WO2024070981A1 - Film de polypropylène étiré biaxialement, emballage pour aliment et emballage alimentaire - Google Patents

Film de polypropylène étiré biaxialement, emballage pour aliment et emballage alimentaire Download PDF

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Publication number
WO2024070981A1
WO2024070981A1 PCT/JP2023/034589 JP2023034589W WO2024070981A1 WO 2024070981 A1 WO2024070981 A1 WO 2024070981A1 JP 2023034589 W JP2023034589 W JP 2023034589W WO 2024070981 A1 WO2024070981 A1 WO 2024070981A1
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Prior art keywords
biaxially oriented
polypropylene film
oriented polypropylene
less
film according
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PCT/JP2023/034589
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English (en)
Japanese (ja)
Inventor
拓也 田村
裕之 若木
琢巳 正本
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三井化学東セロ株式会社
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Priority claimed from JP2022155373A external-priority patent/JP2024049108A/ja
Priority claimed from JP2022155378A external-priority patent/JP2024049113A/ja
Application filed by 三井化学東セロ株式会社 filed Critical 三井化学東セロ株式会社
Publication of WO2024070981A1 publication Critical patent/WO2024070981A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/40—Applications of laminates for particular packaging purposes

Definitions

  • the present invention relates to a biaxially oriented polypropylene film, a food package, and a food package.
  • OPP film Biaxially oriented polypropylene film
  • OPP film has an excellent balance of performance, including processability, water vapor barrier properties, transparency, mechanical strength, and rigidity, and is used, for example, as a packaging film for packaging food.
  • Patent Document 1 JP Patent Publication No. 2008-73926
  • Patent Document 2 JP Patent Publication No. 2004-82499
  • Patent Document 1 describes a biaxially oriented multilayer polypropylene film comprising a biaxially oriented film made of a propylene polymer composition containing 75 to 90 mass % of a propylene homopolymer (A) and 25 to 10 mass % of a tackifier (D), the biaxially oriented film having a layer made of a propylene- ⁇ -olefin random copolymer (C) having a melting point in the range of 125 to 145° C., via a layer made of a propylene polymer (B) having a melting point of 155° C. or higher, on one side thereof, and a layer made of a propylene polymer (E) on the other side thereof.
  • Patent Document 1 describes that the biaxially oriented multilayer polypropylene film can suppress the seepage of petroleum resins and the like onto the film surface, and has excellent lamination strength and moisture resistance.
  • Patent Document 2 describes a multilayer resin film having a biaxially oriented polypropylene resin layer containing 10 to 40% by mass of a highly crystallized resin and 6 to 15% by mass of a petroleum resin, and further having a polyvinyl alcohol resin layer via an adhesive layer on at least one surface of the biaxially oriented polypropylene resin layer, the multilayer resin film being characterized in that the oxygen transmission rate at a relative humidity of 85% RH and a temperature of 23°C is 600 mL/ m2 day MPa or less, and the water vapor transmission rate at a relative humidity of 90% RH and a temperature of 40°C is 3.5 g/ m2 day 20 ⁇ m or less.
  • Patent Document 2 describes that the multilayer resin film has excellent oxygen gas barrier properties and moisture resistance.
  • the present invention was made in consideration of the above circumstances, and provides a biaxially oriented polypropylene film, food packaging material, and food packaging material that have an improved balance of thermal dimensional stability and antistatic properties.
  • the present inventors conducted extensive research to solve the above problems. As a result, they discovered that it is possible to improve the performance balance between the thermal dimensional stability and antistatic properties of a biaxially oriented polypropylene film by adjusting the half-life of the saturated charging voltage to a specific range while adopting a layer structure including a biaxially oriented film layer containing a propylene-based polymer and a surface resin layer containing homopolypropylene (A) that is located on at least one side of the biaxially oriented film layer, and thus arrived at the present invention.
  • the present invention provides the biaxially oriented polypropylene film, food packaging material, and food packaging material shown below.
  • a voltage is applied to the surface of the biaxially oriented polypropylene film on the surface resin layer side for 30 seconds under an environment of an applied voltage of 10 kV, a distance between the sample and the electrode of 20 mm, a temperature of 23° C., and a humidity of 50% RH, and the saturated charging voltage and the half-life of the saturated charging voltage on the surface of the biaxially oriented polypropylene film are calculated in accordance with JIS L1094:2014.
  • the biaxially oriented polypropylene film according to any one of the above [1] to [6], wherein the propylene-based polymer contained in the biaxially oriented film layer comprises a homopolypropylene (A) and at least one polymer (B) selected from the group consisting of a random polypropylene (B1) and an ⁇ -olefin copolymer (B2).
  • the content of the polymer (B) is 1% by mass or more and 50% by mass or less when the entire biaxially stretched film layer is 100% by mass.
  • the content of the homopolypropylene (A) in the surface resin layer is 75% by mass or more and 100% by mass or less, when the entire surface resin layer is 100% by mass.
  • the present invention provides a biaxially oriented polypropylene film with an improved balance of thermal dimensional stability and antistatic properties.
  • FIG. 1 is a cross-sectional view showing a schematic example of the structure of a biaxially oriented polypropylene film according to the present embodiment.
  • FIG. 1 is a cross-sectional view showing a schematic example of the structure of a biaxially oriented polypropylene film according to the present embodiment.
  • ⁇ Biaxially oriented polypropylene film> 1 and 2 are cross-sectional views each showing a schematic example of the structure of a biaxially oriented polypropylene film 100 according to the present embodiment.
  • the biaxially oriented polypropylene film 100 of the present embodiment comprises a biaxially oriented film layer 101 containing a propylene-based polymer, and a surface resin layer 103 located on at least one surface of the biaxially oriented film layer 101 and containing homopolypropylene (A), and has a half-life of saturated charging voltage of 1,300 seconds or less as measured by the following method.
  • a voltage is applied to the surface of the biaxially oriented polypropylene film on the surface resin layer side for 30 seconds under an environment of an applied voltage of 10 kV, a distance between the sample and the electrode of 20 mm, a temperature of 23° C., and a humidity of 50% RH, and the saturated charging voltage and the half-life of the saturated charging voltage on the surface of the biaxially oriented polypropylene film are calculated in accordance with JIS L1094:2014.
  • the antistatic property may not be sufficient.
  • the performance balance between thermal dimensional stability and antistatic property can be improved.
  • the biaxially oriented polypropylene film 100 of this embodiment has improved thermal dimensional stability, it is possible to suppress thermal wrinkles in the sealed portions during bag making, thereby improving bag making properties.
  • the half-life of the saturated charging voltage is 1300 seconds or less, but from the viewpoint of further improving the performance balance between thermal dimensional stability and antistatic properties, it is preferably 1000 seconds or less, more preferably 800 seconds or less, even more preferably 500 seconds or less, even more preferably 400 seconds or less, even more preferably 250 seconds or less, even more preferably 200 seconds or less, and even more preferably 150 seconds or less.
  • the lower limit of the half-life of the saturated charging voltage is not particularly limited, but is, for example, 1 second or more, may be 10 seconds or more, may be 30 seconds or more, or may be 50 seconds or more.
