CN109963714B

CN109963714B - Multilayer stretched film having high adhesion and method thereof

Info

Publication number: CN109963714B
Application number: CN201780070228.XA
Authority: CN
Inventors: M·G·D·奥利韦拉; T·P·卡里亚拉; M·比尔根; J·C·戈梅斯; M·扎内蒂; M·A·莫拉诺尼阿姆皮拉; J·M·罗德里格斯卡梅洛; C·D·威莱; G·A·雷蒙迪
Original assignee: PBBPolisur SRL; Dow Chemical Co Ltd; Dow Global Technologies LLC
Current assignee: PBBPolisur SRL; Dow Chemical Co Ltd; Dow Global Technologies LLC
Priority date: 2016-09-29
Filing date: 2017-09-11
Publication date: 2021-09-10
Anticipated expiration: 2037-09-11
Also published as: MY193008A; BR112019006100A2; CN109963714A; CA3038537A1; JP2019531933A; WO2018063782A1; JP7100628B2; EP3519191A1; MX2019003240A

Abstract

Embodiments disclosed herein include multilayer films having an adhesion layer, a core layer, and a release layer, wherein the adhesion layer comprises a propylene interpolymer, and the core layer comprises a core layer polyethylene composition.

Description

Multilayer stretched film having high adhesion and method thereof

Technical Field

Embodiments of the present disclosure generally relate to multilayer stretched films, and more particularly to multilayer stretched films having high adhesion.

Background

Multilayer films are often used for packaging, and can package a variety of items, for example, bulk farm materials (such as grass and hay) to small grocery items (such as meat and vegetables). For all of these articles, a strong film having sufficient levels of tack or adhesion to be stretchable is often required so that the film can be releasably adhered to itself and/or to the article to which it is wrapped.

Adhesion is one of the key performance requirements for stretch films. To achieve the desired level of adhesion, additives may be incorporated into the adhesive layer to improve the tack of the adhesive layer. However, films including these additives may have a higher cost than the base resin, and may have a significant impact on the overall cost of the stretched film. In addition, films including such additives may have one or more disadvantages, such as 1) excessive noise when unwound from the film-roll when used on high speed wrapping machines, 2) the necessity for aging for a period of time such that the additives migrate to the film surface during the aging period (i.e., bloom), 3) fouling process equipment, and 4) causing double-sided adhesion when single-sided adhesion is desired. In addition, when these additives are in liquid form and drip to an inappropriate degree from the process equipment, improper handling problems may be caused.

The multilayer film may also incorporate high levels of ethylene/alpha-olefin elastomer to achieve higher levels of tack or adhesion; however, ethylene/alpha-olefin elastomers can make multilayer films very expensive.

Accordingly, there may be a need for alternative multilayer films that have improved properties, such as high adhesion, while also being cost effective and/or relatively easy to manufacture using cast film techniques.

Disclosure of Invention

Disclosed in the examples herein are multilayer cast films. The multilayer cast film has an adhesion layer, a core layer, and a release layer, wherein: the adhesion layer comprises a propylene interpolymer comprising at least 60 weight percent units derived from propylene and between 1 and 40 weight percent units derived from ethylene, wherein the propylene interpolymer has 0.840g/cm when measured at 230 ℃ and 2.16kg load according to ASTM D1238³To 0.900g/cm³(ii) a maximum DSC melting peak temperature of 50.0 ℃ to 120.0 ℃, a melt flow rate MFR2 of 1 to 100g/10min, and a Molecular Weight Distribution (MWD) of less than 4.0; and the core layer comprises a core layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the core layer polyethylene composition is characterized by one or more of the following properties: (a) a melt index I2 of 2.5 to 12.0g/10 min; (b) a density of 0.910 to 0.925 g/cc; (c) a melt flow ratio I10/I2 of 6.0 to 7.6; and (d) a molecular weight distribution (Mw/Mn) of 2.25 to 4.0.

Also disclosed in the examples herein are methods of making multilayer cast films. The method comprises coextruding an adhesion layer composition, a core layer composition, and a release layer composition to form a multilayer cast film; wherein the adhesion layer composition comprises a propylene interpolymer comprising at least 60 weight percent of units derived from propylene and between 1 and 40 weight percent of units derived from ethylene, wherein the propylene interpolymer has 0.840g/cm when measured according to ASTM D1238 at 230 ℃ and 2.16kg load³To 0.900g/cm³(ii) a maximum DSC melting peak temperature of 50.0 ℃ to 120.0 ℃, a melt flow rate MFR2 of 1 to 100g/10min, and a Molecular Weight Distribution (MWD) of less than 4.0; wherein the core layer composition comprises a core layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the core layer polyethylene composition is characterized by one or more of the following properties: (a)2.5 to 12.0g/10min of melt indexNumber I2; (b) a density of 0.910 to 0.925 g/cc; (c) a melt flow ratio I10/I2 of 6.0 to 7.6; and (d) a molecular weight distribution (Mw/Mn) of from 2.25 to 4.0; and wherein the release layer composition comprises a linear low density polyethylene or release layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the release layer polyethylene composition is characterized by one or more of the following properties: (a) a melt index I2 of 2.5 to 12.0g/10 min; (b) a density of 0.910 to 0.925 g/cc; (c) a melt flow ratio I10/I2 of 6.0 to 7.6; and (d) a molecular weight distribution (Mw/Mn) of 2.25 to 4.0.

