Multilayer structures, laminates and products with metallic layers

Abstract

This invention provides multilayer structures and articles and laminates formed therefrom. The multilayer structure according to the embodiments disclosed herein includes a membrane and a metal layer comprising a metal deposited on an outer layer of the membrane. The outer layer of the membrane comprises a blend of maleic anhydride-grafted polyethylene and polypropylene homopolymer. This multilayer structure exhibits improved bond strength between the outer layer and the metal layer compared to other multilayer structures.

Description

Technical Field

[0001] This invention relates to multilayer structures comprising metal layers and films, to laminates comprising such multilayer structures, and to articles comprising such multilayer structures or laminates. Background Technology

[0002] Multilayer structures, including metallized films (i.e., metal layers containing metal deposited on the film), are widely used for packaging perishable foods and products. To manufacture such structures, a thin coating of metal (e.g., aluminum) can be adhered to the film via vacuum metallization. When added to the film layer, the thin metal coating can improve barrier properties and prevent or reduce the permeation of liquids, gases, or vapors. However, there are problems with maintaining the adhesion of the metal layer to the film, and the metal layer may be partially or completely removed, resulting in a loss of poor packaging and barrier properties. For example, polypropylene films can be metallized to improve barrier properties (e.g., gas and moisture barrier properties). However, due to the non-polar nature of polypropylene, the bond strength between the film and the metal can be poor. Although polypropylene can be treated to reduce its non-polar properties, external heat or stress applied during or after manufacturing can cause cracking due to insufficient bond strength between the film and the metal. Therefore, there remains a need for multilayer structures including polypropylene that exhibit enhanced bond strength between the metal layer and the film. Summary of the Invention

[0003] This invention provides a multilayer structure comprising a membrane and a metal layer, wherein the metal layer is deposited on the membrane. According to an embodiment, the membrane has an outer layer comprising a blend of maleic anhydride-grafted polyethylene and polypropylene homopolymer, and when the metal is deposited on the outer layer, the resulting multilayer structure exhibits desired properties, such as high adhesion strength between the metal and the membrane.

[0004] In one aspect, the present invention provides a multilayer structure comprising (a) a membrane, wherein the outer layer of the membrane comprises (i) a blend of maleic anhydride-grafted polyethylene with a density of less than 0.905 g / cc and a melt index (I2) greater than 50.0 g / 10 min and (ii) a blend of polypropylene homopolymer with a density of less than 0.905 g / cc and a melt index (I2) greater than 50.0 g / 10 min; and (b) a metal layer comprising a metal deposited on the outer layer of the membrane.

[0005] In another aspect, the present invention provides a layered compound. This layered compound comprises a multilayer structure according to embodiments disclosed herein.

[0006] In another aspect, the present invention provides an article of manufacture, such as food packaging, which includes any of the multilayer structures or laminates of the present invention disclosed herein.

[0007] These and other implementation schemes are described in more detail in the specific embodiments. Detailed Implementation

[0008] The multilayer structures, laminates, and articles of manufacture disclosed herein are described in more detail below. However, this disclosure should not be construed as limiting the embodiments set forth below.

[0009] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. Therefore, the general term polymer encompasses the term homopolymer (used to refer to a polymer prepared from only one type of monomer) and the term copolymer or interpolymer. Trace impurities (e.g., catalyst residues) may be incorporated into and / or within a polymer. A polymer can be a single polymer, a polymer blend, or a mixture of polymers comprising a mixture of polymers formed in situ during polymerization.

[0010] As used herein, the terms "polypropylene" or "propylene-based polymer" should mean a polymer containing more than 50% by weight of polymerizable propylene monomers (based on the total amount of polymerizable monomers) and optionally at least one comonomer. Polypropylene homopolymer is a polymer containing polymerizable propylene monomers but not comonomers.

