomass monomers are monomers derived from any renewable natural raw materials and their residues, including fungi, yeasts, algae, and bacteria, and which are of plant or animal origin, and which contain carbon 14 1 × 10¹¹ C isotopes -12 It contains a certain proportion, and the biomass carbon concentration (pMC) measured according to ASTM D6866 is approximately 100 pMC. Biomass-derived monomers (propylene) can be obtained, for example, by conventionally known methods.

[0065] It is preferable from the viewpoint of reducing environmental impact that the propylene polymer (A) or propylene-α-olefin copolymer (B) contains constituent units derived from biomass-derived monomers. If the polymer production conditions such as polymerization catalyst and polymerization temperature are the same, even if the raw material olefin is a propylene polymer or propylene-α-olefin copolymer containing biomass-derived olefins, 14 1 × 10¹¹ C isotopes -12Aside from the small proportions it contains, its molecular structure is equivalent to that of propylene-based polymers or propylene-α-olefin copolymers composed of fossil fuel-derived monomers. Therefore, its performance is considered to be the same.

[0066] The propylene polymer (A) and the propylene-α-olefin copolymer (B) may contain constituent units derived from at least one type of chemically recycled monomer (propylene). The monomers of the same type constituting the polymer may consist solely of chemically recycled monomers, or they may include chemically recycled monomers, fossil fuel-derived monomers, and / or biomass-derived monomers. Chemically recycled monomers (propylene) can be obtained, for example, by conventionally known methods.

[0067] It is preferable from the viewpoint of reducing environmental impact (mainly waste reduction) that the propylene polymer (A) and the propylene-α-olefin copolymer (B) contain constituent units derived from chemically recycled monomers. Even if the raw material monomers contain chemically recycled monomers, chemically recycled monomers are monomers obtained by depolymerizing polymers such as waste plastics, by thermal decomposition, etc., back to monomer units such as ethylene, and monomers produced using such monomers as raw materials. Therefore, if the polymer production conditions such as polymerization catalysts, polymerization processes, and polymerization temperatures are the same, the molecular structure is equivalent to that of propylene polymers or propylene-α-olefin copolymers made from fossil fuel-derived monomers. Consequently, their performance is also considered to be unchanged.

[0068] [Other ingredients (additives)] The propylene polymer composition (X) may contain additives such as weather stabilizers, heat stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, nucleating agents, decomposing agents, pigments, dyes, plasticizers, hydrochloric acid absorbers, antioxidants, crosslinking agents, crosslinking accelerators, reinforcing agents, fillers, softeners, processing aids, activators, hygroscopic agents, adhesives, flame retardants, and mold release agents, to the extent that it does not impair the objectives of the present invention. One or more additives may be used.

[0069] [Preparation and physical properties of propylene polymer composition (X)] The propylene polymer composition (X) can be produced by any known method, for example, by mixing a propylene polymer (A) and a propylene-α-olefin copolymer (B), and other components as needed, using a Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., or by melt-kneading the mixture using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, rolls, etc., followed by granulation or pulverization.

[0070] In the propylene polymer composition (X1), the content of propylene polymer (A) is 1 to 10 parts by mass, preferably 3 to 10 parts by mass, more preferably 4 to 10 parts by mass, with respect to 100 parts by mass of the total of propylene polymer (A) and propylene-α-olefin copolymer (B1), and the content of propylene-α-olefin copolymer (B1) is 90 to 99 parts by mass, preferably 90 to 97 parts by mass, more preferably 90 to 96 parts by mass.

[0071] The unstretched film according to the present invention, having a content of propylene polymer (A) and propylene-α-olefin copolymer (B) within the above range, exhibits a good balance of rigidity and heat seal performance, as well as a superior appearance when heat-sealed.

[0072] On the other hand, if the content of propylene-α-olefin copolymer (B1) falls below 90 parts by mass, the sealing performance of the film tends to deteriorate, meaning the heat sealing temperature tends to increase, and the appearance of the film may deteriorate after heat sealing. If the content of propylene-α-olefin copolymer (B1) exceeds 99 parts by mass, the rigidity of the film tends to deteriorate, meaning the tensile modulus tends to decrease.

