Biaxially oriented polypropylene-based multilayer film

Abstract

Polypropylene-based multilayer film, which is biaxially oriented, process for manufacturing biaxially oriented multilayer film and its use in flexible packaging.

Description

Technical Field

[0001] This invention relates to a polypropylene-based multilayer film (which is biaxially oriented), a process for manufacturing the biaxially oriented multilayer film, and its use in flexible packaging. Background Technology

[0002] Polypropylene resins are widely used in the food packaging industry because of their excellent tensile strength, stiffness, and transparency, and they offer the added advantage of being non-toxic and odorless. They are typically used in the form of cast film (CPP), biaxially oriented film (BOPP), or water-quenched tubular film (TQPP).

[0003] Biaxially oriented polypropylene (BOPP) film is a film stretched in both the longitudinal (machine direction) and transverse (transverse direction) directions, resulting in molecular chain orientation in both directions.

[0004] Biaxially oriented polypropylene (BOPP) multilayer films are commonly used in the packaging industry, including food packaging.

[0005] Typically, this application includes a sealing layer that provides the necessary sealing performance for an airtight packaging system. However, since this sealing layer comes into direct contact with the packaged food, cleanliness (e.g., low levels of extractables) is crucial.

[0006] Food packaging films are typically transparent, or more generally, they should also have good optical properties, such as low haze, to provide an attractive appearance.

[0007] According to cutting-edge technology in this field, polypropylene is based on Ziegler-Natta catalyst technology, i.e., a heterogeneous catalyst with alkylaluminum activated titanium centers. Therefore, the sealing layer is typically a Ziegler-Natta catalyzed propylene-ethylene-butene terpolymer.

[0008] For example, WO 2009 / 019169 A1 describes a process for providing a Ziegler-Natta-derived PP terpolymer suitable for blown films using a 1,3-diether internal donor catalyst, comprising at least 8 wt% of comonomer units, wherein the comonomer units are derived from ethylene and C4 to C8 α-olefins. According to WO 2009 / 019169 A1, an optimal balance of performance should be observed when an ethylene content of less than 2.5 wt% is combined with a butene-1 content of more than 10 wt%, or when the ethylene content is more than 2.5 wt%, the butene content should be less than 10 wt%. A composition with an ethylene content of 1.2 wt% and a butene content of 11.3 wt%, i.e., a C4 / C2 (wt / wt) ratio of 9.4, yields a SIT of 107.4 °C and a haze of 0.2% (1 mm plate).

[0009] For decades, this solution has adequately met the needs. However, due to changes in market demands, this terpolymer has reached its limits to some extent, for example, its sealing initiation temperature is not low enough, and its optical properties are not as good as required.

[0010] Metallocene catalyst-derived PP terpolymers have also been described for sealing applications.

[0011] For example, EP 20193414A discloses a bimodal C2C3C4 terpolymer, which is produced by polymerization in a ring reactor followed by polymerization in a gas-phase reactor in the presence of a metallocene catalyst. After adjusting the post-polymerization MFR2 (ISO 1133, 2.16 kg, 230 °C) to a final MFR2 (ISO 1133, 2.16 kg, 230 °C) of 2.0 g / 10 min by viscous cracking, the terpolymer was used to manufacture cast films.

[0012] BOPP membranes were mentioned in general, but no verification was conducted.

[0013] WO 2022167368 A discloses a membrane made from a blend of a C2C3C4 terpolymer and a C3C4 random copolymer resin.

[0014] The C2C3C4 terpolymer was prepared as follows: polymerization was carried out in a ring reactor, followed by polymerization in a gas-phase reactor in the presence of a metallocene catalyst, thereby producing a considerably high amount of polymer in the gas-phase reactor (i.e., 59.0 wt%, relative to the final polymer). According to claim 1, the terpolymer has a xylene cold soluble (XCS) content of 5.0 to 25.0 wt%, preferably 15.0 to 19.0 wt%, as measured according to ISO 16152 at 25°C. The terpolymer used in the examples has a considerably high xylene cold soluble (XCS) fraction of 17.1 wt%.

[0015] EP 1358252 B1 (Basell) claims protection for a bi-oriented polypropylene film (BOPP) wherein at least one layer comprises a propylene random copolymer (containing at least 0.8 wt% ethylene) or a propylene polymer composition (containing a propylene random copolymer and containing at least 0.8 wt% of a polymer selected from ethylene and C4-C). 10 (one or more comonomers of α-olefin), wherein the random copolymer or polymer composition has the following characteristics:

[0016] (1) The melting temperature measured by DSC (temperature change at 20°C per minute) is above 155°C; (2) The content of xylene-soluble fraction at room temperature (25°C) is less than 3 wt%, and the ratio of polymer fraction collected in the temperature range of 25 to 95°C by TREF method to xylene-soluble fraction at room temperature is above 8 wt% / wt%; and (3) The melt flow rate (230°C, 2.16 kg load) is 1 to 10 g / 10 min.

[0017] No mention was made of sealing-related performance.

[0018] As mentioned above, BOPP multilayer films are widely used in packaging. Key requirements are sealing performance and low extractable content.

[0019] Therefore, BOPP multilayer films with very good sealing performance and low extractable content are still needed. Summary of the Invention

[0020] Therefore, given the difference between the melting temperature of the metallocene-catalyzed ethylene-propylene-1-butene terpolymer base resin and the sealing initiation temperature of the BOPP multilayer film, one object of the present invention is to provide a novel BOPP multilayer film with improved sealing performance, such as a low sealing initiation temperature (SIT) and a wide processing window.

[0021] Another issue is the recycling of BOPP multilayer films after their first use. Recycling BOPP multilayer films made of different materials (e.g., different types of polymers, such as polyamide or polyester and polypropylene) is more challenging than recycling single-material solutions. On the other hand, different materials are often required to achieve acceptable properties (e.g., sealing performance and mechanical properties). Therefore, another object of the present invention is to provide a polypropylene-based single-material solution that exhibits good sealing performance.

[0022] Therefore, the present invention relates to a biaxially oriented polypropylene multilayer film, which includes at least a core layer (CL), a first outer layer (OL1), and a second outer layer (OL2), wherein,

[0023] The first outer layer (OL1) and the second outer layer (OL2) comprise:

[0024] Based on the total weight of their respective outer layers, 70.0 to 100.0 wt% of a metallocene-catalyzed ethylene-propylene-1-butene terpolymer (mC2C3C4) base resin, wherein the mC2C3C4 base resin has:

[0025] • Relative to the total weight of the mC2C3C4 base resin, through 13C-NMR analysis (as described in the experimental section) showed that the ethylene (C2) content ranged from 0.7 to 2.0 wt%.

[0026] • Relative to the total weight of the mC2C3C4 base resin, through 13 The 1-butene (C4) content, as determined by C-NMR analysis (as described in the experimental section), ranged from 4.0 to 7.8 wt%.

[0027] • Relative to the total weight of the mC2C3C4 base resin, through 13 C-NMR analysis (as described in the experimental section) showed that the propylene (C3) content ranged from 90.2 to 96.0 wt%.

[0028] Therefore, the sum of the units derived from ethylene, propylene, and butene is 100 wt%, and

[0029] • The melt flow rate (MFR2) (230℃ / 2.16kg) measured according to ISO 1133 is 3.0 to 10.0 g / 10min;

[0030] • Based on the total weight of the mC2C3C4 base resin, the xylene cold solubles (XCS) content, measured at 25°C according to ISO 16152, is 2.0 to 5.0 wt%.

[0031] • Melting temperature T measured by DSC according to ISO 11357 m The temperature is between 120 and 129°C.

[0032] • Crystallization temperature T measured by DSC according to ISO 11357 c The temperature is between 80 and 110°C.

[0033] ·pass 13 C-NMR analysis (as described in the experimental section) showed that the number of defects in the 2,1 region ranged from 0.10 to 1.5 mol%.