Additional features and advantages of the embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows and the claims. It is to be understood that both the foregoing and the following description describe various embodiments, and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The description serves to explain the principles and operations of the claimed subject matter.

Detailed Description

Reference will now be made in detail to embodiments of multilayer cast films and materials used to make such films. "multilayer cast film" and "multilayer film" are used interchangeably herein to refer to multilayer cast films described herein. Multilayer cast films can be used in stretch-cling applications. It should be noted, however, that this is merely an illustrative implementation of the examples disclosed herein. Embodiments are applicable to other technologies that are susceptible to problems similar to those discussed above. For example, the multilayer cast films described herein may be used as surface protective films, agricultural films (e.g., silage wrap), or other flexible packaging applications such as shrink films, heavy duty shipping bags, liners, sacks, stand up bags, detergent bags, pouches, and the like, all within the scope of embodiments of the invention.

In embodiments described herein, the multilayer cast film comprises an adhesion layer, a core layer, and a release layer. Optionally, one or more intermediate layers may be positioned between the adhesion layer and the core layer and/or the core layer and the release layer. The adhesion layer is an outer layer of the multilayer cast film having a sufficient level of adhesion such that the adhesion layer of the multilayer cast film can form a releasable bond when in contact with a surface, such as a surface of an article or a surface of a release layer. The release layer is the outer layer of the multilayer cast film, which exhibits low adhesion to the adhesion layer. The release layer can allow separation to occur between the adhesive layer/release layer interface on the roll so that the multilayer cast film can be unwound from the roll without undue force and/or without film tearing.

The thickness of the adhesive layer, core layer and release layer may vary over a wide range. In some embodiments, the thickness of the adhesion layer may be 5-50% of the overall thickness of the film, 5-30% of the overall thickness of the film, or even 5-20% of the overall thickness of the film. The thickness of the core layer may be 20-90% of the overall thickness of the film, 30-90% of the overall thickness of the film, 50-90% of the overall thickness of the film, or 60-90% of the overall thickness of the film. The release layer may have a thickness of 5-50% of the overall thickness of the film, 5-30% of the overall thickness of the film, or even 5-20% of the overall thickness of the film. The thickness ratio between the adhesive layer, release layer, and core layer can be any ratio that provides the desired properties, such as adhesion, release, and the like. In some embodiments, the multilayer cast film may have an adhesion layer thickness, a core layer thickness, and a release layer thickness in a ratio ranging from 1:8:1 to 3:4: 3.

Adhesive layer

The adhesion layer can comprise a propylene interpolymer. As used herein, "polymer" means a polymeric compound prepared by polymerizing monomers of the same or different types. The generic term "polymer" encompasses the terms "homopolymer," copolymer, "" terpolymer, "and" interpolymer. "interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term "interpolymer" includes the term "copolymer" (which is generally used to refer to polymers prepared from two different monomers) as well as the term "terpolymer" (which is generally used to refer to polymers prepared from three different types of monomers). It also encompasses polymers made by polymerizing four or more types of monomers.

Propylene interpolymers generally refer to polymers comprising propylene and an alpha-olefin having 2 carbon atoms or 4 or more carbon atoms. In embodiments herein, the propylene interpolymer comprises at least 60 weight percent of units derived from propylene and between 1 and 40 weight percent of units derived from ethylene (based on the total amount of polymerizable monomers). All individual values and subranges from at least 60 weight percent of the units derived from propylene and between 1 and 40 weight percent of the units derived from ethylene are included and disclosed herein. For example, in some embodiments, the propylene interpolymer comprises (a) at least 65, at least 70, at least 75, at least 80, at least 82, at least 85, at least 87, at least 90, at least 92, at least 95, at least 97, 60 to 99, 65 to 99, 70 to 99, 75 to 99, 80 to 99, 82 to 99, 84 to 99, 85 to 99, 88 to 99, 80 to 97, 82 to 97, 85 to 97, 88 to 97, 80 to 95.5, 82 to 95.5, 84 to 95.5, 85 to 95.5, or 88 to 95.5 weight percent units derived from propylene; (b) between 1 and 40 wt%, e.g., 1 to 35 wt%, 1 and 30 wt%, 1 and 25 wt%, 1 to 20 wt%, 1 to 18 wt%, 1 to 16 wt%, 1 to 15 wt%, 1 to 12 wt%, 3 to 20 wt%, 3 to 18 wt%, 3 to 16 wt%, 3 to 15 wt%, 3 to 12 wt%, 4.5 to 20 wt%, 4.5 to 18 wt%, 4.5 to 16 wt%, 4.5 to 15 wt%, or 4.5 to 12 wt% of units derived from ethylene. Comonomer content can be measured using any suitable technique, such as techniques based on nuclear magnetic resonance ("NMR") spectroscopy and, for example, by 13C NMR analysis as described in U.S. patent 7,498,282, which is incorporated herein by reference.

