Multilayer polyethylene film

Abstract

This invention relates to a multilayer polyethylene film comprising a surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer, wherein the core layer comprises a core layer composition comprising: recycled polyethylene having an MFR2 of 0.1 to 2.0 g / 10 min as determined according to ISO 1133 and a density of 910 to 930 kg / m³ as determined according to ISO 1183. 3 A multimodal ethylene terpolymer with an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 And polyethylene, with an MFR5 of 0.1 to 2.5 g / 10 min as determined according to ISO 1133 and a density of 925 to 950 kg / m³ as determined according to ISO 1183. 3 The present invention also relates to a method for producing the multilayer polyethylene film, the use of the core layer composition as a core layer in the multilayer polyethylene film for improving the haze and SIT of the multilayer polyethylene film, and articles comprising the multilayer polyethylene film.

Description

Technical Field

[0001] This invention relates to a multilayer polyethylene film comprising a surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer. The invention also relates to a method for producing a multilayer polyethylene film, a core layer composition, and the use of the core layer composition as a core layer in a multilayer polyethylene film, as well as articles comprising the core layer composition or the multilayer polyethylene film. Background Technology

[0002] Polyethylene-based materials present a unique challenge due to their widespread use in packaging. Given the enormous volume of waste collected compared to the amount recycled into the stream, there remains significant potential for intelligent reuse of plastic waste streams and mechanical recycling of plastic waste.

[0003] Therefore, it is crucial to establish a circular economy that gives plastic waste a second life—recycling. This not only prevents plastic waste from remaining in the environment but also restores its value.

[0004] Furthermore, in 2017, the European Commission confirmed its focus on the production and use of plastics. The EU's goals are: 1) by 2025, at least 55% of all plastic packaging in the EU should be recycled; 2) by 2030, all plastic packaging on the EU market should be reusable or easily recyclable. This has prompted brand owners and plastic processors to seek solutions using recycled materials or blends of virgin and recycled materials.

[0005] Therefore, polymers obtained from waste are increasingly important in the manufacture of new products, i.e., waste plastics (such as post-consumer recycled materials (PCR)) can be transformed into new plastic products. Thus, environmental and economic aspects can be combined when recycling and reusing waste plastic materials.

[0006] However, due to degradation, pollution, and the mixing of different plastics, recycled plastics are generally of lower quality than virgin plastics. Nevertheless, for packaging applications, a balance of impact strength (e.g., dart impact strength) and mechanical properties (e.g., toughness, tensile strength) in the film, along with good aesthetic properties (e.g., haze and transparency), is ideal. Furthermore, sealing performance is also an important requirement for packaging applications.

[0007] Furthermore, compositions containing recycled polyolefin materials typically exhibit significantly inferior performance compared to virgin materials, unless the amount of recycled polyolefin added to the final composition is extremely low. For example, such materials often possess limited impact strength and poor mechanical properties, thus failing to meet customer requirements.

[0008] Blending recycled plastics with virgin plastics is a common practice to improve the quality of recycled plastics. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a multilayer polyethylene film made partially of recycled polyethylene, and in particular, to provide a multilayer polyethylene film comprising a core layer made partially of recycled polyethylene.

[0010] Another object of the present invention is to provide a multilayer polyethylene film with good mechanical properties, particularly toughness, while having improved optical properties (e.g., haze).

[0011] Another object of the present invention is to provide a multilayer polyethylene film with good sealing performance, namely a low seal initiation temperature (SIT).

[0012] Finally, the object of the present invention is to provide a core layer composition for a multilayer film that allows the use of recycled polyethylene, particularly in large quantities, in the core layer composition.

[0013] Therefore, the present invention provides a multilayer polyethylene film comprising a surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer, preferably composed of a surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer.

[0014] The core layer comprises or is composed of a core layer composition, wherein the core layer composition comprises, preferably, the following components:

[0015] a) Recycled polyethylene with an MFR2 of 0.1 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 ,

[0016] b) Multimodal ethylene terpolymers with an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 The MWD, determined by GPC (gel permeation chromatography), ranged from 2.0 to 7.5.

[0017] c) Polyethylene, with an MFR5 of 0.1 to 2.5 g / 10 min as determined according to ISO 1133; and a density of 925 to 950 kg / m³ as determined according to ISO 1183. 3 The MWD measured by GPC (gel permeation chromatography) ranged from 8.0 to 35.0.

[0018] This invention is based on the discovery that by using recycled polyethylene as a component of the core layer composition, multilayer polyethylene films with improved mechanical and optical properties and low seal initiation temperature (SIT) can be provided, wherein the core layer composition forms the core layer of the multilayer polyethylene film.

[0019] Surprisingly, it was also found that large amounts, up to 95% by weight, of recycled polyethylene could be used in the core layer composition without reducing the mechanical and optical properties of the multilayer polyethylene film.

[0020] In addition to using a large amount of recycled polyethylene in the core layer composition of the multilayer polyethylene film according to the invention, the other polymer components used for the film layers are also polyethylene-based materials. In other words, the multilayer polyethylene film according to the invention is based on or formed from polyethylene-based materials, i.e., the multilayer film of the invention aims to achieve a single-material solution based on polyethylene. Therefore, the multilayer polyethylene film according to the invention has a dual advantage: the multilayer film is structurally made of a single material, polyethylene, and its core layer can use a large amount of recycled polyethylene. Therefore, the multilayer polyethylene film of the invention is designed for recycling.

[0021] The multilayer film according to the invention has at least three layers: a surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer. Typically, the multilayer polyethylene film according to the invention has no more than seven layers, preferably no more than five layers.

[0022] Preferably, the multilayer polyethylene film according to the invention has three layers or is composed of three layers, that is, as described herein, the multilayer polyethylene film according to the invention comprises a surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer. In other words, the multilayer polyethylene film according to the invention is preferably a three-layer polyethylene film.

[0023] Alternatively, the multilayer polyethylene film according to the invention preferably further includes layers other than the surface layer, sealing layer, and core layer as described herein. If present, these additional layers are located between the surface layer and the core layer and / or between the sealing layer and the core layer. Preferably, the additional layers consist of a polyethylene-based composition.

[0024] Preferably, the surface layer and the sealing layer are the outermost layers of the multilayer polyethylene film.

[0025] Core layer

[0026] The core layer includes or is composed of a core layer composition. The core layer composition includes recycled polyethylene (a) as a major component.

[0027] For the purposes of this specification and the following claims, the term "recycled polyethylene" refers to a polymeric material that, in addition to other polymeric components of any nature, primarily comprises units derived from ethylene. For example, such polymeric components may be derived from monomeric units derived from α-olefins (e.g., propylene, butene, hexene, octene, etc.), styrene derivatives (e.g., vinylstyrene), substituted and unsubstituted acrylates, and substituted and unsubstituted methacrylates.

[0028] The polymer material can be obtained through the quantitative method described herein. 13 C1H NMR measurements were used to identify the mixed plastic polyethylene composition. The quantitative methods used herein... 13 In C{1H}NMR measurements, and in the quantitative methods described below for measurement... 13 C1H NMR measurements can distinguish and quantify different units in a polymer chain. These units include ethylene units (C2 units), units with 3, 4, and 6 carbon atoms, and units with 7 carbon atoms.

[0029] Therefore, units with three carbon atoms (C3 units) can be distinguished in NMR spectra as isolated C3 units and continuous C3 units, indicating that the polymer material contains propylene-based polymers. These continuous C3 units can also be identified as iPP units.

[0030] Units with 3, 4, 6, and 7 carbon atoms are described in NMR spectra as units originating from short side chains or branches of two carbon atoms and one carbon atom (isolated C3 unit), two carbon atoms (C4 unit), four carbon atoms (C6 unit), or five carbon atoms (C7 unit) in the polymer backbone.

[0031] Units with 3, 4, and 6 carbon atoms (isolated C3, C4, and C6 units) can come from incorporated comonomers (propylene, 1-butene, and 1-hexene comonomers) or from short-chain branches formed by free radical polymerization.

[0032] The 7-carbon unit (C7 unit) can be clearly attributed to recycled polyethylene, as it cannot originate from any comonomer. The 1-heptene monomer is not used for copolymerization. Instead, the C7 unit represents the presence of LDPE characteristic of recycled materials. It has been found that the amount of C7 units in LDPE resin consistently falls within a different range. Therefore, by quantifying... 13 The amount of C7 units measured by C{1H}NMR can be used to calculate the amount of LDPE in a polyethylene composition.

[0033] Therefore, the quantities of continuous C3 units, isolated C3 units, C4 units, C6 units, and C7 units are quantified as described below. 13 The LDPE content was measured by C{1H}NMR, while the LDPE content was calculated based on the amount of C7 units as described below.

[0034] The total amount of ethylene units (C2 units) is attributed not only to the units of LDPE (i.e., units with longer side chain branches of 6 or more carbon atoms), but also to units in the polymer chain that do not have short side chains of 1-5 carbon atoms.

[0035] Preferably, the recycled polyethylene has an MFR2 of 0.5 to 1.5 g / 10 min as determined by ISO 1133 and a density of 915 to 930 kg / m³ as determined by ISO 1183. 3 .