[0034] and

[0035] The mC2C3C4 base resin is composed of the following:

[0036] (i) Based on the total weight of the mC2C3C4 base resin, 30.0 to 60.0 wt% of a first polymer component (TERPO-1), the first polymer component (TERPO-1) having:

[0037] • The melt flow rate (MFR2) (230℃ / 2.16kg) measured according to ISO 1133 is 1.0 to 10.0 g / 10 min;

[0038] • Relative to the total weight of the first polymer component (TERPO-1), by 13 C-NMR analysis (as described in the experimental section) showed an ethylene (C2) content of 0.7 to 1.3 wt%; and

[0039] • Relative to the total weight of the first polymer component (TERPO-1), by 13 The 1-butene (C4) content, as determined by C-NMR analysis (as described in the experimental section), was 4.0 to 6.0 wt%.

[0040] (ii) Based on the total weight of the ethylene-propylene-1-butene terpolymer, 40.0 to 70.0 wt% of a second polymer component (TERPO-2), the second polymer component (TERPO-2) having:

[0041] • The melt flow rate MFR2 (230℃ / 2.16kg) measured according to ISO 1133 is 10.0 to 20.0 g / 10min;

[0042] • Relative to the total weight of the second polymer component (TERPO-2), by 13 C-NMR analysis (as described in the experimental section) showed an ethylene (C2) content of 1.3 to 2.0 wt%; and

[0043] • Relative to the total weight of the first polymer component (TERPO-2), by 13 The 1-butene (C4) content, as determined by C-NMR analysis (as described in the experimental section), ranged from 6.0 to 10.0 wt%; and

[0044] (iii) Optionally one or more additives, said additives being selected from slip agents, anti-caking agents, UV stabilizers, antistatic agents, α-nucleating agents, antioxidants, and mixtures thereof;

[0045] The core layer (CL) is a polypropylene-based layer;

[0046] The biaxially oriented polypropylene multilayer film has the following characteristics:

[0047] According to the experimental section, the sealing initiation temperature measured on the 25μm biaxially oriented experimental cast film was 80 to 105℃.

[0048] Surprisingly, the biaxially oriented polypropylene multilayer film of the present invention provides improved sealing performance, such as a particularly low seal initiation temperature (SIT) and a wide processing temperature range. Detailed Implementation

[0049] definition

[0050] The use of the term "comprising" in this application specification and claims does not exclude other unstated elements of primary or secondary functional importance. For the purposes of this invention, the term "consisting of" is considered a preferred embodiment of the term "comprising." In the following, if a group is defined as including at least a certain number of embodiments, this should also be understood as disclosing a group preferably consisting only of those embodiments.

[0051] Whenever the terms “include” or “have” are used, they mean equivalent to “include” as defined above.

[0052] When an indefinite or definite article (such as “a,” “a,” or “the”) is used to refer to a singular noun, this includes the plural form of the noun unless otherwise specified.

[0053] In this invention, the metallocene-catalyzed ethylene-propylene-1-butene terpolymer (mC2C3C4) base resin is defined as an ethylene-propylene-1-butene terpolymer base resin prepared in the presence of a metallocene catalyst.

[0054] According to the present invention, a "terpolymer" refers to a polymer made from monomers ethylene, propylene, and 1-butene, wherein these monomers can be found in the polymer chain. The sum of the weight contents of the units derived from these monomers is 100 wt%. Pseudo-terpolymers made from mixtures of two copolymers are not included in the term "terpolymer" of the present invention. Pseudo-terpolymers can be identified by coupling TREF-IR, coupling TREF-NMR, or similar methods. By definition, the terpolymers of the present invention are not mixtures of two copolymers.

[0055] In this invention, a polypropylene layer is defined as a layer made solely of polypropylene polymer, i.e., essentially devoid of polymers other than polypropylene. Therefore, the content of polymers other than polypropylene is less than 5.0 wt%, preferably less than 3.0 wt%, and more preferably less than 2.0 wt%.

[0056] Regional defects

[0057] Regional defects in propylene polymers can be of three different types: 2,1-erythroline (2,le), 2,1-threoline (2,lt), and 3,1-defects. A detailed description of the structure and formation mechanism of regional defects in polypropylene can be found in Chemical Reviews 2000, 100(4), pp. 1316-1327. As described in more detail below, using... 13 These defects were measured by C NMR.

[0058] The term "2,1-region defect" as used in this invention defines the sum of 2,1-erythrotype and 2,1-threotype region defects. The propylene random copolymers or polypropylene homopolymers with a certain number of region defects desired in the propylene compositions of this invention are generally preferably prepared in the presence of a single-center catalyst.

[0059] Catalysts have a significant impact on the microstructure of polymers. Therefore, polypropylene prepared using metallocene catalysts has a different microstructure compared to polypropylene prepared using Ziegler-Natta (ZN) catalysts. The most significant difference is the presence of regional defects in metallocene-based polypropylene, which is absent in polypropylene prepared using Ziegler-Natta (ZN) catalysts.

[0060] It is also understood that the following embodiments can be combined within the meaning of this disclosure.

[0061] Detailed description

[0062] Outer layers (OL1, OL2)

[0063] According to the present invention, the multilayer film includes a first outer layer (OL1) and a second outer layer (OL2), which contain 70.0 to 100.0 wt%, preferably 80.0 to 100.0 wt%, of a metallocene-catalyzed ethylene-propylene-1-butene terpolymer (mC2C3C4) base resin based on each outer layer.

[0064] One possible modifier for the outer layer is a propylene-1-butene random copolymer, characterized by a melting temperature T measured by differential scanning calorimetry (DSC). m The temperature is 70 to 90 degrees Celsius, through 13 C-NMR analysis (as described in the experimental section) showed that the 1-butene content was 20.0 to 35.0 wt% (relative to the total amount of the propylene-1-butene random copolymer), the sum of units derived from propylene and 1-butene was 100 wt%, and the melt flow rate MFR2 (230 °C / 2.16 kg) was 1.0 to 18.0 g / 10 min, as determined according to ISO 1133.

[0065] Another suitable modifier is: propylene-ethylene random copolymer, which is obtained through... 13 The ethylene content, as determined by C-NMR analysis, ranged from 1.0 to 25.0 wt% (relative to the total amount of the propylene-ethylene random copolymer), and the melt flow rate (MFR2, 230 °C / 2.16 kg) was 1.0 to 300.0 g / 10 min, as determined by ISO 1133.

[0066] The content of the modifier may be up to 30.0 wt%, preferably up to 20.0 wt%.

[0067] More preferably, the outer layers (OL1) and (OL2) are composed of a metallocene-catalyzed ethylene-propylene-1-butene terpolymer (mC2C3C4) base resin.

[0068] Metallocene-catalyzed ethylene-propylene-1-butene terpolymer base resin

[0069] The metallocene-catalyzed ethylene-propylene-1-butene terpolymer (mC2C3C4) base resin is characterized by the following properties:

[0070] • Relative to the total weight of the mC2C3C4 base resin, through 13 C-NMR analysis (as described in the experimental section) showed that the ethylene (C2) content ranged from 0.7 to 2.0 wt%.

[0071] • Relative to the total weight of the mC2C3C4 base resin, through 13 The 1-butene (C4) content, as determined by C-NMR analysis (as described in the experimental section), ranged from 4.0 to 7.8 wt%.

[0072] • Relative to the total weight of the mC2C3C4 base resin, through 13 C-NMR analysis (as described in the experimental section) showed that the propylene (C3) content ranged from 90.2 to 96.0 wt%.

[0073] The sum of units derived from ethylene, propylene, and butene is 100 wt%, and

[0074] • The melt flow rate (MFR2) (230℃ / 2.16kg) measured according to ISO 1133 is 3.0 to 10.0 g / 10min;

[0075] • The xylene cold solubles (XCS) content, measured at 25°C according to ISO 16152, is 2.0 to 5.0 wt% based on the weight of the mC2C3C4 base resin.

[0076] • Melting temperature T measured by DSC according to ISO 11357 m The temperature is between 120 and 129°C.

[0077] • Crystallization temperature T measured by DSC according to ISO 11357 c The temperature is between 80 and 110°C.

[0078] ·pass 13 C-NMR analysis (as described in the experimental section) showed that the number of defects in the 2,1 region ranged from 0.10 to 1.5 mol%.

[0079] The ethylene (C2) content of the mC2C3C4 base resin is preferably 0.8 to 1.9 wt%, more preferably 0.9 to 1.8 wt%, and even more preferably 1.0 to 1.8 wt%, relative to the total weight of the mC2C3C4 base resin.