The propylene interpolymers may be made by any process and include random, block, and graft copolymers. In some embodiments, the propylene interpolymer has a random configuration. These include interpolymers made from Ziegler-Natta (Ziegler-Natta), CGC (constrained geometry catalyst), metallocene and non-metallocene, metal-centered, heteroaryl ligand catalysis. Further suitable metal complexes include compounds corresponding to the formula:

wherein:

R²⁰is an aromatic or inertly substituted aromatic group containing from 5 to 20 atoms not counting hydrogen or a polyvalent derivative thereof;

T³is an alkylene or silane group having from 1 to 20 atoms not counting hydrogen, or an inertly substituted derivative thereof;

M³is a group 4 metal, preferably zirconium or hafnium;

g is an anionic, neutral or dianionic ligand group; preferably not counting halide, hydrocarbyl or dihydrocarbylamido groups in which the hydrogen has up to 20 atoms;

g is a number from 1 to 5, indicating the number of such G groups; and is

Covalent bonds and electron donating interactions are indicated by lines and arrows, respectively.

In some embodiments, such complexes correspond to the formula:

wherein:

T³a divalent bridging group of 2 to 20 atoms not counting hydrogen, preferably substituted or unsubstituted C_3-6An alkylene group; and is

Ar²(ii) arylene of 6 to 20 atoms not counting hydrogen, or arylene substituted with alkyl or aryl independently at each occurrence;

M³is a group 4 metal, preferably hafnium or zirconium;

g is independently at each occurrence an anionic, neutral or dianionic ligand group;

g is a number from 1 to 5, indicating the number of such X groups; and is

The electron donating interaction is represented by the arrows.

Examples of metal complexes of the foregoing formula include the following compounds:

wherein M is³Is Hf or Zr;

Ar⁴is C_6-20Aryl or inertly substituted derivatives thereof, especially 3, 5-di (isopropyl) phenyl, carbazole, 3, 5-di (isobutyl) phenyl, dibenzo-1H-pyrrol-1-yl or anthracen-5-yl, and

T⁴independently at each occurrence, contains C_3-6Alkylene radical, C_3-6Cycloalkylene or inertly substituted derivatives thereof;

R²¹independently at each occurrence, hydrogen, halo, hydrocarbyl of up to 50 atoms not counting hydrogen, trihydrocarbylsilyl, or trihydrocarbylsilylhydrocarbyl; and is

G is independently at each occurrence a halo or hydrocarbyl or trihydrocarbylsilyl group of up to 20 atoms not counting hydrogen, or 2G groups together are a divalent derivative of the foregoing hydrocarbyl or trihydrocarbylsilyl group.

Without in any way limiting the scope of the invention, one way to make the propylene interpolymers as described herein is as follows: in a stirred tank reactor, the monomer to be polymerized is introduced continuously with any solvent or diluent, and in some embodiments, the solvent is an alkane solvent, such as ISOPAR^TME. The reactor contains a liquid phase consisting essentially of the monomers, as well as any solvent or diluent and dissolved polymer. The catalyst is introduced, continuously or intermittently, into the liquid phase of the reactor or any recycled portion thereof, along with the cocatalyst and optionally chain transfer agent. Reactor temperature can be controlled by adjusting the solvent/monomer ratio, the catalyst addition rate, and by using cooling or heating coils, jackets, or both. The polymerization rate is controlled by the catalyst addition rate. The pressure is controlled by the monomer flow rate and the partial pressure of the volatile components. Propylene content of the polymer product from propylene copolymerization in the reactorThe ratio of monomers is determined and controlled by manipulating the respective feed rates of these components to the reactor. The polymer product molecular weight is optionally controlled by controlling other polymerization variables such as temperature, monomer concentration, or the flow rate of the chain transfer agent as mentioned previously. Upon exiting the reactor, the effluent is contacted with a catalyst kill agent, such as water, steam, or alcohol. The polymer solution is optionally heated and the polymer product recovered by flashing off gaseous unreacted monomers and residual solvent or diluent under reduced pressure and, if desired, further devolatilization in equipment such as a devolatilizing extruder. In a continuous process, the average residence time of the catalyst and polymer in the reactor is typically from 5 minutes to 8 hours, and in some embodiments from 10 minutes to 6 hours.

Without limiting the scope of the invention in any way, another way to make propylene interpolymers as described herein is as follows: continuous solution polymerization may be carried out in a computer controlled autoclave reactor equipped with an internal stirrer. The purified mixed alkane solvent (ISOPAR available from ExxonMobil Chemical Company) can be used^TME) Ethylene, propylene and hydrogen were continuously supplied to a 3.8L reactor equipped with a jacket for temperature control and an internal thermocouple. The solvent feed to the reactor can be measured by a mass flow controller. A variable speed diaphragm pump controls the solvent flow rate and pressure to the reactor. At the discharge of the pump, a side stream was taken to provide a flushing flow to the catalyst and cocatalyst injection lines and the reactor agitator. These flows are measured by mass flow meters and controlled by control valves or by manually adjusting needle valves. The remaining solvent is combined with monomer and hydrogen and fed to the reactor. The mass flow controller is used to deliver hydrogen to the reactor as needed. The temperature of the solvent/monomer solution is controlled by using a heat exchanger prior to entering the reactor. This stream enters the bottom of the reactor.

