A membrane with high stiffness and a balance between stiffness and toughness.

Abstract

This invention relates to membranes comprising polyolefin compositions and methods for forming such membranes, the polyolefin compositions comprising polyethylene-based materials and polypropylene-based materials.

Description

Technical Field

[0001] This invention relates to membranes comprising polyolefin compositions and methods for forming such membranes, the polyolefin compositions comprising polyethylene-based materials and polypropylene-based materials. Background Technology

[0002] In the production of polymer films, especially cast films, it is desirable to have polymers with good processability to achieve commercial production volumes while maintaining sufficient toughness. Furthermore, the physical properties required for the final film product include stiffness, toughness, and / or tear strength.

[0003] Stiffness and toughness are key properties of polyethylene (PE) films. Applications where stiffness and toughness are critical properties of PE films include stand-up pouches, resealable bags, and heavy-duty bags. Toughness can be characterized, for example, by dart impact resistance and needle punch strength. Stiffness can be characterized, for example, by the longitudinal (MD) 1% secant modulus.

[0004] High-density polyethylene (HDPE) and polypropylene (PP) are two possible blending partners for improving the stiffness of polyethylene (PE) films. However, the choice of PP as a blending partner is limited because PP and PE have different crystalline phases and types, and there is little or no co-crystallization between PP and PE. Those skilled in the art generally believe that blending PP with PE can improve the stiffness of PE films, but will simultaneously reduce the toughness of the PE films.

[0005] On the other hand, PP has many advantages over HDPE, such as lower density, higher stiffness, and higher heat resistance. If PP can be used in most PE formulations to improve film stiffness while still maintaining toughness, it will show great value for thickness reduction in industrial and food packaging applications using PP / PE film structures.

[0006] Furthermore, industrial and food packaging requires films with high stiffness, such as films with a longitudinal (MD) 1% secant modulus greater than 410 MPa. Stand-up packaging, such as stand-up pouches, also requires films with high stiffness. High-stiffness films offer the following advantages: stand-up pouches are less likely to tip over; printing patterns on the packaging surface is more accurate; and for multi-layered packaging, it allows for a better fit between layers, reducing the likelihood of wrinkling.

[0007] Moreover, while possessing high stiffness, industrial and food packaging also require films to have a balance between stiffness and toughness.

[0008] Membranes with high stiffness, such as a longitudinal (MD) 1% secant modulus greater than 410 MPa, while also achieving a balance between stiffness and toughness, are a challenge in this field.

[0009] Relevant publications include, for example, WO 2017 / 068106 and WO 2021 / 040760. Summary of the Invention

[0010] The inventors of this invention unexpectedly discovered that by providing a polyolefin composition using homopolymer polypropylene (hPP) instead of high-density polyethylene (HDPE) and longitudinally oriented (MDO) a film containing (or substantially composed of, or composed of) the polyolefin composition, the present invention successfully obtained a film with high stiffness, for example, a longitudinal (MD) 1% secant modulus greater than 410 MPa, while also having a balance between stiffness and toughness.

[0011] The present invention provides a novel membrane comprising (or substantially composed of, or composed of) a polyolefin composition, wherein the polyolefin composition comprises (or substantially composed of, or composed of) one or more broadly orthogonally distributed (BOCD) polyethylene and one or more homopolymer polypropylene (hPP).

[0012] The film of the present invention is manufactured by a casting process. The film of the present invention undergoes longitudinal orientation (MDO), wherein the stretch ratio is 3X to 5X, for example 3X, 4X, 5X.

[0013] It is generally believed in the art that during longitudinal orientation (MDO) processes, the toughness of the membrane decreases as the stretch ratio increases.

[0014] However, contrary to common knowledge in the art, the inventors of this invention have unexpectedly discovered that by longitudinally oriented (MDO) a film comprising (or substantially composed of, or composed of) the polyolefin composition of this invention, not only is the stiffness of the film significantly improved with increasing draw ratio, but the toughness of the film is also improved. Thus, while achieving high stiffness, the film of this invention also successfully achieves a beneficial balance between stiffness and toughness.

[0015] According to an embodiment of the invention, the polyolefin composition comprises (or is substantially composed of, or is composed of) about 60 wt% to about 95 wt% of BOCD polyethylene and about 5 wt% to about 40 wt% of homopolymer polypropylene, based on the weight of the polyolefin composition.

[0016] According to embodiments of the present invention, the content of BOCD polyethylene, based on the weight of the polyolefin composition, can be, for example, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt%, about 90 wt%, or about 95 wt%. The content range of BOCD polyethylene, based on the weight of the polyolefin composition, can be a combination of any two of the above content values, for example, about 60 wt% to about 95 wt%, about 60 wt% to about 90 wt%, etc.