[0080] The 1-butene (C4) content of the mC2C3C4 base resin is preferably 4.1 to 7.7 wt%, more preferably 4.2 to 7.6 wt%, relative to the total weight of the mC2C3C4 base resin.

[0081] The melt flow rate MFR2 (230°C / 2.16 kg) measured according to ISO 1133 is preferably 4.5 to 9.5 g / 10 min, more preferably 5.0 to 9.0 g / 10 min, and even more preferably 5.5 to 8.5 g / 10 min.

[0082] Based on the weight of the mC2C3C4 base resin, the xylene cold solubles (XCS) content, as measured according to ISO 16152, is preferably 2.5 to 4.8 wt%, more preferably 2.8 to 4.5 wt%.

[0083] The melting temperature T, as measured by DSC according to ISO 11357. m The preferred temperature is 122 to 128°C.

[0084] The crystallization temperature T, as measured by DSC according to ISO 11357, is... c Preferably, the temperature is 82 to 105°C, more preferably 85 to 100°C, and even more preferably 86 to 90°C.

[0085] pass 13 The number of defects in the 2,1 region as determined by C-NMR analysis (as described in the experimental section) is preferably 0.15 to 0.90 mol%, more preferably 0.20 to 0.60 mol%.

[0086] According to the present invention, the mC2C3C4 base resin comprises two polymer components (TERPO-1) and (TERPO-2), wherein component (TERPO-1) is present in an amount of 30.0 to 60.0 wt%, preferably 40.0 to 58.0 wt%, more preferably 45.0 to 55.0 wt% (based on the total weight of the mC2C3C4 base resin), and component (TERPO-2) is present in an amount of 70.0 to 40.0 wt%, preferably 60.0 to 42.0 wt%, more preferably 55.0 to 45.0 wt% (based on the total weight of the mC2C3C4 base resin).

[0087] Optionally, a small amount (typically less than 5.0 wt%, preferably less than 2.0 wt%) of prepolymer component may also be present in the mC2C3C3 base resin based on the total weight of the mC2C3C4 base resin. This prepolymer component (if present) is typically included in the amount of component (TERPO-1).

[0088] In addition, based on the total weight of the ethylene-propylene-1-butene terpolymer, the mC2C3C4 base resin may optionally contain one or more additives selected from slip agents, anti-caking agents, UV stabilizers, antistatic agents, α-nucleating agents, antioxidants, and mixtures thereof.

[0089] Based on the total weight of the mC2C3C4 base resin, the total amount of one or more commonly used additives present in the mC2C3C3 base resin is preferably 0.01 to 5.0 wt%, more preferably 0.05 to 3.0 wt%.

[0090] Preferably, at least one antioxidant is added to the mC2C3C4 base resin of the present invention.

[0091] The total amount of (i) (TERPO-1), (ii) (TERPO-2) and (iii) optional additives is 100.0 wt%.

[0092] The ethylene content of the mC2C3C4 base resin component (TERPO-1) is 0.7 to 1.3 wt%, preferably 0.7 to 1.2 wt%, more preferably 0.8 to 1.2 wt%; and

[0093] The ethylene content of component (TERPO-2) is 1.3 to 2.0 wt%, preferably 1.3 to 1.9 wt%, and more preferably 1.4 to 1.9 wt%.

[0094] Preferably, the ethylene content of component (TERPO-1) is lower than that of component (TERPO-2).

[0095] The 1-butene content of the mC2C3C4 base resin component (TERPO-1) is 4.0 to 6.0 wt%, preferably 4.1 to 6.0 wt%, more preferably 4.1 to 5.9 wt%; and

[0096] The 1-butene content of component (TERPO-2) is 6.0 to 10.0 wt%, preferably 6.5 to 9.5 wt%, and more preferably 7.0 to 9.0 wt%.

[0097] The 1-butene content of component (TERPO-1) is lower than the ethylene content of component (TERPO-2).

[0098] The melt flow rate (MFR2) of component (TERPO-1) as measured according to ISO 1133 (230°C / 2.16 kg) is 1.0 to 10.0 g / 10 min, preferably 2.0 to 9.5 g / 10 min, and more preferably 2.5 to 9.0 g / 10 min.

[0099] The melt flow rate (MFR2) of component (TERPO-2) measured according to ISO 1133 is 10.0 to 20.0 g / 10 min, preferably 10.5 to 19.0 g / 10 min, and more preferably 11.0 to 18.0 g / 19 min.

[0100] The MFR2 of component (TERPO-1) is lower than that of component (TERPO-2).

[0101] In another preferred embodiment of the present invention, the mC2C3C4 base resin is prepared in the presence of a metallocene catalyst, preferably a metallocene catalyst comprising the composite described in any one of the embodiments of WO 2013 / 007650 A1, WO 2015 / 158790 A2, WO 2018 / 122134A1 or WO2019 / 179959.

[0102] Preferably, the composite used to prepare the mC2C3C4 base resin is described, for example, in WO 2019179959.

[0103] A more preferred complex is the complex of formula (i):

[0104]

[0105] In the formula, each R 1 They may be independently identical or different, and are hydrogen or straight-chain or branched C1-C6 alkyl groups;

[0106] R′ is C 1-10 Hydrocarbon group, preferably C 1-4 Hydrocarbon group, more preferably methyl group;

[0107] X can be independently a hydrogen atom, a halogen atom, or a C atom. 1-6 Alkoxy, C 1-6 Alkyl, phenyl, or benzyl.

[0108] Most preferably, X is chlorine, benzyl, or methyl. Preferably, the two X groups are the same. The most preferred choices are two chlorides, two methyl groups, or two benzyl groups, especially two chlorides.

[0109] The preferred metallocene catalyst complexes of the present invention include:

[0110] Racemic-anti-dimethylsilanediyl[2-methyl-4,8-bis(4′-tert-butylphenyl)-1,5,6,7-tetrahydro-s-dipentanecyclobenzo[indacen-1-yl][2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butyl-1-yl]zirconium dichloride;

[0111] Racemic-anti-dimethylsilanediyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-s-dipentanecyclobenzo[2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butyl-1-yl]zirconium dichloride;

[0112] Racemic-anti-dimethylsilanediyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-s-dipentanecyclobenzo[2-methyl-4-(3',5'-di-tert-butylphenyl)-5-methoxy-6-tert-butyl-1-yl]zirconium dichloride;

[0113] Or its corresponding dimethylzirconium analogue.

[0114] In another preferred embodiment of the invention, a cocatalyst system comprising a boron-containing cocatalyst (e.g., a borate cocatalyst and an aluminoxane cocatalyst) is used.

[0115] The catalyst can be used in supported or unsupported form, preferably in supported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina, or zirconium dioxide, or a mixed oxide (e.g., silica-alumina), particularly silica, alumina, or silica-alumina. Silica support is preferred. Those skilled in the art understand the procedures required for supporting metallocene catalysts.

[0116] Particularly preferred is that the carrier is a porous material, which allows the composite to be loaded into the pores of the carrier, for example using processes similar to those described in WO 94 / 14856, WO 95 / 12622 and WO 2006 / 097497.

[0117] The average particle size of silica supports is typically 10 to 100 μm. However, it has been found that if the average particle size of the support is 15 to 80 μm, preferably 18 to 50 μm, special advantages can be obtained.

[0118] The average pore size of the silica support can be 10 to 100 nm, and the pore volume can be 1 to 3 mL / g.

[0119] Examples of suitable support materials include ES757 manufactured and sold by PQ Corporation, Sylopol 948 manufactured and sold by Grace Corporation, or SUNSPERA DM-L-303 silica manufactured by AGC Si Tech Corporation. The support may optionally be calcined prior to use in catalyst preparation to achieve optimal silanol group content.

[0120] The use of these carriers is common practice in this field.

[0121] The ethylene-propylene-1-butene terpolymer base resin can be produced in a sequential polymerization process comprising at least two polymerization reactors (R1) and (R2), wherein a first component (TERPO-1) is produced in the first polymerization reactor (R1) and subsequently transferred to the second polymerization reactor (R2). In the second polymerization reactor (R2), a second component (TERPO-2) is produced in the presence of the first component (TERPO-1).

[0122] Polymerization processes suitable for producing ethylene-propylene-1-butene terpolymer base resins typically include one or two polymerization stages, each of which can be carried out in solution, slurry, fluidized bed, bulk, or gas phase.