The catalyst and co-catalyst component solutions can be metered using pumps and mass flow meters and combined with the catalyst flush solvent and introduced to the bottom of the reactor. The catalyst may be a metal complex as described above. In some embodiments, the catalyst may be bis ((2-oxo-3- (dibenzo-1H-pyrrol-1-yl) -5- (methyl) phenyl) -2-phenoxymethyl) -methylphenyl-1, 2-cyclohexanediylhafnium (IV) dimethyl, as outlined above. The cocatalyst was a combination of a long chain alkylammonium borate salt approximately stoichiometrically equivalent to the dioctadecyl ammonium tetrakis (pentafluorophenyl) borate (MDB) salt and a tri (isobutyl) aluminum Modified Methylalumoxane (MMAO) containing an isobutyl/methyl molar ratio of about 1/3 as the tertiary component. The catalyst/cocatalyst can have a molar ratio, calculated as Hf, of 1.0/1 to 1.5/1, and MMAO (ratio 25/1-35/1, Al/Hf). The reactor can be operated at 500-. The reactor temperature may be in the range of 125 ℃ to 165 ℃, and the propylene conversion may be about 80%. The reactor is operated at a polymer concentration of between about 15 and 20 wt.%. The conversion of propylene in the reactor can be maintained by controlling the catalyst injection rate. The reaction temperature can be maintained by controlling the water temperature throughout the shell side of the heat exchanger. The molecular weight of the polymer can be maintained by controlling the hydrogen flow.

The product is removed at the top of the reactor through an outlet line. All outlet lines from the reactor were trace and insulated with steam. The polymerization can be stopped by adding a small amount of water, as well as any stabilizers or other additives, to the outlet line and passing the mixture through a static mixer. The product stream may then be heated by a heat exchanger prior to devolatilization. The polymer product can be recovered by extrusion using a devolatilizing extruder and a water-cooled pelletizer.

Exemplary propylene interpolymers can include VISTA MAXX from Exxon Mobil chemical Co^TMVERSIFY from polymer and dow chemical company^TMA polymer.

In embodiments herein, the propylene interpolymer has 0.840g/cm³To 0.900g/cm³As measured by ASTM D-792. 0.840g/cm is included and disclosed herein³To 0.900g/cm³All individual values and subranges of (a). For example, in some embodiments, the propylene interpolymer has a density of 0.850g/cm³To 0.890g/cm³、0.850g/cm³To 0.880g/cm³Or 0.850g/cm³To 0.870g/cm³The density of (c).

In addition to density, the propylene interpolymers have a differential scanning calorimetry ("DSC") melting peak temperature of from 50.0 ℃ to 120.0 ℃. All individual values and subranges from 50.0 ℃ to 120.0 ℃ are included herein and disclosed herein. For example, in some embodiments, the propylene interpolymer has a highest DSC melting peak temperature of 50.0 ℃ to 115.0 ℃, 50.0 ℃ to 110.0 ℃, 50.0 ℃ to 100.0 ℃, or 50.0 ℃ to 105.0 ℃.

In addition to density and DSC melting peak temperature, the propylene interpolymers have a melt flow rate of 1 to 100g/10min, as measured according to ASTM d-1238(2.16kg, 230 ℃). All individual values and subranges from 1 to 100g/10min are included herein and disclosed herein. For example, in some embodiments, the propylene interpolymer has a melt flow rate of from 1 to 50g/10min or from 1 to 30g/10 min.

In addition to density, DSC melting peak temperature, and melt flow rate, the propylene interpolymers have a Molecular Weight Distribution (MWD) of less than 4.0. Molecular Weight Distribution (MWD) is the ratio of weight average molecular weight to number average molecular weight (Mw/Mn). Molecular weight can be determined by gel permeation chromatography. All individual values and subranges from less than 4.0 are included herein and disclosed herein. For example, in some embodiments, the propylene interpolymer has a molecular weight distribution from 2.0 to 4.0, from 2.0 to 3.7, from 2.0 to 3.5, from 2.0 to 3.2, from 2.0 to 3.0, or from 2.0 to 2.8.

In addition to density, DSC melting peak temperature, melt flow rate, and MWD, the propylene interpolymers can have a weight average molecular weight (Mw) of at least 50,000 g/mol. All individual values and subranges from at least 50,000g/mol are included herein and disclosed herein. For example, in some embodiments, the propylene interpolymer may have a weight average molecular weight (Mw) of between 50,000 and 1,000,000g/mol, between 50,000 and 500,000 g/mol, between 50,000 and 400,000g/mol, or between 50,000 and 300,000 g/mol.

In addition to density, DSC melting peak temperature, melt flow rate, MWD, and weight average molecular weight, the propylene interpolymers have a% crystallinity, as determined by DSC, in the range of from 0.5% to 45%. All individual values and subranges from 0.5% to 45% are included herein and disclosed herein. For example, in some embodiments, the propylene interpolymer has a% crystallinity, as determined by DSC, in the range of from 2% to 42%.

In embodiments herein, the adhesion layer comprises 3 to 30 weight percent of the propylene interpolymer. All individual values and subranges from 3 to 30 weight percent are included herein and disclosed herein. For example, in some embodiments, the adhesion layer comprises from 3 wt% to 25 wt%, from 3 wt% to 20 wt%, or from 3 wt% to 15 wt% of the propylene interpolymer, based on the weight of the adhesion layer.

