Propylene-based polymer composition and use thereof

Abstract

Provided are: a stretched film which has a good balance between stretchability and heat resistance, has a sufficiently small thermal shrinkage rate (temperature: 150° C), and has good printability; and a propylene-based polymer composition from which the stretched film can be obtained.　Specifically provided are: a propylene-based polymer composition which is characterized by satisfying the below-mentioned requirements (1) to (6); and an extruded sheet, a stretched film and a multilayer film, each of which is obtained from the composition.　Requirement (1): the mesopentad fraction is 95% or more, requirement (2): the comonomer content is 0.2 mol% or less, requirement (3): the MFR is 1-10 g / 10 min, requirement (4): the ratio Mw / Mn of the mass average molecular weight Mw to the number average molecular weight Mn is 5.5 or less, requirement (5): the ratio MZ+1 / Mn of the Z+1 average molecular weight MZ+1 to the number average molecular weight Mn is 50 or more, and requirement (6) the Z+1 average molecular weight MZ+1 is 2,500,000 or more.

Description

Propylene-based polymer composition and its use

[0001] The present invention relates to a propylene polymer composition and uses thereof, such as a stretched film.

[0002] More specifically, the present invention relates to a propylene-based polymer composition and a stretched film obtained therefrom which has a good balance between stretchability and heat resistance and has good printability.

[0003] Biaxially oriented polypropylene (OPP) films are widely used as industrial and food films, and are in high demand. Aiming to further expand demand for OPP, efforts are being made to improve its performance. Among these efforts is the reduction of heat shrinkage (several tens of percent at 150°C). However, for OPP, whose main constituent is a unit derived from propylene, reducing the heat shrinkage (at 150°C) is not easy and involves considerable difficulty.

[0004] Patent Document 1 discloses a stretched polypropylene film. Its mass average molecular weight (Mw) / number average molecular weight (Mn) ratio is 5.5 or more, and it has a relatively wide molecular weight distribution. This stretched film does not have a sufficiently small heat shrinkage rate (at 150°C).

[0005] 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 the amount of sticky components increases, resulting in poor printability.

[0006] 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.

[0007] JP 2014-55276 JP 2022-148047 JP 2021-161381

[0008] An object of the present invention is to provide a stretched film that has a good balance between stretchability and heat resistance, a sufficiently small heat shrinkage rate (at 150°C), and good printability, and a propylene polymer composition from which the same can be obtained.

[0009] The present invention includes any one of the following aspects [1] to [6].

[0010] [1] A propylene polymer composition satisfying the following requirements 1) to 6):

[0011] Requirement 1) Mesopentad fraction is 95% or more. Requirement 2) Comonomer content is 0.2 mol% or less. Requirement 3) MFR is 1 to 10 g / 10 min. Requirement 4) Ratio of mass average molecular weight Mw to number average molecular weight Mn, Mw / Mn, is 5.5 or less. Requirement 5) Z+1 average molecular weight M Ｚ＋１ and the ratio M Ｚ＋１ Requirement 6) Z+1 average molecular weight M Ｚ＋１ [2] The propylene polymer composition according to the above [1], wherein the cold xylene solubles (CXS) is 1.2 mass% or less.

[0012] [3] The propylene polymer composition according to either of the above [1] or [2], comprising the following propylene polymers, Polymer A, Polymer B, and Polymer C, in the following proportions, respectively, wherein the MFR of Polymer A is larger than the MFR of Polymer B, or the Mw / Mn of Polymer A is the same as or smaller than the Mw / Mn of Polymer B.

[0013] Polymer A: 70 to 98 mass% of polymer A having an MFR of 1 g / 10 min or more and less than 9 g / 10 min; Polymer B: 1 to 20 mass% of polymer B having an ethylene content of 1 mol% or less and an Mw / Mn of 5.0 to 10.0; and Polymer C: 1 to 10 mass% of polymer C having an MFR of 9 to 100 g / 10 min and an Mw / Mn of less than 5.0 (the total of polymer A, polymer B and polymer C is defined as 100 mass%). [4] An extruded sheet obtained from the propylene polymer composition according to any one of [1] to [3] above.