[0017] According to embodiments of the present invention, the content of homopolymer polypropylene, based on the weight of the polyolefin composition, can be, for example, about 5 wt%, about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, or about 40 wt%. The content range of homopolymer polypropylene, based on the weight of the polyolefin composition, can be a combination of any two of the above content values, for example, about 5 wt% to about 40 wt%, about 5 wt% to about 35 wt%, etc.

[0018] According to an embodiment of the present invention, BOCD polyethylene contains about 70 mol% to about 99 mol% of ethylene-derived polymer units, based on the total molar number of polymer units in BOCD polyethylene, and has a density of about 0.91 g / cm³. 3 Approximately 0.925 g / cm³ 3 It is measured according to ASTM D-792 or ASTM D-1505, and has a melt index (MI, or I) of about 0.5 g / 10 min to about 3.0 g / 10 min, preferably about 1.0 g / 10 min to about 2.0 g / 10 min. 2.16 It is measured according to ASTM D-1238-E (190℃ / 2.16kg).

[0019] According to an embodiment of the invention, BOCD polyethylene has a composition distribution width index (CDBI) ranging from about 25 wt% to about 55 wt%.

[0020] According to an embodiment of the invention, the homopolymer polypropylene has a melt index from about 1 g / 10 min to about 6 g / 10 min, as determined according to ASTM D1238-L (230°C / 2.16 kg).

[0021] According to an embodiment of the present invention, homopolymer polypropylene has a content of about 0.8 g / cm³. 3 Approximately 0.98 g / cm³ 3 The density is measured according to ASTM D792-13 method.

[0022] According to an embodiment of the invention, the homopolymer polypropylene has a yield tensile strength from about 20 MPa to about 100 MPa, as determined according to ASTM D638.

[0023] According to embodiments of the present invention, films comprising (or substantially consisting of, or consisting of) the polyolefin composition of the present invention have a strength ranging from greater than about 410 MPa, greater than about 420 MPa, greater than about 430 MPa, greater than about 440 MPa, greater than about 450 MPa, greater than about 460 MPa, greater than about 500 MPa, greater than about 550 MPa, greater than about 600 MPa, greater than about 610 MPa, greater than about 620 MPa, greater than about 630 MPa, greater than about 640 MPa, greater than about 650 MPa, greater than about 700 MPa, greater than about 730 MPa, greater than about 740 MPa, greater than about 750 MPa, greater than about 760 MPa, or greater than about 770 MPa to less than about 780 MPa. The longitudinal (MD) 1% secant modulus, less than about 770 MPa, less than about 760 MPa, less than about 750 MPa, less than about 740 MPa, less than about 730 MPa, less than about 700 MPa, less than about 650 MPa, less than about 640 MPa, less than about 630 MPa, less than about 620 MPa, less than about 610 MPa, less than about 600 MPa, less than about 550 MPa, less than about 500 MPa, less than about 480 MPa, less than about 460 MPa, or less than about 450 MPa, is measured when a film containing (or substantially composed of, or composed of) the polyolefin composition of the present invention has a thickness of about 25 μm, wherein the longitudinal (MD) 1% secant modulus is measured according to the ASTM D 882 method.

[0024] According to embodiments of the present invention, films comprising (or substantially composed of, or composed of) the polyolefin compositions of the present invention have a needle penetration strength / μm (mN / μm) ranging from greater than about 90 mN / μm, greater than about 100 mN / μm, greater than about 110 mN / μm, greater than about 120 mN / μm, greater than about 130 mN / μm, or greater than about 140 mN / μm to less than about 150 mN / μm, less than about 140 mN / μm, less than about 130 mN / μm, or less than about 120 mN / μm, wherein the needle penetration strength / μm (mN / μm) is measured according to the CEN 14477 method.

[0025] A membrane comprising (or substantially comprising, or consisting of) the polyolefin composition of the present invention may be a single-layer membrane or a multilayer membrane, wherein any layer of the multilayer membrane may comprise the polyolefin composition of the present invention.

[0026] The thickness of the membrane of the present invention can be selected and determined according to actual needs.

[0027] Films comprising (or substantially composed of, or composed of) the polyolefin compositions of the present invention can be manufactured using casting methods known in the art for manufacturing polyethylene (PE) films, and subsequently subjected to longitudinal orientation (MDO), wherein the stretch ratio is 3X to 5X, for example 3X, 4X, 5X.

[0028] According to embodiments of the present invention, a membrane is provided comprising a polyolefin composition, wherein the polyolefin composition comprises about 60 wt% to about 95 wt% of BOCD polyethylene and about 5 wt% to about 40 wt% of homopolymer polypropylene, based on the weight of the polyolefin composition.