Optionally, the adhesion layer may include one or more additives, such as pigments, inorganic fillers, UV stabilizers, antioxidants, and the like, and/or additional polymers. For example, in some embodiments, the adhesion layer may be dry blended or melt blended with 70 wt% to 95 wt% or 85 wt% to 95 wt% of the linear low density polyethylene or adhesion layer polyethylene composition to form the adhesion layer blend. The tie-layer polyethylene composition comprises the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the tie-layer polyethylene composition is characterized by one or more of the following properties: (a) a melt index I2 of 2.5 to 12.0g/10min or 2.5 to 8.0; (b) a density of 0.910 to 0.925g/cc or 0.912 to 0.920 g/cc; (c) a melt flow ratio I10/I2 of 6.0 to 7.6 or 6.4 to 7.4; and (d) a molecular weight distribution (Mw/Mn) of 2.25 to 4.0 or 2.6 to 3.5. The linear low density polyethylene may have a density in the range of 0.912 to 0.940 g/cc and a melt index in the range of 0.5 to 30g/10 min. The tie-layer polyethylene composition is formed via solution polymerization in the presence of a catalyst composition comprising a multi-metallic procatalyst. In further embodiments, the adhesion layer polyethylene composition may have a CDBI of less than 60% or from 40% to 60%. Exemplary LLDPE for the release layer of the multilayer film may be under the trade name ELITE^TM、TUFLIN^TMAnd DOWLEX^TMPurchased from the dow chemical company. A method for dry blending resins can be found in U.S. patent No. 3,318,538 (needleham), the entire contents of which are incorporated herein by reference. Can be found in U.S. Pat. No. 6,111,019(Arjunan et al)The patent is incorporated herein by reference in its entirety.

Core layer

The core layer comprises a core layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers. The core layer polyethylene composition comprises greater than 50 wt% units derived from ethylene and less than 30 wt% units derived from one or more alpha-olefin comonomers. In some embodiments, the core layer polyethylene composition comprises (a) greater than or equal to 55 wt%, such as greater than or equal to 60 wt%, greater than or equal to 65 wt%, greater than or equal to 70 wt%, greater than or equal to 75 wt%, greater than or equal to 80 wt%, greater than or equal to 85 wt%, greater than or equal to 90 wt%, greater than or equal to 92 wt%, greater than or equal to 95 wt%, greater than or equal to 97 wt%, greater than or equal to 98 wt%, greater than or equal to 99 wt%, greater than or equal to 99.5 wt%, greater than 50 wt% to 99 wt%, greater than 50 wt% to 97 wt%, greater than 50 wt% to 94 wt%, greater than 50 wt% to 90 wt%, 70 wt% to 99.5 wt%, 70 wt% to 99 wt%, 70 wt% to 97 wt%, 70 wt% to 94 wt%, 80 wt% to 99.5 wt%, 80 to 99 weight percent, 80 to 97 weight percent, 80 to 94 weight percent, 80 to 90 weight percent, 85 to 99.5 weight percent, 85 to 99 weight percent, 85 to 97 weight percent, 88 to 99.9 weight percent, 88 to 99.7 weight percent, 88 to 99.5 weight percent, 88 to 99 weight percent, 88 to 98 weight percent, 88 to 97 weight percent, 88 to 95 weight percent, 88 to 94 weight percent, 90 to 99.9 weight percent, 90 to 99.5 weight percent, 90 to 99, 97, 90 to 95, 93 to 99.9, 93 to 99.5, 93 to 99, or 93 to 97 weight percent of units derived from ethylene; and (b) optionally, less than 30 wt%, e.g., less than 25 wt%, or less than 20 wt%, less than 18 wt%, less than 15 wt%, less than 12 wt%, less than 10 wt%, less than 8 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, less than 1 wt%, 0.1 wt% to 20 wt%, 0.1 wt% to 15 wt%, 0.1 wt% to 12 wt%, 0.1 wt% to 10 wt%, 0.1 wt% to 8 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 3 wt%, 0.1 wt% to 2 wt%, 0.5 wt% to 12 wt%, 0.5 wt% to 10 wt%, 0.5 wt% to 8 wt%, 0.5 wt% to 5 wt%, 0.5 wt% to 3 wt%, 0.5 wt% to 2.5 wt%, 1 wt% to 10 wt%, 1 wt% to 8 wt%, 0.5 wt% to 5 wt%, 0.5 wt%, 1 wt% to 10 wt%, 1 wt% to 8 wt%, or a combination thereof, 1 to 5 wt%, 1 to 3 wt%, 2 to 10 wt%, 2 to 8 wt%, 2 to 5 wt%, 3.5 to 12 wt%, 3.5 to 10 wt%, 3.5 to 8 wt%, 3.5 to 7 wt%, or 4 to 12 wt%, 4 to 10 wt%, 4 to 8 wt%, or 4 to 7 wt% of units derived from one or more a-olefin comonomers. Comonomer content can be measured using any suitable technique, such as techniques based on nuclear magnetic resonance ("NMR") spectroscopy and, for example, by 13C NMR analysis as described in U.S. patent 7,498,282, which is incorporated herein by reference.

Suitable comonomers may include alpha-olefin comonomers, which typically have no more than 20 carbon atoms. The one or more alpha-olefins may be selected from the group consisting of: C3-C20 acetylenically unsaturated monomers and C4-C18 dienes. Those skilled in the art will appreciate that the monomers selected are the ideal monomers that do not destroy conventional Ziegler-Natta catalysts. For example, the alpha-olefin comonomer can have 3 to 10 carbon atoms or 3 to 8 carbon atoms. Exemplary alpha-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more alpha-olefin comonomers may for example be selected from the group consisting of: propylene, 1-butene, 1-hexene and 1-octene; or in the alternative, selected from the group consisting of: 1-butene, 1-hexene and 1-octene. In some embodiments, the core layer polyethylene composition comprises greater than 0 wt% and less than 30 wt% units derived from one or more of octene, hexene, or butene comonomers.