[0073] In the propylene polymer composition (X2), the content of propylene polymer (A) is 1 to 18 parts by mass, preferably 3 to 10 parts by mass, more preferably 4 to 10 parts by mass, with respect to 100 parts by mass of the total of propylene polymer (A) and propylene-α-olefin copolymer (B2), and the content of propylene-α-olefin copolymer (B2) is 82 to 99 parts by mass, preferably 90 to 97 parts by mass, more preferably 90 to 96 parts by mass.

[0074] When the content of propylene-α-olefin copolymer (B2) falls below 82 parts by mass, the sealing performance of the film deteriorates, meaning the heat sealing temperature tends to increase. When the content of propylene-α-olefin copolymer (B2) exceeds 99 parts by mass, the rigidity of the film deteriorates, meaning the tensile modulus tends to decrease.

[0075] In the present invention, from the viewpoint of rigidity and heat resistance, and from the viewpoint of reducing fish eyes, it is preferable to prepare a propylene polymer composition (X) by mixing a propylene polymer (A) containing a propylene polymer (a1) and a propylene polymer (a2) obtained by batch-type multi-stage polymerization with a propylene-α-olefin copolymer (B).

[0076] The molecular weight distribution (Mw / Mn) of the propylene polymer composition (X), as measured by gel permeation chromatography (GPC), is preferably 5.0 or higher, more preferably 5.5 or higher, and even more preferably 6.0 or higher. The upper limit is not particularly limited, but is, for example, 25.

[0077] In this invention, since a propylene polymer (a2), a propylene-α-olefin copolymer (B), and a propylene polymer (a1) with a higher molecular weight than these are used, the molecular weight distribution of the propylene polymer composition (X) is large. Therefore, it is presumed that when the propylene polymer composition (X) is formed into a film, the degree of orientation in the MD direction of the molding increases, and the propylene polymer becomes highly crystallized due to the orientation. For this reason, it is thought that a film with excellent rigidity, heat resistance, and gas barrier properties can be obtained.

[0078] The melt flow rate (MFR) of the propylene polymer composition (X), measured at 230°C and a 2.16 kg load, is typically 1 to 20 g / 10 min, preferably 2 to 15 g / 10 min, and more preferably 3 to 10 g / 10 min.

[0079] [Unstretched film] The unoriented film of the present invention is formed from the propylene-based polymer composition (X). The unoriented film of the present invention exhibits higher rigidity, heat resistance, and gas barrier properties compared to conventional unoriented polypropylene films. The unoriented film can be used, for example, as packaging material for food, beverages, industrial parts, general merchandise, toys, daily necessities, office supplies, medical supplies, and the like.

[0080] The thickness of the unoriented film of the present invention is typically less than 200 μm, preferably 10 to 150 μm, and more preferably 15 to 100 μm. Because the unoriented film of the present invention exhibits excellent rigidity, it is also easy to thin it.

[0081] Furthermore, the degree of axial orientation of the PP(110) plane of the unoriented film of the present invention, as determined by wide-angle X-ray diffraction measurement (details of the measurement method will be described later), is preferably 0.85 or higher, more preferably 0.88 or higher. When the degree of axial orientation is within this range, the molecules are sufficiently oriented, and the tensile modulus of the film increases. The upper limit of the degree of axial orientation may be, for example, 0.91. The value of the degree of axial orientation can be increased or decreased, for example, by changing the film molding speed or by changing the intrinsic viscosity [η] of the propylene polymer (a1).

[0082] Examples of film manufacturing methods include extrusion molding methods such as the T-die method and inflation method, compression molding, calendering, and casting.

[0083] Film forming can be carried out, for example, as follows: The components constituting the propylene polymer composition (X) may be directly put into the hopper of a film forming machine, or the components may be pre-mixed using a ribbon blender, Banbury mixer, Henschel mixer, super mixer, etc., or the propylene polymer composition (X) may be obtained by melt-kneading using a single-screw or twin-screw extruder, roll kneader, etc., and then film forming may be carried out.