[0029] BOCD polyethylene contains approximately 70 mol% to approximately 99 mol% of ethylene-derived polymer units, based on the total molar number of polymer units in BOCD polyethylene, and has a density of approximately 0.918 g / cm³. 3 It is measured according to ASTM D-792 and has a melt index (MI, or I) of approximately 1.0 g / 10 min. 2.16 According to ASTM D-1238-E (190℃ / 2.16kg), BOCD polyethylene has a composition distribution width index (CDBI) of approximately 38.6% by weight, or

[0030] BOCD polyethylene contains approximately 70 mol% to approximately 99 mol% of ethylene-derived polymer units, based on the total molar number of polymer units in BOCD polyethylene, and has a density of approximately 0.915 g / cm³. 3 It is measured according to ASTM D-1505 and has a melt index (MI, or I) of approximately 1.4 g / 10 min. 2.16 According to ASTM D-1238-E (190℃ / 2.16kg), BOCD polyethylene has a composition distribution width index (CDBI) of approximately 43% by weight.

[0031] The homopolymer polypropylene has a melt index of 3.2 g / 10 min, which was determined according to ASTM D1238-L (230℃ / 2.16 kg).

[0032] The film is manufactured by a casting process and subsequently subjected to longitudinal orientation (MDO) with a stretch ratio of 3X to 5X.

[0033] The membrane has a longitudinal (MD) 1% secant modulus ranging from greater than about 410 MPa to less than about 780 MPa, measured when the membrane has a thickness of about 25 μm, wherein the longitudinal (MD) 1% secant modulus is measured according to the ASTM D 882 method, or

[0034] Preferably, the homopolymer polypropylene has a content of 0.900 g / cm³. 3 The density, which is measured according to ASTM D792-13 method, or

[0035] Preferably, the membrane has a needle penetration strength / μm (mN / μm) from greater than about 90 mN / μm to less than about 150 mN / μm, wherein the needle penetration strength / μm (mN / μm) is measured according to the CEN 14477 method, or

[0036] Preferably, the homopolymer polypropylene has a yield tensile strength from about 20 MPa to about 100 MPa, as determined according to ASTM D638.

[0037] The present invention also relates to industrial packaging and food packaging, which include the film of the present invention.

[0038] According to embodiments of the present invention, the film manufactured by the present invention is suitable for upright, flexible packaging or pouches. Such packaging will be stiff enough to be shaped to stand upright, for example, with a label on its front, but flexible enough to allow the user to bend and / or squeeze the packaging, thereby forcing and / or pouring out liquids.

[0039] Broadly orthogonal composition distribution (BOCD) polyethylene

[0040] The polyolefin compositions of the present invention comprise one or more broadly orthogonally distributed (BOCD) polyethylenes. Broadly orthogonally distributed (BOCD) polyethylenes are polyethylene homopolymers or polyethylene copolymers, most commonly polyethylene copolymers. It is desirable for polyethylenes to have a broad orthogonal distribution, which provides an enhanced balance of stiffness, toughness, and processability (S / T / P) for polyethylenes and compositions comprising these polymers. Considering that polymers are blends of molecules with different chain length distributions, polymers with BOCD are branched polymers, which have predominant (if not all) branching occurring on the high molecular weight molecules of the polymer, resulting in poorer crystallinity. This microstructure tends to improve certain properties of products made from said BOCD-type polymers (including the polyolefin compositions described herein).

[0041] Polyethylene produced by Ziegler-Natta (“Zn”) often lacks a BOCD structure, with most short-chain branching occurring in the low molecular weight portions of the molecules produced in this way. On the other hand, some metallocene polyethylenes can typically possess a BOCD structure. The value of BOCD polymers relative to conventional polymers is significant.

[0042] In embodiments of the present invention, BOCD polyethylene can have a “broad orthogonal compositional distribution” (“BOCD”). The broad orthogonal compositional distribution can be determined using fractionation techniques such as gel permeation chromatography-differential viscometer (GPC-DV), temperature elution fractionation-differential viscometer (TREF-DV), or cross-fractionation techniques. For example, WO 2015 / 123164A1 (which is incorporated herein by reference) discusses the TREF technique, providing a measurement of the bivariate mass distribution of the crystalline portion of BOCD polyethylene.

[0043] The BOCD polyethylene of the present invention comprises about 70 mol% to about 99 mol% of ethylene-derived units, based on the total molar number of polymer units in the BOCD polyethylene. The lower limit of the range of ethylene-derived unit content based on the total molar number of polymer units in the BOCD polyethylene can be 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, 92 mol%, 94 mol%, 95 mol%, 96 mol%, 97 mol%, 98 mol%, or 99 mol%. The upper limit of the range of ethylene-derived unit content based on the total molar number of polymer units in the BOCD polyethylene can be 80 mol%, 85 mol%, 90 mol%, 92 mol%, 94 mol%, 95 mol%, 96 mol%, 97 mol%, 98 mol%, 99 mol%, 99.5 mol%, or 100 mol%. Any of the above upper limit contents can be combined with any of the above upper limit contents; any of the above upper limit contents can be combined with any of the above lower limit contents; and any of the above upper limit contents can be combined with any of the above lower limit contents.