[0123] The term "polymerization reactor" should indicate the occurrence of the main polymerization reaction. Therefore, in cases where the process consists of one or two polymerization reactors, this definition does not preclude the inclusion of a prepolymerization step, for example, in a prepolymerization reactor. The term "consisting of" is a closed-ended statement only in relation to the main polymerization reactor.

[0124] The term "sequential polymerization process" refers to the production of the ethylene-propylene-1-butene terpolymer base resin in at least two reactors connected in series. Therefore, such a polymerization system includes at least a first polymerization reactor (R1) and a second polymerization reactor (R2), and optionally a third polymerization reactor (R3).

[0125] The preferred multi-stage process is the "cyclic-gas phase" process, such as the process developed by Borealis (referred to as...). The technology is described in, for example, patent documents (e.g., EP 0 887 379, WO 92 / 12182, WO 2004 / 000899, WO 2004 / 111095, WO 99 / 24478, WO 99 / 24479 or WO 00 / 68315).

[0126] Another suitable slurry-vapor phase process is Basel's. Process.

[0127] Preferably, the mC2C3C4 base resin comprising two components (TERPO-1) and (TERPO-2) is produced in a process including the following steps:

[0128] a) Polymerize propylene, ethylene and 1-butene in the first reactor (R1) to obtain polymer component (TERPO-1);

[0129] b) Transfer the polymer component (TERPO-1) and the unreacted comonomer from the first reactor to the second reactor (R2);

[0130] c) Feed propylene, ethylene and 1-butene into the second reactor (R2);

[0131] d) In the second reactor (R2), propylene, ethylene and 1-butene are polymerized in the presence of the polymer component (TERPO-1) to obtain a polymer component (TERPO-2) that is closely mixed with (TERPO-1) and thus to obtain the final mC2C3C4 base resin, wherein polymerization is preferably carried out in the presence of a metallocene catalyst system of any of the embodiments described herein.

[0132] Other polymers that may be present in the outer layer

[0133] Possible modifiers for the outer layer include: a propylene-1-butene random copolymer, characterized by a melting temperature T measured by differential scanning calorimetry (DSC). m The temperature is 70 to 90 degrees Celsius, through 13 The 1-butene content, as determined by C-NMR analysis, ranged from 20.0 to 35.0 wt% (relative to the total amount of the propylene-1-butene random copolymer), and the sum of units derived from propylene and 1-butene was 100 wt%. The melt flow rate (MFR2) (230 °C / 2.16 kg) as determined by ISO 1133 ranged from 1.0 to 18.0 g / 10 min.

[0134] In a preferred embodiment, the elongation at break (ASTM D638) of the propylene-1-butene random copolymer is 100% to 900%, preferably 300% to 850%, and more preferably 500% to 800%.

[0135] In another embodiment, the propylene-1-butene random copolymer further comprises one or more, preferably all of, the following:

[0136] a) The tensile strength at break (ASTM D638) is at least 15 MPa, preferably 16 to 50 MPa, more preferably 20 to 45 MPa, and even more preferably 25 to 40 MPa;

[0137] b) The tensile (Young's) modulus (according to ASTM D638) is at least 200 MPa, preferably 210 to 450 MPa, and more preferably 250 to 400 MPa;

[0138] c) The Shore D hardness (ASTM D2240) is at least 45, preferably 48 to 65, and more preferably 50 to 60.

[0139] propylene-1-butene random copolymers with these characteristics are readily available from Mitsui Chemicals (e.g., the Tafmer XM series).

[0140] Another suitable modifier is: propylene-ethylene random copolymer, which is obtained by... 13 The ethylene content, as determined by C-NMR analysis, ranged from 1.0 to 25.0 wt% (relative to the total amount of the propylene-ethylene random copolymer), and the melt flow rate (MFR2, 230 °C / 2.16 kg) was 1.0 to 300.0 g / 10 min, as determined by ISO 1133.

[0141] The ethylene content is preferably 2.0 to 20.0 wt%, more preferably 4.0 to 18.0 wt%.

[0142] MFR2 is preferably 2.0 to 200 g / 10 min, more preferably 3.0 to 100 g / 10 min, and most preferably 4.0 to 30.0 g / 10 min.

[0143] Propylene-ethylene random copolymers with these characteristics are readily available from ExxonMobil (e.g., under the trade name Vistamaxx).

[0144] The amount of the modifier may be up to 30.0 wt%, preferably up to 20.0 wt%.

[0145] Core layer

[0146] According to the present invention, the multilayer film further includes a core layer (CL), which is a polypropylene-based layer.

[0147] Suitable polypropylene polymers are propylene homopolymers or propylene random copolymers.

[0148] Propylene homopolymer is preferred.

[0149] Propylene homopolymer (H-PP)

[0150] In one embodiment of the invention, the core layer (CL) comprises propylene homopolymer (H-PP). More preferably, the core layer (CL) is composed of propylene homopolymer (H-PP).

[0151] The term "propylene homopolymer" as used in this invention refers to polypropylene that is substantially composed of propylene units, i.e., propylene units exceeding 98.0 wt%, preferably exceeding 99.0 wt%, even more preferably exceeding 99.5 wt%, and still more preferably at least 99.8 wt%. In a preferred embodiment, only propylene units in the propylene homopolymer (HPP) can be detected.

[0152] Therefore, preferably, the xylene soluble content (XCS) of the propylene homopolymer (H-PP) as measured according to ISO 16152 is less than 5.0 wt%, more preferably less than 4.0 wt%, and even more preferably less than 3.5 wt%.

[0153] Preferably, the propylene homopolymer (H-PP) is characterized by high isotacticity.

[0154] Therefore, preferably, the concentration of the propylene homopolymer (H-PP) as measured by NMR spectroscopy is ≥85.0%, more preferably 85.0% to 98.0%, and / or measured by NMR spectroscopy... 13 The percentage of 2,1-type defects measured by C-NMR spectroscopy is less than 1.0%, preferably less than 0.5%, and more preferably less than 0.3%.

[0155] The suitable lower limit for propylene homopolymers catalyzed by Ziegler-Natta is 0.0%, and the suitable lower limit for propylene homopolymers catalyzed by metallocene is 0.05%.

[0156] Particularly preferred is that the weight-average molecular weight (Mw) of the propylene homopolymer (H-PP) is 260 to 1000 kg / mol, more preferably 300 to 700 kg / mol, and even more preferably 380 to 650 kg / mol.

[0157] Furthermore, preferably, the propylene homopolymer (H-PP) has a fairly broad molecular weight distribution (Mw / Mn). Therefore, preferably, the molecular weight distribution (Mw / Mn) of the propylene homopolymer (H-PP) is 3.5 to 10.0, more preferably 4.0 to 8.5.

[0158] Furthermore, preferably, the propylene homopolymer (H-PP) has a very low melt flow rate. Therefore, the melt flow rate of the propylene homopolymer (H-PP) measured according to ISO 1133 (2.16 kg, 230 °C) is preferably 0.1 to 15.0 g / 10 min, more preferably 1.5 to 10.0 g / 10 min, and even more preferably 2.5 to 4.0 g / 10 min.

[0159] In a preferred embodiment, the propylene homopolymer (H-PP) is thermomechanically stable. Therefore, preferably, the melting temperature T of the propylene homopolymer (H-PP) is... mThe temperature is at least 145°C, more preferably at least 150°C, and even more preferably at least 160°C. m The reasonable upper limit is 170℃.

[0160] Preferably, the propylene homopolymer (H-PP) of the present invention is a propylene homopolymer known in the art.

[0161] In particular, the preferred propylene homopolymer (H-PP) is the commercially available propylene homopolymer HC101BF from Borealis.

[0162] Membrane structure

[0163] According to the present invention, the multilayer film includes at least a first outer layer (OL1), a second outer layer (OL2), and a core layer (CL).

[0164] The outer layers (OL1) and (OL2) of the multilayer film according to the present invention are used as sealing layers.

[0165] In this document, the term "sealing layer" is understood in the context of the packaging technology field, meaning that the term "sealing layer" indicates that the layer can be used for sealing purposes, i.e., a seal can be made on the surface of the layer or a portion thereof.