  • the surface resistivity log ⁇ on the surface resin layer 103 side is preferably less than 14.0, more preferably less than 13.5, and even more preferably less than 13.0, from the viewpoint of further improving the performance balance of thermal dimensional stability, antistatic properties, and printing properties.
  • the lower limit of the surface resistivity log ⁇ is not particularly limited, and is, for example, 5.0 or more, may be 8.0 or more, 10.0 or more, or may be 12.0 or more.
  • the surface resistivity value log ⁇ on the surface resin layer 103 side can be measured in accordance with JIS C2139:2018 by the method described in the examples.
  • the surface resistivity on the surface resin layer 103 side is preferably less than 1.0 ⁇ 10 ⁇ , more preferably less than 5.0 ⁇ 10 ⁇ , even more preferably less than 3.0 ⁇ 10 ⁇ , and even more preferably less than 1.0 ⁇ 10 ⁇ , from the viewpoint of further improving the performance balance of thermal dimensional stability, antistatic properties , and printing properties.
  • the lower limit of the surface resistivity is not particularly limited, and may be, for example, 1.0 ⁇ 10 ⁇ or more, 1.0 ⁇ 10 ⁇ or more, 1.0 ⁇ 10 ⁇ or more, 1.0 ⁇ 10 ⁇ or more, or 1.0 ⁇ 10 ⁇ or more.
  • the surface resistivity value on the surface resin layer 103 side can be measured in accordance with JIS C2139:2018 by the method described in the examples.
  • the surface resistivity of the biaxially oriented polypropylene film 100 can be adjusted, for example, by adjusting the type and content ratio of the propylene-based polymer and antistatic agent (C) contained in the biaxially oriented film layer 101, the thickness and stretching ratio of the biaxially oriented film layer 101, the constituent material and thickness of the surface resin layer 103, etc.
  • C propylene-based polymer and antistatic agent
  • the sum (T1 + T2) of the tensile modulus T1 in the MD direction and the tensile modulus T2 in the TD direction of the biaxially oriented polypropylene film 100, measured in accordance with JIS K7127 (1999) using a tensile tester under conditions of a measurement temperature of 23 ⁇ 2 ° C , 50 ⁇ 5% RH, and a tensile speed of 5 mm/min, is preferably 2000 MPa or more, more preferably 2500 MPa or more, even more preferably 2800 MPa or more, and even more preferably 3000 MPa or more, and is preferably 10000 MPa or less, more preferably 8000 MPa or less, even more preferably 7000 MPa or less, even more preferably 6500 MPa or less, and even more preferably 6300 MPa or less.
  • the biaxially oriented polypropylene film 100 can have a better balance of performance such as thermal dimensional stability, formability, water vapor barrier property, mechanical properties, transparency, bag formability, and handleability. Furthermore, the stiffness of the biaxially oriented polypropylene film 100 can be improved, and as a result, the film can be prevented from shifting in position during heat sealing, thereby preventing the occurrence of defective sealing.
  • the biaxially oriented polypropylene film 100 can have a better balance of thermal dimensional stability, formability, water vapor barrier properties, mechanical properties, transparency, bag formability, handleability, and packaging suitability.
  • the surface resistivity of the biaxially oriented polypropylene film 100 can be effectively reduced without increasing the amount of antistatic agent added, and as a result, the antistatic property of the biaxially oriented polypropylene film 100 can be improved while maintaining good heat sealability.
  • Such a tensile modulus is a substitute value for quantitatively measuring the stiffness of a film, and can be adjusted, for example, by adjusting the type and content ratio of the propylene-based polymer and antistatic agent (C) contained in the biaxially stretched film layer 101, the thickness and stretching ratio of the biaxially stretched film layer 101, the constituent material and thickness of the surface resin layer 103, etc.
  • the tensile modulus T1 in the MD direction of the biaxially oriented polypropylene film 100 is preferably 800 MPa or more, more preferably 1000 MPa or more, even more preferably 1200 MPa or more, and even more preferably 1300 MPa or more, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100 in terms of thermal dimensional stability, formability, water vapor barrier property, mechanical properties, transparency, bag formability, handleability, and packaging suitability, and from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100 in terms of thermal dimensional stability, antistatic property, bag formability, and packaging suitability, it is preferably 4000 MPa or less, more preferably 3000 MPa or less, even more preferably 2500 MPa or less, even more preferably 2400 MPa or less, even more preferably 2200 MPa or less, and even more preferably 2000 MPa or less.
  • the biaxially oriented polypropylene film 100 expands in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019.
  • the thermal expansion coefficient in the TD direction of the biaxially oriented polypropylene film 100 when heat-treated at 120°C for 15 minutes is preferably 0.1% or more, more preferably 0.2% or more, from the viewpoint of further improving the performance balance between thermal dimensional stability and bag formability, and from the viewpoint of further suppressing thermal wrinkles in the sealed portion and obtaining a bag product with good thermal wrinkles in the sealed portion, and from the viewpoint of further improving the performance balance between thermal dimensional stability and bag formability, it is preferably 2.0% or less, more preferably 1.5% or less, even more preferably 1.2% or less, even more preferably 1.0% or less, and even more preferably 0.8% or less.
  • a roll of biaxially oriented polypropylene film is unwound in the MD direction, and bag making, coating, deposition, etc. are performed while tension is applied. That is, since no tension is applied in the TD direction, the biaxially oriented polypropylene film is susceptible to heat shrinkage when heated, and heat wrinkles are easily formed in the sealed portion. On the other hand, if the thermal expansion coefficient in the TD direction when heated at 120°C for 15 minutes is within the above range, heat shrinkage is unlikely to occur in the TD direction even when the biaxially oriented polypropylene film 100 is heated, and heat wrinkles in the sealed portion can be further suppressed.
  • the thermal expansion coefficient in the TD direction of the biaxially oriented polypropylene film 100 when it is heat-treated at 120° C. for 15 minutes is calculated by the following method. First, a test piece of 10 cm x 10 cm is cut out from the biaxially stretched polypropylene film 100, and this test piece is heat-treated for 15 minutes at 120° C. Next, when the length in the TD direction of the test piece after the heat treatment is TD 1 [cm], the thermal expansion coefficient in the TD direction [%] is calculated by 100 x (TD 1 - 10)/10.
  • the heat shrinkage rate in the MD direction of the biaxially oriented polypropylene film 100 when heated at 120°C for 15 minutes is, from the viewpoint of further improving the performance balance between thermal dimensional stability and bag formability, and from the viewpoint of further suppressing thermal elongation of the film during processing, preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, even more preferably 2.2% or less, and even more preferably 2.0% or less, and may be 0.1% or more, 0.3% or more, or 0.5% or more.
  • a roll of biaxially oriented polypropylene film is unwound in the MD direction, and bag making, coating, deposition, etc. are performed while tension is applied.
  • the heat shrinkage rate in the MD direction of the biaxially oriented polypropylene film 100 when it is heat-treated at 120° C. for 15 minutes is calculated by the following method. First, a test piece of 10 cm x 10 cm is cut out from the biaxially stretched polypropylene film 100, and this test piece is heat-treated for 15 minutes at 120° C. Next, when the length in the MD direction of the test piece after heat treatment is MD 1 [cm], the heat shrinkage rate [%] in the MD direction is calculated by 100 x (10 - MD 1 )/10.