[0036] The total amount of ethylene units (C2 units) of the recovered polyethylene, as measured by NMR of the soluble fraction of d2-tetrachloroethylene, is preferably 80.0 to 96.0 wt%, more preferably 82.5 wt% to 95.5 wt%, even more preferably 85.0 wt% to 95.5 wt%, and most preferably 87.5 wt% to 95.0 wt%, wherein the total amount of C2 units is based on the total weight of monomer units in the recovered polyethylene and according to quantitative... 13 C1H NMR measurement was used for measurement.

[0037] The total amount of continuous units (continuous C3 units) with three carbon atoms corresponding to polypropylene in the recycled polyethylene is preferably 0.2 to 6.5% by weight, more preferably 0.4% to 6.0% by weight, even more preferably 0.6% to 5.5% by weight, and most preferably 0.75% to 5.0% by weight; the total amount of continuous C3 units is based on the total weight of monomer units in the recycled polyethylene and according to the quantitative... 13 C1H NMR measurement was used for measurement.

[0038] The total amount of isolated C3 units (isolated C3 units) with 3 carbon atoms in the recycled polyethylene is preferably 0.00% to 0.50% by weight, more preferably 0.00% to 0.40% by weight, even more preferably 0.00% to 0.30% by weight, and most preferably 0.00% to 0.25% by weight.

[0039] The total amount of units having 4 carbon atoms (C4 units) is preferably 0.50 to 5.00% by weight, more preferably 0.75% to 4.00% by weight, even more preferably 1.00% to 3.50% by weight, and most preferably 1.25% to 3.00% by weight;

[0040] The total amount of units having 6 carbon atoms (C6 units) is preferably 0.50 to 7.50% by weight, more preferably 0.75% to 6.50% by weight, even more preferably 1.00% to 5.50% by weight, and most preferably 1.25% to 5.00% by weight;

[0041] The total amount of units having 7 carbon atoms (C7 units) is preferably from 0.20% to 2.50% by weight, more preferably from 0.30% to 2.00% by weight, even more preferably from 0.40% to 1.50% by weight, and most preferably from 0.45% to 1.25% by weight.

[0042] The LDPE content is preferably from 20.0% to 65.0% by weight, more preferably from 25.0% to 62.5% by weight, even more preferably from 30.0% to 60.0% by weight, and most preferably from 32.0% to 55.0% by weight.

[0043] The total amount of C2 units, continuous C3 units, isolated C3 units, C4 units, C6 units, and C7 units, as well as the LDPE content, are based on the total weight of monomer units in the recycled polyethylene, and according to quantitative... 13 C{1H}NMR measurements are used for measurement or calculation.

[0044] Preferably, the total amount of units attributable to comonomers (i.e., isolated C3, C4, and C6 units) in the recycled polyethylene is from 4.00% to 20.00% by weight, more preferably from 4.50% to 17.50% by weight, even more preferably from 4.75% to 15.00% by weight, and most preferably from 5.00% to 12.50% by weight, and according to the quantitative... 13 C1H NMR measurements were performed.

[0045] The recycled polyethylene preferably does not contain carbon black. More preferably, the recycled polyethylene does not contain any pigments other than carbon black.

[0046] Recycled polyethylene may also include:

[0047] 0 to 10% by weight of alpha-olefin-derived units, 0 to 3.0% by weight of stabilizers, 0 to 3.0% by weight of talc, 0 to 3.0% by weight of chalk, and 0 to 6.0% by weight of other components, all percentages relative to recycled polyethylene.

[0048] The recycled polyethylene preferably has one or more of the following properties in any combination, more preferably all of them:

[0049] MFR5 (ISO 1133, 5.0 kg, 190 °C) is 1.5 to 5.0 g / 10 min, more preferably 2.0 to 4.0 g / 10 min;

[0050] MFR 21(ISO 1133, 21.6 kg, 190 °C) is 20.0 to 50.0 g / 10 min, more preferably 25.0 to 45.0 g / 10 min;

[0051] The polydispersity index (PI) ranges from 1.0 to 3.5s. -1 More preferably 1.3 to 3.0s -1 ;

[0052] Shear thinning index SHI 2.7 / 210 The value is 15 to 40, more preferably 20 to 35;

[0053] The complex viscosity eta300 at a frequency of 300 rad / s is 500 to 750 Pa·s, more preferably 550 to 700 Pa·s;

[0054] The complex viscosity eta0.05 at a frequency of 0.05 rad / s is 15,000 to 30,000 Pa·s, more preferably 15,500 to 27,500 Pa·s;

[0055] The strain hardening modulus (SH) is 12.5 to 20.0 MPa, more preferably 13.0 to 17.5 MPa.

[0056] Preferably, the recycled polyethylene has a relatively low gel content, especially compared to other recycled polyethylene blends.

[0057] For gels with a size of 600 μm to 1000 μm, the gel content of the recycled polyethylene is preferably no more than 1000 gels / m³. 2 More preferably, no more than 850 gels / m 2 For gels with a size of 600 μm to 1000 μm, the lower limit for gel content is typically 100 gels / m³. 2 Preferably, it is 150 gels / m 2 .

[0058] Furthermore, for gels with a size exceeding 1000 μm, the gel content of the mixed plastic polyethylene composition is preferably no more than 200 gels / m. 2 More preferably, no more than 150 gels / m 2 For gels with a size exceeding 1000 μm, the lower limit for gel content is typically 10 gels / m. 2 Preferably 14 gels / m 2 .

[0059] Based on the total core composition, the amount of recycled polyethylene present in the core composition is preferably 50 to 95% by weight, more preferably 55 to 90% by weight, more preferably 60 to 85% by weight, and even more preferably 65 to 75% by weight.

[0060] The core layer composition also includes b) a multimodal ethylene terpolymer.

[0061] Typically, ethylene polymers can be unimodal or multimodal, such as bimodal. As used herein, a polymer's "modality" refers to the structure of its molecular weight distribution, that is, the appearance of a curve representing the number of molecules as a function of molecular weight. If the curve shows a single maximum, the polymer is called "unimodal," while if the curve shows a very wide maximum or two or more maximums and the polymer consists of two or more fractions, the polymer is called "bimodal," "multimodal," etc. For example, if a polymer is produced in a sequential multistage process using reactors connected in series and different conditions in each reactor, the polymer fractions produced in each reactor will each have their own molecular weight distribution and weight-average molecular weight. When the molecular weight distribution curves of such polymers are recorded, superimposing these fraction curves onto the molecular weight distribution curve of the entire resulting polymer product typically produces a curve with two or more distinct maximums.

[0062] In the production of unimodal ethylene polymers, the polymers are produced in a reactor under specific conditions, including monomer composition, hydrogen pressure, temperature, and pressure. In ethylene copolymerization, other olefins with up to 12 carbon atoms are typically used as comonomers, such as α-olefins with 3 to 12 carbon atoms, including propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and 1-decene.

[0063] For example, in the production of bimodal ethylene polymers, the first ethylene polymer is produced in a first reactor under specific conditions, including monomer composition, hydrogen pressure, temperature, and pressure. After polymerization in the first reactor, the reaction mixture including the resulting polymer is fed into a second reactor, where further polymerization takes place under different conditions. Typically, a first polymer with a high melt flow rate (low molecular weight) is produced in the first reactor with the addition of appropriate or small amounts of comonomer, or no comonomer at all, while a second polymer with a low melt flow rate (high molecular weight) is produced in the second reactor with the addition of more comonomer. The resulting final product consists of a close mixture of polymers from both reactors, whose different molecular weight distributions together form a molecular weight distribution curve with a wide maximum or two maximums; that is, the final product is a bimodal polymer mixture.

[0064] Multimodal ethylene terpolymer b) preferably comprises or consists of a copolymer of ethylene and at least two different α-olefin comonomers having 4 to 10 carbon atoms, wherein the copolymer is composed of the following substances:

[0065] (i) 30.0 to 70.0% by weight of ethylene polymer component (A), with a density of 920 to 950 kg / m³ as determined according to ISO 1183. 3 According to ISO 1133, the MFR2 ranged from 2.0 to 40.0 g / 10 min; and

[0066] (ii) 70.0 to 30.0% by weight of ethylene polymer component (B), with a density of 880 to 915 kg / m³ as determined according to ISO 1183. 3 The MFR2, as determined by ISO 1133, ranged from 0.01 to 1.5 g / 10 min.

[0067] or

[0068] (i) 30.0 to 70.0% by weight of ethylene polymer fraction (A-1) and ethylene polymer fraction (A-2), wherein the density of ethylene polymer fraction (A-1) is 920 to 960 kg / m³ as determined according to ISO 1183. 3 The MFR2, as determined by ISO 1133, is 1.0 to 50.0 g / 10 min, and the density of the ethylene polymer fraction (A-2), as determined by ISO 1183, is 930 to 950 kg / m³. 3 The MFR2, determined according to ISO 1133, ranged from 3.0 to 60.0 g / 10 min; the ratio of the MFR2 of the ethylene polymer fraction (A-1) to that of the ethylene polymer component (A) was greater than 0.3; and

[0069] (ii) 70.0 to 30.0% by weight of ethylene polymer component (B), with a density of 880 to 915 kg / m³ as determined according to ISO 1183. 3 The MFR2, as determined by ISO 1133, ranged from 0.01 to 1.5 g / 10 min.