[0084] To explain a specific example of film production using the T-die method, the above components are put into an extruder, melted and kneaded at a temperature of usually 180-280°C, preferably 200-270°C, then extruded into a film shape from the die lip of the T-die, this molten film is cooled and taken up by a take-up machine such as a nip roll to obtain the film.

[0085] Methods for cooling molten film include, for example, cooling methods using rolls and air cooling using the air knife method or air chamber method, narrow-pressure cooling methods such as the polishing roll method, swing roll method, and belt cast method, and contact cooling methods using refrigerants such as water cooling.

[0086] The resulting unstretched film can be subjected to film processing methods commonly used in film forming, such as corona discharge treatment and liquid coating treatment.

[0087] [Sealant films and multilayer sealant films] The sealant film of the present invention has an unstretched film according to the first embodiment of the present invention as a surface layer.

[0088] The sealant film of the present invention consists of a laminate having a sealant film body and a surface layer in this order. Examples of methods for manufacturing the sealant film include co-extrusion and extrusion coating.

[0089] The sealant film body and surface layer may each be a single layer or a multi-layer structure.

[0090] The multilayer sealant film of the present invention has an unstretched film according to a second embodiment of the present invention as an intermediate layer.

[0091] The multilayer sealant film of the present invention consists of a laminate having an outer layer, an intermediate layer, and a sealant layer in that order. Examples of methods for manufacturing the multilayer sealant film include co-extrusion and extrusion coating.

[0092] The outer layer, intermediate layer, and sealant layer may each be a single layer or multiple layers.

[0093] Examples of materials for the sealant layer include materials used in conventional sealant layers, such as ethylene-based resins.

[0094] The sealant film body and the outer layer include a base material layer.

[0095] The base layer is made of a material having relatively high rigidity and strength. Examples of the material include films (which may be stretched films) containing at least one thermoplastic resin selected from the group consisting of polyamide resins such as nylon 11 and nylon 12, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin resins such as polyethylene resin and polypropylene resin, polyvinylidene chloride resin, ethylene-vinyl acetate copolymer saponified product, polycarbonate resin, polystyrene resin, and acrylic resin, ceramic vapor-deposited films such as metal foil, metal vapor-deposited film, and inorganic oxide vapor-deposited film, paper, nonwoven fabric, and at least one selected from laminates thereof.

[0096] The thickness of the aforementioned substrate layer is typically around 5 to 50 μm.

[0097] Examples of the sealant film body and the outer layer include, in addition to the base layer, a barrier layer for gases such as water vapor and oxygen, a sound-absorbing layer, a light-shielding layer, an adhesive layer, a bonding layer, a coloring layer, a conductive layer, and a recycled resin-containing layer (these layers, in addition to the base layer, are collectively referred to as "other layers").

[0098] In the sealant film, examples of materials for forming the other layers include olefin polymer compositions other than the propylene polymer composition (X1), gas barrier resin compositions, and adhesive resin compositions.

[0099] In the multilayer sealant film, examples of materials for forming the other layers include olefin polymer compositions other than the propylene polymer composition (X2), gas barrier resin compositions, and adhesive resin compositions.

[0100] The sealant film of the present invention has an unstretched film according to the first embodiment of the present invention as its surface layer, enabling heat sealing at low temperatures, specifically at a sealing start temperature lower than 140°C, preferably 135°C or lower, as described later, and possessing a high tensile modulus. It also exhibits excellent appearance when heat-sealed.

[0101] The multilayer sealant film of the present invention has an unstretched film according to the second embodiment of the present invention as an intermediate layer. Therefore, the intermediate layer contributes to heat sealing at a lower temperature than when a propylene homopolymer is used as the intermediate layer. Furthermore, the multilayer sealant film of the present invention has a higher tensile modulus than when a conventional propylene-α-olefin copolymer is used.