In some embodiments, the core layer polyethylene composition of the core layer is formed via solution polymerization in the presence of a catalyst composition comprising a multi-metallic procatalyst. The multi-metallic procatalyst used to produce the reaction product is at least trimetallic, but may also include more than three transition metals, and thus may be more fully defined as multi-metallic in one embodiment. These three or more transition metals are selected prior to the production of the catalyst. In one particular embodiment, the multi-metallic catalyst comprises titanium as one element.

The catalyst composition may be prepared first starting with the preparation of the conditioned magnesium halide based support. The preparation of the conditioned magnesium halide based support begins with the selection of an organomagnesium compound or a complex comprising an organomagnesium compound. Such compounds or complexes are desirably soluble in an inert hydrocarbon diluent. The concentration of the components is preferably such that when an active halide, such as a metal or non-metal halide, and a magnesium complex are combined, the resulting slurry is from about 0.005 to about 0.25 moles (moles/liter) relative to magnesium. Examples of suitable inert organic diluents include liquefied ethane, propane, isobutane, n-butane, n-hexane, various isomeric hexanes, isooctane, paraffin mixtures of alkanes having 5 to 10 carbon atoms, cyclohexane, methylcyclopentane, dimethylcyclohexane, dodecane, industrial solvents composed of saturated or aromatic hydrocarbons, such as kerosene, naphtha, and combinations thereof, particularly when free of any olefinic compounds and other impurities and particularly those having a boiling point in the range of about-50 ℃ to about 200 ℃. Also included as suitable inert diluents are ethylbenzene, cumene, decalin, and combinations thereof.

Suitable organomagnesium compounds and complexes can include, for example, magnesium C2-C8 alkyl and aryl groups, magnesium alkoxides and aryl oxides, magnesium carboxylated alkoxides, and magnesium carboxylated aryl oxides. Preferred sources of magnesium moieties may include magnesium C2-C8 alkyls and C1-C4 alkoxides. Such organomagnesium compounds or complexes can be reacted with a metal or nonmetal halide source (e.g., chloride, bromide, iodide, or fluoride) under suitable conditions to produce a magnesium halide compound. Such conditions may include a temperature in the range of-25 ℃ to 100 ℃, alternatively 0 ℃ to 50 ℃; a time in the range of 1 to 12 hours, alternatively 4 to 6 hours; or both. The result is a support based on magnesium halide.

The magnesium halide support is then reacted with a selected modulating compound containing an element selected from the group consisting of: boron, aluminum, gallium, indium, and tellurium. This compound is then contacted with a magnesium halide support under conditions sufficient to produce a conditioned magnesium halide support. Such conditions may include a temperature in the range of from 0 ℃ to 50 ℃, or alternatively from 25 ℃ to 35 ℃; a time in the range of 4 to 24 hours, or alternatively 6 to 12 hours; or both. The adjusting compounds have a specific molar ratio constitution and are regarded as important features in ensuring the desired catalyst performance. In particular, the procatalyst desirably exhibits a molar ratio of magnesium to the modulating compound in the range of 3:1 to 6: 1. Without wishing to be bound by any theory of mechanism, it is suggested that this aging serves to promote or enhance the adsorption of additional metals onto the support.

Once the conditioned support is prepared and suitably aged, it is contacted with a titanium compound, which may be added alone or as a mixture with a "second metal". In certain preferred embodiments, a titanium halide or alkoxide, or a combination thereof, may be selected. Conditions may include a temperature in the range of 0 ℃ to 50 ℃, alternatively 25 ℃ to 35 ℃; a time in the range of 3 hours to 24 hours, alternatively 6 hours to 12 hours; or both. The result of this step is the adsorption of at least a portion of the titanium compound onto the conditioned magnesium halide support.

Finally, for convenience, one or two additional metals, referred to herein as "second metal" and "third metal", will also be adsorbed onto the magnesium-based support, the "second metal" and "third metal" being independently selected from zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), and tungsten (W). These metals may be incorporated in any of a variety of ways known to those skilled in the art, but in general, contact between the conditioned magnesium-based halide support, including titanium in, for example, a liquid phase (e.g., a suitable hydrocarbon solvent), and the selected second and third metals will be suitable to ensure deposition of additional metals to form what may now be referred to as a "procatalyst," which is a multi-metal procatalyst.

The multi-metal procatalyst has a specific molar ratio composition and is considered an important feature in ensuring desirable polymer properties attributable to the catalyst prepared from the procatalyst. In particular, the procatalyst desirably exhibits a molar ratio of magnesium to the combination of titanium and the second and third metals in the range of 30:1 to 5:1 under conditions sufficient to form the multi-metallic procatalyst. Thus, the overall molar ratio of magnesium to titanium is in the range of 8:1 to 80: 1.