[0070] The MFR2 of the ethylene polymer component (A) as determined according to ISO 1133 is preferably 2.0 to 40 g / 10 min, more preferably 2.5 to 30 g / 10 min, more preferably 3.0 to 20 g / 10 min, and even more preferably 3.2 to 10 g / 10 min.

[0071] The MFR2 of the ethylene polymer fraction (A-1) as determined according to ISO 1133 is preferably 1.0 to 50.0 g / 10 min, more preferably 1.5 to 40.0 g / 10 min, even more preferably 2.0 to 30.0 g / 10 min, and even more preferably 2.5 to 20.0 g / 10 min, and most preferably 3.0 to 10.0 g / 10 min.

[0072] The ethylene polymer fraction (A-2) has a higher MFR2 than the ethylene polymer fraction (A-1), that is, the MFR2 of the ethylene polymer fraction (A-2) as determined according to ISO 1133 is 3.0 to 60.0 g / 10 min, preferably 3.2 to 30.0 g / 10 min, more preferably 3.5 to 20.0 g / 10 min, and most preferably 3.5 to 15.0 g / 10 min.

[0073] The MFR2 of the ethylene polymer component (B) as determined according to ISO 1133 is preferably 0.01 to 1.5 g / 10 min, more preferably 0.05 to 1.5 g / 10 min, more preferably 0.1 to 1.3 g / 10 min, and even more preferably 0.2 to 1.2 g / 10 min.

[0074] In addition, the ratio of the MFR2 of the ethylene polymer fraction (A-1) to the MFR2 of the ethylene polymer component (A) is preferably greater than 0.3, preferably in the range of 0.50 to 1.0, more preferably in the range of 0.60 to 1.0, and even more preferably in the range of 0.70 to 1.0, for example, 0.80 to 0.98.

[0075] Furthermore, the ratio of the MFR2 of the ethylene polymer component (A) to the MFR2 of the final multimodal ethylene terpolymer (b) is greater than 2.1, preferably 2.3 to 12.0, more preferably 2.5 to 10.0, and even more preferably 2.8 to 8.0.

[0076] The at least two α-olefin comonomers having 4 to 10 carbon atoms in the multimodal ethylene terpolymer are preferably butene and hexene.

[0077] The α-olefin comonomers of ethylene polymer component (A) and ethylene polymer fractions (A-1) and (A-2) are preferably the same. Therefore, components (A) and fractions (A-1) and (A-2) use the same α-olefin comonomers having 4 to 10 carbon atoms. More preferably, components (A) and fractions (A-1) and (A-2) have 1-butene as the α-olefin comonomer. In other words, ethylene polymer component (A) is an ethylene-1-butene copolymer, ethylene polymer fraction (A-1) is an ethylene-1-butene copolymer, and ethylene polymer fraction (A-2) is an ethylene-1-butene copolymer. Preferably, ethylene polymer component (B) is an ethylene-1-hexene copolymer.

[0078] Most preferably, the ethylene polymer component (A) is an ethylene-1-butene copolymer, the ethylene polymer component (B) is an ethylene-1-hexene copolymer, or the ethylene polymer fraction (A-1) is an ethylene-1-butene copolymer, the ethylene polymer fraction (A-2) is an ethylene-1-butene copolymer, and the ethylene polymer component (B) is an ethylene-1-hexene copolymer.

[0079] The α-olefin comonomer content of components (A) and (B) can be measured, or, in a preferred case, one of the components is produced first, and then another component is produced in the presence of the first-produced component in a so-called multi-stage process. In this case, the α-olefin comonomer content of the first-produced component (e.g., component (A)) can be measured, and the comonomer content of the other component (e.g., component (B)) can be calculated according to the following formula.

[0080] Comonomer content in component B (mol%) = (Comonomer content in the final product (mol%) - (Weight fraction of component A * Comonomer content in component A (mol%)) / (Weight fraction of component B)

[0081] More preferably, based on the multimodal ethylene terpolymer, the total amount of α-olefin comonomer present in the multimodal ethylene terpolymer (b) is 0.5 to 10.0 mol%, preferably 1.0 to 8.0 mol%, more preferably 1.5 to 6.0 mol%, and more preferably 2.0 to 5.0 mol%.

[0082] Based on the multimodal ethylene terpolymer, the total amount of 1-butene is preferably in the range of 0.05 to 1.0 mol%, more preferably in the range of 0.10 to 0.8 mol%, and even more preferably in the range of 0.15 to 0.5 mol%.

[0083] Based on the multimodal ethylene terpolymer, the total amount of 1-hexene is preferably in the range of 0.45 to 9.0 mol%, more preferably in the range of 0.90 to 7.2 mol%, and even more preferably in the range of 1.35 to 5.5 mol%.

[0084] Preferably, based on the ethylene polymer component (A), the total amount (mol%) of α-olefin comonomers having 4 to 10 carbon atoms (preferably selected from butene, hexene, and octene, especially butene) in the ethylene polymer component (A) is 0.05 to 5.0 mol%, more preferably 0.1 to 4.0 mol%, even more preferably 0.2 to 3.0 mol%, even more preferably 0.3 to 2.0 mol%, and most preferably 0.3 to 1.0 mol%.

[0085] In one embodiment, based on the ethylene polymer component (B), the amount (mol%) of α-olefin comonomers having 6 to 10 carbon atoms (preferably hexene and octene, especially hexene) present in the ethylene polymer component (B) is 2.5 to 10.0 mol%, preferably 3.0 to 9.0 mol%, more preferably 3.5 to 8.0 mol%, and even more preferably 4.0 to 7.0 mol%.

[0086] Preferably, the density of ethylene polymer component (A) is different from the density of ethylene polymer component (B), and is preferably higher than the density of ethylene polymer component (B).

[0087] According to ISO 1183, the density of the ethylene polymer component (A) is between 920 and 950 kg / m³. 3 Within the range, preferably 925 to 950 kg / m 3 More preferably, it is 930 to 945 kg / m 3 And / or, as determined according to ISO 1183, the density of the ethylene polymer component (B) is between 880 and 915 kg / m³. 3 Within the range, preferably 890 to 905 kg / m 3 .

[0088] According to ISO 1183, the density of the polymer fraction (A-1) is between 920 and 960 kg / m³. 3 Within the range, preferably 925 to 955 kg / m 3 More preferably, it is 930 to 950 kg / m 3 The optimal value is 935 to 945 kg / m³. 3 .

[0089] According to ISO 1183, the density of the polymer fraction (A-2) is between 930 and 950 kg / m³. 3 Within the range, preferably 935 to 945 kg / m 3 .

[0090] Based on the multimodal ethylene terpolymer, the amounts of ethylene polymer fractions (A-1) and (A-2) are preferably 30.0 to 70.0% by weight, more preferably 32.0 to 55.0% by weight, and even more preferably 34.0 to 45.0% by weight. Preferably, the weight ratio of the first and second ethylene polymer fractions (A-1 and A-2) is 4:1 to 1:4, for example 3:1 to 1:3, or 2:1 to 1:2, or 1:1.

[0091] Based on the multimodal ethylene terpolymer, the amount of ethylene polymer component (A) is preferably 30.0 to 70.0% by weight, preferably 32.0 to 55.0% by weight, and even more preferably 34.0 to 45.0% by weight.

[0092] Therefore, based on the multimodal ethylene terpolymer, the amount of ethylene polymer component (B) is preferably 70.0 to 30.0% by weight, preferably 68.0 to 45.0% by weight, and more preferably 66.0 to 55.0% by weight.

[0093] The MFR2 of the multimodal ethylene terpolymer, as determined according to ISO 1133, is preferably 0.75 to 1.75 g / 10 min, and / or preferably, has a density of 914 to 922 kg / m³, as determined according to ISO 1183. 3 .

[0094] MFR of multimodal ethylene terpolymer determined according to ISO 1133 21 Preferably, the concentration is 20 to 40 g / 10 min, more preferably 25 to 35 g / 10 min, and most preferably 28 to 32 g / 10 min.

[0095] The preferred multimodal ethylene terpolymer is the bimodal ethylene terpolymer.

[0096] The multimodal ethylene terpolymer is preferably a metallocene-catalyzed multimodal ethylene terpolymer. In other words, multimodal ethylene terpolymer b) is obtained by a metallocene-catalyzed polymerization process. The metallocene-catalyzed multimodal ethylene terpolymer can be produced by a three-stage process, preferably including a first slurry reactor (circulating reactor 1), wherein the first slurry circulating reactor is connected in series with another slurry reactor (circulating reactor 2), such that the first ethylene polymer fraction (A-1) produced in circulating reactor 1 is fed into circulating reactor 2, wherein a second ethylene polymer fraction (A-2) is produced in the presence of the first fraction (A-1). Circulating reactor 2 is thus connected in series with a gas-phase reactor (GPR) to produce multimodal ethylene terpolymer c). In this case, the reaction conditions in the two slurry reactors are selected such that products with different MFRs and / or densities are produced in the two slurry reactors.

