Multilayer polyethylene film and method for producing the same

Abstract

The present invention relates to a multilayer polyethylene film comprising: an outer layer, an inner layer and a core layer located between the outer layer and the inner layer; wherein the core layer comprises a core layer composition comprising: A) 65 to 95 wt% of a polyethylene and B) 5 to 35 wt% of a propylene-based elastomer, based on the weight of the core layer composition.

Description

Technical Field

[0001] This invention relates to a multilayer polyethylene film and its preparation method. Background Technology

[0002] Polyethylene has a wide range of applications, and its manufacture of films is a significant one. Applications of polyethylene films include, but are not limited to, shopping bags and food packaging films. Longitudinal (MD) trouser tear strength is an important performance indicator for polyethylene films, reflecting the film material's ability to resist tearing after the tear has begun. For polyethylene, increased density leads to increased crystallinity and stronger intermolecular forces between polymer chains. This increased crystallinity and stronger intermolecular forces help the film material resist tear propagation; therefore, with increasing density, the longitudinal trouser tear strength also increases. However, increasing polyethylene density usually leads to a decrease in the toughness of the polyethylene film, such as needle punch strength. Therefore, achieving a good balance between longitudinal trouser tear performance and toughness is a problem that urgently needs to be solved.

[0003] Therefore, it is still necessary to find a polyethylene film that has both good toughness and improved longitudinal trouser-shaped tear resistance. Summary of the Invention

[0004] Therefore, the present invention provides a multilayer polyethylene film comprising: outer layer, Inner layer, and The core layer is located between the outer and inner layers; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers.

[0005] The present invention also relates to a method for preparing the polyethylene film.

[0006] The multilayer polyethylene film of the present invention achieves a good balance between toughness and longitudinal trouser-shaped tear resistance. Attached Figure Description

[0007] Figure 1The longitudinal (MD) trouser-type tear strength of polyethylene films shown in Comparative Example 1 (where the core layer contains 100 wt% Exceed™ Stiff m 1327, by weight of the core layer), Example 1 (where the core layer contains 90 wt% Exceed™ Stiff m 1327 and 10 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer), Example 2 (where the core layer contains 80 wt% Exceed™ Stiff m 1327 and 20 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer), and Example 3 (where the core layer contains 70 wt% Exceed™ Stiff m 1327 and 30 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer) is displayed.

[0008] Figure 2 The longitudinal (MD) trouser-type tear strength of polyethylene films shown in Comparative Example 2 (where the core layer contains 100 wt% Exceed™ Flow+ m 0216, by weight of the core layer), Example 4 (where the core layer contains 90 wt% Exceed™ Flow+ m 0216 and 10 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer), Example 5 (where the core layer contains 80 wt% Exceed™ Flow+ m 0216 and 20 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer), and Example 6 (where the core layer contains 70 wt% Exceed™ Flow+ m 0216 and 30 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer) is displayed.

[0009] Figure 3The needle penetration strength (needle penetration force / thickness) of polyethylene films shown in Comparative Example 1 (where the core layer contains 100 wt% of Exceed™ Stiff m 1327, by weight of the core layer), Example 1 (where the core layer contains 90 wt% of Exceed™ Stiff m 1327 and 10 wt% of Vistamaxx™ Performance Polymer 6102, by weight of the core layer), Example 2 (where the core layer contains 80 wt% of Exceed™ Stiff m 1327 and 20 wt% of Vistamaxx™ Performance Polymer 6102, by weight of the core layer), and Example 3 (where the core layer contains 70 wt% of Exceed™ Stiff m 1327 and 30 wt% of Vistamaxx™ Performance Polymer 6102, by weight of the core layer) are displayed.