Once the procatalyst is formed, it can be used to form the final catalyst by combining it with a cocatalyst consisting of at least one organometallic compound, such as an alkylaluminum or haloalkylaluminum halide, alkylaluminum halide, grignard reagent, alkali metal aluminum hydride, alkali metal borohydride, alkali metal hydride, alkaline earth metal hydride, and the like. The formation of the final catalyst from the reaction of the procatalyst with the organometallic cocatalyst may be carried out in situ or just prior to entering the polymerization reactor. Thus, the combination of the cocatalyst and the procatalyst can be carried out under various conditions. Such conditions may include, for example, contacting them under an inert atmosphere (such as nitrogen, argon, or other inert gas) at a temperature in the range of from 0 ℃ to 250 ℃, preferably from 15 ℃ to 200 ℃. In the preparation of the catalytic reaction product, it is not necessary to separate the hydrocarbon soluble components from the hydrocarbon insoluble components. The contact time between the main catalyst and the cocatalyst may desirably be, for example, in the range of 0 to 240 seconds, preferably 5 to 120 seconds. Various combinations of these conditions may be used.

In embodiments described herein, the core layer polyethylene composition may have greater than or equal to 1 combined weight part of at least three metal residues per one million parts of the metal catalyst residues of the polyethylene polymer, wherein the at least three metal residues are selected from the group consisting of: titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, and combinations thereof, and wherein each of the at least three metal residues is present at greater than or equal to 0.2ppm, such as in the range of 0.2 to 5 ppm. All individual values and subranges from greater than or equal to 0.2ppm are included herein and disclosed herein; for example, the core layer polyethylene composition may further comprise greater than or equal to 2 combined parts by weight of at least three metal residues remaining from the multi-metal polymerization catalyst per one million parts of the core layer polyethylene composition.

In some embodiments, the core layer polyethylene composition comprises at least 0.75ppm V (vanadium). All individual values and subranges from at least 0.75ppm V are included herein and disclosed herein; for example, the lower limit of V in the core layer polyethylene composition may be 0.75, 1, 1.1, 1.2, 1.3, or 1.4ppm to the upper limit of V in the core layer polyethylene composition may be 5, 4, 3, 2, 1.9, 1.8, 1.7, 1.6, 1.5, or 1 ppm. The vanadium catalyst metal residue concentration for the core layer polyethylene composition may be measured using the neutron activation method for metals described below.

In some embodiments, the core layer polyethylene composition comprises at least 0.3ppm Zr (zirconium). All individual values and subranges from at least 0.3ppm Zr are included herein and disclosed herein; for example, the lower limit of Zr in the core layer polyethylene composition may be 0.3, 0.4, 0.5, 0.6, or 0.7 ppm. In another embodiment, the upper limit of Zr in the core layer polyethylene composition may be 5, 4, 3, 2, 1, 0.9, 0.8, or 0.7 ppm. The zirconium catalyst metal residue concentration for the core layer polyethylene composition may be measured using the neutron activation method for metals described below.

In embodiments described herein, the core layer polyethylene composition may have a density of from 0.910g/cc to 0.925 g/cc. All individual values and subranges from at least 0.910g/cc to 0.925g/cc are included herein and disclosed herein. For example, in some embodiments, the polyethylene has a density of 0.910 to 0.923g/cc, 0.912 to 0.923g/cc, or 0.912 to 0.920 g/cc. Density can be measured according to ASTM D792.

In addition to density, the core layer polyethylene composition may have a melt index I2 of 2.5g/10min to 12.0g/10 min. All individual values and subranges from at least 2.5g/10min to 12.0g/10min are included herein and disclosed herein. For example, in some embodiments, the core layer polyethylene composition may have a melt index I2 of 2.5g/10min to 10.0g/10min, 2.5g/10min to 8.0g/10min, or 2.5g/10min to 5.0g/10 min. Melt index I2 can be measured according to ASTM D1238(190 ℃ C. and 2.16 kg).

In addition to the density and melt index I2, the core layer polyethylene composition may have a melt flow ratio I10/I2 of 6.0 to 7.6. All individual values and subranges from 6.0 to 7.6 are included herein and disclosed herein. For example, in some embodiments, the core layer polyethylene composition may have a melt flow ratio I10/I2 within a lower limit of 6.0, 6.2, 6.3, or 6.5 to an upper limit of 7.6, 7.5, 7.3, 7.1, or 7.0. In other embodiments, the core layer polyethylene composition may have a melt flow ratio I10/I2 of 6.0 to 7.4 or 6.4 to 7.4. Melt index I10 can be measured according to ASTM D1238(190 ℃ C. and 10.0 kg).

In addition to the density, melt index I2, and melt flow ratio I10/I2, the core layer polyethylene composition may have a molecular weight distribution (Mw/Mn) of 2.25 to 4.0. All individual values and subranges from 2.25 to 4.0 are included herein and disclosed herein. For example, the core layer polyethylene composition may have a Mw/Mn ratio with a lower limit of 2.5, 2.6, 2.7, or 2.8 to an upper limit of 4.0, 3.9, 3.7, 3.5, 3.2, or 3.0. In some embodiments, the core layer polyethylene composition may have a Mw/Mn ratio of 2.5 to 3.5, 2.6 to 3.5, or 2.6 to 3.2. The molecular weight distribution can be described as the weight average molecular weight (M)_w) And number average molecular weight (M)_n) Ratio of (i.e., M)_w/M_n) And can be measured by gel permeation chromatography techniques.