[0166] In a preferred embodiment, the multilayer biaxially oriented polymer film comprises at least three layers, namely at least one core layer (CL) and two separate sealing outer layers (OL1 and OL2), namely a first separate sealing outer layer (OL1) and a second separate sealing outer layer (OL2), wherein the multilayer biaxially oriented polymer film has the following stacking order: first separate sealing outer layer (OL1) - core layer (CL) - second separate sealing outer layer (OL2).

[0167] The first and second sealing outer layers (OL1) can be chemically different, for example, different mC2C3C4 base resins (as described above) or different blends containing modifiers, or chemically identical, i.e., the same mC2C3C3 base resin, the latter being preferred.

[0168] The membrane according to the invention may further include one or two connecting layers (TL1) and (TL2). Optionally, the connecting layer is located between the core layer (CL) and one or both of the outer layers (OL1) and / or (OL2).

[0169] Therefore, one possible membrane structure is OL1 / TL1 / CL / TL2 / OL2.

[0170] In one embodiment, the connecting layer (TL1) and the connecting layer (TL2) are made of a polypropylene-based polymer, preferably the same propylene-based polymer.

[0171] Suitable polypropylene polymers are as defined above for the core layer (CL).

[0172] In a preferred embodiment, the connecting layer (TL1) and the connecting layer (TL2) are made of the same polypropylene polymer as the core layer (CL), and more preferably of the same propylene homopolymer (H-PP).

[0173] Preferably, the multilayer biaxially oriented polymer film is obtained by co-extrusion. Co-extrusion can be performed on a blown film production line or a cast film production line, the latter being preferred. After co-extrusion, the multilayer oriented polymer film is biaxially stretched.

[0174] Conventional membrane manufacturing techniques can be used to produce the multilayer membranes of this invention. Typically, these layers of the membrane are co-extruded and then oriented in a manner known in the art to produce biaxially oriented (BOPP) multilayer membranes.

[0175] Therefore, after co-extruding these layers, the resulting multilayer film is oriented in both the longitudinal direction (MDO) and the transverse direction (TDO).

[0176] In the case of producing multilayer biaxially oriented polymer films using cast film technology, molten polymer is extruded through a flat extrusion die onto a cooling roller to cool the polymer into a solid film of at least three layers.

[0177] The production of multilayer biaxially oriented polymer films is carried out as follows: A melt of polymer for the core layer (CL), a propylene-ethylene random copolymer for the outer layers (OL1 and OL2), and optionally a polymer for the connecting layers (TL1 and / or TL2) (corresponding to the individual layers of the multilayer biaxially oriented polymer film) is co-extruded through a flat die. The resulting polymer film is then removed from one or more rolls for curing. Conventionally, in the co-extrusion process, the polymer for each individual layer is first compressed and liquefied in the extruder. During this stage, any additives can be pre-added to the polymer or introduced via masterbatch. The melt is then simultaneously pressed through a flat die (groove die), removing the extruded multilayer polymer film from one or more take-off rolls. During this process, the film cools and cures.

[0178] It has been shown that maintaining more than one take-off roller is particularly advantageous, through which the extruded film is cooled and cured. Orientation can be achieved by first stretching or pulling the film in the longitudinal direction (MD) and then orienting it in the transverse direction (TD), for example, in a tenter-frame orientation process. Depending on the desired film characteristics, orientation can be performed sequentially or simultaneously. Preferred orientation ratios are typically 3 to 6 (in the longitudinal direction) and 4 to 10 (in the transverse direction).

[0179] Therefore, in a BOPP film, each layer can have the following thickness:

[0180] Each outer layer has a thickness of 0.3 μm to 3.0 μm, preferably 0.4 μm to 2.0 μm, and more preferably 0.5 μm to 1.5 μm. Preferably, the two outer layers have the same thickness.

[0181] Core layer: 5 to 40 μm, preferably 10 to 35 μm, more preferably 15 to 25 μm.

[0182] Each connecting layer (if present): 1.0 to 5 μm, preferably 1.5 to 4.5 μm, more preferably 2.0 to 4.50 μm. Preferably, the two connecting layers have the same thickness.

[0183] The total thickness of the BOPP film is 8 to 80 μm, preferably 10 to 60 μm, and more preferably 15 to 40 μm.

[0184] As is known in the art, the thickness of a film layer can be determined using microscopy techniques (e.g., optical microscopy or electron microscopy). As an example, a thin film is cut perpendicular to the film plane using a microtome blade. The film is cooled in liquid nitrogen within a microtome holder. The microtome blade then cuts several slices with a thickness of approximately 10 to 15 μm. These slices are then observed using an optical microscope, and an image is obtained by projecting them. Software programs known in the art can be used to measure the thickness of each layer as shown in the projected image. Measurements can be taken at different points on the image, and an average value can then be determined. The film layers are clearly distinguishable due to their varying contrast.

[0185] Alternatively, one or both surfaces of the multilayer biaxially oriented polymer film can be corona-treated or flame-treated by one of the known methods. For corona treatment, the film passes between two conductive elements serving as electrodes, and a high voltage, typically an alternating current voltage (approximately 10,000 V and 100,005 Hz), can cause spray or corona discharge when applied between the electrodes. Due to the spray or corona discharge, the air above the film surface is ionized and reacts with molecules on the film surface, resulting in the formation of polar inclusions within the essentially nonpolar polymer matrix. After production, the treatment intensity is typically preferably 38 to 45 dynes / cm.

[0186] The biaxially oriented polypropylene multilayer film according to the present invention is characterized in that the sealing initiation temperature, as described in the experimental section, is 80 to 105°C, preferably 90 to 104°C, and more preferably 100 to 104°C on a 25 μm thick BOPP film.

[0187] The multilayer biaxially oriented polymer film of the present invention is fully recyclable, thus improving sustainability, because it is a "100% PP" solution containing no other polymers besides propylene-based polymers.

[0188] Furthermore, the present invention also relates to the use of the multilayer biaxially oriented polymer film of the present invention as a packaging material, particularly as a packaging material for food and / or non-food products, such as textiles, flowers, pet food, detergents, and protective films for cartons containing tobacco products or perfumes.

[0189] The invention will be further described with reference to the following non-limiting examples.

[0190] Experimental Section

[0191] Measurement methods

[0192] Unless otherwise defined, the following terms and methods of determination apply to the general description of the invention above and the embodiments described below.

[0193] Melt flow rate of ethylene-propylene-1-butene terpolymer base resin

[0194] Melt flow rate (MFR) was determined according to ISO 1133 (Determination of melt mass flow rate (MFP) and melt volumetric flow rate (MVR) of thermoplastics—Part 1: Standard methods), and the unit is g / 10 min. MFR indicates the flowability of a polymer, and therefore its processing properties. A higher melt flow rate generally indicates a lower polymer viscosity. The MFR2 of polypropylene was determined at a temperature of 230°C and a load of 2.16 kg.

[0195] Comonomer content of the second polymer component (TERPO-2)

[0196] The comonomer content of the second polymer component (TERPO-2) is calculated according to formula (I).

[0197]

[0198] In the formula

[0199] w(A-1) is the weight fraction [wt%] of the first polymer component (TERPO-1).

[0200] w(A-2) is the weight fraction [wt%] of the second polymer component (TERPO-2).

[0201] C(A-1) represents the comonomer content [wt%] of the first polymer component (TERPO-1).

[0202] C(A) represents the comonomer content [wt%] of the ethylene-propylene-1-butene terpolymer (TERPO).

[0203] C(A-2) represents the calculated comonomer content [wt%] of the second polymer component (TERPO-2).

[0204] Calculation of melt flow rate (MFR2) of polymer component (TERPO-2)

[0205] The MFR of the second polymer component (RACO-2) is calculated according to formula (II).

[0206]

[0207] In the formula

[0208] w(A1) is the weight fraction [wt%] of the polymer component TERPO-1.

[0209] w(A2) represents the weight fraction [wt%] of the polymer component TERPO-2.

[0210] MFR(A1) is the melt flow rate MFR2 (230℃) [g / 10min] of polymer component TERPO-1.

[0211] MFR(A) is the melt flow rate of the entire ethylene-propylene-1-butene terpolymer (TERPO), MFR2 (230℃) [g / 10min].

[0212] MFR(A2) is the calculated melt flow rate MFR2 (230℃) [g / 10min] of the polymer component TERPO-2.