  • X TD [%] and X MD [%] when the heat shrinkage rate in the TD direction and the heat shrinkage rate in the MD direction when heated at 150° C. for 15 minutes are X TD [%] and X MD [%], respectively, X TD +X MD is preferably less than 7.0%, more preferably 6.5% or less, even more preferably 6.0% or less, and even more preferably less than 5.0%, from the viewpoint of further improving the performance balance of the thermal dimensional stability and bag formability of the biaxially stretched polypropylene film 100. Moreover, X TD [%] and X MD [%] of the biaxially stretched polypropylene film 100 are calculated by the following method.
  • a test piece of 10 cm x 10 cm is cut out from the biaxially stretched polypropylene film 100, and this test piece is heat-treated for 15 minutes at 150° C.
  • TD 1 [cm] the length in the TD direction of the test piece after heat treatment
  • MD 1 [cm] the length in the MD direction of the test piece after heat treatment
  • X TD [%] is calculated by 100 x (10 - TD 1 )/10
  • X MD [%] is calculated by 100 x (10 - MD 1 )/10.
  • the thermal expansion coefficient and thermal shrinkage coefficient of the biaxially oriented polypropylene film 100 can be adjusted, for example, by adjusting the type and content ratio of the propylene-based polymer and antistatic agent (C) contained in the biaxially oriented film layer 101, the thickness and stretching ratio of the biaxially oriented film layer 101, the constituent material and thickness of the surface resin layer 103, etc.
  • the thermal expansion coefficient and thermal shrinkage coefficient of the biaxially oriented polypropylene film 100 can be measured in accordance with JIS C2151:2019.
  • the heat fusion strength (TD tensile direction) of the part heat-sealed under the conditions of 200 ° C, pressure 2.0 kgf, and sealing time 1.0 second is preferably 6.0 N / 15 mm or less, more preferably 5.0 N / 15 mm or less, even more preferably 4.0 N / 15 mm or less, even more preferably 3.0 N / 15 mm or less, even more preferably 2.5 N / 15 mm or less, even more preferably 2.0 N / 15 mm or less, even more preferably 1.5 N / 15 mm or less, and even more preferably 1.3 N / 15 mm or less.
  • the lower limit of the heat fusion strength at 200 ° C of the biaxially oriented polypropylene film 100 is not particularly limited, but may be 0.01 N / 15 mm or more, 0.05 N / 15 mm or more, or 0.1 N / 15 mm or more.
  • the heat fusion strength is used as an index of the heat fusion resistance of the biaxially oriented polypropylene film surface. It can be determined that the lower the heat fusion strength, the better the heat fusion resistance of the biaxially oriented polypropylene film surface.
  • the heat fusion strength at 200°C can be measured by the following method.
  • two biaxially oriented polypropylene films 100 are heat fused under the conditions of 200°C, pressure of 2.0 kgf, and sealing time of 1.0 second to obtain a laminated film.
  • the two biaxially oriented polypropylene films 100 are peeled under the conditions of 15 mm width, 90 degree peel, peel speed of 300 mm/min, and tension in the TD direction, and the peel strength at that time is taken as the heat fusion strength.
  • the heat fusion strength at 200°C can be adjusted, for example, by adjusting the types and contents of the propylene-based polymer and antistatic agent (C) contained in the biaxially oriented film layer 101, the thickness and stretching ratio of the biaxially oriented film layer 101, the constituent material and thickness of the surface resin layer 103, etc.
  • the haze of the biaxially oriented polypropylene film 100 is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.5% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, even more preferably 2.0% or less, even more preferably 1.5% or less, and even more preferably 1.3% or less, from the viewpoint of further improving the transparency of the biaxially oriented polypropylene film 100.
  • Such haze can be adjusted, for example, by adjusting the type and content ratio of the propylene-based polymer and antistatic agent (C) contained in the biaxially oriented film layer 101, the thickness and stretching ratio of the biaxially oriented film layer 101, the constituent material and thickness of the surface resin layer 103, etc.
  • C propylene-based polymer and antistatic agent
  • the food packaging produced using the biaxially oriented polypropylene film 100 exhibits sufficient performance in terms of water vapor barrier properties. Therefore, the biaxially oriented polypropylene film 100 can be particularly suitably used as a food packaging film for packaging foods that require water vapor barrier properties.
  • the water vapor permeability of the biaxially oriented polypropylene film 100 is preferably 20.0 g/( m2 ⁇ 24 h) or less, more preferably 18.0 g/( m2 ⁇ 24 h) or less, even more preferably 15.0 g/( m2 ⁇ 24 h) or less, even more preferably 12.0 g/( m2 ⁇ 24 h) or less, and even more preferably 10.0 g/( m2 ⁇ 24 h) or less. (Measuring method) The biaxially oriented polypropylene film 100 is folded and two sides are heat sealed to form a bag.
  • Calcium chloride is then placed in the bag as the content.
  • the other side is then heat sealed to create a bag with a surface area of 0.01 m2 .
  • the resulting bag is then stored for 72 hours under conditions of 40°C and 90% RH.
  • the mass of calcium chloride before and after storage is measured, and the water vapor transmission rate (g/( m2 ⁇ 24h)) is calculated from the difference.
  • Such water vapor permeability can be adjusted, for example, by adjusting the type and content ratio of the propylene-based polymer and antistatic agent (C) contained in the biaxially oriented film layer 101, the thickness and stretching ratio of the biaxially oriented film layer 101, the constituent material and thickness of the surface resin layer 103, etc.
  • the amount of structural units derived from ⁇ -olefins other than propylene contained in the biaxially oriented polypropylene film 100, when the total amount of structural units derived from monomers contained in the biaxially oriented polypropylene film 100 is taken as 100 mol %, is, from the viewpoint of further improving the performance balance of the formability, antistatic properties, thermal dimensional stability, and bag formability of the biaxially oriented polypropylene film 100, preferably 0.05 mol % or more, more preferably 0.1 mol % or more, even more preferably 0.3 mol % or more, even more preferably 0.5 mol % or more, even more preferably 1.0 mol % or more, even more preferably 3.0 mol % or more, and even more preferably 5.
  • the biaxially oriented polypropylene film 100 is preferably 50.0 mol% or less, more preferably 30.0 mol% or less, even more preferably 25.0 mol% or less, even more preferably 20.0 mol% or less, even more preferably 15.0 mol% or less, even more preferably 12.0 mol% or less, even more preferably 10.0 mol% or less, and even more preferably 8.0 mol% or less.
  • the softening effect of the structural units derived from ⁇ -olefins exerts an effect of suppressing the yield point stress at the start of stretching in the stretching process, improving ease of formability.
  • the low melting point effect of the structural units derived from ⁇ -olefins more efficiently relieves residual stress in the heat setting process during film molding, improving formability and suppressing thickness unevenness.
  • the thermal dimensional stability of the biaxially stretched polypropylene film 100 can be further improved.
  • the amount of structural units derived from ⁇ -olefins other than propylene in the biaxially oriented polypropylene film 100 can be measured by the method described in the Examples.