[0011] As used herein, the term "polyethylene" or "ethylene-based polymer" should mean a polymer comprising a majority amount (>50 mol%) of units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include low-density polyethylene (LDPE); linear low-density polyethylene (LLDPE); ultra-low-density polyethylene (ULDPE); very low-density polyethylene (VLDPE); single-point catalytic linear low-density polyethylene, including linear and substantially linear low-density resins (m-LLDPE); ethylene-based plastomers (POP) and ethylene-based elastomers (POE); medium-density polyethylene (MDPE); and high-density polyethylene (HDPE).

[0012] As used herein, the term "multilayer structure" refers to any structure having more than one layer. For example, a multilayer structure can have two, three, four, five, or more layers. A multilayer structure can be described as having layers represented by letters. For example, a three-layer structure having a core layer B and two outer layers A and C can be designated as A / B / C. Similarly, a structure having two core layers B and C and two outer layers A and D is designated as A / B / C / D. The multilayer structures disclosed herein include structures comprising a membrane and a metal layer, wherein the membrane has one or more layers.

[0013] The term "adhesive contact" means that one surface of one layer touches and adheres to another surface of another layer, such that one layer cannot be removed from the other layer without damaging the interlayer surfaces (i.e., the contact surfaces) of the two layers.

[0014] The terms “comprising,” “including,” “having,” and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not such components, steps, or procedures are specifically disclosed. For the avoidance of any doubt, unless stated otherwise, all compositions claimed using the term “comprising” may include any additional additives, adjuvants, or compounds, whether polymerized or otherwise. In contrast, the term “substantially constitutes…” excludes any other components, steps, or procedures from any subsequently listed scope, except those that are not essential for operability. The term “consisting of…” excludes any ingredients, steps, or procedures not specifically described or listed.

[0015] In an embodiment, the present invention provides a multilayer structure comprising (a) a membrane, wherein the outer layer of the membrane comprises (i) a blend of maleic anhydride-grafted polyethylene with a density of less than 0.905 g / cc and a melt index (I2) greater than 50.0 g / 10 min and (ii) a polypropylene homopolymer of 65 wt% to 92 wt%; and (b) a metal layer comprising metal deposited on the outer layer of the membrane. Without wishing to be bound by any particular theory, it is believed that a specific blend of maleic anhydride-grafted polyethylene and polypropylene homopolymer with a relatively low density and a high melt index (I2) enhances the bond strength between the outer layer of the membrane and the metal of the metal layer.

[0016] The multilayer structure of the present invention may include a combination of two or more embodiments described herein.

[0017] In other embodiments, the present invention relates to a laminate comprising any of the multilayer structures of the present invention disclosed herein and a second film. The laminate according to the embodiments disclosed herein comprises any of the multilayer structures of the present invention disclosed herein in adhesive contact with a second film. The second film of the laminate is not particularly limited and may comprise polyamide, polyethylene terephthalate, polypropylene, or polyethylene.

[0018] In other embodiments, the present invention relates to an article, such as for packaging perishable foods and products. In embodiments, the article comprises any of the multilayer structures of the invention disclosed herein. In embodiments, the article comprises any of the laminates of the invention disclosed herein. The article or laminate of the invention may comprise a combination of two or more embodiments as described herein.

[0019] membrane

[0020] The multilayer structure of the present invention includes a membrane. In some embodiments, the membrane of the multilayer structure includes an outer layer that enhances the adhesion strength between the metal layers (described below) and advantageously provides a good combination of barrier, sealing, mechanical and optical properties in a single multilayer structure or metallized membrane.

[0021] The membrane can be a single-layer or multi-layer membrane. In some embodiments, the membrane can be used as a sealant membrane and may include a sealant layer that is a second outer layer opposite to the metallized outer layer.

[0022] The outer layer of the metallized membrane comprises a blend of maleic anhydride-grafted polyethylene and polypropylene homopolymer. In embodiments, the blend comprises 8 wt% to 35 wt% maleic anhydride-grafted polyethylene. This document includes and discloses all individual values ​​and sub-ranges of 8 wt% to 35 wt% maleic anhydride-grafted polyethylene. For example, the blend may comprise 8 wt% to 35 wt%, 9 wt% to 35 wt%, 10 wt% to 35 wt%, 8 wt% to 30 wt%, 9 wt% to 30 wt%, 10 wt% to 30 wt%, 8 wt% to 20 wt%, 9 wt% to 20 wt%, 10 wt% to 20 wt%, or 12 wt% to 18 wt% maleic anhydride-grafted polyethylene, wherein the weight percentages (wt%) are based on the total weight of the blend.