[0010] Figure 4 The needle penetration strength (needle penetration force / thickness) of the polyethylene films shown in Comparative Example 2 (where the core layer contains 100 wt% Exceed™ Flow+ m 0216, by weight of the core layer), Example 4 (where the core layer contains 90 wt% Exceed™ Flow+ m 0216 and 10 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer), Example 5 (where the core layer contains 80 wt% Exceed™ Flow+ m 0216 and 20 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer), and Example 6 (where the core layer contains 70 wt% Exceed™ Flow+ m 0216 and 30 wt% Vistamaxx™ Performance Polymer 6102, by weight of the core layer) is displayed. Detailed Implementation

[0011] As used herein, the term "polyethylene" means polyethylene containing at least 50 mol% ethylene units, preferably at least 70 mol% ethylene units, more preferably at least 80 mol% ethylene units, and even more preferably at least 90 mol% ethylene units.

[0012] As used in this article, density was measured according to the ASTM D792 standard method.

[0013] As used in this article, the melt index (MI) was measured according to the ASTM D1238 standard method, 190°C / 2.16kg.

[0014] As used in this article, the dart impact strength was measured according to the ASTM D1709 standard method.

[0015] As used in this article, longitudinal (MD) tensile strength at break and transverse (TD) tensile strength at break were measured according to the ASTM D882 standard method.

[0016] As used in this article, needle penetration intensity was measured according to the CEN 14477 standard method.

[0017] As used in this article, longitudinal (MD) trouser tear strength was measured according to the ASTM D1938 standard method.

[0018] As used herein, molecular weight and molecular weight distribution (MWD) were measured using gel permeation chromatography (“GPC”) equipped with a differential refractive index (“DRI”) detector.

[0019] Multilayer polyethylene film

[0020] According to the present invention, the multilayer polyethylene film comprises: outer layer, Inner layer, and The core layer is located between the outer and inner layers; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers.

[0021] In one embodiment, the multilayer polyethylene film has a thickness of 5-200µm, such as 10µm, 20µm, 30µm, 40µm, 50µm, 60µm, 70µm, 80µm, 90µm, 100µm, 110µm, 120µm, 130µm, 140µm, 150µm, 160µm, 170µm, 180µm, or 190µm.

[0022] In one embodiment, the core layer of the multilayer polyethylene film comprises or is composed of a core layer composition.

[0023] In one embodiment, both the outer and inner layers of the multilayer polyethylene film are made of polyethylene.

[0024] In a preferred embodiment, the polyethylene in the outer and inner layers of the multilayer polyethylene film is the same as the polyethylene in the core layer composition.

[0025] In one embodiment, the multilayer polyethylene film of the present invention may be a 3-6 layer polyethylene film, especially a five-layer polyethylene film.

[0026] In one embodiment, the multilayer polyethylene film is a five-layer polyethylene film having an outer layer / secondary outer layer / core layer / secondary inner layer / inner layer layer structure.

[0027] In one embodiment, in the five-layer polyethylene film, the thickness ratio of the outer layer / secondary outer layer / core layer / secondary inner layer / inner layer can be, for example, about 1:1:1:1:1, about 1:1:2:1:1, about 1:1:3:1:1, about 1:2:2:2:1, about 1:2:3:2:1, about 1:2:4:2:1, or vary within any combination of the values ​​described herein.

[0028] In a preferred embodiment, the outer layer, the second outer layer, the second inner layer, and the inner layer of the multilayer polyethylene film are all made of polyethylene.

[0029] In a preferred embodiment, the polyethylene in the outer, second outer, second inner, and inner layers of the multilayer polyethylene film is the same as the polyethylene in the core layer composition.

[0030] According to the present invention, the multilayer polyethylene film has a MD trouser tear strength of 5-35 cN / µm, for example, 10 cN / µm, 15 cN / µm, 20 cN / µm, 25 cN / µm, and 30 cN / µm.

[0031] According to the present invention, the multilayer polyethylene film has a needle penetration strength of 40-100 mN / µm, for example, 50 mN / µm, 60 mN / µm, 70 mN / µm, 80 mN / µm, and 90 mN / µm.

[0032] Core layer composition

[0033] In one embodiment, the core layer composition in the multilayer polyethylene film comprises, based on a weight of the core layer composition: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers.