  • the thickness of the biaxially oriented polypropylene film 100 is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, even more preferably 12 ⁇ m or more, and even more preferably 15 ⁇ m or more, from the viewpoint of further improving the balance of performance such as antistatic properties, thermal dimensional stability, moldability, water vapor barrier properties, cost, mechanical properties, transparency, bag formability, ease of handling, appearance, and light weight, and is preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less, even more preferably 40 ⁇ m or less, even more preferably 30 ⁇ m or less, and even more preferably 25 ⁇ m or less.
  • the layers that make up the biaxially oriented polypropylene film 100 are described below.
  • the biaxially oriented film layer 101 (also called a biaxially oriented polypropylene-based film layer) contains a propylene-based polymer.
  • the biaxially stretched film layer 101 is formed, for example, by biaxially stretching a film made of a propylene-based polymer composition (X) containing a propylene-based polymer.
  • the biaxially stretched film layer 101 may be a single layer or may be a laminate of multiple layers made of the propylene-based polymer composition (X), but it is necessary that it is biaxially stretched.
  • the thickness of the biaxially oriented film layer 101 is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, even more preferably 12 ⁇ m or more, and even more preferably 15 ⁇ m or more, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100, such as thermal dimensional stability, formability, water vapor barrier properties, cost, mechanical properties, transparency, bag formability, handleability, appearance, and light weight, and is preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less, even more preferably 40 ⁇ m or less, even more preferably 30 ⁇ m or less, and even more preferably 20 ⁇ m or less.
  • the ratio of the thickness of the biaxially oriented film layer 101 to the total thickness of the biaxially oriented polypropylene film 100 is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, even more preferably 75% or more, and preferably 100% or less, more preferably 99% or less, even more preferably 95% or less, even more preferably 90% or less.
  • the propylene polymer composition (X) of the present embodiment contains a propylene polymer.
  • the propylene polymer content in the propylene polymer composition (X) of the present embodiment i.e., the biaxially oriented film layer 101, is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and for example, 100% by mass or less, based on the entire propylene polymer composition (X) being 100% by mass.
  • the propylene-based polymer of the present embodiment is a polymer containing a structural unit derived from propylene, and examples thereof include homopolypropylene (A); at least one polymer (B) selected from the group consisting of random polypropylene (B1) and ⁇ -olefin copolymer (B2); and the like.
  • the propylene-based polymer of the present embodiment preferably contains a homopolypropylene (A) and at least one polymer (B) selected from the group consisting of a random polypropylene (B1) and an ⁇ -olefin copolymer (B2).
  • the antistatic property may not be sufficient.
  • a layer structure comprising a biaxially oriented film layer 101 containing homopolypropylene (A), at least one polymer (B) selected from the group consisting of random polypropylene (B1) and ⁇ -olefin copolymer (B2), and an antistatic agent (C), and a surface resin layer 103 located on at least one surface of the biaxially oriented film layer 101 and containing homopolypropylene (A)
  • the residual stress of the film can be efficiently relaxed, thereby improving the thermal dimensional stability of the biaxially oriented polypropylene film and further improving the antistatic properties.
  • the biaxially oriented film layer 101 contains homopolypropylene (A), at least one polymer (B) selected from the group consisting of random polypropylene (B1) and ⁇ -olefin copolymer (B2), and an antistatic agent (C), thereby further improving the performance balance between thermal dimensional stability and antistatic properties. Furthermore, since the thermal dimensional stability of such a biaxially oriented polypropylene film 100 is further improved, thermal wrinkles in the sealed portions during bag making can be further suppressed, and as a result, bag making properties can be further improved.
  • homopolypropylene (A) examples include propylene homopolymers and propylene copolymers having a content of structural units derived from ⁇ -olefins other than propylene of 2.0 mol % or less.
  • the content of structural units derived from propylene in the homopolypropylene (A) is 98.0 mol % or more, preferably 98.5 mol % or more, more preferably 98.7 mol % or more, even more preferably 99.0 mol % or more, even more preferably 99.5 mol % or more, even more preferably 99.8 mol % or more, and is, for example, 100.0 mol % or less.
  • the ⁇ -olefin other than propylene includes, for example, one or more selected from the group consisting of ethylene and ⁇ -olefins having 4 to 20 carbon atoms, preferably one or more selected from the group consisting of ethylene and ⁇ -olefins having 4 to 6 carbon atoms, more preferably at least one selected from the group consisting of ethylene and 1-butene, and even more preferably ethylene.
  • the content of structural units derived from ⁇ -olefins other than propylene, when the entire homopolypropylene (A) is taken as 100 mol %, is preferably 2.0 mol % or less, more preferably 1.5 mol % or less, even more preferably 1.3 mol % or less, even more preferably 1.0 mol % or less, even more preferably 0.5 mol % or less, and even more preferably 0.2 mol % or less.
  • the homopolypropylene (A) in the biaxially oriented film layer 101 may be used alone or in combination of two or more kinds.
  • the isotactic mesopentad fraction (mmmm) of the homopolypropylene (A) is preferably 96.0% or more, more preferably 96.5% or more, even more preferably 97.0% or more, even more preferably 97.3% or more, even more preferably 97.5% or more, even more preferably 97.8% or more, and even more preferably 98.0% or more, from the viewpoint of further improving the balance of performance such as thermal dimensional stability, heat resistance, water vapor barrier property, mechanical properties, rigidity, and bag formability of the biaxially stretched polypropylene film 100.
  • the upper limit of the isotactic mesopentad fraction (mmmm) of the homopolypropylene (A) is not particularly limited, but from the viewpoint of ease of production, it is 99.5% or less, more preferably 99.3% or less, and even more preferably 99.0% or less.
  • the isotactic mesopentad fraction (mmmm) is an index of stereoregularity and can be determined by a known method from 13 C-nuclear magnetic resonance (NMR) spectrum.
  • the isotactic mesopentad fraction of the homopolypropylene (A) can be the isotactic mesopentad fraction of a mixture obtained by melt blending two or more types of homopolypropylene (A) by a known method.
  • the melt flow rate (MFR) of the homopolypropylene (A), measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg, is preferably 0.5 g/10 min or more, more preferably 1.0 g/10 min or more, and even more preferably 2.0 g/10 min or more, from the viewpoint of further improving the balance of performance between fluidity and moldability, and is preferably 20.0 g/10 min or less, more preferably 10.0 g/10 min or less, and even more preferably 7.0 g/10 min or less, from the viewpoint of further stabilizing moldability.
  • the MFR of the homopolypropylene (A) can be the MFR of a mixture obtained by melt blending two or more types of homopolypropylene (A) by a known method.
  • the melting point of the homopolypropylene (A) is preferably 150°C or higher, more preferably 155°C or higher, even more preferably 160°C or higher, and even more preferably 163°C or higher, and is preferably 180°C or lower, more preferably 175°C or lower, even more preferably 170°C or lower, and even more preferably 168°C or lower.
  • the melting point of the homopolypropylene (A) is the peak temperature of the maximum melting peak.
  • Homopolypropylene (A) can be produced by various methods. For example, it can be produced using known catalysts such as Ziegler-Natta catalysts and metallocene catalysts.