[0213] The microstructure (comonomer content and regional defects) of the ethylene-propylene-1-butene terpolymer base resin was quantitatively analyzed by NMR spectroscopy.

[0214] The comonomer content of the polymer was quantified using quantitative nuclear magnetic resonance (NMR) spectroscopy.

[0215] Recordings were performed using a Bruker Avance III 500 NMR spectrometer at 500.13 and 125.76 MHz in the molten state for the study of... 1 H and 13 Quantitative analysis of C 13 C{ 1 ¹H NMR spectroscopy. All spectra were performed using ¹H NMR spectroscopy. 13A C-optimized 7mm magic angle rotation (MAS) probe was used for recording at 180°C, with nitrogen used for all pneumatic devices. Approximately 200 mg of material was loaded into a 7mm outer diameter zirconia MAS rotor and rotated at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. Standard single-pulse excitation was employed, utilizing a NOE with a 3-second short cycle delay and an RS-HEAPT decoupling scheme. A total of 1024 (1k) transients were acquired for each spectrum.

[0216] Quantitative 13 C{ 1 The ¹H NMR spectra were processed and integrated, and the relevant quantitative properties were determined based on the integration. All chemical shifts were internally referenced to the isotactic pentatonic methyl group (mmmm) at 21.85 ppm.

[0217] The content of comonomers was quantified by observing the characteristic signal {brandolini01} corresponding to the incorporation of 1-butene.

[0218] The amount of isolated 1-butene incorporated into the PBP sequence was quantified by using the integral of the αB2 site at 43.6 ppm as the percentage of reporter sites per comonomer.

[0219] B = I αB2 / 2

[0220] The amount of sequentially incorporated 1-butene in the PBBP sequence was quantified by using the integral of the ααB2B2 site at 40.5 ppm relative to the number of reporter sites in each comonomer.

[0221] BB = 2 * I ααB2B2

[0222] In the presence of BB, the value of B must be corrected for the effect of BB on the αB2 site:

[0223] B = (I αB2 / 2)–BB / 2

[0224] The total 1-butene content was calculated based on the sum of the isolated and continuously incorporated 1-butene:

[0225] B 总 =B+BB

[0226] The content of comonomers was quantified by observing the characteristic signal {brandolini01} corresponding to the ethylene incorporation.

[0227] The amount of separated ethylene incorporated into the PEP sequence was quantified by using the integral of the Sββ site at 24.3 ppm relative to the number of reporter sites per comonomer:

[0228] E = I Sββ

[0229] If a characteristic signal corresponding to the continuous incorporation of ethylene in the PEE sequence is observed, quantification is performed using the Sβδ site at 27.0 ppm:

[0230] EE = I Sβ δ

[0231] Characteristic signals {resconi00} corresponding to regional defects were observed. Two methyl sites at 17.7 ppm and 17.2 ppm, and a methylene site at 42.4 ppm, indicate the presence of separated 2,1-erythrotype defects, which were confirmed by other characteristic sites. 2,1-regional defects exist near the ethylene unit, indicated by two inequivalent Sαβ signals at 34.8 ppm and 34.4 ppm, and a Tγγ signal at 33.7 ppm, respectively.

[0232] Using the integral of the methylene site at 42.4 ppm (I e9 To quantitatively separate 2,1-erythromorphic defects (P) 21e分离 ) quantity:

[0233] P 21e分离 =I e9

[0234] If a 2,1 region defect exists, then the methylene site at 33.7 ppm (I) is used. Tγγ To quantify defects in the 2,1 region near ethylene (P) E21 ) quantity:

[0235] P E21 =I Tγγ

[0236] The total ethylene content is then calculated by summing the separated ethylene, the continuously incorporated ethylene, and the ethylene from defects in the adjacent 2,1 region:

[0237] E 总 =E + EE + P E21

[0238] Based on the Sαα methylene site at 46.7 ppm, including all other propylene units not accounted for by Sαα (e.g., factor 3*P). 21e分离 The amount of propylene unit is quantified by representing the three missing propylene units from the separated 2,1-erythromorph defect.

[0239] P 总=I Sαα +3*P 21e分离 +B+0.5*BB+E+0.5*EE+2*P E21

[0240] Then, the total mole fraction of 1-butene and ethylene in the polymer is calculated as follows:

[0241] fB = B 总 / (E 总 +P 总 +B 总 )

[0242] fE=E 总 / (E 总 +P 总 +B 总 )

[0243] Calculate the molar percentage of comonomer incorporated from the molar fraction:

[0244] B[mol%]=100*fB

[0245] E[mol%]=100*fE

[0246] Calculate the weight percentage of comonomer incorporated from the mole fraction:

[0247] B[wt%]=100*(fB*56.11) / ((fE*28.05)+(fB*56.11)+((1-(fE+fB))*42.08)

[0248] E[wt%]=100*(fE*28.05) / ((fE*28.05)+(fB*56.11)+((1-(fE+fB))*42.08)

[0249] The molar percentage of isolated 2,1-erythroform defects relative to all propylene was quantified as follows:

[0250] [21e]mol% = 100*P 21e分离 / P 总

[0251] The molar percentage of defects in the 2,1 region adjacent to ethylene relative to all propylene was quantified as follows:

[0252] [E21]mol% = 100*P E21 / P 总

[0253] The total number of defects in 2.1 is quantified as follows:

[0254]

[21] mol% = [21e] + [E21]

[0255] No characteristic signal {resconi00} was observed corresponding to other types of regional defects (2,1-Su type, 3,1 insertion).

[0256] References (as stated above):

[0257] klimke06 Klimke,K.,Parkinson,M.,Piel,C.,Kaminsky,W.,Spiess,HW,

[0258] Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.

[0259] parkinson07 Parkinson,M.,Klimke,K.,Spiess,HW,Wilhelm,M.,

[0260] Macromol. Chem. Phys. 2007;208:2128.

[0261] pollard04 Pollard,M.,Klimke,K.,Graf,R.,Spiess,HW,Wilhelm,M.,

[0262] Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813.

[0263] filip05 Filip,X.,Tripon,C.,Filip,C.,J.Mag.Resn.2005,176,239

[0264] griffin07 Griffin,JM,Tripon,C.,Samoson,A.,Filip,C.,and Brown,SP,

[0265] Mag.Res.in Chem.2007 45,S1,S198.

[0266] castignolles09 Castignolles,P.,Graf,R.,Parkinson,M.,Wilhelm,M.,Gaborieau,M.,Polymer 50(2009)2373.

[0267] resconi00 Resconi,L.,Cavallo,L.,Fait,A.,Piemontesi,F.,Chem.Rev.2000,100,1253.

[0268] brandolini01 AJBrandolini,DDHills, “NMR spectra of polymers and

[0269] polymer additives”, Marcel Deker Inc., 2000.

[0270] Xylene-soluble matter (XCS, wt%)

[0271] The xylene-soluble fraction (XCS) defined and described in this invention was determined according to ISO 16152 as follows: 2.0 g of polymer was dissolved in 250 mL of xylene at 135 °C with stirring. After 30 minutes, the solution was cooled to ambient temperature for 15 minutes, and then allowed to stand at 25 ± 0.5 °C for 30 minutes. The solution was filtered through filter paper into two 100 mL flasks. The solution in the first 100 mL container was evaporated under a nitrogen stream, and the residue was dried under vacuum at 90 °C until constant weight was achieved. The xylene-soluble fraction (percentage) was then determined as follows:

[0272] XCS%=(100*m*V0) / (m0*v)m0=initial polymer amount (g);

[0273] m = weight of residue (g);

[0274] V0 = Initial volume (mL);

[0275] v = Volume of the sample being analyzed (mL).

[0276] DSC analysis, melt flow (T) m ) and crystallization temperature (T) c )

[0277] Data were measured using a TA Instruments Q2000 Differential Scanning Calorimeter (DSC) with samples ranging from 5 to 7 mg. The DSC was operated according to ISO 11357 / Part 3 / Method C2 in a temperature range of -30 to +225 °C at a scan rate of 10 °C / min in hot / cold / hot cycling.

[0278] Crystallization temperature (T) c ) and crystallization enthalpy (H c The melting temperature (T) is determined by the cooling step, while the melting temperature (T) is determined by the cooling step. m ) and enthalpy of fusion (H mThe result is determined by the second heating step.