[0034] In one embodiment, the core layer composition in the multilayer polyethylene film comprises, based on a weight of the core layer composition: A) 70-90% by weight of polyethylene, and B) 10-30% by weight of propylene-based elastomers.

[0035] In one embodiment, the core layer composition in the multilayer polyethylene film comprises, based on a weight of the core layer composition: A) 80-90% by weight of polyethylene, and B) 10-20% by weight of propylene-based elastomer.

[0036] In one embodiment, the core layer composition in the multilayer polyethylene film comprises, based on a weight of the core layer composition: A) 70-80% by weight of polyethylene, and B) 20-30% by weight of propylene-based elastomer.

[0037] polyethylene

[0038] According to the present invention, the core layer composition in the multilayer polyethylene film contains 65-95% by weight of polyethylene, for example 70%, 75%, 80%, 85% or 90% by weight of polyethylene, based on the weight of the core layer composition.

[0039] According to the present invention, the polyethylene is derived from ethylene and one or more C3-C... 20 α-olefin comonomer.

[0040] In one embodiment, the polyethylene is ethylene mixed with C3-C4. 20 α-olefins, preferably C3-C 10 Random or block copolymers of one or more comonomers of α-olefins. Preferably, the comonomers are present in an amount of 0.1% to 50% by weight of the copolymer, for example, 0.5% to 30% by weight, 1% to 15% by weight, or 0.1% to 5% by weight.

[0041] In one embodiment, the polyethylene is a random or block copolymer of ethylene and one or more comonomers selected from butene, pentene, and hexene.

[0042] In a preferred embodiment, the polyethylene is a copolymer derived from ethylene and 1-hexene.

[0043] In one embodiment, the polyethylene has a content of 0.860 to 0.930 g / cm³. 3 The density, for example, 0.870 g / cm³. 3 0.880 g / cm 3 0.890 g / cm 3 0.900 g / cm 3 0.910 g / cm 3 0.915 g / cm 3 0.920 g / cm 3 0.925 g / cm 3 The density.

[0044] In one embodiment, the polyethylene has a melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238, 190°C / 2.16 kg standard method, for example, melt indices of 0.5 g / 10 min, 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, and 4 g / 10 min.

[0045] In one embodiment, the polyethylene has a molecular weight distribution of 1.5 to 5 as measured by GPC, for example, a molecular weight distribution of 1.5 to 4 or 2 to 3.

[0046] In one embodiment, the polyethylene has a content of 0.910 to 0.930 g / cm³. 3 Its density, melt index of 0.5 to 3 g / 10 min, and molecular weight distribution of 1.5 to 5.

[0047] In one embodiment, the polyethylene has a weight-average molecular weight greater than or equal to 8,000 g / mol, greater than or equal to 10,000 g / mol, greater than or equal to 12,000 g / mol, or greater than or equal to 20,000 g / mol, and less than or equal to 1,000,000 g / mol or less than or equal to 800,000 g / mol, for example 30,000 g / mol, 50,000 g / mol, 80,000 g / mol, 100,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, 600,000 g / mol, or 700,000 g / mol.

[0048] In one embodiment, the polyethylene has a MD trouser tear strength of 1-16 cN / µm, such as 5 cN / µm, 8 cN / µm, 10 cN / µm, 12 cN / µm, or 14 cN / µm.

[0049] In one embodiment, the polyethylene has a tensile strength at break of 50-75 MPa, measured according to the ASTM D882 standard method, for example, tensile strength at break of 55 MPa, 60 MPa, 65 MPa, or 70 MPa.

[0050] In one embodiment, the polyethylene has a TD tensile strength at break of 45-65 MPa, measured according to the ASTM D882 standard method, for example, a TD tensile strength at break of 50 MPa, 55 MPa, or 60 MPa.

[0051] In one embodiment, the polyethylene has a dart impact strength of 5-45 g / µm, measured according to the ASTM D1709 standard method, such as 10 g / µm, 15 g / µm, 20 g / µm, 25 g / µm, 30 g / µm, 35 g / µm, and 40 g / µm.