[0102] The non-stretched film, sealant film, and multilayer sealant film of the present invention can be used as packaging films in a wide range of packaging fields, such as various food packaging fields for fresh foods such as vegetables and fish, snacks, dried foods such as noodles, and aquatic foods such as soups and pickles; packaging fields for medical-related products used for various forms of medical products such as tablets, powders, and liquids, and medical peripheral materials; packaging fields for various electrical equipment such as cassette tapes and electrical components.

Examples

[0103] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. The measurement and evaluation of various properties of the polymers, polymer compositions, and non-stretched films obtained in each example were carried out as follows.

[0104] (1) Mass fraction In Production Example 1, the mass fractions of the propylene-based polymer obtained in the first stage (corresponding to the propylene-based polymer (a1)) and the propylene-based polymer obtained in the second stage (corresponding to the propylene-based polymer (a2)) were determined from the amount of heat gradually absorbed from the reaction heat generated during polymerization.

[0105] (2) Intrinsic viscosity [η] The intrinsic viscosity [η] (dl / g) was measured in a tetralin solvent at 135°C. The intrinsic viscosity [η]2 of the propylene-based polymer obtained in the second stage (corresponding to the propylene-based polymer (a2)) is a value calculated from the following formula.

[0106] [η]2 = ([η] total ×100 - [η]1×W1) / W2 [η] total : Intrinsic viscosity of the entire propylene-based polymer [η]1: Intrinsic viscosity of the propylene-based polymer obtained in the first stage W1: Mass fraction (%) of the propylene-based polymer obtained in the first stage W2: Mass fraction (%) of the propylene-based polymer obtained in the second stage

[0107] (3) Comonomer content The measurement was performed using o-dichlorobenzene-d4 as the solvent, under the following conditions: measurement temperature 120°C, spectral width 20 ppm, pulse repetition time 7.0 seconds, and pulse width 6.15 μs (450 pulses) (400 MHz, JEOL ECX400P). 1 The 1H-NMR spectrum was measured, and the comonomer content was calculated.

[0108] (4) Melt Flow Rate (MFR) The melt flow rate (MFR) (g / 10 min) was measured in accordance with JIS-K7210, at a measurement temperature of 230°C and a load of 2.16 kgf (21.2 N).

[0109] (5) Percentage of high molecular weight regions with molecular weight of 1.5 million or more, ML, MH / ML The proportion of the high molecular weight region (molecular weight 1.5 million or more) is the area ratio of the high molecular weight region (molecular weight 1.5 million or more) to the total area enclosed by the molecular weight distribution curve (specifically, the molecular weight distribution curve and the horizontal axis) measured by gel permeation chromatography (GPC) under the following apparatus and conditions. Here, the horizontal axis is molecular weight (logarithmic value), and the vertical axis is dw / dLog(M) [w: integrated mass fraction, M: molecular weight]. The peak molecular weight MH on the high molecular weight side and the peak molecular weight ML on the low molecular weight side of the molecular weight distribution curve were obtained, and MH / ML was calculated.

[0110] GPC measurement device Gel Chromatograph HLC-8321 GPC / HT type (manufactured by Tosoh Corporation) analysis device Data processing software Empower 3 (manufactured by Waters) Measurement conditions Column: TSKgel GMH6-HT×2 + TSKgel GMH6-HTL×2 (All are 7.5mm I.D. x 30cm, manufactured by Tosoh Corporation) Column temperature: 140℃ Mobile phase: o-dichlorobenzene (containing 0.025% BHT) Detector: Differential refractometer Flow rate: 1.0mL / min Sample concentration: 0.1% (w / v) Injection volume: 0.4mL Sampling time interval: 1s Column calibration: Monodisperse polystyrene (manufactured by Tosoh Corporation) Molecular weight conversion: PP conversion / General calibration method (viscosity conversion coefficient K for PS (polystyrene)) PS = 0.000138 dl / g, α PS = 0.700, viscosity conversion coefficient K for PP (polypropylene) PP = 0.000242 dl / g, α PP =0.707)

[0111] (6) Melting point The crystal melting point was determined according to JIS-K7121 by measuring it using a differential scanning calorimeter (DSC, PerkinElmer (Diamond DSC)) under the following measurement conditions. The peak of the endothermic peak in step 4 of the measurement under the following conditions was defined as the crystal melting point (Tm). If there were multiple endothermic peaks, the peak with the maximum height was defined as the crystal melting point (Tm).