  • the polymer (B) includes at least one selected from the group consisting of random polypropylene (B1) and an ⁇ -olefin copolymer (B2).
  • the melt flow rate (MFR) of the polymer (B), measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg, is, from the viewpoint of further improving the performance balance of the formability, antistatic property, and thermal dimensional stability of the biaxially oriented polypropylene film 100, preferably 0.01 g/10 min or more, more preferably 0.1 g/10 min or more, even more preferably 0.5 g/10 min or more, even more preferably 1.0 g/10 min or more, even more preferably 2.0 g/10 min or more, and is preferably 30.0 g/10 min or less, more preferably 20.0 g/10 min or less, even more preferably 15.0 g/10 min or less, even more preferably 12.0 g/10 min or less, and even more preferably 10.0 g/10 min or less.
  • the MFR of a mixture obtained by melt blending two or more types of the polymer (B) by a known method can be adopted.
  • the melting point of the polymer (B) is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, and even more preferably 73°C or higher, and is preferably 155°C or lower, more preferably 150°C or lower, even more preferably 148°C or lower, and even more preferably 145°C or lower.
  • the melting point of polymer (B) is the peak temperature of the maximum melting peak.
  • the weight average molecular weight (Mw) of the polymer (B) is preferably 100,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, and even more preferably 220,000 or more, from the viewpoint of further improving the performance balance of the formability, thermal dimensional stability, blocking resistance, and sheet payout property of the biaxially oriented polypropylene film 100, and is preferably 1,000,000 or less, more preferably 800,000 or less, more preferably 600,000 or less, even more preferably 500,000 or less, and even more preferably 450,000 or less, from the viewpoint of further improving the thermal dimensional stability.
  • the weight average molecular weight (Mw)/number average molecular weight (Mn) of the polymer (B) is preferably 1.5 or more, more preferably 1.8 or more, from the viewpoint of further improving the performance balance of the formability, thermal dimensional stability, blocking resistance, and sheet payout ability of the biaxially oriented polypropylene film 100, and is preferably 8.0 or less, more preferably 7.5 or less, even more preferably 7.0 or less, and even more preferably 6.8 or less, from the viewpoint of further improving the performance balance of the formability, thermal dimensional stability, blocking resistance, and sheet payout ability of the biaxially oriented polypropylene film 100.
  • the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer (B) can be the weight average molecular weight (Mw) and number average molecular weight (Mn) of a mixture obtained by melt blending two or more kinds of the polymer (B) by a known method.
  • the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer (B) can be measured by the method described in the examples.
  • the content of polymer (B) is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, even more preferably 4% by mass or more, even more preferably 5% by mass or more, and even more preferably 8% by mass or more, when the entire biaxially oriented film layer 101 is taken as 100% by mass, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100, such as the antistatic property, formability, and thermal dimensional stability, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100, such as the thermal dimensional stability, water vapor barrier property, transparency, mechanical properties, rigidity, bag formability, fluidity, and formability.
  • the random polypropylene (B1) includes a random copolymer of propylene and an ⁇ -olefin other than propylene, in which the content of structural units derived from an ⁇ -olefin other than propylene is more than 2.0 mol % and not more than 15.0 mol %.
  • the ⁇ -olefin other than propylene includes, for example, one or more selected from the group consisting of ethylene and ⁇ -olefins having 4 to 20 carbon atoms, preferably one or more selected from the group consisting of ethylene and ⁇ -olefins having 4 to 6 carbon atoms, more preferably at least one selected from ethylene and 1-butene, and even more preferably ethylene.
  • the content of structural units derived from an ⁇ -olefin other than propylene in the random polypropylene (B1), when the entire random polypropylene (B1) is taken as 100 mol%, is preferably more than 2.0 mol%, more preferably 2.5 mol% or more, even more preferably 3.0 mol% or more, even more preferably 3.5 mol% or more, and even more preferably 4.0 mol% or more, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100 in terms of antistatic property, formability, thermal dimensional stability, and bag formability, and is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, even more preferably 10.0 mol% or less, even more preferably 8.0 mol% or less, and even more preferably 6.5 mol% or less, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100 in terms of thermal dimensional stability, water vapor barrier property, bag formability, and transparency.
  • the random polypropylene (B1) preferably contains one or more selected from the group consisting of a propylene-ethylene random copolymer, a propylene-ethylene-1-butene random copolymer, and a propylene-1-butene random copolymer, more preferably contains one or more selected from the group consisting of a propylene-ethylene random copolymer, and a propylene-1-butene random copolymer, and even more preferably contains a propylene-ethylene random copolymer.
  • the random polypropylene (B1) in the biaxially oriented film layer 101 may be used alone or in combination of two or more kinds.
  • the ⁇ -olefin copolymer (B2) is a copolymer of two or more kinds of ⁇ -olefins, and includes, for example, an ⁇ -olefin copolymer in which the content of structural units derived from an ⁇ -olefin other than propylene exceeds 15.0 mol %.
  • the ⁇ -olefin copolymer (B2) includes a random copolymer of propylene and an ⁇ -olefin other than propylene, in which the content of structural units derived from an ⁇ -olefin other than propylene exceeds 15.0 mol %.
  • the ⁇ -olefin other than propylene includes, for example, one or more selected from the group consisting of ethylene and ⁇ -olefins having 4 to 10 carbon atoms, preferably one or more selected from the group consisting of ⁇ -olefins having 4 to 8 carbon atoms, more preferably at least one selected from 1-butene and 1-octene, and even more preferably 1-butene.
  • the content of structural units derived from an ⁇ -olefin other than propylene in the ⁇ -olefin copolymer (B2), when the entire ⁇ -olefin copolymer (B2) is taken as 100 mol%, is preferably more than 15.0 mol%, more preferably 18.0 mol% or more, even more preferably 20.0 mol% or more, even more preferably 23.0 mol% or more, and even more preferably 25.0 mol% or more, from the viewpoint of further improving the performance balance of the formability, thermal dimensional stability, and bag formability of the biaxially oriented polypropylene film 100, and is preferably 99.0 mol% or less, more preferably 98.0 mol% or less, even more preferably 95.0 mol% or less, even more preferably 92.0 mol% or less, and even more preferably 90.0 mol% or less, from the viewpoint of further improving the performance balance of the thermal dimensional stability, water vapor barrier property, bag formability, and transparency of the biaxially
  • the ⁇ -olefin copolymer (B2) preferably comprises a random copolymer of propylene and one or more ⁇ -olefins selected from the group consisting of ethylene and ⁇ -olefins having 4 to 10 carbon atoms, more preferably a random copolymer of propylene and one or two ⁇ -olefins selected from the group consisting of 1-butene and 1-octene, and even more preferably a random copolymer of propylene and 1-butene.
  • the ⁇ -olefin copolymer (B2) in the biaxially stretched film layer 101 may be used alone or in combination of two or more kinds.
  • Polymer (B) can be produced by various methods. For example, it can be produced using known catalysts such as Ziegler-Natta catalysts and metallocene catalysts.