[0279] Sealing performance

[0280] Sealing start temperature (SIT); Sealing end temperature (SET); Sealing range:

[0281] Measurements were performed according to a slightly modified version of ASTM F1921-12, in which the test parameters of sealing pressure, delay time, and clamp separation rate were modified.

[0282] The lower limit (heat seal initiation temperature (SIT)) is the sealing temperature at which a 5N seal strength is achieved. The upper limit (seal end temperature (SET)) is reached when the membrane adheres to the sealing device.

[0283] The sealing range was determined on a J&B 4000 universal sealing machine, and the produced film is shown below. The blown film thickness is 60 μm, and it has the following other parameters:

[0284] Adjustment time: >96 hours

[0285] Sample width: 25mm

[0286] Sealing pressure: 0.67 N / mm 2 (PP)

[0287] Sealing time: 1 second

[0288] Delay time: 30 seconds

[0289] Sealing claw size: 50×5mm

[0290] Sealing claw shape: flat

[0291] Sealing claw coating: Niptef

[0292] Sealing temperature: ambient temperature -240℃

[0293] Sealing temperature range: 5℃

[0294] Starting temperature: 50℃

[0295] Grip separation speed: 42mm / second

[0296] The sealing initiation temperature under 2N force was evaluated using linear interpolation.

[0297] The sealing force at 120°C (unit: N) is evaluated based on the sealing curve.

[0298] 2. Example

[0299] Preparation of propylene-ethylene random copolymer (mC2C3C4)

[0300] Catalysts: Metallocene Synthesis

[0301] Metallocene complex (metallocene MC-2) has been produced in accordance with the description of MC-2 in WO2019 / 179959.

[0302]

[0303] Preparation of MAO silica carrier

[0304] The steel reactor, equipped with a mechanical stirrer and filter, was flushed with nitrogen, and the reactor temperature was set to 20°C. Next, 5.0 kg of silica-grade DM-L-303 from AGC Si-Tech was added to the feed tank and pre-calcined at 600°C, followed by careful pressurization and depressurization with nitrogen using a manual valve. Toluene (22 kg) was then added. The mixture was stirred for 15 minutes. Next, a toluene solution (9.0 kg) of 30 wt% MAO from Lanxess was added through the feed line at the top of the reactor over 70 minutes. The reaction mixture was then heated to 90°C and stirred at 90°C for two hours. The slurry was allowed to settle, and the mother liquor was filtered off. The catalyst was washed twice with toluene (22 kg) at 90°C, followed by precipitation and filtration. The reactor was cooled to 60°C, and the solids were washed with heptane (22.2 kg). Finally, the MAO-treated SiO2 was dried at 60°C for 2 hours under a nitrogen stream, followed by drying under vacuum (-0.5 bar) with stirring for 5 hours. The MAO-treated support was collected as a free-flowing white powder and found to contain 12.2 wt% Al.

[0305] Preparation of catalyst system 1 (ICS1) of the present invention

[0306] At 20°C, 30 wt% MAO (0.7 kg) in toluene was added to a steel nitrogen-covered reactor via a burette. Then, toluene (5.4 kg) was added with stirring. Metallocene MC-2 (93 g) was added from a metal cylinder and then washed with 1 kg of toluene. The mixture was stirred at 20°C for 60 minutes. Then, triphenylmethyltetra(pentafluorophenyl)borate (91 g) was added from a metal cylinder and then washed with 1 kg of toluene. The mixture was stirred at room temperature for 1 hour. The resulting solution was added to a stirred cake of MAO-silica support prepared as described above within 1 hour. The cake was left to stand for 12 hours, then dried under a nitrogen stream at 60°C for 2 hours, followed by further drying under vacuum (-0.5 bar) with stirring for 5 hours.

[0307] The dried catalyst was sampled as a pink, free-flowing powder containing 13.9% Al and 0.11% Zr.

[0308] Using the catalyst system described above, ethylene-propylene-1-butene terpolymer base resin was prepared by polymerization in a Borstar pilot plant with two reactor configurations (a ring-gas phase reactor (GPR)) and a prepolymerizer.

[0309] Table 1 shows the polymerization conditions and final properties of the ethylene-propylene-1-butene terpolymer base resin of the present invention and the comparative ethylene-propylene-1-butene terpolymer base resin.

[0310] Table 1: Polymerization conditions and final properties of the ethylene-propylene-1-butene terpolymer base resin (IE1) of the present invention and the comparative ethylene-propylene-1-butene terpolymer base resin:

[0311]

[0312] In a Coperion ZSK 70 co-rotating twin-screw extruder, at 220°C, polymer powder was compounded with the following components: 0.1 wt% anti-caking agent (synthetic silica; CAS No. 7631-86-9); 0.05 wt% antioxidant (tris(2,4-di-tert-butylphenyl)phosphite, CAS No. 31570-04-4, commercially available from BASF SE as Irgafos 168FF); 0.05 wt% sterically hindered phenol (pentaerythritolyl-tetra(3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate, CAS No. 6683-19-8, commercially available from BASF SE as Irganox 1010FF); and 0.05 wt% (each based on the total weight of the polymer) of synthetic hydrotalcite (CAS No. 11097-59-9) as an acid scavenger.

[0313] Multilayer BOPP film

[0314] The biaxially oriented multilayer films (IE1) and (IE2) of the present invention

[0315] For the core layer (CL), the commercial product HC101BF from Borealis was used, which is a homopolymer with an MFR2 (230°C) of 3.2 g / 10 min.

[0316] For the outer layers (OL1) and (OL2), the C2C3C4 terpolymer of the present invention is used.

[0317] Multilayer BOPP film was produced on a pilot production line in BOPP.

[0318] To produce the aforementioned BOPP film, three layers were first extruded using three extruders to produce a cast film. The extrusion conditions are shown in Table 2. The casting roll temperature was 35°C, and the water batch temperature was 30°C.

[0319] The thickness of the original cast film is selected / adjusted based on the final thickness of the final BOPP film and the stretch ratio in MD / TM.

[0320] Table 2: Production conditions for IE1 and IE2 membranes (temperature and yield are the same for all examples):

[0321] extruder main Co-extrusion 1 Co-extrusion 2 layer CL OL1 OL2 resin HC101BF This invention C2C3C4 This invention C2C3C4 Melting temperature ℃ 254 254 254 IE1 production kg / h 0.2 4.6 0.2 IE2 production kg / h 0.1 4.8 0.1

[0322] Then, biaxial orientation is performed:

[0323] Longitudinal stretching (MDO)

[0324] MD stretch ratio = 4.7 (in step 1 - the first fast roller contacts the bath-side skin)

[0325] MDO roll temperature: Preheat 120℃ / Stretching 118℃ / Annealing 120℃

[0326] Lateral stretching (TDO)

[0327] TD stretch ratio = 8.8

[0328] TDO oven temperatures: Preheat 183-180-175℃ / Stretching 158-158℃ / Annealing 162-162℃

[0329] TDO rail width: 195-195-195-195 / 850-1500 / 1450-1400-1395mm

[0330] deal with

[0331] Top corona discharge on the casting machine skin: 2.4kW, equivalent to 25.0Wmin / m 2

[0332] Table 3: The membrane structures of IE1 and IE2 after biaxial orientation are as follows:

[0333] layer resin IE1 final thickness IE2 film thickness A total of 1 (OL1) was extruded. This invention mC2C3C4 1μm 0.5μm Main (CL) HC101BF 23.0μm 24.0μm Co-extruded 2 (OL2) This invention mC2C3C4 1μm 0.5μm

[0334] Comparison of biaxially oriented multilayer films CE1, CE2, and CE3

[0335] For CE1, the outer layer uses the comparative (CE1)mC2C3C4 copolymer prepared above, and the core layer is HC101BF.

[0336] For CE2, the outer layer uses the comparative (CE2)mC2C3C4 copolymer prepared above, and the core layer is HC101BF.

[0337] For CE3, the outer layer uses a C2C3C4 terpolymer produced by Ziegler-Natta catalyst TD310BF, characterized by an MFR2 of 6.0 g / 10 min and a melting temperature T m It has a temperature rating of 130℃ and can be purchased commercially from Borealis; the core layer is HC101BF.