[0097] Such processes are described in particular in WO 2016 / 198273, WO 2021 / 009189, WO 2021 / 009190, WO 2021 / 009191 and WO2021 / 009192. Complete details on how to prepare suitable metallocene-catalyzed multimodal ethylene terpolymers can be found in these references.

[0098] The appropriate process is the Borstar PE 3G process.

[0099] The multimodal ethylene terpolymer is preferably linear low-density polyethylene. The MWD of the bimodal or multimodal ethylene terpolymer is preferably 3.0 to 5.0, more preferably 3.5 to 4.5, and most preferably 3.7 to 4.3, as determined by GPC (gel permeation chromatography).

[0100] Based on the total core composition, the amount of the multimodal ethylene terpolymer present in the core composition is preferably 5 to 30% by weight, more preferably 10 to 25% by weight, and even more preferably 15 to 20% by weight.

[0101] The core layer composition also includes c) polyethylene.

[0102] Preferably, the polyethylene is multimodal, more preferably trimodal, and / or a terpolymer.

[0103] More preferably, the polyethylene is a trimodal copolymer comprising or composed of the following components:

[0104] a) 10 to 30% by weight of the first ethylene homopolymer;

[0105] b) 15 to 35% by weight of a second ethylene homopolymer, whose MFR2 is at least 50 g / 10 min higher than that of component a); and

[0106] c) 40 to 65% by weight of a third ethylene copolymer having at least one α-olefin comonomer.

[0107] Even more preferably, the polyethylene is a trimodal terpolymer comprising or composed of the following components:

[0108] a) 10 to 30% by weight of the first ethylene homopolymer;

[0109] b) 15 to 35% by weight of a second ethylene homopolymer, whose MFR2 is at least 50 g / 10 min higher than that of component a); and

[0110] c) 40 to 65% by weight of a third ethylene terpolymer having at least two α-olefin comonomers.

[0111] Preferably, the third fraction c) of polyethylene c) is an ethylene-1-hexene copolymer or a terpolymer of ethylene with at least two α-olefin comonomers (e.g., 1-butene and 1-hexene), i.e., an ethylene-1-butene-1-hexene terpolymer. In other words, the third ethylene copolymer having at least one α-olefin comonomer is preferably an ethylene-1-hexene copolymer, or the third ethylene terpolymer having at least two α-olefin comonomers is preferably an ethylene-1-butene-1-hexene terpolymer.

[0112] Preferably, based on the total polyethylene, the total amount of α-olefin comonomers present in polyethylene (c) is 1.0 to 15.0 wt%, more preferably 2.0 to 10.0 wt%, more preferably 3.5 to 8.0 wt%, and most preferably 4.0 to 6.5 wt%.

[0113] If polyethylene (c) is a trimodal copolymer, wherein the third ethylene copolymer having at least one α-olefin comonomer is an ethylene-1-hexene copolymer, then based on the total trimodal copolymer, the total amount of 1-hexene is preferably 1.0 to 10.0 wt%, more preferably 2.0 to 7.0 wt%, more preferably 3.0 to 5.0 wt%, and most preferably 3.1 to 4.6 wt%.

[0114] If polyethylene c) is a trimodal terpolymer, wherein the third ethylene terpolymer having at least two α-olefin comonomers is an ethylene-1-butene-1-hexene terpolymer, then based on the total trimodal terpolymer, the total amount of 1-butene is preferably 0.1 to 5.0 wt%, more preferably 0.4 to 4.0 wt%, more preferably 0.7 to 3.0 wt%, more preferably 0.9 to 2.5 wt%, and most preferably 1.0 to 2.2 wt%, and / or based on the total trimodal terpolymer, the total amount of 1-hexene is preferably 1.0 to 10.0 wt%, more preferably 2.0 to 7.0 wt%, more preferably 3.0 to 5.0 wt%, and most preferably 3.1 to 4.6 wt%.

[0115] Preferably, the MFR2 of polyethylene, as determined according to ISO 1133, is 0.2 to 0.5 g / 10 min.

[0116] Preferably, the MFR5 of polyethylene, as determined according to ISO 1133, is 1 to 2.0 g / 10 min, more preferably 1.25 to 1.75 g / 10 min, and the density, as determined according to ISO 1183, is preferably 925 to 945 kg / m³. 3 More preferably, it is 930 to 945 kg / m 3 .

[0117] In addition to MFR5 and density, the MFR of polyethylene is determined according to ISO 1133. 21 Preferably, the concentration is 25 to 45 g / 10 min, more preferably 30 to 40 g / 10 min, and most preferably 32 to 38 g / 10 min.

[0118] FRR of polyethylene 21 / 5 Preferably, it is in the range of 18 to 28.

[0119] Polyethylene is preferably Ziegler-Natta catalyzed polyethylene. In other words, polyethylene (c) is obtained by a Ziegler-Natta catalyzed polymerization process. The MWD of polyethylene is preferably 10 to 30, more preferably 15 to 25, and most preferably 19 to 22, as determined by GPC (gel permeation chromatography).

[0120] Based on the total core composition, the content of polyethylene in the core composition is preferably 5 to 30% by weight, more preferably 6 to 25% by weight, and even more preferably 8 to 15% by weight.

[0121] surface layer

[0122] The multilayer polyethylene film of the present invention further includes a surface layer. The surface layer is preferably the outermost layer of the multilayer polyethylene film.

[0123] Preferably, the surface layer comprises or is composed of a surface layer composition comprising, or is composed of, a multimodal ethylene terpolymer and / or low-density polyethylene, wherein the multimodal ethylene terpolymer has an MFR2 of 0.5 to 2.0 g / 10 min, preferably 0.75 to 1.75 g / 10 min, as determined according to ISO 1133, and an MFR of 910 to 930 kg / m³, as determined according to ISO 1183. 3 Optimal weight is 914 to 922 kg / m³. 3 The low-density polyethylene has a density of 2.0 to 7.5 as determined by GPC (gel permeation chromatography), and an MFR2 of 0.1 to 2.0 g / 10 min, preferably 0.5 to 1.25 g / 10 min, as determined according to ISO 1133, and a density of 910 to 950 kg / m³ as determined according to ISO 1183. 3 Optimal weight is 915 to 930 kg / m³. 3 More preferably 918 to 927 kg / m 3 The density. The multimodal ethylene terpolymer of the surface layer is preferably the same as the multimodal ethylene terpolymer of the core layer, as described in all embodiments herein.

[0124] More preferably, the surface layer comprises a surface layer composition comprising a multimodal ethylene terpolymer as defined in all embodiments herein and low-density polyethylene as defined in all embodiments herein.

[0125] MFR of low-density polyethylene as determined according to ISO 1133 21 Preferably, the concentration is 48 to 68 g / 10 min, more preferably 53 to 63 g / 10 min, and most preferably 56 to 60 g / 10 min.

[0126] The MWD of low-density polyethylene, as determined by GPC (gel permeation chromatography), is preferably 4.0 to 9.0, more preferably 5.0 to 8.0, and most preferably 6.0 to 7.4. The low-density polyethylene is preferably high-pressure tubular LDPE. In other words, this LDPE is produced in a tubular reactor under high pressure conditions, typically 100 to 400 MPa.

[0127] Based on the total surface composition, the amount of the multimodal ethylene terpolymer present in the surface composition is preferably 80 to 95% by weight, more preferably 85 to 93% by weight.

[0128] Based on the total surface composition, the amount of low-density polyethylene present in the surface composition is preferably 5 to 20% by weight, more preferably 5 to 20% by weight, and even more preferably 7 to 15% by weight.

[0129] sealing layer

[0130] The multilayer polyethylene film of the present invention further includes a sealing layer, which is preferably the outermost layer of the multilayer polyethylene film.

[0131] Preferably, the sealing layer comprises or is composed of a sealing layer composition, said sealing layer composition comprising a copolymer of ethylene and an α-olefin comonomer having 4 to 8 carbon atoms and / or a multimodal ethylene terpolymer, or composed of a copolymer of ethylene and an α-olefin comonomer having 4 to 8 carbon atoms and / or a multimodal ethylene terpolymer, wherein the copolymer of ethylene and the α-olefin comonomer having 4 to 8 carbon atoms has an MFR2 of 0.5 to 2.0 g / 10 min, preferably 0.75 to 1.25 g / 10 min, as determined according to ISO 1133, and a density of 870 to 910 kg / m³ as determined according to ISO 1183. 3 Preferred weight is 890 to 910 kg / m³. 3 The multimodal ethylene terpolymer has an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 As described in all embodiments herein, the multimodal ethylene terpolymer of the sealing layer is preferably the same as the multimodal ethylene terpolymer of the core layer.

[0132] More preferably, the sealing layer comprises a sealing layer composition comprising a copolymer of ethylene and an α-olefin having 4 to 8 carbon atoms as defined in all embodiments herein, and a multimodal ethylene terpolymer as defined in all embodiments herein.