[0052] In one embodiment, the polyethylene is metallocene-catalyzed linear low-density polyethylene, Ziegler-Natta-catalyzed linear low-density polyethylene, or a combination thereof.

[0053] The polyethylene is not limited to any particular preparation method and can be formed using any method known in the art. For example, polyethylene can be formed using gas-phase, solution, or slurry methods.

[0054] In one embodiment, polyethylene is formed in the presence of a Ziegler-Natta catalyst. In another embodiment, polyethylene is formed in the presence of a metallocene catalyst. For example, polyethylene can be prepared in solution, slurry, high pressure, or gas phase using a combination of a mono- or di-cyclopentadienyl transition metal catalyst with an aluminoxane and / or a non-coordinated anionic activator. The catalyst and activator can be supported or unsupported, and the cyclopentadienyl ring can be substituted or unsubstituted.

[0055] In this invention, the polyethylene used includes those commercially available from ExxonMobil, such as those sold under the trade names Exceed™ Stiff m 1327, Exceed™ Flow+ m 0216, Exxtra™ Seal m 1012, Exceed™ m 1018, Exceed™ Flow m 0520, Exceed™ Flow m 0322, and Exceed™ Flow m 0527.

[0056] Propylene-based elastomers

[0057] According to the present invention, the core layer composition in the multilayer polyethylene film contains 5-35% by weight of a propylene-based elastomer, for example, 10%, 15%, 20%, 25%, or 30% by weight of the propylene-based elastomer.

[0058] In one embodiment, the core composition may comprise one or more propylene-based elastomers.

[0059] In one embodiment, the propylene-based elastomer is composed of isotactic propylene repeating units and randomly distributed ethylene repeating units.

[0060] In one embodiment, the propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer.

[0061] According to the present invention, the propylene-based elastomer has a content of 0.850-0.925 g / cm³. 3 The preferred concentration is 0.860-0.890 g / cm³. 3 The density.

[0062] According to the present invention, the propylene-based elastomer has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, for example, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 15 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, and 25 g / 10 min.

[0063] The propylene-based elastomers of this invention can be commercially available or prepared according to conventional methods in the art. According to this invention, the method for preparing the propylene-based elastomers can be a continuous polymerization method or a batch polymerization method.

[0064] In one embodiment, the propylene-based elastomer is, for example, Vistamaxx™ Performance Polymer 6102 from ExxonMobil.

[0065] additive

[0066] According to the present invention, the core layer composition may further comprise additives commonly known in the art, such as dispersants, lubricants, anti-drip agents, anti-fogging agents, flame retardants, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, nucleating agents, plasticizers, and colorants such as dyes or pigments. The additives may be present in the core layer composition in an amount of 0.1-5% by weight, based on the weight of the core layer composition.

[0067] In one embodiment, the multilayer polyethylene film comprises, from the outside to the inside: outer layer, Second outer layer, Core layer The innermost layer, and Inner layer; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers. The polyethylene described herein has a strength of 0.860 to 0.930 g / cm³, as measured according to the ASTM D792 standard method. 3 The density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg. The propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer. The propylene-based elastomer described herein has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, and The outer layer, the second outer layer, the second inner layer, and the inner layer are all made of the same polyethylene as the polyethylene in the core layer composition.

[0068] In yet another embodiment, the multilayer polyethylene film of the present invention comprises, from the outside to the inside: outer layer, Second outer layer, Core layer The innermost layer, and Inner layer; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 70-90% by weight of polyethylene, and B) 10-30% by weight of propylene-based elastomers, The polyethylene described herein has a strength of 0.860 to 0.930 g / cm³, as measured according to the ASTM D792 standard method. 3 The density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg. The propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer. The propylene-based elastomer described herein has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, and The outer layer, the second outer layer, the second inner layer, and the inner layer are all made of the same polyethylene as the polyethylene in the core layer composition.