[0023] In the embodiments, maleic anhydride-grafted polyethylene has a density of less than 0.905 g / cc. This document includes and discloses all individual values ​​and sub-ranges less than 0.905 g / cc. For example, maleic anhydride-grafted polyethylene may have densities with upper limits of 0.905 g / cc, 0.900 g / cc, 0.895 g / cc, 0.890 g / cc, 0.885 g / cc, 0.880 g / cc, 0.875 g / cc, and 0.870 g / cc, or may have densities in the range of 0.860 g / cc to 0.900 g / cc, 0.860 g / cc to 0.890 g / cc, or 0.860 g / cc to 0.880 g / cc.

[0024] In the implementation, the maleic anhydride-grafted polyethylene has a melt index (I2) greater than 50.0 g / 10 min. This document discloses and includes all individual values ​​and subranges greater than 50.0 g / 10 min. For example, maleic anhydride-grafted polyethylene may have a melt index (I2) greater than 100.0 g / 10 min, greater than 200.0 g / 10 min, greater than 300.0 g / 10 min, greater than 400.0 g / 10 min, greater than 500.0 g / 10 min, or greater than 600.0 g / 10 min, or may have a melt index (I2) in the range of 100.0 to 1000.0 g / 10 min, 200.0 to 900.0 g / 10 min, 300.0 to 800.0 g / 10 min, 400.0 to 700.0 g / 10 min, 500.0 to 700.0 g / 10 min, or 600.0 to 700.0 g / 10 min.

[0025] In the embodiments, the maleic anhydride-grafted polyethylene has a maleic anhydride level greater than 0.5 wt%. This document includes and discloses all individual values ​​and sub-ranges greater than 0.5 wt%. For example, the maleic anhydride-grafted polyethylene may have a maleic anhydride level greater than 0.5 wt%, greater than 0.8 wt%, greater than 1.0 wt%, greater than 1.2 wt%, or greater than 1.4 wt%, or may have a maleic anhydride level in the range of 0.6 wt% to 2.0 wt%, 0.8 wt% to 2.0 wt%, or 1.0 wt% to 2.0 wt%, wherein the weight percentage (wt%) is based on the total weight of the maleic anhydride-grafted polyethylene.

[0026] In the embodiments, maleic anhydride-grafted polyethylene has a Brinell viscosity of 8.0 to 18.0 Pa·s at 177°C (350°F). All individual values ​​and sub-ranges of 8.0 Pa·s to 18.0 Pa·s are disclosed and included herein. For example, maleic anhydride-grafted polyethylene may have Brinell viscosities of 8.0 Pa·s to 18.0 Pa·s, 9.0 Pa·s to 17.0 Pa·s, 10.0 Pa·s to 16.0 Pa·s, 11.0 Pa·s to 15.0 Pa·s, or 12.0 Pa·s to 14.0 Pa·s at 177°C (350°F), wherein the Brinell viscosity at 177°C (350°F) is measured according to ASTM D1084.

[0027] In some implementations, examples of maleic anhydride-grafted polyethylene that can be used for the outer layer include RETAIN, which is commercially available from The Dow Chemical Company (Midland, MI). TM Maleic anhydride-grafted polyethylene, such as RETAIN TM 3000.