[0014] [5] A uniaxially or biaxially stretched film obtained from the propylene polymer composition according to any one of [1] to [3] above.

[0015] [6] A multilayer film having the stretched film according to [5] above in at least one layer.

[0016] According to the present invention, it is possible to provide a stretched film that has a good balance between stretchability and heat resistance, a small heat shrinkage rate (at 150°C), little stickiness, and good printability, and a propylene polymer composition from which the same can be obtained.

[0017] FIG. 1 shows the relationship between the stretchability indicated by the value of Fm / Fy and the shrinkage rate (%) in the TD direction for Example 1 and Comparative Examples 1 to 4.

[0018] The following describes the respective components of the polypropylene polymer composition of the present invention, and the extruded sheet and uniaxially or biaxially stretched film obtained therefrom. <Propylene Polymer Composition> The propylene polymer composition of the present invention is characterized by satisfying the following requirements 1) to 6).

[0019] Requirement 1) Mesopentad fraction is 95% or more. Requirement 2) Comonomer content is 0.2 mol% or less. Requirement 3) MFR is 1 to 10 g / 10 min. Requirement 4) Ratio of mass average molecular weight Mw to number average molecular weight Mn, Mw / Mn, is 5.5 or less. Requirement 5) Z+1 average molecular weight M Ｚ＋１ and the ratio M Ｚ＋１Requirement 6) Z+1 average molecular weight M Ｚ＋１ Each requirement is explained below. Regarding requirement 1), the mesopentad fraction ([mmmm]%) of the propylene polymer 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.

[0020] The mesopentad fraction ([mmmm]%) is an index showing the stereoregularity of the propylene polymer composition, and within this range, the composition exhibits high crystallinity and a small heat shrinkage rate (at 150° C.).

[0021] The mesopentad fraction ([mmmm]%) is １３ The content of the comonomer in the propylene polymer composition of the present invention is 0.2 mol % or less.

[0022] Examples of the propylene polymer composition of the present invention include various propylene resin compositions. The propylene polymer used in the propylene polymer composition of the present invention includes various propylene polymers, including propylene resins. A homopolypropylene consisting solely of units derived from propylene is preferred. However, a copolymer with a comonomer may also be used. In such a case, the comonomer content is 0.2 mol % or less. Preferably, the comonomer content is 0.1 mol % or less. Examples of comonomers include ethylene and α-olefins having 4 to 8 carbon atoms, with ethylene and 1-butene being preferred. Within this range, the heat shrinkage rate (at 150°C) is reduced. Regarding requirement 3), the propylene polymer composition has an MFR (melt flow rate, 230°C, load 2.16 kgf) of 1 to 10 g / 10 min. Furthermore, 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, and more preferably 8.0 g / 10 min. By setting the upper limit in this range, the heat shrinkage at high temperatures can be reduced. Regarding requirement 4), the ratio Mw / Mn of the mass average molecular weight (Mw) to the number average molecular weight (Nw) of the propylene-based polymer composition of the present invention is 5.5 or less.

[0023] Mw and Mn are determined by gel permeation chromatography (GPC), and the details of how to determine them will be explained in the Examples.

[0024] The upper limit of the Mw / Mn value is preferably 5.0. The lower limit is preferably 2.0, more preferably 2.5. By setting the value in this range, the heat shrinkage rate at high temperatures can be reduced. Regarding requirement 5) The Z+1 average molecular weight M of the propylene-based polymer composition of the present invention is Ｚ＋１ and the ratio M Ｚ＋１ / Mn is 50 or more. The lower limit of this ratio is preferably 60 or more, and more preferably 70 or more. The upper limit is generally about 300 or less, and preferably 200 or less. In addition to the above, MＺ＋１ In one embodiment, the range of / Mn is preferably 50 or more and 80 or less, more preferably 50 or more and 70 or less.

[0025] 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:

[0026] Z+1 average molecular weight M Ｚ＋１ =Σ(Xi·Mi ４ ) / Σ(Xi·Mi ３ ) (Each Σ represents the sum of the values ​​at all elution positions.

[0027] That is, the sum of the weight fractions Xi is ΣXi=1.) Details of the measurement will be explained in the examples.