[0338] For the membrane structure of the present invention, the preparation of the biaxially oriented multilayer membrane is carried out as described above.

[0339] Table 4 shows the membrane structure of the present invention and the membrane performance of the comparative membrane.

[0340] Table 4: Membrane Performance

[0341]

[0342] *Linear interpolation

[0343] It can be seen that, compared with CE (approximately 107°C, 2N), IE1 shows a 5°C reduction in SIT (approximately 102°C, 2N). Furthermore, despite having half the thickness, IE2 exhibits similar SIT and sealing power to IE1 at 120°C.

[0344] Compared to CE2, despite having similar C2 and C4 contents and similar thermodynamic (DSC) results, IE exhibits a lower SIT and a wider processing window. Therefore, this highlights the importance of polymer design and appropriate property selection for better results in the final application.

Claims

1. A biaxially oriented polypropylene multilayer film, wherein the biaxially oriented polypropylene multilayer film comprises at least a core layer CL, a first outer layer OL1, and a second outer layer OL2, wherein, Both the first outer layer OL1 and the second outer layer OL2 include: Based on the total weight of their respective outer layers, 70.0 to 100.0 wt% of a metallocene-catalyzed ethylene-propylene-1-butene terpolymer mC2C3C4 base resin, wherein the mC2C3C4 base resin has: • Relative to the total weight of the mC2C3C4 base resin, as described in the experimental section 13 C-NMR analysis revealed that the ethylene C2 content ranged from 0.7 to 2.0 wt%. • Relative to the total weight of the mC2C3C4 base resin, as described in the experimental section 13 The 1-butene C4 content, as determined by C-NMR analysis, ranged from 4.0 to 7.8 wt%. • Relative to the total weight of the mC2C3C4 base resin, as described in the experimental section 13 C-NMR analysis revealed that the propylene C3 content ranged from 90.2 to 96.0 wt%. Therefore, the sum of the units derived from ethylene, propylene, and butene is 100 wt%, and • The melt flow rate (MFR2) measured at 230 °C / 2.16 kg according to ISO 1133 is 3.0 to 10.0 g / 10 min; • Based on the total weight of the mC2C3C4 base resin, the xylene cold-soluble content (XCS) measured at 25 °C according to ISO 16152 is 2.0 to 5.0 wt%; • Melting temperature T measured by DSC according to ISO 11357 m The temperature is between 120 and 129°C. • Crystallization temperature T measured by DSC according to ISO 11357 c The temperature is between 80 and 110 °C. • By means of the experimental section 13 C-NMR analysis revealed that the number of defects in the 2,1 region ranged from 0.10 to 1.5 mol%, and The mC2C3C4 base resin is composed of the following: composition: Based on the total weight of the mC2C3C4 base resin, the first polymer component TERPO-1 comprises 30.0 to 60.0 wt%, and the first polymer component TERPO-1 has the following properties: • The melt flow rate (MFR2) measured at 230 °C / 2.16 kg according to ISO 1133 is 1.0 to 10.0 g / 10 min; • Relative to the total weight of the first polymer component TERPO-1, as described in the experimental section 13 C-NMR analysis revealed an ethylene C2 content ranging from 0.7 to 1.3 wt%; and • Relative to the total weight of the first polymer component TERPO-1, as described in the experimental section 13 The 1-butene C4 content, as determined by C-NMR analysis, ranged from 4.0 to 6.0 wt%. ii. Based on the total weight of the mC2C3C4 base resin, 40.0 to 70.0 wt% of the second polymer component TERPO-2, which has the following properties: • The melt flow rate (MFR2) measured at 230 °C / 2.16 kg according to ISO 1133 is 10.0 to 20.0 g / 10 min; • Relative to the total weight of the second polymer component TERPO-2, as described in the experimental section 13 C-NMR analysis revealed an ethylene C2 content of 1.3 to 2.0 wt%; and • Relative to the total weight of the second polymer component TERPO-2, as described in the experimental section 13 The 1-butene C4 content, as determined by C-NMR analysis, ranged from 6.0 to 10.0 wt%; and iii. Optionally, one or more additives, wherein the additives are selected from slip agents, anti-caking agents, UV stabilizers, antistatic agents, α-nucleating agents, antioxidants, and mixtures thereof; The core layer CL is a polypropylene-based layer; The biaxially oriented polypropylene multilayer film has the following characteristics: As described in the experimental section, the sealing initiation temperature measured on a 25 µm biaxially oriented experimental cast film was 80 to 105 °C.

2. The biaxially oriented polypropylene multilayer film according to claim 1, wherein, The mC2C3C4 base resin comprises two polymer components, TERPO-1 and TERPO-2. Based on the total weight of the mC2C3C4 base resin, component TERPO-1 is present in an amount of 40.0 to 58.0 wt%, and component TERPO-2 is present in an amount of 60.0 to 52.0 wt%, based on the total weight of the mC2C3C4 base resin.

3. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, Based on the total weight of component TERPO-1, the ethylene content of component TERPO-1 in the mC2C3C4 base resin is 0.7 to 1.2 wt%, and based on the total weight of component TERPO-2, the ethylene content of component TERPO-2 is 1.3 to 1.9 wt%; and Based on the total weight of component TERPO-1, the 1-butene content of component TERPO-1 in the mC2C3C4 base resin is 4.1 to 6.0 wt%, and based on the total weight of component TERPO-2, the 1-butene content of component TERPO-2 is 6.5 to 9.5 wt%. Thus, the 1-butene content of component TERPO-1 is lower than the ethylene content of component TERPO-2.

4. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The melt flow rate (MFR2) of component TERPO-1, measured according to ISO 1133 at 230 °C / 2.16 kg, is 2.0 to 9.5 g / 10 min, while that of component TERPO-2, measured according to ISO 1133 at 230 °C / 2.16 kg, is 10.5 to 19.0 g / 10 min. Therefore, the MFR2 of component TERPO-1 is lower than that of component TERPO-2.

5. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The mC2C3C4 base resin has the following characteristics: The ethylene C2 content is 0.8 to 1.9 wt% relative to the total weight of the mC2C3C4 base resin; and The 1-butene C4 content is 4.1 to 7.7 wt% relative to the total weight of the mC2C3C4 base resin.

6. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The mC2C3C4 base resin has the following properties: According to ISO 1133, the melt flow rate (MFR2) measured at 230 °C / 2.16 kg is 4.5 to 9.5 g / 10 min; or Based on the weight of the mC2C3C4 base resin, the xylene cold soluble content (XCS) measured according to ISO 16152 is 2.5 to 4.8 wt%.

7. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The mC2C3C4 base resin has the following properties: The melting temperature T, as measured by DSC according to ISO 11357. m The temperature is 122 to 128 °C; and The crystallization temperature T, as measured by DSC according to ISO 11357, is... c The temperature ranges from 82 to 105°C.

8. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The outer layers OL1 and OL2 are composed of the mC2C3C4 base resin as defined in claim 1 or 2.

9. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The core layer CL comprises propylene homopolymer H-PP.

10. The biaxially oriented polypropylene multilayer film according to claim 9, wherein, The propylene homopolymer H-PP is characterized in that the xylene-soluble content XCS, as measured according to ISO 16152, is less than 5.0 wt%, and / or the melting temperature T, as measured by DSC, is... m The temperature should be at least 145°C.

11. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The membrane may also include one or two connecting layers TL1 and TL2, with the connecting layers optionally located between the core layer CL and one or both of the outer layers OL1 and / or OL2.

12. The biaxially oriented polypropylene multilayer film according to claim 11, wherein, Both the connecting layer TL1 and the connecting layer TL2 are made of polypropylene polymers.

13. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The thickness of the biaxially oriented layer is as follows: Each outer layer: 0.3 to 3.0 µm; Core layer: 5 to 40 µm; and Each connecting layer, if present: 1.0 to 5 µm; and The total thickness of the BOPP membrane is 8 to 80 µm.

14. The biaxially oriented polypropylene multilayer film according to claim 1 or 2, wherein, The membrane is characterized in that, as described in the experimental section, the sealing initiation temperature measured on a 25 µm thick BOPP membrane is 90 to 104 °C.

15. Use of the biaxially oriented polypropylene multilayer film according to claim 1 or 2 as a packaging material.

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