  • the biaxially oriented film layer 101 may further contain an antistatic agent (C) from the viewpoint of further improving the balance of thermal dimensional stability and antistatic properties of the biaxially oriented polypropylene film 100 .
  • the total content of the homopolypropylene (A), polymer (B) and antistatic agent (C) in the propylene-based polymer composition (X) of this embodiment, i.e., the biaxially stretched film layer 101, is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and for example 100% by mass or less, when the entire propylene-based polymer composition (X) is taken as 100% by mass, from the viewpoint of further improving the performance balance of the biaxially stretched polypropylene film 100, such as antistatic property, thermal dimensional stability, environmental compatibility, heat resistance, water vapor barrier property, transparency, cost, mechanical properties, rigidity, bag formability, fluidity, moldability, handleability, appearance and lightness.
  • the antistatic agent (C) is not particularly limited, and for example, a known antistatic agent that is added to a polyolefin resin can be used.
  • known antistatic agents include anionic surfactants such as fatty acid salts, higher alcohol sulfates, aliphatic amines, sulfates of amides, phosphate salts of aliphatic alcohols, alkylarylsulfonates, and sulfonates of dibasic acid aliphatic esters; cationic surfactants such as aliphatic amine salts, quaternary ammonium salts of alkylamine sulfates, and alkylpyridinium salts; nonionic surfactants such as polyoxyethylene alkylphenol ethers, polyoxyethylene alkylamines, sorbitans (polyoxyethylene sorbitan alkyl esters), alkyldiethanolamines such as stearyldiethanolamine, and polyhydric alcohol fatty acid esters; and ampho
  • polyhydric alcohol fatty acid esters examples include glycerin fatty acid esters, diglycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, alkyl glucosides, and polycarboxylic acid esters.
  • glycerin fatty acid esters i.e., fatty acid monoglycerides
  • examples of glycerin fatty acid esters include stearic acid monoglyceride, oleic acid monoglyceride, linoleic acid monoglyceride, lauric acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, behenic acid monoglyceride, margaric acid monoglyceride, etc.
  • diglycerin fatty acid esters examples include stearic acid diglyceride, oleic acid diglyceride, linoleic acid diglyceride, lauric acid diglyceride, palmitic acid diglyceride, myristic acid diglyceride, behenic acid diglyceride, margaric acid diglyceride, etc.
  • the antistatic agent (C) preferably contains one or more compounds selected from the group consisting of diethanolamine compounds, amine ester compounds, and glycerin fatty acid esters.
  • the diethanolamine compound may be, for example, one or more selected from the group consisting of lauryl diethanolamine, myristyl diethanolamine, palmityl diethanolamine, stearyl diethanolamine, and oleyl diethanolamine.
  • Examples of the amine ester compound include one or more selected from the group consisting of lauryl diethanolamine monostearate, myristyl diethanolamine monooleate, palmityl diethanolamine monostearate, stearyl diethanolamine monolaurate, stearyl diethanolamine monostearate, stearyl diethanolamine monooleate, stearyl diethanolamine monobehenate, and oleyl diethanolamine monostearate.
  • glycerin fatty acid esters examples include ester compounds obtained by known methods such as esterification reaction between monoglycerin and fatty acid, or transesterification reaction between monoglycerin and fatty acid lower alkyl alcohol ester.
  • Glycerin fatty acid esters are preferably monoglycerin fatty acid ester compounds obtained from monoglycerin and fatty acid having 8 to 22 carbon atoms, but di-fatty acid esters and tri-fatty acid esters may also be present. These may be distilled or may be used as they are.
  • fatty acids having 8 to 22 carbon atoms include saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, arachidic acid, and behenic acid, and unsaturated fatty acids such as decenoic acid, undecenoic acid, dodecenoic acid, tetradecenoic acid, oleic acid, erucic acid, linoleic acid, linolenic acid, and ricinoleic acid.
  • the fatty acids having 8 to 22 carbon atoms are preferably one or more selected from the group consisting of lauric acid, myristic acid, palmitic acid, and stearic acid, and more preferably one or two selected from the group consisting of palmitic acid and stearic acid, from the viewpoint of further improving antistatic properties.
  • the content of the antistatic agent (C) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more, when the entire biaxially oriented film layer 101 is taken as 100% by mass, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100's antistatic properties, formability, and thermal dimensional stability, and from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100's thermal dimensional stability, water vapor barrier properties, transparency, mechanical properties, rigidity, bag formability, fluidity, formability, etc., is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, even more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less.
  • additives such as a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an antiblocking agent, an antifogging agent, a pigment, a dye, and an inorganic or organic filler may be added as necessary within a range that does not impair the object of the present embodiment.
  • the propylene polymer composition (X) of the present embodiment can be prepared by mixing or melt-kneading the respective components by dry blending, a tumbler mixer, a Banbury mixer, a single-screw extruder, a twin-screw extruder, a high-speed twin-screw extruder, a heated roll, or the like.
  • the biaxially oriented polypropylene film 100 has a surface resin layer 103 containing homopolypropylene (A) on at least one side of the biaxially oriented film layer 101 in order to impart functions such as heat resistance, heat sealability, antistatic properties, blocking resistance, printability, and slip properties to the film surface depending on the purpose.
  • the surface resin layer 103 is preferably provided on both sides of the biaxially stretched film layer 101.
  • the surface resin layer 103 is preferably provided on the outermost layer of the biaxially oriented polypropylene film 100 in order to further improve the functions of the biaxially oriented polypropylene film 100, such as heat resistance, heat sealability, antistatic properties, blocking resistance, printability, slip properties, etc., depending on the purpose.
  • the surface resin layer 103 is preferably provided so as to be in direct contact with the surface of the biaxially oriented film layer 101. This simplifies the manufacturing process of the biaxially oriented polypropylene film 100.
  • the thickness of the surface resin layer 103 is preferably 0.1 ⁇ m or more, more preferably 0.2 ⁇ m or more, even more preferably 0.5 ⁇ m or more, even more preferably 1.0 ⁇ m or more, and even more preferably 1.5 ⁇ m or more, from the viewpoint of further improving the functions of the biaxially oriented polypropylene film 100 such as heat fusion resistance, antistatic properties, blocking resistance, printability, and slip properties, and is preferably 10.0 ⁇ m or less, more preferably 8.0 ⁇ m or less, even more preferably 6.0 ⁇ m or less, even more preferably 5.0 ⁇ m or less, and even more preferably 3.0 ⁇ m or less, from the viewpoint of further improving the performance balance of the biaxially oriented polypropylene film 100 such as heat fusion resistance, thermal dimensional stability, formability, cost, mechanical properties, transparency, environmental compatibility, and light weight.
  • the thickness of the surface resin layer 103 refers to the thickness of the surface resin layer 103 provided on one side of the biaxially stretched film layer 101. That is, in this embodiment, when the surface resin layer 103 is provided on both sides of the biaxially stretched film layer 101, the above-mentioned thickness of the surface resin layer 103 indicates the thickness of the surface resin layer 103 provided on one side of the biaxially stretched film layer 101.
  • the surface resin layer 103 is a single layer. This makes it possible to further simplify the manufacturing process of the biaxially oriented polypropylene film 100.