[0028] M Ｚ＋１ / Mw indicates a 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 represents the sum of the values ​​at all elution positions.

[0029] That is, the sum of the weight fractions Xi is ΣXi=1.) and Mn, Ｚ Regarding requirement 6), the Z+1 average molecular weight M of the propylene polymer composition is expressed by emphasizing the contribution of the molecular weight more than the Z+1 average molecular weight M of the propylene polymer composition. Ｚ＋１ is 2,500,000 or more. The lower limit is preferably 2,600,000 or more. Furthermore, it is more preferably 2,700,000 or more. The upper limit is usually 4,000,000 or less, and preferably 3,800,000 or less. Within this range, the high molecular weight component is sufficient, and the effects of the present invention are easily obtained. Furthermore, stretch molding of a stretched film can be performed stably.

[0030] The propylene polymer composition of the present invention preferably has a cold xylene soluble fraction (CXS) of 1.2% by mass or less, more preferably 1.0% by mass or less. Of these, 0.8% by mass or less is even more preferable. The cold xylene soluble fraction (CXS) is generally 0.1% by mass or more. The cold xylene soluble fraction (CXS) can be determined by the following method. Cold xylene soluble fraction (CXS) (unit: mass%) 2 g of a sample made of a propylene 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.

[0031] After 48 hours, the precipitate and filtrate are separated by filtration, and after evaporating the p-xylene from the filtrate, the filtrate is 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 the CXS.

[0032] 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 with high stereoregularity.

[0033] When the CXS is within the above range, the crystallinity of the propylene polymer is sufficiently high, and the high-temperature heat shrinkage (at 150° C.) of the stretched film obtained from the polymer can be made smaller.

[0034] Furthermore, the ink is less sticky and has good printability.

[0035] The melting point of the propylene polymer composition of the present invention is usually 145 to 170° C. The lower limit is preferably 150° C. or higher, more preferably 155° C. or higher. The upper limit is preferably 170° C. or lower, more preferably 168° C. or lower.

[0036] The propylene polymer composition of the present invention that satisfies the above requirements 1) to 6) can be produced by various methods, such as by producing propylene polymers having different molecular weights through multistage polymerization to form a composition, by producing propylene polymers having different molecular weights through polymerization and then blending them in a kneader to form a composition, or by polymerizing propylene polymers using a plurality of polymerization catalysts having different performances to form a composition.

[0037] The polymerization catalyst used may be a Ziegler-Natta catalyst, a metallocene catalyst, or the like, and the molecular weight of the propylene polymer may be adjusted by adjusting the amount of hydrogen present in the polymerization system. Two or more propylene polymers may be blended together by mixing or melt-kneading the propylene polymers simultaneously or sequentially using a mixing device such as a Banbury mixer, a single-screw extruder, or a twin-screw extruder.

[0038] The propylene polymer used in the present invention may be a propylene homopolymer or a copolymer of propylene with ethylene or an α-olefin having 4 to 20 carbon atoms as a comonomer, as long as it satisfies the above requirements 1) to 6). 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.

[0039] 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 biomass-derived propylene alone, 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 a plant-derived or animal-derived material, including fungi, yeast, algae, and bacteria, and its residues, and contains propylene as carbon. １４ C isotope 10 ―１２The propylene polymer contains biomass-derived propylene in a proportion of about 100 pMC, and has a biomass carbon concentration (pMC) of about 100 pMC as measured in accordance with ASTM D 6866. Biomass-derived propylene can be 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 greenhouse gas emissions). 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 homopolymer, which is made from fossil fuel-derived propylene. Therefore, its performance is said to be the same.

[0040] The propylene-based polymer used in the present invention may contain propylene or a comonomer such as ethylene that constitutes the polymer derived from chemical recycling. For example, the propylene that constitutes the polymer may be solely propylene derived from chemical recycling, or may contain propylene derived from chemical recycling together with fossil fuel-derived propylene and / or biomass-derived propylene. Chemical recycling-derived propylene can be obtained by a conventionally known method. It is preferable that the propylene-based polymer of the present invention contain propylene derived from chemical recycling from the viewpoint of reducing environmental impact (mainly waste reduction). 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 plastics back into a monomer unit such as propylene, or a monomer produced using such a monomer as a raw material. Therefore, if the polymer production conditions, such as the polymerization catalyst, polymerization process, and polymerization temperature, are equivalent, the molecular structure of the propylene-based polymer is equivalent to that of a propylene-based polymer derived from a monomer derived from fossil fuel.