[0112] (Measurement conditions) Measurement environment: Nitrogen gas atmosphere Sample amount: 5 mg Sample shape: Pressed film (molded at 230°C, 400 μm thickness) Sample pan: Aluminum sample pan with a flat bottom. Step 1: Heat from 30°C to 200°C at a rate of 320°C / min, and hold for 10 minutes.

[0113] Step 2: Cool down to 30°C at a rate of 20°C / min.

[0114] Step 3: Hold at 30°C for 10 minutes.

[0115] Step 4: Increase the temperature to 200°C at a rate of 20°C / min.

[0116] (7) Film modulus The tensile modulus (MPa) was measured according to the method of JIS K7161. The measurement was performed at 23°C relative to the extrusion direction (MD) of molding. A higher tensile modulus indicates higher rigidity.

[0117] (8) Sealing start temperature Using a Toyo Seiki heat seal tester, 100mm wide and 150mm long test pieces were cut from the film produced in the examples, etc., folded in half, and heat-sealed at a predetermined heater temperature, pressure of 0.2MPa, and sealing time of 1.0 seconds. After that, the sealed test pieces were cut into 15mm wide test pieces, and the peel strength (N / 15mm) was measured using an Orientec Tensilon RT1225 model at a test speed of 300mm / min. The measurement was repeated by changing the heater temperature in 1°C increments to determine the minimum heater temperature required to achieve a peel strength of 2.94N / 15mm or higher (hereinafter referred to as the "seal start temperature").

[0118] (9) Degree of axial orientation Using a wide-angle X-ray diffractometer (Rigaku RINT2550, accessory: rotating sample stage, X-ray source: CuKα, output: 40kV, 370mA, detector: scintillation counter), the sample was fixed to the sample holder with the MD direction as the reference axis, and the azimuthal angle distribution intensity of the crystal plane peak (110) was measured. From the obtained azimuthal angle distribution curve (X-ray interferogram), the degree of orientation F (axial orientation) was calculated and evaluated using the following formula based on the degree of crystallinity and the full width at half maximum (α) of the peak.

[0119] Orientation degree (F)=(180°-α) / 180° (α is the full width at half maximum of the orientation-derived peak)

[0120] [Manufacturing Example 1] (1) Preparation of magnesium compounds A reaction vessel with a stirrer (internal volume 500 liters) was thoroughly purged with nitrogen gas, and 97.2 kg of ethanol, 640 g of iodine, and 6.4 kg of metallic magnesium were added. The reaction was carried out under reflux conditions with stirring until no more hydrogen gas was generated in the system, yielding a solid reaction product. The reaction solution containing this solid reaction product was dried under reduced pressure to obtain the target magnesium compound (support for the solid catalyst).

[0121] (2) Preparation of solid titanium catalyst components In a reaction vessel (internal volume 500 liters) equipped with a stirrer and thoroughly purged with nitrogen gas, 30 kg of the magnesium compound (unpulverized), 150 liters of purified heptane (n-heptane), 4.5 liters of silicon tetrachloride, and 5.4 liters of di-n-butyl phthalate were added. Maintaining the system temperature at 90°C, 144 liters of titanium tetrachloride were added while stirring, and the mixture was reacted at 110°C for 2 hours. After that, the solid components were separated and washed with purified heptane at 80°C. Furthermore, 228 liters of titanium tetrachloride were added, and the mixture was reacted at 110°C for 2 hours, after which it was thoroughly washed with purified heptane to obtain a solid titanium catalyst component.