[0028] In an embodiment, the blend of the outer layer of the membrane comprises a polypropylene homopolymer. In an embodiment, the blend comprises 65 wt% to 92 wt% of a polypropylene homopolymer. All individual values ​​and sub-ranges of 65 wt% to 92 wt% are disclosed and included herein. For example, the blend may comprise 65 wt% to 92 wt%, 65 wt% to 91 wt%, 65 wt% to 90 wt%, 70 wt% to 92 wt%, 70 wt% to 91 wt%, 70 wt% to 90 wt%, 80 wt% to 92 wt%, 80 wt% to 91 wt%, 80 wt% to 90 wt%, 80 wt% to 95 wt%, or 82 wt% to 88 wt% of a polypropylene homopolymer, wherein the weight percentage (wt%) is based on the total weight of the blend.

[0029] In some embodiments, examples of polypropylene homopolymers that can be used for the outer layer include Total Polypropylene 3365, which is commercially available from Total Petrochemical USA (Houston, TX); HD601CF, which is commercially available from Borealis AG (Vienna, Austria); and PP F320, which is commercially available from Sinopec Shanghai Petrochemical Company Limited (Shanghai, China).

[0030] In the embodiments, the polypropylene homopolymer of the blend has a melt flow rate of less than 12.0 g / 10 min. All individual values ​​and sub-ranges of less than 12.0 g / 10 min are disclosed and included herein. For example, the polypropylene homopolymer may have melt flow rates of less than 12.0 g / 10 min, 10.0 g / 10 min, 8.0 g / 10 min, 6.0 g / 10 min, or 4.0 g / 10 min, or may have melt flow rates in the range of 0.5 to 10.0 g / 10 min, 1.0 to 10.0 g / 10 min, 1.0 to 6.0 g / 10 min, 1.0 to 5.0 g / 10 min, or 1.0 to 4.0 g / 10 min, wherein the melt flow rate is measured according to ASTM D1238 (230°C, 2.16 kg).

[0031] In embodiments, the blend or outer layer of the membrane may contain one or more additives as known in the art. Such additives include antioxidants such as IRGANOX 1010 and IRGANOS 168 (available from BASF), UV absorbers, antistatic agents, pigments, dyes, nucleating agents, fillers, slip agents, flame retardants, plasticizers, processing aids, lubricants, stabilizers, smoke suppressants, viscosity control agents, surface modifiers, and antiblocking agents.

[0032] In embodiments where the membrane is a multilayer membrane, depending on the application, the membrane may also include other layers typically included in multilayer membranes, including, for example, a sealant layer, a barrier layer, a bonding layer, or other layers. The membrane can be formed using techniques known to those skilled in the art, based on the teachings herein. For example, the membrane can be prepared as a blown or cast membrane, and the membrane layers can be treated (e.g., corona or plasma treatment) and / or co-extruded using techniques known to those skilled in the art, based on the teachings herein.

[0033] The membranes according to the embodiments disclosed herein can have various thicknesses, depending on, for example, the number of layers. For example, in embodiments, the membrane can have a thickness of 2 micrometers to 200 micrometers, 15 micrometers to 100 micrometers, 20 micrometers to 80 micrometers, or 25 micrometers to 75 micrometers. In embodiments where the membrane is a multilayer membrane, the outer layer of the membrane (comprising the blends described herein) can have a thickness of 2 micrometers to 100 micrometers, 5 micrometers to 75 micrometers, or 10 micrometers to 50 micrometers, or can constitute 5% to 50%, 10% to 40%, or 15% to 35% of the entire membrane structure.

[0034] Metal layer

[0035] The multilayer structure also includes a metal layer comprising metal deposited on the outer layer of the film (comprising the blend described herein). The metal layer can be applied to the outer layer of the film using vacuum metallization. Vacuum metallization is a known technique for depositing metals, in which a metal source evaporates in a vacuum environment, and the metal vapor condenses on the surface of the film as the film passes through a vacuum chamber, thereby forming a thin layer.

[0036] Metals that can be deposited on the outer layer of the film include Al, Si, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, or oxides thereof. In some embodiments, the metal layer is formed of aluminum or an oxide of aluminum (e.g., Al₂O₃).