[0133] The α-olefin comonomer having 4 to 8 carbon atoms is preferably 1-octene. In other words, the copolymer of ethylene with an α-olefin comonomer having 4 to 8 carbon atoms is preferably an ethylene-1-octene copolymer.

[0134] Based on the copolymer of total ethylene and α-olefin comonomer having 3 to 8 carbon atoms, the amount of α-olefin comonomer in the copolymer is preferably 10 to 30% by weight, more preferably 12 to 24% by weight, and most preferably 14 to 18% by weight.

[0135] MFR of copolymers of ethylene with α-olefin comonomers having 4 to 8 carbon atoms, as determined according to ISO 1133. 21 Preferably, the concentration is 28 to 48 g / 10 min, more preferably 33 to 43 g / 10 min, and most preferably 36 to 40 g / 10 min.

[0136] The copolymer of ethylene with an α-olefin comonomer having 4 to 8 carbon atoms is preferably a metallocene-catalyzed copolymer of ethylene with an α-olefin comonomer having 4 to 8 carbon atoms. In other words, the copolymer of ethylene with an α-olefin comonomer having 4 to 8 carbon atoms is obtained by a metallocene-catalyzed polymerization process. The MWD of the copolymer of ethylene with an α-olefin comonomer having 4 to 8 carbon atoms, as determined by GPC (gel permeation chromatography), is preferably 2.0 to 4.0, more preferably 2.5 to 3.5, and most preferably 2.7 to 3.3.

[0137] Based on the total sealing layer composition, the copolymer of ethylene and α-olefin comonomer having 4 to 8 carbon atoms is preferably present in the sealing layer composition at an amount of 50 to 90 wt%, more preferably 55 to 80 wt%, and even more preferably 55 to 65 wt%.

[0138] Based on the total sealing layer composition, the amount of the multimodal ethylene terpolymer present in the sealing layer composition is preferably 10 to 50% by weight, more preferably 20 to 45% by weight, and even more preferably 35 to 45% by weight.

[0139] Each layer of the multilayer polyethylene film according to the present invention has a certain thickness.

[0140] The thickness of the surface layer is preferably 1 to 100 μm, more preferably 5 to 50 μm, and most preferably 10 to 20 μm.

[0141] The thickness of the core layer is preferably 10 to 200 μm, more preferably 20 to 100 μm, and most preferably 30 to 50 μm.

[0142] The thickness of the sealing layer is preferably 1 to 50 μm, more preferably 5 to 50 μm, and most preferably 10 to 20 μm.

[0143] The thickness of the multilayer polyethylene film according to the present invention is preferably 12 to 350 μm, more preferably 30 to 200 μm, and most preferably 50 to 90 μm.

[0144] The longitudinal (MD) tensile modulus of the multilayer polyethylene film, measured on a 60 μm test film according to ISO 527-3, is preferably 150 MPa or more, more preferably 200 MPa or more, and / or the transverse (TD) tensile modulus, measured on a 60 μm test film according to ISO 527-3, is preferably 150 MPa or more, more preferably 200 MPa or more.

[0145] Typically, the longitudinal (MD) tensile modulus of the multilayer polyethylene film, measured on a 60 μm test film according to ISO 527-3, is not higher than 1000 MPa, preferably not higher than 800 MPa, more preferably not higher than 600 MPa, and / or the transverse (TD) tensile modulus, measured on a 60 μm test film according to ISO 527-3, is not higher than 1000 MPa, preferably not higher than 800 MPa, more preferably not higher than 600 MPa.

[0146] The multilayer polyethylene film, as determined according to ISO 7765 on a 60 μm test film, preferably has a dart impact strength (DDI) greater than 300 g, more preferably greater than 350 g, and most preferably greater than 375 g, and / or a seal initiation temperature (SIT) less than 82°C, more preferably less than 80°C, and most preferably less than 78°C. The SIT is determined as described herein.

[0147] Typically, the dart impact strength (DDI) of the multilayer polyethylene film, measured according to ISO 7765 on a 60 μm test film, is not greater than 2000 g, preferably not greater than 1500 g, more preferably not greater than 1000 g, and / or the seal initiation temperature (SIT) is greater than 70°C, more preferably greater than 74°C, and most preferably greater than 76°C. The SIT is determined as described herein.

[0148] The multilayer polyethylene film of the present invention is preferably a blown film.

[0149] The present invention also provides a method for producing a multilayer polyethylene film according to the invention, wherein the surface layer, sealing layer and core layer are co-extruded.

[0150] The different polymer components in any layer of a multilayer polyethylene film are typically tightly mixed before layer formation, for example using a twin-screw extruder, preferably a counter-rotating extruder. The blend is then converted into a co-extruded film structure. Preferably, the conversion is performed on a blown film production line.

[0151] To manufacture such a multilayer polyethylene film according to the invention, at least two polymer melt streams are typically extruded simultaneously through a multichannel tubular, annular, or circular die (i.e., co-extrusion) to form a tube, which is then inflated, ventilated, and / or cooled with air (or a combination of gases) to form a film. The manufacture of blown films is a well-known process.

[0152] Blow molding co-extrusion can be carried out at temperatures from 160°C to 240°C and cooled by blowing (usually air) at temperatures from 10°C to 50°C to provide a frosting height of 1 to 8 times the mold diameter.

[0153] The blow-up ratio (BUR) should generally be in the range of 1.2 to 6, preferably in the range of 1.5 to 4.

[0154] All preferred embodiments of the multilayer polyethylene film according to the present invention are also preferred embodiments of the method for producing multilayer polyethylene film.

[0155] The present invention also provides a core layer composition comprising:

[0156] a) Recycled polyethylene having an MFR2 of 0.1 to 2.0 g / 10 min, preferably 0.5 to 1.5 g / 10 min, as determined according to ISO 1133, and a density of 910 to 930 g / min as determined according to ISO 1183.

[0157] kg / m 3 Preferably, it is 915 to 930 kg / m³ 3 ,

[0158] b) Multimodal ethylene terpolymers with an MFR2 of 0.5 to 2.0 as determined according to ISO 1133.

[0159] The density, measured according to ISO 1183, is 910 to 930 kg / m³. 3 Furthermore, the MWD, as determined by GPC (gel permeation chromatography), ranged from 2.0 to 7.5.

[0160] c) Polyethylene, having an MFR5 of 0.1 to 2.5 g / 10 min, preferably 1 to 2.0 g / 10 min, as determined according to ISO 1133, and a density of 925 to 950 kg / m³, as determined according to ISO 1183. 3 Preferably, it is 935 to 945 kg / m³ 3 The MWD, as determined by GPC (gel permeation chromatography), ranged from 8.0 to 35.0.

[0161] All preferred embodiments of the core layer composition for the multilayer polyethylene film according to the present invention described above are also preferred embodiments of the core layer composition according to the present invention. Furthermore, all preferred embodiments of recycled polyethylene, multimodal ethylene terpolymer, and polyethylene as defined above are also preferred embodiments of the core layer composition according to the present invention.

[0162] The present invention also relates to the use of a core layer composition as a core layer of a multilayer film to improve the haze and SIT of the multilayer film.

[0163] The above-described core layer composition for the multilayer polyethylene film according to the present invention and all preferred embodiments of the core layer composition of the present invention are also preferred embodiments for use according to the present invention.

[0164] Finally, the present invention provides an article comprising a multilayer polyethylene film according to the present invention or a core layer composition according to the present invention. Preferably, the article is a bag, such as a stand-up pouch, sack, bag, or pouch. Detailed Implementation

[0165] Measurement and determination methods

[0166] Unless otherwise defined, the following terms and measurement methods apply to the general description of the invention above and the following embodiments.

[0167] a) Measurement of melt flow rate (MFR)

[0168] Melt flow rate (MFR) is determined according to ISO 1133, expressed in g / 10 min. A higher melt flow rate corresponds to a lower polymer viscosity. For polyethylene, at 190°C, the loading is 2.16 kg (MFR2), 5.00 kg (MFR5), or 21.6 kg (MFR6). 21 MFR was measured under these conditions.

[0169] FRR (Flow Rate Ratio) is an indicator of molecular weight distribution, representing the flow rate ratio under different loads. Therefore, FRR 21 / 5 MFR 21 The value of / MFR5.

[0170] b) Density

[0171] The density of the polymer, in kg / m³, is determined on a compression-molded sample prepared according to ISO 17855-2, according to ISO 1183-1:2004 (Method A). 3 .

[0172] The density of the polymer blend is calculated as follows: dblender b Calculation as follows

[0173]

[0174] Where wi and di are the weight percentage and density of fraction i in the polymer blend.

[0175] c) Comonomer content

[0176] The comonomer content is determined as described on pages 31 to 34 of WO 2019081611.

[0177] d) Mechanical properties

[0178] Tensile modulus

[0179] According to ISO 527-3, using Sample 2 of the blown film shown below, the tensile properties of the film were determined at 23°C. The longitudinal (MD) tensile modulus and transverse (TD) tensile modulus, i.e., the 1% secant modulus, were determined according to ASTM D882 at a test speed of 5 mm / min and a gauge length of 50 mm.

[0180] The production of the thin film samples is described in the "Examples" below.