[0044] The BOCD polyethylene of the present invention may have equal to or less than 30 mol% of polymer units derived from C3-C20 olefins, such as C3-C20 α-olefins, such as hexene or octene. Based on the total molar number of polymer units in the BOCD polyethylene, the upper limit of the content range of polymer units derived from C3-C20 olefins may be 30 mol%, 25 mol%, 20 mol%, 15 mol%, 10 mol%, 8 mol%, 6 mol%, 5 mol%, 4 mol%, 3 mol%, 2 mol%, 1 mol%, or 0.5 mol%. Based on the total molar number of polymer units in the BOCD polyethylene, the lower limit of the content range of polymer units derived from C3-C20 olefins may be 0 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 15 mol%, 20 mol%, or 25 mol%. Any of the above upper limit contents may be combined with any of the above upper limit contents; any of the above upper limit contents may be combined with any of the above lower limit contents; and any of the above upper limit contents may be combined with any of the above lower limit contents.

[0045] According to an embodiment of the present invention, the density of BOCD polyethylene, measured according to ASTM D-792 or ASTM D-1505, can be 0.910 g / cm³. 3 Up to 0.925 g / cm 3 Or 0.910 g / cm 3 Up to 0.923 g / cm 3 0.910 g / cm 3 Up to 0.920 g / cm 3 0.915g / cm 3 Up to 0.921 g / cm 3 0.910 g / cm 3 Up to 0.918 g / cm 3 0.912 g / cm 3 Up to 0.918 g / cm 3 Or 0.912 g / cm 3 Up to 0.917 g / cm 3 .

[0046] According to an embodiment of the invention, BOCD polyethylene has a melt index (MI, or I) of about 0.5 g / 10 min to about 3.0 g / 10 min, preferably about 1.0 g / 10 min to about 2.0 g / 10 min. 2.16 It is measured according to ASTM D-1238-E (190℃ / 2.16kg).

[0047] The term "Composition Distribution Width Index (CDBI)" refers to the weight percentage of copolymer molecules having a comonomer content within 50% of the total molar content of all comonomers. As measured by the Composition Distribution Width Index (CDBI), the BOCD polyethylene of the present invention typically has a broad composition distribution.

[0048] The CDBI of copolymers can be measured using techniques known in the art. The CDBI of copolymers is readily determined using well-known techniques for separating individual fractions of copolymer samples. One such technique is temperature elution fractionation (TREF), as described by Wild et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, pp. 441-455 (1982), which is incorporated herein by reference. Generally, a high CDBI indicates that most components are eluted over a shorter time period (smaller temperature range), indicating a narrower comonomer distribution; a low CDBI indicates that most components are eluted over a longer time period (larger temperature range), indicating a wider comonomer distribution.

[0049] Details regarding the determination of copolymer CDBI are known to those skilled in the art; see, for example, PCT patent application WO 1993 / 003093 published on February 18, 1993 (which is incorporated herein by reference), for details concerning CDBI, such as paragraph 4 on page 13, the transition paragraphs on pages 14-15, and the transition paragraphs on pages 18-19.

[0050] According to an embodiment of the invention, BOCD polyethylene is characterized by having a composition distribution width index (CDBI) ranging from about 25% by weight to about 55% by weight.

[0051] Materials and methods for manufacturing BOCD polyethylene have been described in the following documents, for example, U.S. Patent No. 6,956,088, particularly Example 1; U.S. Patent Application Publication No. 2009 / 0297810, particularly Example 1; U.S. Patent Application Publication No. 2015 / 0291748, particularly PE1-PE5 in the examples; and WO 2014 / 099356, particularly PE3 mentioned on page 12 and in the examples, including the use of a silica-supported hafnium transition metallocene / methylaluminoxane catalyst system, as described, for example, in U.S. Patent Nos. 6,242,545 and 6,248,845 (particularly Example 1).

[0052] Many types of BOCD polyethylene are commercially available. One or more BOCD polyethylenes are commercially available from: ExxonMobilChemical Company, Houston, TX, and via Exceed. TMXP metallocene polyethylene (mPE) for sale. Exceed TM XPmPE offers advantageous properties such as dart impact strength, resistance to flexural cracking and longitudinal (MD) tearing, and maintaining stiffness at lower densities. TM XP mPE also offers a good balance of melt strength, toughness, stiffness and sealing ability, making this type of polymer ideal for applications such as blown film / sheet molding.

[0053] Other BOCD polyethylenes, including Exceed, are commercially available from ExxonMobil Chemical Company, Houston, TX. TM S 9333 series, EXP609CB CAST, EXT515, etc.