[0041] Therefore, the performance is said to be unchanged.

[0042] The propylene polymer composition of the present invention contains the following propylene polymers, Polymer A, Polymer B, and Polymer C, in the following proportions, respectively, and is characterized in that the MFR of Polymer A is larger than the MFR of Polymer B, or the Mw / Mn of Polymer A is the same as or smaller than the Mw / Mn of Polymer B, and is preferably produced by blending these polymers in the following proportions.

[0043] Polymer A: MFR of 1 g / 10 min or more and less than 9 g / 10 min, 70 to 98 mass% Polymer B: ethylene content of 1 mol% or less and Mw / Mn of 5.0 to 10.0, 1 to 20 mass% Polymer C: MFR of 9 to 100 g / 10 min and Mw / Mn of less than 5.0, 1 to 10 mass% (The total of Polymer A, Polymer B, and Polymer C is 100 mass%) Polymer A, Polymer B, and Polymer C are described below. <Polymer A> Polymer A, which is a propylene polymer, has an MFR (melt flow rate, 230°C, load 2.16 kgf) of 1 g / 10 min or more and less than 9 g / 10 min.

[0044] The polymer A preferably has the following physical properties in the ranges below.

[0045] That is, the mesopentad fraction ([mmmm]%) of polymer A is preferably 95% or more, more preferably 96% or more, and even more preferably 97% or more. The upper limit is preferably 99.5% or less.

[0046] Polymer A is preferably a so-called homopolypropylene consisting only of units derived from propylene, but may also be a copolymer with a comonomer, in which case the comonomer content is preferably 0.2 mol % or less, more preferably 0.1 mol % or less. Examples of comonomers include ethylene and α-olefins having 4 to 8 carbon atoms, and among these, ethylene and 1-butene are preferred.

[0047] The MFR (melt flow rate, 230°C, load 2.16 kgf) of polymer A is 1 g / 10 min or more and less than 9 g / 10 min, preferably with a lower limit of 2.0 g / 10 min, more preferably 2.5 g / 10 min, and more preferably with an upper limit of 8.0 g / 10 min.

[0048] The Mw / Mn of polymer A is preferably 5.5 or less, more preferably 5.0 or less, and the lower limit is preferably 2.0 or more, more preferably 2.5 or more.

[0049] M of polymer A Ｚ＋１ / Mn is preferably 20 or more, more preferably 25 or more, and particularly preferably 28 or more. The upper limit is generally about 300, and preferably 200 or less.

[0050] M of polymer A Ｚ＋１ is preferably 1,500,000 or more, more preferably 1,800,000 or more. The upper limit is usually 4,000,000 or less, preferably 3,800,000 or less.

[0051] Furthermore, the polymer A preferably has a cold xylene solubles (CXS) content of 1.2 mass% or less. <Polymer B> The polymer B, which is a propylene-based polymer, has a comonomer content of 1 mol% or less and an Mw / Mn ratio of 5.0 to 10.0.

[0052] Polymer B preferably has physical properties in the following ranges.

[0053] That is, the mesopentad fraction ([mmmm]%) of polymer B is preferably 95% or more, more preferably 96% or more, and even more preferably 97% or more. The upper limit is preferably 99.5% or less.

[0054] Polymer B may be a so-called homopolypropylene consisting only of units derived from propylene, or may be a copolymer with a comonomer, in which case the comonomer content is 1 mol % or less, more preferably 0.8 mol % or less. Examples of the comonomer include ethylene and α-olefins having 4 to 8 carbon atoms, with ethylene being preferred.

[0055] The MFR (melt flow rate, 230°C, load 2.16 kgf) of polymer B is not particularly limited, but is preferably 0.1 g / 10 min or more, and the upper limit is preferably 4.0 g / 10 min. The upper limit of MFR is more preferably less than 1, even more preferably 0.9 or less, and particularly preferably 0.5 or less.