  • the surface resin layer 103 is preferably formed by biaxial stretching at the same time as the biaxially stretched film layer 101 in a state before biaxial stretching. This allows the biaxially stretched polypropylene film 100 to be produced using a molding method such as co-extrusion molding, i.e., a laminated film produced in a single molding operation, thereby further simplifying the manufacturing process of the biaxially stretched polypropylene film 100. Therefore, it is preferable that the surface resin layer 103 is biaxially stretched.
  • the surface resin layer 103 may be subjected to a surface treatment in order to further improve the balance of printability and blocking resistance of the biaxially oriented polypropylene film 100.
  • a surface activation treatment such as corona treatment, flame treatment, plasma treatment, primer coat treatment, or ozone treatment may be performed.
  • the surface resin layer 103 is composed of, for example, a propylene-based polymer composition (Y) containing homopolypropylene (A).
  • Y propylene-based polymer composition
  • the preferred embodiment of the homopolypropylene (A) constituting the surface resin layer 103 is the same as the homopolypropylene (A) contained in the biaxially stretched film layer 101 described above.
  • the content of homopolypropylene (A) in the propylene-based polymer composition (Y), i.e., the surface resin layer 103, is preferably 75% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and preferably 100% by mass or less, when the entire propylene-based polymer composition (Y), i.e., the entire surface resin layer 103, is taken as 100% by mass, from the viewpoint of further improving the balance of performance such as antistatic property, heat resistance, heat adhesion property, thermal dimensional stability, heat resistance, water vapor barrier property, transparency, mechanical properties, rigidity, bag formability, fluidity, and moldability of the biaxially oriented polypropylene film 100.
  • additives such as a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slipping agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent, a pigment, a dye, and an inorganic or organic filler may be added as necessary within a range that does not impair the object of this embodiment.
  • the propylene polymer composition (Y) can be prepared, for example, by mixing or melt-kneading each component by means of a dry blend, a tumbler mixer, a Banbury mixer, a single-screw extruder, a twin-screw extruder, a high-speed twin-screw extruder, a heat roll or the like.
  • the biaxially stretched polypropylene film 100 can be obtained, for example, by co-extrusion molding a propylene-based polymer composition (X) for forming the biaxially stretched film layer 101 and a propylene-based polymer composition (Y) for forming the surface resin layer 103 into a film, and then biaxially stretching the film obtained by the co-extrusion molding using a known biaxially stretched film production method such as a simultaneous biaxial stretching method, a sequential biaxial stretching method, or an inflation biaxial stretching method.
  • the molding device and molding conditions are not particularly limited, and conventionally known molding devices and molding conditions can be adopted.
  • the molding device a T-die extruder, a multi-layer T-die extruder, an inflation molding machine, a multi-layer inflation molding machine, or the like can be used.
  • the biaxial stretching conditions for example, known OPP film manufacturing conditions can be adopted. More specifically, in the sequential biaxial stretching method, for example, the stretching temperature in the MD direction may be set to 100°C to 145°C, the stretching ratio in the MD direction may be set to a range of 4.5 to 6 times, the stretching temperature in the TD direction may be set to 130°C to 190°C, and the stretching ratio in the TD direction may be set to a range of 9 to 11 times.
  • the biaxially oriented polypropylene film 100 can also be obtained by separately forming the biaxially oriented film layer 101 and the surface resin layer 103, laminating them together, and heat-forming them.
  • the biaxially oriented polypropylene film 100 can also be suitably used as a food packaging film that constitutes a food package.
  • the food packaging of this embodiment is a packaging that uses a biaxially oriented polypropylene film 100, and is, for example, a packaging bag used for the purpose of containing food. Furthermore, the food packaging of this embodiment may use the biaxially oriented polypropylene film 100 in only a portion thereof depending on the application, or the biaxially oriented polypropylene film 100 may be used for the entire food packaging.
  • the food packaging of this embodiment includes the food packaging of this embodiment and food inside the food packaging.
  • the food packaging of this embodiment is the food packaging of this embodiment that contains food.
  • the biaxially oriented polypropylene film 100 may further include one or more layers selected from the group consisting of a sealant layer and a coating layer.
  • the biaxially oriented polypropylene film 100 can also be used as a raw material for coating.
  • h-PP1 homopolypropylene (MFR: 3.0 g/10 min, melting point: 165° C., isotactic mesopentad fraction (mmmm): 98.0%, Mw: 370,000, Mn: 68,000, Mw/Mn: 5.4, content of propylene-derived structural units: 100 mol%)
  • h-PP2 homopolypropylene (MFR: 3.0 g/10 min, melting point: 159°C, isotactic mesopentad fraction (mmmm): 97.5%, Mw: 469,000, Mn: 56,300, Mw/Mn: 8.3, content of ethylene-derived structural units: 1.2 mol%, content of propylene-derived structural units: 98.8 mol%)
  • Masterbatch of Antistatic Agent (C) C1 A masterbatch obtained by kneading the above h-PP2 (90% by mass) with 10% by mass of an antistatic agent (stearyl diethanolamine 2.0% by mass, stearyl diethanolamine monostearate 5.1% by mass, glycerin monostearate 2.9% by mass).
  • an antistatic agent stearyl diethanolamine 2.0% by mass, stearyl diethanolamine monostearate 5.1% by mass, glycerin monostearate 2.9% by mass.
  • Isotactic mesopentad fraction (mmmm) of homopolypropylene A
  • the isotactic mesopentad fraction (mesopentad fraction, (mmmm)) was measured by 13 C-NMR using a nuclear magnetic resonance apparatus (AVANCE III cryo-500 model, manufactured by Bruker Biospin). The sample was dissolved in the following measurement solvent and measured, and the evaluation was made from the integrated intensity of each signal.
  • Measurement nucleus 13C (125MHz) Measurement mode: Single pulse proton broadband decoupling Pulse width: 45° Number of points: 64k Repeat time: 5.5 seconds Measurement solvent: orthodichlorobenzene/heavy benzene (4:1) Sample concentration: 50 mg/0.6 mL Measurement temperature: 120°C Window function: exponential (BF: 0.5 Hz) Chemical shift reference: mmmm (CH 3 ): 21.59 ppm
  • Weight average molecular weight (Mw) and number average molecular weight (Mn) of homopolypropylene (A) and polymer (B) The weight average molecular weight (Mw) and number average molecular weight (Mn) of the homopolypropylene (A) and the polymer (B) were measured by gel permeation chromatography (GPC).
  • the GPC method was performed using a gel permeation chromatograph (Tosoh Corporation, HLC-8321 GPC/HT type) as follows.
  • the separation columns were two TSKgel GNH6-HT and two TSKgel GNH6-HTL, each with a diameter of 7.5 mm and a length of 300 mm, the column temperature was 145° C., the mobile phase was o-dichlorobenzene and 0.025 mass% BHT as an antioxidant, and the flow rate was 1.0 mL/min, the sample concentration was 0.1% (w/v), the sample injection amount was 400 ⁇ L, and a differential refractometer was used as a detector.
  • the molecular weight was calculated as polypropylene equivalent molecular weight using monodisperse polystyrene as a standard.