[0054] The following BOCD polyethylene is used in the embodiments of this application:

[0055] Exceed TM XP 8318 is a polyethylene purchased from ExxonMobil Chemical Company, Houston, TX. It is a copolymer of ethylene and 1-hexene and has a strength of 0.918 g / cm³ as measured according to ASTM D792. 3 The density and melt index of 1.0 g / 10 min as measured according to ASTM D1238-E (190℃ / 2.16 kg), and composition distribution width index (CDBI) of approximately 38.6% by weight;

[0056] EXT515 is a polyethylene purchased from ExxonMobil Chemical Company, Houston, TX. It is a copolymer of ethylene and 1-hexene and has a strength of 0.915 g / cm³ as measured according to ASTM D1505. 3 It has a density and a melt index of 1.4 g / 10 min as measured according to ASTM D1238-E (190℃ / 2.16 kg), and a composition distribution width index (CDBI) of approximately 43% by weight.

[0057] Homopolymer polypropylene (hPP)

[0058] The polyolefin compositions of the present invention include one or more homopolymer polypropylenes.

[0059] According to embodiments of the present invention, homopolymer polypropylene (hPP) can have a melt index from about 1 g / 10 min, about 1.2 g / 10 min, about 1.4 g / 10 min, about 1.6 g / 10 min, or about 1.8 g / 10 min to about 2 g / 10 min, about 2.2 g / 10 min, about 2.5 g / 10 min, about 2.8 g / 10 min, about 3 g / 10 min, about 3.5 g / 10 min, about 4 g / 10 min, about 4.5 g / 10 min, about 5 g / 10 min, about 5.5 g / 10 min, or about 6 g / 10 min, as determined according to ASTM D1238-L (230°C / 2.16 kg). Any combination of the above upper and lower limits is also within the scope of the present invention.

[0060] According to an embodiment of the present invention, homopolymer polypropylene (hPP) can have a content of about 0.8 g / cm³. 3 Approximately 0.82 g / cm³ 3 Approximately 0.84 g / cm³ 3 Approximately 0.85 g / cm³ 3 Approximately 0.86 g / cm³ 3 or approximately 0.88 g / cm³ 3 Approximately 0.9 g / cm³ 3 Approximately 0.92 g / cm³ 3 Approximately 0.95 g / cm³ 3 Or approximately 0.98 g / cm³ 3 The density is measured according to ASTM D792-13 method. Any combination of the above upper and lower limits is also within the scope of this invention.

[0061] According to embodiments of the present invention, homopolymer polypropylene (hPP) can have a yield tensile strength from about 20 MPa, about 25 MPa, about 30 MPa, or about 35 MPa to about 40 MPa, about 45 MPa, about 50 MPa, about 60 MPa, about 80 MPa, or about 100 MPa, as determined according to ASTM D638. Any combination of the above upper and lower limits is also within the scope of the present invention.

[0062] In the embodiments of the present invention, T30S from Maoming Petrochemical, namely, "PP PPH-T03(T30S) Sinopec / fiber grade" polypropylene homopolymer is used as homopolymer polypropylene (hPP).

[0063] The polypropylene homopolymer of "PP PPH-T03(T30S) Sinopec / fiber grade" has the following performance parameters:

[0064] Melt index: 3.2 g / 10 min, measured at 230 °C and 2.16 kg.

[0065] Isotropic index of all structures: 97.2%;

[0066] Ash content: 0.02%;

[0067] Nominal strain at tensile fracture: 498%;

[0068] Yield tensile strength: 31.5 MPa;

[0069] Density: 0.900 g / cm³ 3 It is measured according to ASTM D792-13 method.

[0070] High-density polyethylene

[0071] The high-density polyethylene (HDPE) according to the present invention has a content greater than 0.940 g / cm³. 3 The density and melt index are approximately 0.5 g / 10 min to approximately 10 g / 10 min, wherein the density is measured according to ASTM D-1505 and the melt index is measured according to ASTM D1238-E (190℃ / 2.16 kg).

[0072] In embodiments of the present invention, ExxonMobil is used TM HDPE HTA 108, a high-density polyethylene, was purchased from ExxonMobil Chemical Company, Houston, TX.

[0073] ExxonMobil TM HDPE HTA 108 has the following performance parameters:

[0074] Density: 0.961 g / cm³ 3 Measured according to ASTM D-1505;

[0075] Melt index: 0.70 g / 10 min, measured according to ASTM D-1238-E (190℃ / 2.16 kg).

[0076] additive

[0077] According to embodiments of the present invention, other additives may also be present in the polyolefin composition and film of the present invention.

[0078] These additives may include antioxidants (e.g., hindered phenols and phosphites), stabilizers such as lactones and vitamin E, nucleating agents (α-nucleating agents and β-nucleating agents), clarifying agents, colorants (dyes or pigments), fillers (silica or talc), UV stabilizers, release agents, slip agents, tackifiers, antistatic agents, deacidifying agents (e.g., calcium stearate), anti-blocking agents, anti-frosting agents, polymer processing aid masterbatch (PPA MB) additives / reagents, and hydrocarbon resins such as Optera. TM Resins or combinations thereof.

[0079] Longitudinal Orientation (MDO) process

[0080] As is well known in the art, longitudinal orientation (MDO) processes involve uniaxial stretching of films or sheets to improve physical and barrier properties.