[0056] The Mw / Mn of polymer B is 5.0 to 10.0, preferably 6 to 9.

[0057] M of polymer B Ｚ＋１ / Mn is preferably 50 or more, more preferably 60 or more, and particularly preferably 70 or more. The upper limit is generally 300 or less, and preferably 200 or less.

[0058] M of polymer B Ｚ＋１ is preferably 3,000,000 or more, more preferably 4,500,000 or more, and particularly preferably 6,000,000 or more. The upper limit is usually 10,000,000 or less, and preferably 8,000,000 or less.

[0059] Furthermore, the cold xylene solubles (CXS) of Polymer B is preferably 1.2 mass% or less. <Polymer C> Polymer C, which is a propylene-based polymer, has an MFR of 9 to 100 g / 10 min and an Mw / Mn of less than 5.0.

[0060] The polymer C preferably has the following physical properties in the ranges below.

[0061] That is, the mesopentad fraction ([mmmm]%) of polymer C is preferably 95% or more, more preferably 96% or more, and even more preferably 97% or more. The upper limit is preferably 99.5% or less.

[0062] Polymer C may be a so-called homopolypropylene consisting only of units derived from propylene, or may be a copolymer with a comonomer, in which case the comonomer content is 1 mol % or less, more preferably 0.8 mol % or less. Examples of the comonomer include ethylene and α-olefins having 4 to 8 carbon atoms, with ethylene being preferred.

[0063] The MFR (melt flow rate, 230° C., load 2.16 kgf) of polymer C is 9 to 100 g / 10 min, preferably 20 to 100 g / 10 min, and more preferably 40 to 100 g / 10 min.

[0064] The Mw / Mn of polymer C is less than 5.0, but is preferably 4.5 or less, and the lower limit is preferably 2.0 or more, more preferably 2.5 or more.

[0065] M of polymer C Ｚ＋１ / Mn is preferably 50 or less, more preferably 40 or less, and particularly preferably 30 or less. The lower limit is generally about 8, and preferably 10 or more.

[0066] M of polymer C Ｚ＋１ is preferably 2,000,000 or less, more preferably 1,000,000 or less, and particularly preferably 800,000 or less. The lower limit is usually 200,000 or more, and preferably 400,000 or more.

[0067] Furthermore, the polymer C preferably has a cold xylene solubles (CXS) content of 1.2 mass % or less.

[0068] The propylene polymer composition of the present invention is preferably prepared from 70 to 98 mass% of polymer A, 1 to 20 mass% of polymer B, and 1 to 10 mass% of polymer C, and particularly preferably from 72 to 90 mass% of polymer A, 3 to 15 mass% of polymer B, and 2 to 8 mass% of polymer C. (The total of polymer A, polymer B, and polymer C is defined as 100 mass%.) Various additives such as heat stabilizers, weather stabilizers, antioxidants, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers may be added to the propylene polymer composition of the present invention, as needed, within limits that do not impair the object of the present invention.

[0069] 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 powdered silica, polymethyl methacrylate powder, silicone resins, etc.

[0070] Examples of slip agents include bisamides such as ethylene bisstearamide, and higher fatty acid amides such as oleic acid amide and erucic acid amide.

[0071] 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.

[0072] 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. <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. Molding methods include extrusion molding, such as sheet molding, T-die film molding, stretched film molding, calender molding, and inflation molding.

[0073] The extruded sheet generally 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.

[0074] 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.

[0075] The stretching ratio is usually 1.5 to 10 times for a uniaxially stretched film, and 1.5 to 7 times in the machine direction and 2 to 10 times in the transverse direction for a sequentially biaxially stretched film.

[0076] The stretching temperature is usually 100 to 140° C. for uniaxial stretching and simultaneous biaxial stretching, and in sequential biaxial stretching, the stretching temperature in the machine direction is usually 100 to 140° C. and the stretching temperature in the transverse direction is usually 140 to 180° C. The thickness of the uniaxially or biaxially stretched film is 5 μm or more, preferably 5 to 100 μm.