[0037] In the implementation, the metal layer has a thickness of 10 nanometers to 60 nanometers. This document discloses and includes all individual values ​​and sub-ranges of 10 nanometers to 60 nanometers. For example, the metal layer may have a thickness of 10 nanometers to 60 nanometers, 15 nanometers to 60 nanometers, 10 nanometers to 45 nanometers, 15 nanometers to 45 nanometers, or 15 nanometers to 40 nanometers.

[0038] Multi-layer structure

[0039] In some embodiments, the multilayer structure of the present invention includes a membrane and a metal layer deposited thereon (as described above). Introducing a specific blend (i.e., a blend of maleic anhydride-grafted polyethylene and polypropylene homopolymer with relatively low density and a high melt index (I2)) into the outer layer of the membrane advantageously provides improved adhesion between the metal and the outer layer of the membrane, which benefits the performance of the structure and other structures (e.g., laminates) in which the structure can be introduced. As described above, the metal layer provides good barrier properties, and including a sealant layer in the membrane allows the membrane to be used as a sealant membrane in a multilayer structure.

[0040] Layers

[0041] The multilayer structures of the various embodiments described herein can be used to form layered compounds. Such layered compounds can be formed from any of the multilayer structures described herein.

[0042] The laminate may include a multilayer structure of various embodiments that adhere to one or more additional films. For example, a multilayer structure of one or more embodiments described above may be adhered to a second film. The second film may include, for example, polyethylene, polyamide, polyethylene terephthalate, polypropylene, or combinations thereof. As is known to those skilled in the art, the multilayer structure may be adhered to the second film by an adhesive layer.

[0043] Products

[0044] The multilayer structures or laminates of the present invention can be used to form articles, such as packaging. Such articles can be formed from any of the multilayer structures or laminates described herein.

[0045] Examples of articles that can be formed from the multilayer structure or laminate of the present invention may include flexible packaging, pouches, stand-up pouches, and pre-packaged packaging or pouches. In some embodiments, the multilayer structure or article of the present invention can be used for food packaging. Examples of foods that can be contained in such packaging include meat, cheese, grains, nuts, juices, sauces, etc. Based on the teachings herein and based on the specific purpose of the packaging (e.g., the type of food, the quantity of food, etc.), techniques known to those skilled in the art can be used to form such articles.

[0046] Test methods

[0047] Unless otherwise indicated herein, the following analytical methods are used to describe various aspects of the invention:

[0048] density

[0049] Density is measured according to ASTM D792 and expressed in grams per cubic centimeter (g / cc or g / cm³). 3 )express.

[0050] Melt index (I2) and melt flow rate

[0051] Melt index (I2) was measured at 190°C and 2.16 kg according to ASTM D-1238 (except for propylene-based polymers). Melt flow rate was used for propylene-based polymers and measured at 230°C and 2.16 kg according to ASTM D-1238. Melt index values ​​are reported in g / 10 min, corresponding to the number of grams eluted per 10 minutes.

[0052] Brinell viscosity

[0053] The Brinell viscosity was measured at 177°C (350°F) according to ASTM D1084. Brinell viscosity values ​​are reported in Pascal-seconds (Pa.S).

[0054] Example

[0055] The following examples illustrate the features of this disclosure, but are not intended to limit the scope of this disclosure. The following materials are used in cast films as part of a multilayer structure embodiment.

[0056] BYNEL TM 50E803 (“Poly.1”), an anhydride-modified polypropylene resin commercially available from Dow Chemical Company (Midland, MI), has a density of 0.90 g / cc and a melt flow rate of 470 g / 10 min.

[0057] FUSABOND TM 525 (“Poly.2”), an anhydride-modified ethylene copolymer commercially available from Dow Chemical Company (Midland, MI), with a density of 0.88 g / cc and a melt index (I2) of 3.7 g / 10 min.

[0058] RETAIN TM 3000 (“Poly.3”), maleic anhydride-grafted polyethylene, commercially available from Dow Chemical Company (Midland, MI), with a density of 0.87 g / cc, a melt index (I2) of 660 g / 10 min, a maleic anhydride content greater than 0.5 wt%, and a Brookfield viscosity of 13.0 Pascal-second at 177 °C (350 °F).