[0069] In yet another embodiment, the multilayer polyethylene film of the present invention comprises, from the outside to the inside: outer layer, Second outer layer, Core layer The innermost layer, and Inner layer; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 80-90% by weight of polyethylene, and B) 10-20% by weight of propylene-based elastomer, The polyethylene described herein has a strength of 0.860 to 0.930 g / cm³, as measured according to the ASTM D792 standard method. 3 The density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg. The propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer. The propylene-based elastomer described herein has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, and The outer layer, the second outer layer, the second inner layer, and the inner layer are all made of the same polyethylene as the polyethylene in the core layer composition.

[0070] In yet another embodiment, the multilayer polyethylene film of the present invention comprises, from the outside to the inside: outer layer, Second outer layer, Core layer The innermost layer, and Inner layer; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 70-80% by weight of polyethylene, and B) 20-30% by weight of propylene-based elastomer, The polyethylene described herein has a strength of 0.860 to 0.930 g / cm³, as measured according to the ASTM D792 standard method. 3 The density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg. The propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer. The propylene-based elastomer described herein has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, and The outer layer, the second outer layer, the second inner layer, and the inner layer are all made of the same polyethylene as the polyethylene in the core layer composition.

[0071] Methods for preparing thin films

[0072] The films described herein can be prepared using any conventional techniques known in the art, including blown film, casting, blow molding, extrusion, injection molding, etc.

[0073] In one embodiment, the film of the present invention can be prepared using a blown film technique. For example, the multilayer polyethylene film described herein can be extruded through an annular die in a molten state, then inflated and cooled to form a tubular blown film, which can then be axially cut and unfolded to form a planar film.

[0074] In one embodiment, a blown film can be prepared as follows: A multilayer polyethylene film is introduced into the feed hopper of an extruder and then extruded through a die to form a film, cooled by blowing air onto the film surface. The film is pulled from the die, typically forming a cylindrical film, cooled, unwound, and optionally subjected to desired auxiliary methods, such as cutting, processing, sealing, or printing. In blown film, the film can be pulled upwards by, for example, pinch rolls after leaving the die, while simultaneously expanding and laterally stretching to a degree quantifiable by the blow-up ratio (BUR). Expansion provides lateral (TD) stretching, while upward pulling by the pinch rolls provides longitudinal (MD) stretching. Typical melt temperatures are from about 180°C to about 190°C. The final film can be wound into rolls for later processing. Specific blown film methods and apparatus suitable for forming films according to embodiments of the present invention are described in U.S. Patent No. 5,569,693. Of course, other blown film forming methods can also be used.

[0075] The multilayer polyethylene film of the present invention can be used, for example, in shopping bags, food packaging films, etc.

[0076] Those skilled in the art will be able to more readily understand the present invention based on the following embodiments: Implementation Scheme 1. A multilayer polyethylene film, comprising: outer layer, Inner layer, and The core layer is located between the outer and inner layers; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers.

[0077] Implementation Scheme 2. The multilayer polyethylene film according to Implementation Scheme 1, wherein the multilayer polyethylene film has a thickness of 5-200µm.

[0078] Implementation Scheme 3. The multilayer polyethylene film according to Implementation Scheme 1 or 2, wherein both the outer layer and the inner layer are made of polyethylene.

[0079] Implementation Scheme 4. The multilayer polyethylene film according to Implementation Scheme 3, wherein the polyethylene in the outer and inner layers is the same as the polyethylene in the core layer composition.

[0080] Implementation Scheme 5. A multilayer polyethylene film according to any one of Implementation Schemes 1-4, wherein the multilayer polyethylene film is a five-layer polyethylene film having an outer layer / secondary outer layer / core layer / secondary inner layer / inner layer layer structure.

[0081] Implementation Scheme 6. The multilayer polyethylene film according to Implementation Scheme 5, wherein the outer layer, the second outer layer, the second inner layer and the inner layer are all made of polyethylene.