[0077] The uniaxially or biaxially stretched film of the present invention is obtained from a characteristic propylene polymer composition, and not only has excellent mechanical strength, rigidity properties, and optical properties but also has a small heat shrinkage rate (at 150°C), and it is expected that its use in a wide range of applications such as industrial packaging materials, food packaging, textile packaging, etc. will expand, further increasing demand. <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.

[0078] Examples of 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, and other films, as well as sheets made of these films, aluminum foil, paper, and the like.

[0079] As a method for laminating the uniaxially or biaxially stretched film etc. of the present invention with the other layer, a commonly used lamination method can be employed, and in addition to forming these multilayer films by multilayer coextrusion, an adhesive layer can be provided between the uniaxially or biaxially stretched film etc. and the other layer. For example, a method of applying a urethane-based or isocyanate-based anchor coating agent to the other layer and then dry-laminating the uniaxially or biaxially stretched film of the present invention, or a method of extrusion laminating or extrusion coating the other layer onto the uniaxially or biaxially stretched film can be employed.

[0080] 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, and polyamide layer / polyvinylidene chloride layer / polyester layer / biaxially oriented film.

[0081] The multilayer film of the present invention has excellent seal strength (peel strength) and blocking resistance when a portion of the film is used in a heat-sealed portion for uniaxial or biaxial stretching. Furthermore, the other layers of the multilayer film provide mechanical strength, gas barrier properties, and other functions, and it is expected to be used in a wider range of applications as a variety of packaging materials. [Examples] Next, the present invention will be explained in more detail through examples and comparative examples, but the present invention is not limited to these examples. <Mesopentad fraction (unit: %)> The mesopentad fraction (mmmm fraction) is a value determined by the assignments shown in A. Zambelli et al., Macromolecules, 8, 687 (1975), 13 Measurement was carried out by C-NMR under the following conditions. The mesopentad fraction is a value expressed by the following formula:

[0082] Mesopentad fraction = ((peak area at 21.7 ppm) / (peak area at 19 to 23 ppm)) × 100 Measurement conditions Apparatus: JNM-Lambda 400 (trade name, manufactured by JEOL Ltd.) Resolution: 400 MHz Measurement temperature: 125°C Solvent: 1,2,4-trichlorobenzene / deuterated benzene = 7 / 4 (mass ratio) Pulse width: 7.8 μsec Pulse interval: 5 sec Number of accumulations: 2000 Shift reference: TMS = 0 ppm Mode: Single pulse broadband decoupling <Content of ethylene as a comonomer in propylene-based polymer (unit: mol%)> When the propylene-based polymer contains ethylene as a comonomer, the content is １３ It is measured using Fourier transform infrared spectroscopy (FTIR) calibrated with C-NMR.

[0083] -CH of the film used as a sample (thickness: about 300 μm, multiple films may be stacked as necessary) ２ -Absorption peak area 775-670 cm -１ (0.2-3% ethylene) or 758-702 cm -１ (3-33% ethylene) absorption peak. <MFR (unit: g / 10 min)> The MFR (melt flow rate) of the propylene polymer was measured in accordance with JIS K7210 at 230°C under a load of 2.16 kgf. <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 and using the calculated values, Mw / Mn and M Ｚ＋１ , M Ｚ＋１ / Mn was obtained. Apparatus: HLC-8321GPC / HT (detector: RI) Column: TSK gel guard column H ＨＲ (30) HT (7.5 mm I.D. x 7.5 cm) x 1 and TSKgel GMH ＨＲThree connected -H(20)HT (7.8 mm ID x 30 cm) tubes (manufactured by Tosoh Corporation). Eluent: 1,2,4-trichlorobenzene (GPC grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) + BHT (0.05%). Flow rate: 1.0 mL / min. Detection conditions: polarity = (-). Injection volume: 0.3 mL. Column temperature: 140°C. System temperature: 40°C. Sample concentration: 1 mg / mL. Pretreatment: The sample was weighed, TCB (without BHT) was added, and the mixture was dissolved by shaking at 140°C for 1 hour. The mixture was then heated and filtered using a sintered filter with a pore size of 0.5 μm (visually confirmed to be free of insoluble matter). Calibration curve: A quintic approximation curve using standard polystyrene manufactured by Tosoh Corporation. The molecular weight was converted to PP equivalent molecular weight using the Q factor. <Cold xylene soluble fraction (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 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 the CXS. Physical properties of biaxially stretched film <Tensile modulus (unit: MPa)> The tensile modulus (MPa) of the biaxially stretched film was measured in accordance with JIS K7127 under the following conditions.