[0059] Total Polypropylene 3365 (“PP-1”) is a commercially available homopolymer of polypropylene from Total Petrochemical USA (Houston, TX) with a density of 0.905 g / cc and a melt flow rate of 3.8 g / 10 min.

[0060] Total Polypropylene Z9450 (“PP-2”) is a random copolymer polypropylene commercially available from Total Petrochemical USA (Houston, TX).

[0061] The above materials were used to manufacture multiple three-layer cast films using a three-layer cast film production line with three extruders. Each film was prepared under the same conditions. Specific formulations for each film were supplied via three extruders (one extruder per layer). If a layer comprised multiple resins, they were dry-mixed before being loaded into the extruders. The bus speed was set to 20 m / min. The total film thickness was 50 micrometers, and the layer ratio was 1 / 1 / 1 (16.67 micrometers per layer). The process parameters for the cast film production line are shown in Table 1 below.

[0062] Table 1

[0063]

[0064] The composition of the cast film layers is reported in Table 2. It can be seen that the outer layer of films 1-9 comprises a blend of PP-1 with 5%, 10%, or 15% of Poly.1, Poly.2, or Poly.3.

[0065] Table 2

[0066] Membrane 1 90% PP-1 + 10% Poly.1 100% PP-1 100% PP-2 Membrane 2 90% PP-1 + 10% Poly.2 100% PP-1 100% PP-2 Membrane 3 90% PP-1 + 10% Poly.3 100% PP-1 100% PP-2 Membrane 4 95% PP-1 + 5% Poly.1 100% PP-1 100% PP-2 Membrane 5 95% PP-1 + 5% Poly.2 100% PP-1 100% PP-2 Membrane 6 95% PP-1 + 5% Poly.3 100% PP-1 100% PP-2 Membrane 7 85% PP-1 + 15% Poly.1 100% PP-1 100% PP-2 Membrane 8 85% PP-1 + 15% Poly.2 100% PP-1 100% PP-2 Membrane 9 85% PP-1 + 15% Poly.3 100% PP-1 100% PP-2 Membrane 10 100% PP-1 100% PP-1 100% PP-2

[0067] After membrane preparation, they were stored under ambient conditions for more than a week to allow additives to migrate to the membrane surface, simulating commercial conditions. After more than a week of storage, the membranes were subjected to corona treatment using techniques known to those skilled in the art.

[0068] Following corona treatment, the outer layer of the membrane (containing the blend) is metallized. Metallization of the outer layer is performed in a laboratory-scale vacuum deposition chamber manufactured by the Shenyang Vacuum Technology Research Institute. The membrane is taped to a substrate holder, and aluminum wire is inserted into the container of a resistance heater (heating boat). The vacuum pump is initially operated to generate a pressure below 50 Pa in the chamber, with the cooling system set at 15°C. The chamber evacuation device is switched from a vacuum pump to a molecular pump by rapidly opening the shut-off valve, closing the angle valve, and opening the butterfly valve. Through this operation, the chamber is evacuated to a much higher vacuum by the molecular pump, while the operation of the molecular pump is not protected by the vacuum pump. When the vacuum level reaches 3*10... -3 At pa, turn on the heating boat. Adjust the mask to temporarily cover the substrate surface while simultaneously turning on the rotating component to drive the substrate to rotate at a constant speed, thus promoting more uniform deposition. Then turn on the thickness monitor based on a QCM (Quartz Crystal Microbalance, Fil-Tech Inc.). Adjust the current on the heating boat to obtain the desired aluminum deposition rate (typically 10 Å / s to 50 Å / s), then quickly remove the mask from the substrate and simultaneously reset the thickness reading on the QCM to zero. Continue deposition until a thickness of approximately 20 nm is reached. Then immediately turn off the heating boat. The molecular pump stops but does not shut down until the rate drops to zero. During this stage, the vacuum pump protection continues. After shutting down the vacuum pump, vent the chamber to the atmosphere. The metallized multilayer structure is then removed from the chamber and placed in a dustproof box.