[0122] (3) Production of prepolymerization catalyst 10 mmol of triethylaluminum, 2 mmol of dicyclopentyl dimethoxysilane, and 1 mmol (in terms of titanium atoms) of the solid titanium catalyst component obtained in (2) above were added to 200 mL of heptane. The internal temperature was maintained at 20°C, and propylene was continuously introduced while stirring. After 60 minutes, stirring was stopped, and a prepolymerization catalyst slurry was obtained in which 4.0 g of propylene was polymerized per 1 g of solid titanium catalyst component.

[0123] (4) This polymerization 336 liters of propylene were placed in a 600-liter autoclave and heated to 60°C. Then, 8.7 mL of triethylaluminum, 11.4 mL of dicyclopentyl dimethoxysilane, and 2.9 g of the prepolymerization catalyst slurry obtained in (3) above were added as a solid titanium catalyst component, and polymerization was started. 75 minutes after the start of polymerization, the temperature was lowered to 50°C over 10 minutes (completion of the first stage of polymerization).

[0124] The intrinsic viscosity [η] of the propylene polymer (a1-1) polymerized under the same conditions as the first stage was 11 dl / g.

[0125] After cooling, hydrogen was continuously added to maintain a constant pressure of 3.3 MPaG, and polymerization was carried out for 151 minutes. Next, the vent valve was opened, and the unreacted propylene was purged through an integrated flow meter (end of the second stage of polymerization).

[0126] Thus, 51.8 kg of powdered propylene polymer was obtained. Based on the mass balance, the proportion of the propylene polymer (a1-1) produced in the first polymerization stage to the total propylene polymer was 25% by mass, the proportion of the propylene polymer (a2-1) produced in the second polymerization stage was 75% by mass, and the intrinsic viscosity [η] was 0.99 dl / g.

[0127] To this propylene polymer, 2000 ppm of Irganox 1010 (BASF), 2000 ppm of Irgaphos 168 (BASF), and 1000 ppm of Sandstab P-EPQ (Clariant Japan) were added as antioxidants, and 1000 ppm of calcium stearate was added as a neutralizing agent. The mixture was then melt-kneaded in a twin-screw extruder to obtain pelletized propylene polymer (A-1). The final MFR of the propylene polymer (A-1) obtained in this way was 1.2 g / 10 min.

[0128] The physical properties of the polymer obtained in Production Example 1 are summarized in Table 1.

[0129] [Table 1] [Manufacturing Example 2] (1) Preparation of magnesium compounds A reaction vessel with a stirrer (internal volume 500 liters) was thoroughly purged with nitrogen gas, and 97.2 kg of ethanol, 640 g of iodine, and 6.4 kg of metallic magnesium were added. The reaction was carried out under reflux conditions with stirring until no more hydrogen gas was generated in the system, yielding a solid reaction product. The reaction solution containing this solid reaction product was dried under reduced pressure to obtain the target magnesium compound (support for the solid catalyst).

[0130] (2) Preparation of solid titanium catalyst components In a reaction vessel (internal volume 500 liters) equipped with a stirrer and thoroughly purged with nitrogen gas, 30 kg of the magnesium compound (unpulverized), 150 liters of purified heptane (n-heptane), 4.5 liters of silicon tetrachloride, and 5.4 liters of di-n-butyl phthalate were added. Maintaining the system temperature at 90°C, 144 liters of titanium tetrachloride were added while stirring, and the mixture was reacted at 110°C for 2 hours. After that, the solid components were separated and washed with purified heptane at 80°C. Furthermore, 228 liters of titanium tetrachloride were added, and the mixture was reacted at 110°C for 2 hours, after which it was thoroughly washed with purified heptane to obtain a solid titanium catalyst component.

[0131] (3) Pretreatment 230 liters of purified heptane were added to a 500-liter reaction vessel equipped with a stirrer. 25 kg of the solid catalyst component, triethylaluminum at a ratio of 1.0 mol / mol relative to the titanium atoms in the solid catalyst component, and dicyclopentyl dimethoxysilane at a ratio of 1.8 mol / mol relative to the titanium atoms in the solid catalyst component were then added. Subsequently, propylene was added at a propylene partial pressure of 0.3 kgf / cm². 2 The mixture was introduced until it reached G, and the reaction was carried out at 25°C for 4 hours. After the reaction was complete, the solid catalyst components were washed several times with purified heptane, and then carbon dioxide was supplied and the mixture was stirred for 24 hours.