[0181] dart impact strength

[0182] DDI was measured on a thin film according to ISO 7765-1:1988 / Method A, the film thickness as shown in the "Examples," and the film was manufactured according to the "Examples" below. This test method covers the determination of the energy required to cause the film to rupture when struck by a free-falling dart from a specified height under specified conditions, such energy would cause 50% of the test samples to rupture (step method A). A uniform increment of projectile mass was used during the test, and the projectile weight was decreased or increased in a uniform increment after each sample test, based on the observed result (ruptured or unruptured).

[0183] Standard conditions:

[0184] Adjustment time: >96 hours

[0185] Test temperature: 23℃

[0186] Darthead material: phenolic resin

[0187] Dart diameter: 38mm

[0188] Drop height: 660mm

[0189] result:

[0190] Impact damage weight -50% [g]

[0191] e) Optical properties

[0192] Haze is a measure of the optical appearance of a thin film, which is determined on the film according to ASTM D1003, the thickness of which is shown in the “Examples” below and produced according to the “Examples” below.

[0193] f) Sealing Initiation Temperature (SIT)

[0194] This method determines the sealing temperature range (sealing range) of polyethylene films (particularly blown or cast films). The sealing temperature range is the temperature range under which the film can be sealed according to the conditions given below.

[0195] The lower limit (heat seal initiation temperature (SIT)) is the sealing temperature at which the seal strength reaches 5N. The upper limit (seal end temperature (SET)) is reached when the film adheres to the sealing device.

[0196] Measurements were performed according to a slightly modified version of ASTM F1921-12, in which the test parameters of sealing pressure, cooling time, and test speed were modified. The force / temperature profile was determined until the film underwent thermal failure.

[0197] The sealing range was determined by a J&B General Purpose Sealing Machine Model 4000 using a blown film produced as shown below, with further parameters as follows:

[0198] Adjustment time: >96 hours

[0199] Sample width: 25mm

[0200] Sealing pressure: 0.4 N / mm² (PE)

[0201] Sealing time: 1 second

[0202] Delay time: 30 seconds

[0203] Sealing jaw size: 50x5 mm

[0204] Sealing jaw shape: flat

[0205] Sealing jaw coating: Niptef

[0206] Sealing temperature: ambient temperature -240℃

[0207] Sealing temperature interval: 5℃

[0208] Starting temperature: 50℃

[0209] Clamping separation rate: 42 mm / s

[0210] g) Thickness

[0211] The film thickness was determined according to ISO 4593.

[0212] h) Quantitative analysis of C2, iPP (continuous C3), LDPE, and short-chain branches of polyethylene in recycled materials.

[0213] Quantitative recordings were performed in solution using a Bruker Avance III 400MHz NMR spectrometer. 13C{ 1 H NMR spectrum, 1 H and 13 C was operated at 400.15 and 100.62 MHz, respectively. All spectra were performed using... 13 A C-optimized 10mm extended temperature probe was used for recording at 125°C, and nitrogen was used for all pneumatic devices. Approximately 200 mg of material was dissolved with chromium-(III)-acetylacetone (Cr(acac)3) in 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) to obtain a 65 mM relaxant solution in solvent {singh09}. To ensure solution homogeneity, after initial sample preparation in a heating block, the NMR tube was further heated in a rotary furnace for at least 1 hour. The tube was inserted into a magnet and rotated at 10 Hz. This setup was chosen primarily because of its high resolution, which is necessary for accurate quantification of ethylene content. Standard single-pulse excitation without NOE was used, with an optimized tip angle, a 1-second cycle delay, and a dual-stage WALTZ16 decoupling scheme {zhou07,busico07}. A total of 6144 (6 k) transients were acquired for each spectrum.

[0214] Processing and quantitative integration using proprietary computer programs. 13 C1H NMR spectra were used, and relevant quantitative characteristics were determined from the integration. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. Characteristic signals corresponding to polyethylene (B1, B2, B4, B5, B6plus) and polypropylene with different short-chain branches were observed.

[0215] Characteristic signals were observed corresponding to the presence of polyethylene containing isolated B1 branches (starB1 33.3 ppm), isolated B2 branches (starB2 39.8 ppm), isolated B4 branches (twoB4 23.4 ppm), isolated B5 branches (threeB5 32.8 ppm), all branches longer than 4 carbons (starB4plus 38.3 ppm), and the third carbon at the end of the saturated aliphatic chain (3s 32.2 ppm). The intensity of ethylene main chain methylene carbon (ddg) containing a combination of polyethylene main chain carbon (dd 30.0 ppm), γ-carbon (g 29.6 ppm), 4s, and threeB4 carbon (compensated later) was taken between 30.9 ppm and 29.3 ppm, excluding Tββ in polypropylene. The amount of C2-related carbon was quantified using all the above signals according to the following formula:

[0216] fC C2total=(Iddg–ItwoB4)+(IstarB1*6)+(IstarB2*7)+(ItwoB4*9)+I(threeB5*10)+((IstarB4plus-ItwoB4-IthreeB5)*7)+(I3s*3)

[0217] Characteristic signals corresponding to the presence of polypropylene (iPP, continuous C3) were observed at 46.7 ppm, 29.0 ppm, and 22.0 ppm. The amount of PP-related carbon was quantified using the Sαα integral at 46.6 ppm.

[0218] fC PP =Isαα*3

[0219] The weight percentages of C2 fraction and polypropylene can be quantified using the following formula:

[0220] wt C2fraction =fC C2total *100 / (fC C2total +fC PP )

[0221] wt PP =fC PP *100 / (fC C2total +fC PP )

[0222] Characteristic signals corresponding to various short-chain branches were observed, and their weight percentages were quantified. Since the relevant branches would be α-olefins, the weight fraction of each branch was quantified first:

[0223] fwtC2=fC C2total –((IstarB1*3)–(IstarB2*4)–(ItwoB4*6)–(IthreeB5*7)

[0224] fwtC3(isolated C3) = IstarB1 * 3

[0225] fwtC4=IstarB2*4

[0226] fwtC6=ItwoB4*6

[0227] fwtC7=IthreeB5*7

[0228] Standardizing all weight fractions yields the weight percentage of all relevant branches:

[0229] fsum wt％total =fwtC2+fwtC3+fwtC4+fwtC6+fwtC7+fC PP

[0230] wtC2total=fwtC2*100 / fsum wt％total

[0231] wtC3total = fwtC3 * 100 / fsum wt％total

[0232] wtC4total = fwtC4 * 100 / fsum wt％total

[0233] wtC6total = fwtC6 * 100 / fsum wt％total

[0234] wtC7total = fwtC7 * 100 / fsum wt％total

[0235] We can assume that the B5 branch (generated solely by the polymerization of ethylene under high pressure) is almost constant in LDPE, thus estimating the LDPE content. We found that if B5 is quantified as C7, its average content is 1.46% by weight. Based on this assumption, a range of LDPE contents (approximately between 20% and 80% by weight) can be estimated, depending on the SNR ratio of the three B5 signals:

[0236] wt%LDPE=wtC7total*100 / 1.46

[0237] References

[0238] zhou07 Zhou,Z.,Kuemmerle,R.,Qiu,X.,Redwine,D.,Cong,R.,Taha,A.,Baugh,D.Winniford,B.,J.Mag.Reson.187(2007)225

[0239] busico07 Busico,V.,Carbonniere,P.,Cipullo,R.,Pellecchia,R.,Severn,J.,Talarico,G.,Macromol.Rapid Commun.2007,28,1128

[0240] singh09 Singh,G.,Kothari,A.,Gupta,V.,Polymer Testing 28 5(2009),475

[0241] randall89 J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.

[0242] brandolini00 AJ Brandolini, DDHills, NMR Spectra of Polymers and Polymer Additives, Marcel Dekker Inc., 2000

[0243] i) Dynamic shear measurement (frequency scan measurement)

[0244] The characterization of polymer compositions or polymer melts by dynamic shear measurements, as described above or below, conforms to ISO standards 6721-1 and 6721-10. Measurements were performed on an Anton Paar MCR501 stress-controlled rotational rheometer equipped with a 25 mm parallel plate geometry. Measurements were conducted on compression-molded plates using a nitrogen atmosphere and with strains set within the linear viscoelastic range. Oscillatory shear tests were performed at 190 °C, with applied frequencies ranging from 0.01 to 600 rad / s and a 1.3 mm gap.

[0245] In the dynamic shear experiment, the probe undergoes uniform deformation under sinusoidally varying shear strain or shear stress (strain and stress control modes, respectively). In the controlled strain experiment, the probe is subjected to sinusoidal strain, which can be expressed as...

[0246] γ(t)=γ0sin(ωt) (1)

[0247] If the applied strain is within the linear viscoelastic range, the resulting sinusoidal stress response can be given by the following equation:

[0248] σ(t)=σ0sin(ωt+δ) (2)

[0249] in

[0250] σ0 and γ0 are the stress and strain amplitudes, respectively.

[0251] ω is the angular frequency

[0252] δ represents the phase shift (the loss angle between the applied strain and the stress response).