[0084] (Measurement Conditions) A sample of biaxially stretched film was cut into a strip of 10 mm width and 150 mm length and stretched at a crosshead speed of 500 mm / min in a tensile test. The machine direction was defined as MD, and the direction perpendicular to MD as TD. <Heat Shrinkage (Temperature 150°C) (Unit: %)> The sample of biaxially stretched film was placed in a hot air oven and heated for 15 minutes in an atmosphere of 150°C. The heat shrinkage was defined as 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. <Stretchability> (Fm / Fy) Evaluation was performed using the following method, with reference to Satoshi Tamura, Kuramoto Kuramoto, and Toshitaka Kanai, Proceedings of the 17th Autumn Meeting of the Society of Plastics Molding and Processing (November 6-7, 2009, Nagasaki).

[0085] An unstretched raw sheet approximately 150 mm wide was prepared using a 30 mmφ sheet forming machine (manufactured by GM Engineering), and cut into a length of 90 mm x width of 90 mm. The sheet was stretched 5 times in the machine direction (MD) at a stretching temperature of 153°C for a preheating time of 90 seconds in a table tenter biaxial stretching machine (manufactured by Bruckner) and 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 ratio of these stretching forces, Fm / Fy, was calculated as an index of stretchability.

[0086] The Fm / Fy value is an index showing the stretchability when the film is stretched, and a larger value indicates better stretchability. Example 1 In Example 1, a propylene-based polymer composition containing polymer A, polymer B, and polymer C shown in Table 2 in the proportions shown in Table 2 was used. The physical property values ​​of this composition are as shown in Tables 1 and 2.

[0087] However, the following were used: Polymer A: A commercially available propylene polymer (manufactured by Prime Polymer Co., Ltd., trade name F133A) Polymer B (1) Polymer B-1: The polymer obtained in the following Reference Example (Polymer B-1) was used. (2) Polymer B-2: A commercially available propylene polymer (manufactured by Prime Polymer Co., Ltd., trade name E-100GV) (3) Polymer B-3: A commercially available propylene polymer (manufactured by Prime Polymer Co., Ltd., trade name B221WC) (4) Polymer B-4: The polymer obtained in the following Reference Example (Polymer B-4) was used.

[0088] Polymer C (1) Polymer C-1: Commercially available propylene polymer (manufactured by Prime Polymer Co., Ltd., trade name S119) (2) Polymer C-2: Commercially available propylene polymer (manufactured by Prime Polymer Co., Ltd., trade name H-50000) Reference Example (Polymer B-1): Polymer B-1 was obtained as follows.

[0089] A propylene-based polymer was prepared by two-stage random copolymerization using a supported titanium-based catalyst (high stereoregularity catalyst) with dicyclopentyldimethoxysilane as the electron donor, to give a content of 0.6 mol% of ethylene structural units, adjusting the amounts to give 52% by weight of a high molecular weight polymer having an intrinsic viscosity [η] of 4.3 dL / g and 48% by weight of a low molecular weight polymer having an intrinsic viscosity [η] of 2.1 dL / g, thereby obtaining a propylene-ethylene copolymer with a broadened molecular weight distribution.

[0090] To 100% by weight of the copolymer, 0.1 part by weight of tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (manufactured by BASF Ltd.), a phenolic antioxidant, 0.1 part by weight of 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite (manufactured by ADEKA Corporation), a phosphorus-based antioxidant, and 0.1 part by weight of calcium stearate (manufactured by NOF Corporation) 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. Reference Example (Polymer B-4) Polymer B-4 was obtained as follows.

[0091] A magnesium compound (support for the solid catalyst), silicon tetrachloride, and titanium tetrachloride were reacted to obtain a solid catalyst component, which was then prepolymerized with propylene to obtain a prepolymerized catalyst.