[0082] Implementation Scheme 7. The multilayer polyethylene film according to Implementation Scheme 6, wherein the polyethylene in the outer layer, the second outer layer, the second inner layer and the inner layer are all the same as the polyethylene in the core layer composition.

[0083] Implementation Scheme 8. A multilayer polyethylene film according to any one of Implementation Schemes 1-7, wherein the polyethylene has a strength of 0.860 to 0.930 g / cm³ as measured according to the ASTM D792 standard method. 3 Its density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg.

[0084] Implementation Scheme 9. A multilayer polyethylene film according to any one of Implementation Schemes 1-8, wherein the polyethylene is metallocene-catalyzed linear low-density polyethylene, Ziegler-Natta-catalyzed linear low-density polyethylene, or a combination thereof.

[0085] Implementation Scheme 10. A multilayer polyethylene film according to any one of Implementation Schemes 1-9, wherein the polyethylene is derived from ethylene and 1-hexene comonomers.

[0086] Implementation Scheme 11. A multilayer polyethylene film according to any one of Implementation Schemes 1-10, wherein the propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer.

[0087] Implementation Scheme 12. The multilayer polyethylene film according to any one of Implementation Schemes 1-11, wherein the propylene-based elastomer has a melt index of 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg.

[0088] Implementation Scheme 13. A multilayer polyethylene film according to any one of Implementation Schemes 1-12, wherein the propylene-based elastomer has a content of 0.850-0.925 g / cm³ as measured according to the ASTM D792 standard method. 3 The preferred concentration is 0.860-0.890 g / cm³. 3 The density.

[0089] Implementation Scheme 14. A multilayer polyethylene film according to any one of Implementation Schemes 1-13, wherein the propylene-based elastomer is composed of isotactic propylene repeating units and randomly distributed ethylene repeating units.

[0090] Implementation Scheme 15. A multilayer polyethylene film according to any one of Implementation Schemes 1-14, wherein the multilayer polyethylene film has a longitudinal trouser tear strength of 5-35 cN / µm as measured according to the ASTM D1938 standard method.

[0091] Implementation Scheme 16. A multilayer polyethylene film according to any one of Implementation Schemes 1-15, wherein the multilayer polyethylene film has a needle penetration strength of 40-100 mN / µm as measured according to the CEN 14477 standard method.

[0092] Implementation Scheme 17. A multilayer polyethylene film according to any one of Implementation Schemes 1-16, wherein the core layer composition comprises 70-90% by weight of polyethylene, preferably 80-90% by weight, based on the weight of the core layer composition.

[0093] Implementation Scheme 18. A multilayer polyethylene film according to any one of Implementation Schemes 1-17, wherein the core layer composition comprises 10-30% by weight of a propylene-based elastomer, preferably 20-30% by weight, based on the weight of the core layer composition.

[0094] Implementation Scheme 19. A multilayer polyethylene film, comprising, from the outside to the inside: outer layer, Second outer layer, Core layer The innermost layer, and Inner layer; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers. The polyethylene described herein has a strength of 0.860 to 0.930 g / cm³, as measured according to the ASTM D792 standard method. 3The density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg. The propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer. The propylene-based elastomer described herein has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, and The outer layer, the second outer layer, the second inner layer, and the inner layer are all made of the same polyethylene as the polyethylene in the core layer composition.

[0095] Example

[0096] The nature and purpose of the present invention are further understood through the following embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0097] Material

[0098] Exceed™ Stiff m 1327 and Exceed™ Flow+ m 0216 are polyethylene products purchased from ExxonMobil.

[0099] Vistamaxx™ Performance Polymer 6102 is a propylene-based elastomer purchased from ExxonMobil.

[0100] Preparation of five-layer polyethylene film

[0101] Five-layer polyethylene films were prepared according to the formulations shown in Table 1, and the properties of the resulting polyethylene films were tested. The results are compared and shown in Table 1. Figures 1-4 middle.