[0132] (4) Polymerization In a polymerization apparatus with a stirrer and an internal volume of 200 liters, the treated solid catalyst components were supplied at a rate of 3 mmol / hr (calculated based on the amount of titanium atoms in the component), triethylaluminum at 4 mmol / kg-PP, and dicyclopentyl dimethoxysilane at 1 mmol / kg-PP. The polymerization temperature was 80°C and the polymerization pressure (total pressure) was 28 kgf / cm². 2 Propylene, ethylene, 1-butene, and hydrogen were reacted in a reaction chamber (G). During this reaction, the supply amounts of ethylene, 1-butene, and hydrogen were adjusted to achieve the desired ethylene and 1-butene content and MFR (Method Factor Reaction Rate). Composition analysis (gas chromatography) of the gas section inside the polymerization apparatus showed an ethylene concentration of 3.5 mol%, a 1-butene concentration of 4.9 mol%, and a hydrogen concentration of 2.5 mol%.

[0133] To the propylene-ethylene-1-butene copolymer obtained in this way, 2000 ppm of Irganox 1010 (BASF), 2000 ppm of Irgaphos 168 (BASF), and 1000 ppm of Sandstab P-EPQ (Clariant Japan) were added as antioxidants, and 1000 ppm of calcium stearate was added as a neutralizing agent. The mixture was then melt-kneaded in a twin-screw extruder to obtain pelletized propylene-ethylene-1-butene random copolymer (B-1).

[0134] [Manufacturing Example 3] In step (4) Polymerization, the ethylene supply, 1-butene supply, and hydrogen supply were adjusted so that the ethylene concentration (gas chromatography analysis) of the gas section inside the polymerization apparatus was 2.0 mol%, the 1-butene concentration was 0 mol%, and the hydrogen concentration was 5.5 mol%. Otherwise, pelletized propylene-ethylene random copolymer (B-2) was obtained in the same manner as in Production Example 2.

[0135] [Manufacturing Example 4] In step (4) Polymerization, the ethylene supply, 1-butene supply, and hydrogen supply were adjusted so that the ethylene concentration (gas chromatography analysis) of the gas section inside the polymerization apparatus was 1.6 mol%, the 1-butene concentration was 0 mol%, and the hydrogen concentration was 4.2 mol%. Otherwise, pelletized propylene-ethylene random copolymer (B-3) was obtained in the same manner as in Production Example 2.

[0136] [Manufacturing Example 5] In step (4) Polymerization, the ethylene supply, 1-butene supply, and hydrogen supply were adjusted so that the ethylene concentration (gas chromatographic analysis) of the gas portion inside the polymerization apparatus was 1.7 mol%, the 1-butene concentration was 4.0 mol%, and the hydrogen concentration was 2.3 mol%. Otherwise, the process was carried out in the same manner as in Production Example 2 to obtain pelletized propylene-ethylene-1-butene random copolymer (B-4).

[0137] [Manufacturing Example 6] In step (4) Polymerization, the ethylene supply, 1-butene supply, and hydrogen supply were adjusted so that the ethylene concentration (gas chromatographic analysis) of the gas portion inside the polymerization apparatus was 1.3 mol%, the 1-butene concentration was 0 mol%, and the hydrogen concentration was 3.5 mol%. Otherwise, pelletized propylene-ethylene random copolymer (B-5) was obtained in the same manner as in Production Example 2.

[0138] [Manufacture example 7: F-704NP] Prime Polymer Co., Ltd.'s product "Prime PolyPro F-704NP" was used. For convenience, this is labeled as a manufacturing example.

[0139] The physical properties of the polymers obtained in manufacturing examples 2-7 are summarized in Table 2.