[0092] Next, 336 L of propylene was charged into a 600 L autoclave and heated to 60° C. Then, 8.7 mL of triethylaluminum, 11.4 mL of dicyclopentyldimethoxysilane, and 2.9 g of the above prepolymerization catalyst were charged to initiate polymerization. 75 minutes after the start of polymerization, the temperature was lowered to 50° C. over 10 minutes (completion of first-stage polymerization).

[0093] The propylene polymer (a1) polymerized under the same conditions as in the first stage had an intrinsic viscosity [η] of 11 dl / g.

[0094] After the temperature was lowered, hydrogen was continuously introduced to maintain a constant pressure of 3.3 MPaG, and polymerization was carried out for 151 minutes. Then, the vent valve was opened, and unreacted propylene was purged via an integrating flow meter (completion of the second-stage polymerization).

[0095] In this way, 51.8 kg of a powdery propylene polymer (A) was obtained.

[0096] To this propylene polymer composition, 2000 ppm of Irganox 1010 (manufactured by BASF Corporation), 2000 ppm of Irgaphos 168 (manufactured by BASF Corporation), and 1000 ppm of Sandstab P-EPQ (manufactured by Clariant Japan K.K.) were added as antioxidants, and 1000 ppm of calcium stearate was added as a neutralizing agent, and the mixture was melt-kneaded in a twin-screw extruder to obtain a pellet-shaped propylene polymer (polymer B-4).

[0097]

[0043] Using the propylene polymer composition of Example 1, an unstretched raw sheet was prepared using 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 for a preheating time of 90 seconds using a table tenter biaxial stretching machine. The stretching temperature was then 153°C, and the stretching was then 8 times in the transverse direction (TD) at the same stretching temperature (stretching speed of 286% / sec in both machine and transverse stretching), followed by relaxation 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). Comparative Examples 1 to 4

[0044] Using the propylene polymer compositions shown in Table 1 and Table 3 (Comparative Example 1) to Table 6 (Comparative Example 4), biaxially stretched films were molded in the same manner as in Example 1. The physical properties of the obtained biaxially stretched films are shown in Table 1.

[0098] For Example 1 and Comparative Examples 1 to 4, the relationship between the stretchability indicated by the value of Fm / Fy and the shrinkage rate (%) in the TD direction is shown in FIG.

[0099] FIG. 1 shows that Example 1 maintains good stretchability (the Fm / Fy value is 1.43, which is an appropriate value), while the shrinkage rate (%) in the TD direction of the biaxially stretched film is small, at 5.5%.

[0100] In contrast, the shrinkage rates (%) of Comparative Examples 1 to 4 are all clearly larger than those of Example 1.

Claims

1. A propylene-based polymer composition characterized by satisfying the following requirements 1) to 6): Requirement 1) A mesopentad fraction is 95% or more; Requirement 2) A comonomer content is 0.2 mol% or less; Requirement 3) MFR is 1 to 10 g / 10 min; Requirement 4) A ratio Mw / Mn of the mass average molecular weight Mw to the number average molecular weight Mn is 5.5 or less; and Requirement 5) A Z+1 average molecular weight M Ｚ＋１ and the ratio M Ｚ＋１ Requirement 6) Z+1 average molecular weight M Ｚ＋１ More than 2,500,000 2. The propylene polymer composition according to claim 1, characterized in that the cold xylene solubles (CXS) is 1.2 mass% or less.

3. A propylene-based polymer composition according to claim 1 or 2, characterized in that it contains the following propylene-based polymers, Polymer A, Polymer B, and Polymer C, in the following proportions, respectively, and the MFR of Polymer A is greater than the MFR of Polymer B, or the Mw / Mn of Polymer A is equal to or smaller than the Mw / Mn of Polymer B. Polymer A: MFR of 1 g / 10 min or more and less than 9 g / 10 min, 70 to 98 mass% Polymer B: Ethylene content of 1 mol% or less and Mw / Mn of 5.0 to 10.0, 1 to 20 mass% Polymer C: MFR of 9 to 100 g / 10 min and Mw / Mn of less than 5.0, 1 to 10 mass% (The total of Polymer A, Polymer B, and Polymer C is 100 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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