[0081] MDO (Medium Deposition) is a process used to modify and improve the following film properties: optical properties (haze and gloss), tensile properties, stiffness (secant modulus), dead wrinkles, and OTR (Optical Transformation), WTR (Waste Reduction), etc. Attached Figure Description

[0082] Figure 1 shows the MD tensile strength at break (MPa) of the following formulations: pure Exceed TM XP 8318, using a 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% T30S, using 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% HTA 108, using a 4X MDO draw ratio; and

[0083] Pure EXT 515, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% HTA 108, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% T30S, with MDO draw ratios of 3X, 4X or 5X respectively.

[0084] Figure 2 shows the MD elongation at break (%) of the following formulations: pure Exceed TM XP 8318, using a 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% T30S, using 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% HTA 108, using a 4X MDO draw ratio; and

[0085] Pure EXT 515, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% HTA 108, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% T30S, with MDO draw ratios of 3X, 4X or 5X respectively.

[0086] Figure 3 shows the MD 1% secant modulus (MPa) of the following formulations: pure Exceed TM XP 8318, using a 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% T30S, using 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% HTA 108, using a 4X MDO draw ratio; and

[0087] Pure EXT 515, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% HTA 108, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% T30S, with MDO draw ratios of 3X, 4X or 5X respectively.

[0088] Figure 4 shows the dart strength / thickness (g / μm) of the following formulations: pure Exceed TM XP 8318, using a 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% T30S, using 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% HTA 108, using a 4X MDO draw ratio; and

[0089] Pure EXT 515, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% HTA 108, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% T30S, with MDO draw ratios of 3X, 4X or 5X respectively.

[0090] Figure 5 shows the needle penetration strength / μm (mN / μm) of the following formulations: pure Exceed TM XP 8318, using a 4X MDO draw ratio; 80wt% Exceed TM XP 8318 + 20wt% T30S, using 4X MDO draw ratio; 80wt% Exceed TMXP 8318 + 20wt% HTA 108, using a 4X MDO draw ratio; and

[0091] Pure EXT 515, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% HTA 108, with MDO draw ratios of 3X, 4X or 5X respectively; 80wt% EXT 515 + 20wt% T30S, with MDO draw ratios of 3X, 4X or 5X respectively. Detailed Implementation

[0092] To better understand the technical solution of this invention, the applicant provides the following embodiments for illustrative purposes. These embodiments are merely illustrative and do not limit the scope of protection of this invention in any way.

[0093] Measurement methods

[0094] The present invention uses the following measurement method.

[0095] Table 1

[0096]

[0097]

[0098] Example

[0099] Examples 1-2 are both single-layer films with a thickness of 25 μm. Examples 1-2 were manufactured under the same casting process conditions described below.

[0100] The casting process uses the following steps:

[0101] 1- Heating / preheating roller: (80-130℃)

[0102] The temperature of the film is raised to the temperature of longitudinal (MD) orientation (hereinafter referred to as the melt temperature). The temperature depends on material properties (including density, Mw, LCB, etc.), production line speed, draw ratio, co-extrusion formulation, etc.

[0103] 2-Stretch ratio / tensile tension:

[0104] Stretching up to 10 times;

[0105] Tension controlled at a certain stretch ratio: material properties.

[0106] 3- Annealing roller: (100-120℃):

[0107] Membrane properties obtained after heat fixation in MDO;

[0108] Control reactions that may be exposed to heat in the future, such as by sealing.

[0109] 4-Cooling roller: (70-20℃):

[0110] The membrane is cooled and its temperature is cooled to room temperature before rewinding.

[0111] Specifically, the following conditions shall be used:

[0112]

[0113] Example 1

[0114] In the MDO process, membranes with the following compositions were stretched at stretch ratios of 3X, 4X, and 5X, respectively, and the properties of each membrane were tested. All membranes were single-layer membranes with a thickness of 25 μm.

[0115] (1) Pure EXT 515;

[0116] (2)80wt%EXT 515+20wt%HTA 108;

[0117] (3)80wt%EXT 515+20wt%T30S.

[0118] Table 2

[0119]

[0120] As shown in Table 2, the film comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition of the present invention achieves high stiffness, i.e., a longitudinal (MD) 1% secant modulus greater than 410 MPa. Specifically, using draw ratios of 3X, 4X, and 5X, the film comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition of the present invention achieves longitudinal (MD) 1% secant modulus of 442.0 MPa, 634.0 MPa, and 774.0 MPa, respectively. In particular, using a draw ratio of 5X, the film comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition of the present invention can obtain a longitudinal (MD) 1% secant modulus as high as 774.0 MPa.

[0121] It is generally believed in the art that during longitudinal orientation (MDO) processes, the toughness of the membrane decreases as the stretch ratio increases.