[0102] Table 1: Composition of multilayer polyethylene film (where the percentages are weight percentages, based on 100% by weight for each layer)

[0103] Note: The weight percentage of each component in Table 1 is based on the weight of each layer, where the sum of the contents of each component in each layer is 100% by weight.

[0104] The preparation process conditions of the five-layer polyethylene film are shown in Table 2. The film parameters are as follows: the thickness ratio of each layer (outer layer / secondary outer layer / core layer / secondary inner layer / inner layer) is 1 / 2 / 4 / 2 / 1, and the film thickness is 50 μm. In Comparative Example 1 and Comparative Example 2, each layer is composed of polyethylene. In Examples 1-6, except for the core layer which is composed of polyethylene and propylene-based elastomer, all other layers are composed of polyethylene. Specifically, in Example 1, the core layer comprises 90 wt% polyethylene (Exceed™ Stiff m1327) and 10 wt% propylene-based elastomer (Vistamaxx™ Performance Polymer 6102), based on the weight of the core layer; in Example 2, the core layer comprises 80 wt% polyethylene (Exceed™ Stiff m1327) and 20 wt% propylene-based elastomer (Vistamaxx™ Performance Polymer 6102), based on the weight of the core layer; in Example 3, the core layer comprises 70 wt% polyethylene (Exceed™ Stiff m1327) and 30 wt% propylene-based elastomer (Vistamaxx™ Performance Polymer 6102), based on the weight of the core layer; and in Example 4, the core layer comprises 90 wt% polyethylene (Exceed™ Flow+ m0216) and 10 wt% propylene-based elastomer (Vistamaxx™ Performance Polymer). 6102), based on the weight of the core layer; in Example 5, the core layer comprises 80 wt% polyethylene (Exceed™ Flow+ m 0216) and 20 wt% propylene-based elastomer (Vistamaxx™ Performance Polymer 6102), based on the weight of the core layer; in Example 6, the core layer comprises 70 wt% polyethylene (Exceed™ Flow+ m 0216) and 30 wt% propylene-based elastomer (Vistamaxx™ Performance Polymer 6102), based on the weight of the core layer.

[0105] Table 2: Preparation process of five-layer polyethylene film

[0106] The longitudinal trouser-shaped tear strength of each polyethylene film was tested (e.g., Figure 1 and Figure 2 (as shown) and acupuncture intensity (as shown) Figure 3 and Figure 4 (As shown).

[0107] Figure 1 and Figure 2It is clearly shown that the longitudinal (MD) trouser-shaped tear strength of the polyethylene film of the present invention is improved compared to the comparative example of pure polyethylene film. For example... Figure 2 As shown, for the low-density grade Exceed™ Flow+ m 0216, which inherently has poor longitudinal trouser tear strength, the addition of 30% Vistamaxx™ Performance Polymer 6102 to the core material (Example 6) resulted in an almost 10-fold increase in longitudinal trouser tear strength, far exceeding expectations given a density of 0.862 g / cm³. 3 The longitudinal trouser tear strength of Vistamaxx™ Performance Polymer 6102 was also poor. The results indicate that the two raw materials with poor trouser tear strength exhibited an unexpected synergistic effect when mixed, producing a film with better longitudinal trouser tear strength than the individual raw materials combined.

[0108] Figure 3 and Figure 4 The addition of propylene-based elastomers showed no significant effect on the needle punch strength of the polyethylene film, meaning that the film's toughness was maintained. In summary, the addition of propylene-based elastomers to the core layer unexpectedly improved the longitudinal trouser tear strength of the polyethylene film while preserving its toughness.

[0109] Although specific embodiments of the invention have been shown and described, it should be understood that other modifications, alternatives, and alternatives are known to those skilled in the art. Such modifications, alternatives, and alternatives may be made without departing from the spirit and scope of the invention as defined by the appended claims. Various features of the invention are described in the appended claims.

Claims

1. A multilayer polyethylene film, comprising: outer layer, Inner layer, and The core layer is located between the outer and inner layers; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers.