  • Measurement nucleus 13C (125MHz) Measurement mode: Single pulse proton broadband decoupling Pulse width: 45° Number of points: 64k Repeat time: 5.5 seconds Measurement solvent: orthodichlorobenzene/heavy benzene (4:1) Sample concentration: 50 mg/0.6 mL Measurement temperature: 120°C Window function: exponential (BF: 0.5 Hz) In addition, the content of structural units derived from ⁇ -olefins other than propylene contained in the biaxially oriented polypropylene film was measured using the biaxially oriented polypropylene film as a sample.
  • Tensile modulus A test piece of 15 mm x 15 cm was cut out from the biaxially stretched polypropylene film.
  • the tensile modulus of elasticity in the MD direction T1 and the tensile modulus of elasticity in the TD direction T2 of the test piece were measured using a tensile tester manufactured by Orientec Co., Ltd. in accordance with JIS K7127 (1999) under the conditions of a measurement temperature of 23 ⁇ 2 °C, 50 ⁇ 5% RH, and a tensile speed of 5 mm/min.
  • Thermal expansion coefficient and thermal shrinkage coefficient of biaxially oriented polypropylene film at 120 ° C were measured in accordance with JIS C2151:2019.
  • a test piece of 10 cm x 10 cm was cut out from the biaxially oriented polypropylene film.
  • the test piece was heat-treated at 120 ° C for 15 minutes.
  • the test piece was heated in a hot air circulation type thermostatic chamber (manufactured by ADVANTEC, product name: DRM620DE) while hanging without applying force.
  • the test piece was cooled to room temperature, and the length of the test piece was measured.
  • the length of the test piece in the TD direction after the heat treatment was taken as TD 1 [cm]
  • the thermal expansion coefficient [%] in the TD direction was calculated by 100 ⁇ (TD 1 -10) / 10.
  • the length of the test piece in the MD direction after the heat treatment was taken as MD 1 [cm]
  • the thermal shrinkage coefficient [%] in the MD direction was calculated by 100 ⁇ (10 - MD 1 ) / 10.
  • the above measurement was performed three times, and the average values of the obtained measurements were adopted as the thermal expansion coefficient and thermal shrinkage coefficient of the biaxially oriented polypropylene film at 120 ° C., respectively.
  • the surface resistivity of the biaxially stretched polypropylene film was measured by the following method in accordance with JIS C2139:2018. First, a 10 cm x 10 cm test piece was cut out from the biaxially stretched polypropylene film. The test piece was then stored for 24 hours under an environment of 23°C temperature and 50% RH humidity. Then, using an R8340 (digital ultra-high resistance/microcurrent meter) manufactured by Advantest Corporation, the surface (corona-treated surface) of the surface resin layer 2 side of the obtained biaxially stretched polypropylene film was measured under conditions of 23°C temperature and 50% RH humidity, and the surface resistivity and surface resistivity log ⁇ were calculated, respectively.
  • R8340 digital ultra-high resistance/microcurrent meter
  • Stretching temperature in TD direction [°C]: See Table 1.
  • Stretching ratio in TD direction [times]: See Table 1.
  • Relaxation rate [%]: See Table 1.
  • the relaxation rate refers to the maximum stretching ratio width in the device settings divided by the tenter exit width.
  • the notation "A/B/C" for the stretching temperature in Table 1 means "preheating temperature (temperature for heating the original film before stretching)/stretching temperature (temperature during stretching)/heat setting temperature (temperature during heat setting (annealing) after stretching)".
  • the biaxially oriented polypropylene film of the embodiment had a better balance of thermal dimensional stability and antistatic properties than the biaxially oriented polypropylene film of the comparative example.
  • the present invention can also take the following forms:
  • a biaxially stretched film layer including a homopolypropylene (A), at least one polymer (B) selected from the group consisting of a random polypropylene (B1) and an ⁇ -olefin copolymer (B2), and an antistatic agent (C); a surface resin layer located on at least one surface of the biaxially oriented film layer and containing homopolypropylene (A);
  • a biaxially oriented polypropylene film comprising: 2. The biaxially oriented polypropylene film according to 1., wherein the surface resin layer side has a surface resistivity log ⁇ of less than 14.0. 3. The biaxially stretched polypropylene film according to 1.
  • the antistatic agent (C) comprises one or more selected from the group consisting of diethanolamine compounds, amine ester compounds, and glycerin fatty acid esters. 4.
  • the ⁇ -olefin copolymer (B2) comprises a random copolymer of propylene and one or more ⁇ -olefins selected from the group consisting of ethylene and ⁇ -olefins having 4 to 10 carbon atoms.

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Abstract

Est divulgué un film de polypropylène étiré biaxialement (100) qui comprend une couche de film étiré biaxialement (101) qui contient un polymère de propylène, et une couche de résine de surface (103) qui est positionnée sur au moins une surface de la couche de film étiré biaxialement (101) et contient un homopolypropylène (A), la demi-vie de la tension chargée saturée telle que déterminée par le processus décrit ci-dessous étant inférieure ou égale à 1300 secondes. (Processus) Une tension est appliquée à la surface du côté de la couche de résine de surface (103) du film de polypropylène étiré biaxialement (100) pendant 30 secondes à une tension d'application de 10 kV, une température de 23 °C et une humidité de 50 % RH, la distance entre l'échantillon et l'électrode étant de 20 mm, et la tension chargée saturée de la surface du film de polypropylène étiré biaxialement (100) et la demi-vie de la tension chargée saturée étant calculées conformément à la norme JIS L1094 (2014).
PCT/JP2023/034589 2022-09-28 2023-09-22 Film de polypropylène étiré biaxialement, emballage pour aliment et emballage alimentaire WO2024070981A1 (fr)

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JP2022-155378 2022-09-28
JP2022155373A JP2024049108A (ja) 2022-09-28 2022-09-28 二軸延伸ポリプロピレンフィルム、食品用包装体および食品包装体
JP2022-155373 2022-09-28
JP2022155378A JP2024049113A (ja) 2022-09-28 2022-09-28 二軸延伸ポリプロピレンフィルム、食品用包装体および食品包装体

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004306588A (ja) * 2003-03-27 2004-11-04 Futamura Chemical Industries Co Ltd 二軸延伸複層フィルム
JP2012012032A (ja) * 2010-06-29 2012-01-19 Asahi Kasei Chemicals Corp カバーテープ
WO2015056781A1 (fr) * 2013-10-17 2015-04-23 日清食品ホールディングス株式会社 Feuille en résine thermoplastique et corps moulé
WO2017170244A1 (fr) * 2016-03-28 2017-10-05 東洋紡株式会社 Film de polypropylène à orientation biaxiale

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004306588A (ja) * 2003-03-27 2004-11-04 Futamura Chemical Industries Co Ltd 二軸延伸複層フィルム
JP2012012032A (ja) * 2010-06-29 2012-01-19 Asahi Kasei Chemicals Corp カバーテープ
WO2015056781A1 (fr) * 2013-10-17 2015-04-23 日清食品ホールディングス株式会社 Feuille en résine thermoplastique et corps moulé
WO2017170244A1 (fr) * 2016-03-28 2017-10-05 東洋紡株式会社 Film de polypropylène à orientation biaxiale

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