[0069] The bond strength between the metal layer and the outer layer of each multilayer structure was then measured as follows. The multilayer structure was heat-sealed to a 100-micron membrane (“EAA membrane”) made of an ethylene-acrylic acid copolymer with an acrylic acid content of ~7%, with the metal layer of the multilayer structure in contact with the EAA membrane. The multilayer structure and the EAA membrane were heat-sealed by placing the membrane between an upper jaw at 110°C and a lower jaw at 70°C, with the upper jaw in contact with the EAA membrane and the lower jaw in contact with the multilayer structure. The jaws were in contact with the EAA membrane and the multilayer structure for 20 seconds at a pressure of 5 bar. After aging at room temperature for 24 hours, the bond strength was measured using an Instron 5567 tensile testing machine by measuring T-peel strength at a test speed of 12 inches / minute using a 100 N load sensor. The average value was used as the bond strength between the outer layer of the membrane and the metal layer. The results are shown in Table 3.

[0070] Table 3

[0071] Comparison of multi-layer structures 1 Membrane 1 0.246 Comparison of multi-layer structures 2 Membrane 2 0.374 The multi-layer structure of the present invention 1 Membrane 3 0.566 Comparison of multi-layer structures 3 Membrane 4 0.310 Comparison of multi-layer structures 4 Membrane 5 0.310 Comparison of multi-layer structures 5 Membrane 6 0.286 Comparison of multi-layer structures 6 Membrane 7 0.209 Comparison of multi-layer structures 7 Membrane 8 0.615 The multi-layer structure of the present invention 3 Membrane 9 1.451 Comparison of multi-layer structures 8 Membrane 10 0.352

[0072] As shown above, when the outer layer of the membrane contains a blend of 10% or 15% by weight maleic anhydride-grafted polyethylene and polypropylene homopolymer (multilayer structures 1 and 3 of the present invention), the bonding strength is significantly greater than that of the corresponding comparative multilayer structures (e.g., comparative multilayer structures 1-2 and 6-7).

Claims

1. A multi-layer structure, the multi-layer structure comprising: (a) A membrane, wherein the outer layer of the membrane comprises (i) 8% to 35% by weight of a blend of maleic anhydride-grafted polyethylene with a density of less than 0.905 g / cc and greater than or equal to 0.860 g / cc and a melt index I2 of greater than 50.0 g / 10 min and less than or equal to 1000.0 g / 10 min and (ii) 65% to 92% by weight of a polypropylene homopolymer; as well as (b) A metal layer comprising a metal deposited on the outer layer of the film.

2. The multilayer structure according to claim 1, wherein the maleic anhydride-grafted polyethylene has a maleic anhydride content of greater than 0.5% by weight.

3. The multilayer structure according to claim 1 or 2, wherein the maleic anhydride-grafted polyethylene has a Brookfield viscosity of 8.0 Pa·s to 18.0 Pa·s at 177°C.

4. The multilayer structure according to claim 1 or 2, wherein the metal is selected from Al, Si, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, their oxides and combinations thereof.

5. The multilayer structure according to claim 1 or 2, wherein the metal comprises Al metal, Al oxide, or both.

6. The multilayer structure according to claim 1 or 2, wherein the metal is deposited on the film by vacuum metallization.

7. The multilayer structure according to claim 1 or 2, wherein the metal layer has a thickness of 10 nanometers to 60 nanometers.

8. The multilayer structure according to claim 1, wherein the outer layer of the membrane comprises (i) a blend of (i) 12% to 35% by weight of the maleic anhydride-grafted polyethylene and (ii) 65% to 88% by weight of the polypropylene homopolymer, and wherein the maleic anhydride-grafted polyethylene has a maleic anhydride content of greater than 0.5% to 2.0% by weight.

9. A layered compound comprising a multilayer structure according to any one of claims 1-8 in adhesive contact with a second membrane.

10. An article comprising the layered compound according to claim 9.

Images