[0140] [Table 2] [Reference examples and comparative examples relating to the first aspect of the present invention] [Reference example 1-1] A 25 μm thick unstretched film was prepared from 5 parts by mass of the propylene polymer (A-1) obtained in Production Example 1 and 95 parts by mass of the propylene-ethylene-1-butene random copolymer (B-1) obtained in Production Example 2, using an unstretched film molding machine with a 75 mm screw diameter extruder (1 unit) connected to a 600 mm wide single-layer die, under the following molding conditions.

[0141] ·Resin temperature: 248℃ • Chill temperature: 30°C ·Forming speed: 150m / min The physical properties of the film are shown in Table 3.

[0142] [Reference Example 1-2, Comparative Examples 1-1 to 1-6] An unstretched film was prepared in the same manner as in Reference Example 1-1, except that the compound composition was changed as shown in Table 3.

[0143] [Table 3] [Examples and comparative examples according to a second aspect of the present invention] [Example 2-1] An unstretched film with a thickness of 25 μm was prepared from 5 parts by mass of the propylene polymer (A-1) obtained in Production Example 1 and 95 parts by mass of the propylene-ethylene random copolymer (B-3) obtained in Production Example 4, using an unstretched film molding machine with a screw diameter of 75 mm (1 unit) connected to a single-layer die with a width of 600 mm, under the molding conditions described below.

[0144] ·Resin temperature: 248℃ • Chill temperature: 30°C ·Forming speed: 150m / min The physical properties of the film are shown in Table 4.

[0145] [Examples 2-2 to 2-5, Comparative Examples 2-1 to 2-8] An unstretched film was prepared in the same manner as in Example 2-1, except that the compound composition was changed as shown in Table 4.

[0146] The results above are summarized in Table 4.

[0147] [Table 4]

Claims

1. A propylene polymer (A) containing 20 to 50% by mass of a propylene polymer (a1) having an intrinsic viscosity [η] in the range of 10 to 12 dl / g as measured at 135°C in tetralin solvent, and 50 to 80% by mass of a propylene polymer (a2) having an intrinsic viscosity [η] in the range of 0.5 to 1.5 dl / g as measured at 135°C in tetralin solvent [provided that the total amount of propylene polymer (a1) and propylene polymer (a2) is 100% by mass], It contains a propylene-α-olefin copolymer (B2) having a melt flow rate (230°C, 2.16 kg load) of 0.1 to 30 g / 10 min, an intrinsic viscosity [η] measured at 135°C in tetralin solvent greater than 1.5 dl / g and less than or equal to 5.0 dl / g, and containing 1 mol% or more and less than 5.5 mol% of constituent units derived from α-olefins (excluding propylene), An unstretched film comprising a propylene polymer composition (X2) wherein, with a total of 100 parts by mass of the propylene polymer (A) and the propylene-α-olefin copolymer (B2), the content of the propylene polymer (A) is 1 to 18 parts by mass, and the content of the propylene-α-olefin copolymer (B2) is 82 to 99 parts by mass.

2. The unstretched film according to claim 1, wherein the melt flow rate (MFR) of the propylene polymer (A), measured at 230°C and a 2.16 kg load, is 0.01 to 5 g / 10 min.

3. The unstretched film according to claim 1, wherein the propylene polymer (A) has an area ratio of 7% or more of the area of ​​the high molecular weight region with a molecular weight of 1.5 million or more in the total area of ​​the region enclosed by the molecular weight distribution curve measured by gel permeation chromatography (GPC).

4. The unstretched film according to claim 1, wherein the propylene polymer (A) has a molecular weight distribution curve measured by GPC that has two peaks, and the ratio of the peak molecular weight MH on the high molecular weight side to the peak molecular weight ML on the low molecular weight side (MH / ML) is 50 or more.

5. The unstretched film according to claim 1, wherein the axial orientation of the PP(110) plane, as determined by wide-angle X-ray diffraction measurement, is 0.85 or greater.

6. A multilayer sealant film having an outer layer, an intermediate layer, and a sealant layer in this order, wherein the intermediate layer is the unstretched film described in claim 1.

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