[0253] t is time

[0254] Dynamic test results are typically represented by several different rheological functions, namely shear storage modulus G', shear loss modulus G”, complex shear modulus G*, complex shear viscosity η*, dynamic shear viscosity η′, the heterogeneous component of complex shear viscosity η”, and loss tangent tanδ, which can be expressed as follows:

[0255]

[0256] G * =G′+iG″[Pa] (5)

[0257] η * =η′-iη″[Pa.s] (6)

[0258]

[0259] The so-called shear thinning index is related to MWD but not to Mw, and its determination is shown in Equation 9.

[0260]

[0261] For example, SHI (2.7 / 210) Defined as: the complex viscosity value (in Pas) determined when the G* value is equal to 2.7 kPa, divided by the complex viscosity value (in Pas) determined when the G* value is equal to 210 kPa.

[0262] The values ​​of storage modulus (G′), loss modulus (G″), complex modulus (G*), and complex viscosity (η*) are all obtained as a function of frequency (ω).

[0263] Therefore, for example, η* 300rad / s (eta* 300rad / s η* is an abbreviation for complex viscosity at a frequency of 300 rad / s. 0.05rad / s (eta* 0.05rad / s () is an abbreviation for complex viscosity at a frequency of 0.05 rad / s.

[0264] The loss tangent tan(δ) is defined as the ratio of the loss modulus (G″) to the storage modulus (G′) at a given frequency. Therefore, for example, tan... 0.05 It is an abbreviation for the ratio of loss modulus (G″) to storage modulus (G′) at 0.05 rad / s. 300 It is an abbreviation for the ratio of loss modulus (G″) to energy storage modulus (G′) at 300 rad / s.

[0265] Elastic balance tan 0.05 / tan 300 Defined as the loss tangent tan 0.05 tan and loss angle 300The ratio.

[0266] In addition to the rheological functions mentioned above, other rheological parameters can be determined, such as the so-called elasticity index EI(x). The elasticity index EI(x) is the storage modulus (G′) determined for the loss modulus (G″) value at x kPa, and can be described by Equation 10.

[0267] EI(x)=G′(G″=x kpa)[Pa] (10)

[0268] For example, EI (5 kPa) is defined by the value of the energy storage modulus (G′), which is determined by G″ being equal to 5 kPa.

[0269] The polydispersity index PI is defined by formula 11.

[0270]

[0271] Where ω COP It is the cross angular frequency, which is determined to be the angular frequency at which the energy storage modulus G′ is equal to the loss modulus G″.

[0272] These values ​​were determined using a single-point interpolation procedure defined in the Rheoplus software. In cases where a given G* value could not be achieved experimentally, it was determined by extrapolation, using the same procedure as before. In both cases (interpolation or extrapolation), the Rheoplus options "Interpolate y-values ​​to x-values ​​from parameter" and "logarithmic interpolation type" were applied.

[0273] References:

[0274] [1]Rheological characterization of polyethylene fractions” Heino, EL, Lehtinen, A., Tanner J., J.,Neste Oy,Porvoo,Finland,Theor.Appl.Rheol.,Proc.Int.Congr.Rheol,11th(1992),1,360-362

[0275] [2]The influence of molecular structure on some rheologicalproperties of polyethylene", Heino, EL, Borealis Polymers Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995.).

[0276] [3]Definition of terms relating to the non-ultimate mechanicalproperties of polymers,Pure&Appl.Chem.,Vol.70,No.3,pp.701-754,1998.

[0277] j) Strain hardening (SH) modulus

[0278] The strain hardening test is a modified tensile test performed on specially prepared thin samples at 80°C. Strain hardening modulus (MPa) <gp>It is calculated based on the true strain-true stress curve; the slope of the curve is used in the true strain λ region (between 8 and 12).

[0279] The true strain λ is calculated based on the length l (mm) and the gauge length l0 (mm), as shown in Formula 1.

[0280]

[0281] Where Δl is the increase in the specimen length between gauge marks, (mm). True stress σ true (MPa) Calculated according to Formula 2, assuming the volume between gauge marks is conserved:

[0282] σ true =σ n λ (2)

[0283] Where σ n It is engineering stress.

[0284] The Neo-Hookean constitutive model (Equation 3) was used to fit the true strain-true stress data, thereby calculating the values ​​when 8 < λ < 12. <gp>(MPa).

[0285]

[0286] Where C is a mathematical parameter describing the constitutive model that extrapolates the yield stress to λ = 0.

[0287] Five samples were initially measured. If <gp>If the coefficient of variation is greater than 2.5%, two additional samples are measured. If the test bar becomes strained in the fixture, the test results are discarded.

[0288] PE material granules are compressed into sheets with a thickness of 0.30 mm according to the compression parameters specified in ISO 17855-2.

[0289] After the sheet is compressed and formed, it is annealed to eliminate any orientation or thermal history and maintain an isotropic sheet. The sheet is annealed in an oven at (120±2)℃ for 1 hour, and then the temperature chamber is closed for slow cooling to room temperature. During this process, the sheet is allowed to move freely.

[0290] Next, the test specimens are stamped from the pressed sheet. The specimen geometry adopts the revised ISO 37:1994 Type 3 (Figure 3).

[0291] The sample has a large clamping area to prevent slippage during clamping; the dimensions are shown in Table 0.

[0292] Table 0: Dimensions of Type 3 (Revised ISO 37:1994)

[0293] Dimension Dimensions (mm) L Starting length between clamps 30.0+ / -0.5 l0 Gauge length 12.5+ / -0.1 l1 prism length 16.0+ / -1.0 l3 Total length 70 R1 radius 10.0+ / -0.03 R2 radius 8.06+ / -0.03 b1 Prism width 4.0+ / -0.01 b2 clamp width 20.0+ / -1.0 h thickness 0.30+0.05 / 0.30-0.03

[0294] The stamping process is carried out in a manner that prevents deformation, cracking, or other irregularities from occurring in the specimen.

[0295] The sample thickness was measured at three points in the parallel region of the sample; the smallest of these measurements was used for data processing.

[0296] 1. Perform the following steps on a universal tensile testing machine equipped with a controlled temperature chamber and a non-contact elongation meter:

[0297] 2. Before starting the test, acclimate the specimen in a temperature chamber at (80±1)℃ for at least 30 minutes.

[0298] 3. Clip the specimen onto it.

[0299] 4. Close the temperature chamber.

[0300] 5. Close the lower clamp after the temperature reaches (80±1)℃.

[0301] 6. Before applying the load and starting the measurement, balance the sample between the clamps for 1 minute.

[0302] 7. Apply a preload of 0.5 N at a speed of 5 mm / min.

[0303] 8. Stretch the specimen along its main axis at a constant transverse speed (20 mm / min) until the specimen breaks.

[0304] During the test, the load on the sample was measured using a 200N load cell. Elongation was measured using a non-contact elongation meter.

[0305] k) Gel content

[0306] Gel counting was measured using a gel counting device consisting of a measuring extruder ME 25 / 5200V1, 25*25D (with five temperature control zones, temperature profiles adjustable to 170 / 180 / 190 / 190 / 190℃), an adapter, and a slit die (0.5*150mm opening). It was also equipped with a cooling roller unit (13cm diameter, temperature set to 50℃), a line camera (4096-pixel CCD for dynamic digital processing of grayscale images), and a winding unit.

[0307] To measure the gel count content, the material was extruded at a screw speed of 30 revolutions per minute, a stretching speed of 3-3.5 m / min, and a cooling roller temperature of 50°C to produce a thin cast film with a thickness of 70 μm and a width of approximately 110 mm.

[0308] On the thin film, the camera resolution was 25 μm x 25 μm. The camera operated in transmission mode with constant grayscale values ​​(auto-set boundary level = 170). The system was able to distinguish between 256 grayscale values, from black = 0 to white = 256. For gel detection, a dark sensitivity level of 25% was used. For each material, a 10m line camera was used for inspection. 2 The average number of gel dots on the film surface area. Gel dot size is distinguished based on the following line camera settings:

[0309] Gel size (the longest dimension of the gel)

[0310] 300μm to 599μm

[0311] 600μm to 999μm

[0312] 1000μm and above

[0313] l) GPC Measurement

[0314] The molecular weight average (M) was determined by gel permeation chromatography (GPC) according to ISO 16014-1:2003, ISO 16014-2:2003, ISO 16014-4:2003 and ASTM D 6474-12. z M W and M n Molecular weight distribution (MWD) and its width are described by the polydispersity index (PDI) = M W / M n (where M) n M is the number average molecular weight. w (where the weight-average molecular weight is 1), the formula is as follows:

[0315]

[0316] For a constant elution volume interval ΔV i A i and M i These are respectively related to the elution volume V i The relevant chromatographic peak slice area and polyolefin molecular weight (MW), where N equals the number of data points obtained from the chromatogram between the integration limits.

[0317] A high-temperature GPC instrument equipped with an infrared (IR) detector (PolymerChar IR4 or IR5 from Valencia, Spain) or an Agilent Technologies differential refractometer (RI) was used, with 3 x Agilent-PLgel Olexis and 1 x Agilent-PLgel Olexis Guard columns. 1,2,4-Trichlorobenzene (TCB) (stabilized with 250 mg / L 2,6-di-tert-butyl-4-methylphenol) was used as the mobile phase. The chromatographic system was run at a column temperature of 160 °C and a detector temperature of 160 °C, with a constant flow rate of 1 mL / min. 200 μL of sample solution was injected for each analysis. Data collection was performed using Agilent Cirrus software version 3.3 or PolymerChar GPC-IR control software.