[0122] Surprisingly, the film comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition of the present invention exhibits improved toughness with increasing draw ratio. Specifically, using draw ratios of 3X, 4X, and 5X, the film comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition of the present invention achieves needle penetration strengths of 111.45 mN / μm, 141.97 mN / μm, and 140.35 mN / μm, respectively.

[0123] In particular, compared to a draw ratio of 3X, the film of the present invention comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition unexpectedly exhibits a 27.4% increase in needle penetration strength / μm when using a draw ratio of 4X. Using draw ratios of 4X and 5X, the film of the present invention comprising the 80wt% EXT 515 + 20wt% T30S polyolefin composition unexpectedly exhibits substantially the same needle penetration strength / μm (mN / μm), namely, 141.97 mN / μm and 140.35 mN / μm.

[0124] Therefore, the above embodiments illustrate that by providing a polyolefin composition in which homopolymer polypropylene is used instead of high-density polyethylene and by longitudinally oriented the film, the film of the present invention has a beneficial balance of stiffness and toughness while having high stiffness.

[0125] Furthermore, compared to films comprising an 80wt% EXT 515 + 20wt% HTA 108 polyolefin composition (where HTA108 is high-density polyethylene), the films of the present invention comprising an 80wt% EXT 515 + 20wt% T30S polyolefin composition unexpectedly exhibit increased longitudinal (MD) 1% secant modulus of 60.7%, 86.5%, and 58.3%, respectively, when using stretch ratios of 3X, 4X, and 5X.

[0126] Moreover, compared to films containing an 80wt% EXT 515 + 20wt% HTA 108 polyolefin composition (where HTA108 is high-density polyethylene), the films of the present invention containing an 80wt% EXT 515 + 20wt% T30S polyolefin composition unexpectedly exhibit increased needle penetration strength / μm by 14.7%, 33.5%, and 6.0%, respectively, when using stretch ratios of 3X, 4X, and 5X.

[0127] Furthermore, compared to films comprising an 80wt% EXT 515 + 20wt% HTA 108 polyolefin composition (where HTA108 is high-density polyethylene), the films of the present invention comprising an 80wt% EXT 515 + 20wt% T30S polyolefin composition unexpectedly exhibit increased dart strength / thickness (g / μm) by 8.7%, 47.4%, and 35%, respectively, when using stretch ratios of 3X, 4X, and 5X.

[0128] Therefore, the above embodiments illustrate that by providing a polyolefin composition that uses homopolymer polypropylene instead of high-density polyethylene and longitudinally oriented the film, compared with the prior art films that use high-density polyethylene, the film of the present invention not only has significantly improved stiffness but also improved toughness, successfully achieving a beneficial balance between stiffness and toughness.

[0129] Example 2

[0130] In the MDO process, membranes with the following composition were stretched at a stretch ratio of 4X, and the properties of each membrane were tested. All membranes were single-layer membranes with a thickness of 25 μm:

[0131] (1) Pure Exceed TM XP 8318;

[0132] (2) 80wt% Exceed TM XP 8318 + 20wt% HTA 108;

[0133] (3) 80wt% Exceed TM XP 8318+20wt%T30S.

[0134] Table 3

[0135]

[0136] As can be seen from Table 3, when using a 4X draw ratio, compared to containing 80wt% Exceed TM Compared to the film of the XP 8318+20wt% HTA 108 polyolefin composition, the film of the present invention contains 80wt% Exceed TM While maintaining substantially the same toughness, i.e., with needle penetration strength / μm (mN / μm) of 109.04 mN / μm and 102.62 mN / μm respectively, the film of the present invention achieves a significant increase in stiffness of 41.1%, i.e., a significant increase in longitudinal (MD) 1% secant modulus of 41.1%.

[0137] All documents described herein, including any priority documents and / or experimental procedures, are incorporated by reference to all rights, without prejudice to the present invention. It will be apparent from the foregoing overview and specific embodiments that, while the form of this disclosure has been illustrated and described, various modifications may be made without departing from the spirit and scope of this disclosure. Therefore, it is not intended that this disclosure be limited thereto. Similarly, the term “comprising” is considered synonymous with the term “including.” Likewise, whenever a composition, element, or group of elements precedes the transitional term “comprising,” it should be understood that the same composition or group of elements preceding the enumerated composition, element, or element, and vice versa, is also considered to have the transitional terms “consistently composed of,” “composed of,” “selected from,” or “is” preceding the enumerated composition, element, or elements.

[0138] For simplicity, only certain numerical ranges are explicitly disclosed in this document. However, a lower limit can be combined with any other upper limit to define a range that is not explicitly stated, and similarly, a lower limit can be combined with any other lower limit to define a range that is not explicitly stated; likewise, an upper limit can be combined with any upper limit to define a range that is not explicitly stated. Furthermore, even if not explicitly stated, every point or individual value between the two endpoints is included within the range. Therefore, each point or individual value itself can serve as a lower or upper limit, combined with other points or individual values ​​or other lower or upper limits to define a range that is not explicitly stated.