2. The multilayer polyethylene film according to claim 1, wherein the multilayer polyethylene film has a thickness of 5-200µm.

3. The multilayer polyethylene film according to claim 1 or 2, wherein both the outer layer and the inner layer are made of polyethylene.

4. The multilayer polyethylene film according to claim 3, wherein the polyethylene in the outer layer and the inner layer is the same as the polyethylene in the core layer composition.

5. The multilayer polyethylene film according to any one of claims 1-4, wherein the multilayer polyethylene film is a five-layer polyethylene film having an outer layer / secondary outer layer / core layer / secondary inner layer / inner layer layer structure.

6. The multilayer polyethylene film according to claim 5, wherein the outer layer, the second outer layer, the second inner layer and the inner layer are all made of polyethylene.

7. The multilayer polyethylene film according to claim 6, wherein the polyethylene in the outer layer, the second outer layer, the second inner layer and the inner layer are all the same as the polyethylene in the core layer composition.

8. The multilayer polyethylene film according to any one of claims 1-7, wherein the polyethylene has a strength of 0.860 to 0.930 g / cm³ as measured according to the ASTM D792 standard method. 3 Its density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg.

9. The multilayer polyethylene film according to any one of claims 1-8, wherein the polyethylene is metallocene-catalyzed linear low-density polyethylene, Ziegler-Natta-catalyzed linear low-density polyethylene, or a combination thereof.

10. The multilayer polyethylene film according to any one of claims 1-9, wherein the polyethylene is derived from the ethylene and 1-hexene comonomer.

11. The multilayer polyethylene film according to any one of claims 1-10, wherein the propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer.

12. The multilayer polyethylene film according to any one of claims 1-11, wherein the propylene-based elastomer has a melt index of 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg.

13. The multilayer polyethylene film according to any one of claims 1-12, wherein the propylene-based elastomer has a content of 0.850-0.925 g / cm³ as measured according to the ASTM D792 standard method. 3 The preferred concentration is 0.860-0.890 g / cm³. 3 The density.

14. The multilayer polyethylene film according to any one of claims 1-13, wherein the propylene-based elastomer is composed of isotactic propylene repeating units and randomly distributed ethylene repeating units.

15. The multilayer polyethylene film according to any one of claims 1-14, wherein the multilayer polyethylene film has a longitudinal trouser tear strength of 5-35 cN / µm as measured according to the ASTM D1938 standard method.

16. The multilayer polyethylene film according to any one of claims 1-15, wherein the multilayer polyethylene film has a needle penetration strength of 40-100 mN / µm as measured according to the CEN 14477 standard method.

17. The multilayer polyethylene film according to any one of claims 1-16, wherein the core layer composition comprises 70-90% by weight of polyethylene, preferably 80-90% by weight, based on the weight of the core layer composition.

18. The multilayer polyethylene film according to any one of claims 1-17, wherein the core layer composition comprises 10-30% by weight of a propylene-based elastomer, preferably 20-30% by weight, based on the weight of the core layer composition.

19. A multilayer polyethylene film, comprising, from the outside to the inside: outer layer, Second outer layer, Core layer The innermost layer, and Inner layer; The core layer comprises a core layer composition, which, based on a weight of the core layer composition, contains: A) 65-95% by weight polyethylene, and B) 5-35% by weight of propylene-based elastomers. The polyethylene described herein has a strength of 0.860 to 0.930 g / cm³, as measured according to the ASTM D792 standard method. 3 The density and melt index of 0.1 to 5 g / 10 min, measured according to the ASTM D1238 standard method at 190°C / 2.16 kg. The propylene-based elastomer comprises 10-20% by weight of ethylene-derived units, based on the weight of the propylene-based elastomer. The propylene-based elastomer described herein has a melt index ranging from 1 g / 10 min to 30 g / 10 min as determined by ASTM D1238 190°C / 2.16 kg, and The outer layer, the second outer layer, the second inner layer, and the inner layer are all made of the same polyethylene as the polyethylene in the core layer composition.

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