[0318] The column set was calibrated using 19 narrow MWD polystyrene (PS) standards ranging from 0.5 kg / mol to 11,500 kg / mol. The PS standards were dissolved at room temperature for several hours. The peak molecular weight of polystyrene was converted to the molecular weight of polyolefins using the Mark Houwink equation and the following Mark Houwink constants:

[0319] K PS =19 x 10 -3 mL / g, α PS =0.655

[0320] K PE =39 x 10 -3 mL / g, α PE =0.725

[0321] Third-order polynomial fitting was used to fit the calibration data.

[0322] All samples were in the concentration range of approximately 1 mg / ml and were dissolved at 160°C for 3 (tri) hours to dissolve PE in freshly distilled TCB stabilized with 250 ppm Irgafos 168 under continuous gentle shaking.

[0323] Example

[0324] The invention will be further illustrated below by way of non-limiting embodiments.

[0325] a) Materials

[0326] Table 1 below lists the polymers used to manufacture the multilayer film structures of the embodiments and comparative embodiments of the present invention.

[0327] Table 1:

[0328]

[0329] *MFR5 (g / 10min)

[0330] The polymers used can be purchased from the manufacturers listed in Table 1.

[0331] NAV101 is a low-density polyethylene (LDPE) post-consumer recycled material blend available from EcoplastKunststoffrecycling GmbH. The properties of NAV101 are shown in Table A.

[0332] Table A:

[0333] Ethylene content (wt%) 90.67 isol.C3 content (wt%) 0 C4 content (wt%) 2.23 C6 content (wt%) 2.73 C7 content (wt%) 0.48 iPP content (by weight %) 3.89 LDPE content (wt%) 33.00 <![CDATA[Density (kg / m 3 )]]> 923.9 <![CDATA[MFR2(g / 10min)]]> 1.02 <![CDATA[MFR5(g / 10min)]]> 3.57 <![CDATA[MFR 21 (g / 10min)]]> 41.56 SHI2.7 / 210 22.16 eta0.05 (Pa·s) 16187 eta300 (Pa·s) 618 PI(s-1) 1.46 SH modulus (MPa) 14.3 Gel content (>1000μm) (1 / m2) 16.9 Gel content (600-1000μm) (1 / m2) 175.1 Gel content (300-599) (μm / 1m2) 885.9

[0334] b) Thin film production

[0335] A three-layer film consisting of a core layer, a top layer, and a sealing layer was produced on a laboratory-scale production line at Collin 30. Production was conducted as follows: melt temperature 210°C, total output 7 kg / h, BUR 1:2.5, and film thickness 60 μm. The composition and structure of the produced three-layer film are shown in Table 2 below.

[0336] Table 2: Structure of the three-layer thin film

[0337]

[0338] The properties of the three-layer film are shown in Table 3 below. The density of each layer was calculated using the formula for polymer blends provided in section b) of "Measurement and Determination Methods" above.

[0339] Table 3: Properties of the three-layer thin film

[0340] CE1 IE1 Density (surface layer) <![CDATA[kg / m 3 ]]> 918.5 918.5 Density (core layer) <![CDATA[kg / m 3 ]]> 936.4 924.5 Density (sealing layer) <![CDATA[kg / m 3 ]]> 910.2 910.2 Tensile modulus MD MPa 385 207 Tensile modulus TD MPa 455 235 Dart Impact Intensity (DDI) g 383 383 SIT ℃ 82 77 Haze ％ 8.39 7.56

[0341] As can be seen from Table 3, the use of recycled polyethylene in the core layer does not reduce toughness (expressed as dart impact strength), but improves the optical properties (haze) and sealing properties (SIT) of the multilayer polyethylene film.< / gp> < / gp> < / gp>

Claims

1. A multilayer polyethylene film, comprising: A surface layer, a sealing layer, and a core layer located between the surface layer and the sealing layer. in, The core layer comprises a core layer composition, the core layer composition comprising: a) Recycled polyethylene with an MFR2 of 0.1 to 2.0 g / 10 min as determined according to ISO 1133 and a density of 910 to 930 kg / m³ as determined according to ISO 1183. 3 , b) Multimodal ethylene terpolymers with an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 and the MWD determined by gel permeation chromatography was 2.0 to 7.5, and c) Polyethylene, with an MFR5 of 0.1 to 2.5 g / 10 min as determined according to ISO 1133, and a density of 925 to 950 kg / m³ as determined according to ISO 1183. 3 The MWD, as determined by gel permeation chromatography, ranged from 8.0 to 35.

0.

2. The multilayer polyethylene film according to claim 1, wherein, The surface layer includes a surface layer composition comprising: Multimodal ethylene terpolymer with an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 Furthermore, the MWD determined by gel permeation chromatography ranged from 2.0 to 7.

5. and / or Low-density polyethylene with an MFR2 of 0.1 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 950 kg / m³ as determined by ISO 1183. 3 .

3. The multilayer polyethylene film according to claim 1, wherein, The sealing layer includes a sealing layer composition comprising: A copolymer of ethylene with an α-olefin comonomer having 4 to 8 carbon atoms, wherein the copolymer has an MFR2 of 0.5 to 2.0 g / 10 min as determined according to ISO 1133 and a density of 870 to 910 kg / m³ as determined according to ISO 1183. 3 , and / or Multimodal ethylene terpolymer with an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 The MWD measured by gel permeation chromatography ranged from 2.0 to 7.

5.

4. The multilayer polyethylene film according to any one of claims 1-3, wherein, Based on the total core composition, the recycled polyethylene is present in the core composition at an amount of 50 to 90% by weight. and / or The multimodal ethylene terpolymer is present in the core layer composition at an amount of 5 to 30% by weight, based on the total core layer composition. and / or The polyethylene is present in the core layer composition in an amount of 5 to 30% by weight, based on the total core layer composition.

5. The multilayer polyethylene film according to claim 2, in, Based on the total surface composition, the multimodal ethylene terpolymer is present in the surface composition at an amount of 80 to 95% by weight. and / or The low-density polyethylene is present in the surface composition at an amount of 5 to 20% by weight, based on the total surface composition.

6. The multilayer polyethylene film according to claim 3, in, Based on the total sealing layer composition, the copolymer of ethylene and α-olefin comonomer having 4 to 8 carbon atoms is present in the sealing layer composition in an amount of 50 to 90% by weight. and / or The multimodal ethylene terpolymer is present in the total sealing layer composition at an amount of 10 to 50% by weight.

7. The multilayer polyethylene film according to any one of claims 1-3, wherein, The multimodal ethylene terpolymer is a bimodal ethylene terpolymer.

8. The multilayer polyethylene film according to claim 3, wherein, The copolymer of ethylene and an α-olefin comonomer having 4 to 8 carbon atoms is an ethylene-1-octene copolymer.

9. The multilayer polyethylene film according to any one of claims 1-3, wherein, The surface layer has a thickness of 1 to 100 μm. and / or The core layer has a thickness of 10 to 200 μm. and / or The thickness of the sealing layer is 1 to 50 μm.

10. The multilayer polyethylene film according to any one of claims 1-3, wherein, The multilayer polyethylene film has a longitudinal tensile modulus (MD) of 150 MPa or more, measured on a 60 µm test film according to ISO 527-3, and / or a transverse tensile modulus (TD) of 150 MPa or more, measured on a 60 µm test film according to ISO 527-3.

11. The multilayer polyethylene film according to any one of claims 1-3, wherein, The multilayer polyethylene film has a dart impact strength greater than 300g and / or a sealing initiation temperature less than 82°C, wherein the dart impact strength is determined according to ISO 7765 on a 60 µm test film.

12. A method for producing a multilayer polyethylene film according to any one of claims 1-11, wherein, The surface layer, the sealing layer, and the core layer are co-extruded.

13. A core layer composition comprising: a) Recycled polyethylene with an MFR2 of 0.1 to 2.0 g / 10 min as determined according to ISO 1133 and a density of 910 to 930 kg / m³ as determined according to ISO 1183. 3 , b) Multimodal ethylene terpolymers with an MFR2 of 0.5 to 2.0 g / 10 min as determined by ISO 1133 and a density of 910 to 930 kg / m³ as determined by ISO 1183. 3 The MWD, as determined by gel permeation chromatography, ranged from 2.0 to 7.

5. c) Polyethylene, with an MFR5 of 0.1 to 2.5 g / 10 min as determined according to ISO 1133, and a density of 925 to 950 kg / m³ as determined according to ISO 1183. 3 The MWD, as determined by gel permeation chromatography, ranged from 8.0 to 35.

0.

14. Use of the core layer composition according to claim 13 as the core layer of a multilayer polyethylene film to improve the haze and sealing initiation temperature of the multilayer polyethylene film.

15. An article comprising a multilayer polyethylene film according to any one of claims 1 to 11 or a core layer composition according to claim 13.

Images