Claims

1. A membrane comprising a polyolefin composition, wherein the polyolefin composition comprises 60 wt% to 95 wt% of BOCD polyethylene and 10 wt% to 40 wt% of homopolymer polypropylene, based on the weight of the polyolefin composition. BOCD polyethylene contains 70 mol% to 99 mol% of ethylene-derived polymer units, based on the total molar number of polymer units in BOCD polyethylene, and has a density of 0.91 g / cm³. 3 Up to 0.925 g / cm 3 It is measured according to ASTM D-792 or ASTM D-1505, and has a melt index I of 0.5 g / 10min to 3.0 g / 10min. 2.16 It was measured according to ASTM D-1238-E at 190°C / 2.16 kg, and BOCD polyethylene has a composition distribution width index (CDBI) ranging from 20 wt% to less than 50 wt%. The homopolymer polypropylene has a melt index ranging from 1 g / 10min to 6 g / 10min, determined according to ASTM D1238-L at 230℃ / 2.16 kg. The film is manufactured by a casting process and subsequently subjected to longitudinal orientation (MDO) with a stretch ratio of 3X to 5X. The membrane has a longitudinal (MD) 1% secant modulus ranging from greater than 410 MPa to less than 780 MPa, measured when the membrane has a thickness of 25 µm, wherein the longitudinal (MD) 1% secant modulus is measured according to the ASTM D 882 method.

2. The membrane according to claim 1, wherein the BOCD polyethylene has a melt index of 1 from 1.0 g / 10 min to 2.0 g / 10 min. 2.16 It was measured according to ASTM D-1238-E at 190℃ / 2.16kg.

3. The membrane according to any one of claims 1 to 2, wherein the membrane has a needle penetration strength / μm (mN / μm) from greater than 90 mN / μm to less than 150 mN / μm, wherein the needle penetration strength / μm (mN / μm) is measured according to the CEN 14477 method.

4. The membrane according to any one of claims 1 to 2, wherein the homopolymer polypropylene has a content of 0.8 g / cm³. 3 Up to 0.98 g / cm 3 The density is measured according to ASTM D792-13 method.

5. The membrane according to any one of claims 1 to 2, wherein the homopolymer polypropylene has a yield tensile strength from 20 MPa to 100 MPa, as determined according to ASTM D638.

6. A membrane comprising a polyolefin composition, wherein the polyolefin composition comprises 60 wt% to 95 wt% of BOCD polyethylene and 10 wt% to 40 wt% of homopolymer polypropylene, based on the weight of the polyolefin composition. BOCD polyethylene contains 70 mol% to 99 mol% of ethylene-derived polymer units, based on the total molar number of polymer units in BOCD polyethylene, and has a density of 0.918 g / cm³. 3 It is measured according to ASTM D-792 and has a melt index I of 1.0 g / 10min. 2.16 It was measured according to ASTM D-1238-E at 190°C / 2.16 kg, and BOCD polyethylene has a composition distribution width index (CDBI) of 38.6% by weight, or BOCD polyethylene contains 70 mol% to 99 mol% of ethylene-derived polymer units, based on the total molar number of polymer units in BOCD polyethylene, and has a density of 0.915 g / cm³. 3 It was measured according to ASTM D-1505 and has a melt index I of 1.4 g / 10min. 2.16 It was measured according to ASTM D-1238-E at 190℃ / 2.16kg, and BOCD polyethylene has a composition distribution width index (CDBI) of 43% by weight. The homopolymer polypropylene has a melt index of 3.2 g / 10min, which was determined according to ASTM D1238-L at 230℃ / 2.16kg. The film is manufactured by a casting process and subsequently subjected to longitudinal orientation (MDO) with a stretch ratio of 3X to 5X. The membrane has a longitudinal (MD) 1% secant modulus ranging from greater than 410 MPa to less than 780 MPa, measured when the membrane has a thickness of 25 µm, wherein the longitudinal (MD) 1% secant modulus is measured according to the ASTM D 882 method.

7. The membrane according to claim 6, wherein the homopolymer polypropylene has a content of 0.900 g / cm³. 3 The density, which is measured according to ASTM D792-13 method; and / or, the homopolymer polypropylene has a yield tensile strength from 20 MPa to 100 MPa, which is determined according to ASTM D638.

8. The membrane according to claim 6 or 7, wherein the membrane has a needle penetration strength / μm (mN / μm) from greater than 90 mN / μm to less than 150 mN / μm, wherein the needle penetration strength / μm (mN / μm) is measured according to the CEN 14477 method.

9. Industrial packaging comprising the film according to any one of claims 1 to 8.

10. Food packaging comprising a film according to any one of claims 1 to 8.

11. A method of manufacturing a membrane according to any one of claims 1 to 8, wherein the polyolefin composition is formed into a membrane by casting, and the membrane is subsequently subjected to longitudinal orientation (MDO), wherein the stretch ratio is 3X to 5X.

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