In addition to density, melt index I2, melt flow ratio I10/I2, and molecular weight distribution (Mw/Mn), the core layer polyethylene composition may have a number average molecular weight Mn (g/mol) of 30,000 to 50,000 g/mol. All individual values and subranges from 30,000 to 50,000g/mol are included herein and disclosed herein. For example, the core layer polyethylene composition may have a Mw of 33,000 to 50,000g/mol, 33,000 to 45,000g/mol, or 33,000 to 40,000 g/mol.

In addition to density, melt index I2, melt flow ratio I10/I2, molecular weight distribution (Mw/Mn), and number average molecular weight, the core layer polyethylene composition may have a weight average molecular weight Mw (g/mol) of 60,000 to 110,000 g/mol. All individual values and subranges from 60,000 to 110,000g/mol are included herein and disclosed herein. For example, the core layer polyethylene composition may have a Mw of 65,000 to 105,000g/mol, 75,000 to 100,000g/mol, or 85,000 to 100,000 g/mol.

In addition to density, melt index I2, melt flow ratio I10/I2, molecular weight distribution (Mw/Mn), number average molecular weight, and weight average molecular weight, the core layer polyethylene composition may have a z-average molecular weight Mz (g/mol) of 200,000 to 325,000 g/mol. All individual values and subranges from 200,000 to 325,000g/mol are included herein and disclosed herein. For example, the core layer polyethylene composition may have an Mz of 240,000 to 325,000, 240,000 to 315,000g/mol, or 240,000 to 300,000 g/mol.

In addition to the density, melt index I2, melt flow ratio I10/I2, molecular weight distribution (Mw/Mn), number average molecular weight, weight average molecular weight, and z average molecular weight, the core layer polyethylene composition may have a viscosity ratio (viscosity at 0.1 rad/s/viscosity at 100rad/s, both measured at 190 ℃) of 2 to 6. All individual values and subranges from 2 to 6 are included herein and disclosed herein. For example, the core layer polyethylene composition may have a viscosity ratio of 2 to 4, 2.0 to 2.9, or 2.5 to 3.5.

In addition to density, melt index I2, melt flow ratio I10/I2, molecular weight distribution (Mw/Mn), number average molecular weight, weight average molecular weight, z average molecular weight, and viscosity ratio, the core layer polyethylene composition may have a tan delta at 0.1rad/s measured at 190 ℃ of 15 to 40. All individual values and subranges from 15 to 40 are included herein and disclosed herein. For example, the core layer polyethylene composition may have a tan delta at 0.1rad/s measured at 190 ℃ of 20 to 40, or 25 to 40.

In addition to density, melt index I2, melt flow ratio I10/I2, molecular weight distribution (Mw/Mn), number average molecular weight, weight average molecular weight, z average molecular weight, viscosity ratio, and tan delta, the core layer polyethylene composition may have a composition distribution breadth index CDBI of less than 60%. All individual values and subranges from less than 60% are included herein and disclosed herein. For example, in some embodiments, the core layer polyethylene composition may have a CDBI of from 37% to 60%, or from 40% to 60%.

CDBI can be defined as the weight percent of polymer molecules having a comonomer content within 50% of the median total molar comonomer content. The CDBI of the linear polyethylene without comonomer is defined as 100%. The CDBI of the copolymer is readily calculated from data obtained from crystallization elution fractionation ("CEF"), as described below. Unless otherwise specified, terms such as "comonomer content," "average comonomer content," and the like refer to the bulk comonomer content of a given interpolymer blend, blend component, or fraction, on a molar basis.

In embodiments herein, the core layer comprises 60 to 100 wt% of the core layer polyethylene composition. All individual values and subranges from 60 to 100 weight percent are included herein and disclosed herein. For example, in some embodiments, the core layer comprises from 70 wt% to 100 wt%, from 80 wt% to 100 wt%, from 90 wt% to 100 wt%, or from 95 wt% to 100 wt% of the core layer polyethylene composition, based on the weight of the polymer present in the core layer.

In embodiments described herein, the core layer may further comprise Linear Low Density Polyethylene (LLDPE), Low Density Polyethylene (LDPE), or blends thereof. In some embodiments, the core layer may further comprise LLDPE, LDPE, or blends thereof in an amount in the range of 1 to 40 weight percent, 1 to 30 weight percent, 1 to 25 weight percent, 5 to 25 weight percent, or 5 to 20 weight percent, based on the weight of the core layer. The LLDPE can have a density in the range of 0.912 to 0.940 g/cc and a melt index in the range of 0.5 to 30g/10 min. The LDPE may have a viscosity of from 0.910 to 0.935g/cm³A density in the range and a melt index in the range of 0.2 to 20g/10 min. The core layer may further comprise one or more additives such as pigments, inorganic fillers, UV stabilizers, antioxidants, and the like.

Release layer

The release layer comprises one or more LDPE, LLDPE, or release layer polyethylene composition, wherein the release layer polyethylene composition is characterized by one or more of the following properties: (a) a melt index I2 of 2.5 to 12.0g/10min or 2.5 to 8.0g/10 min; (b) a density of 0.910 to 0.925g/cc or 0.912 to 0.920 g/cc; (c) a melt flow ratio I10/I2 of 6.0 to 7.6 or 6.4 to 7.4; and (d) a molecular weight distribution (Mw/Mn) of 2.25 to 4.0 or 2.6 to 3.5. The release layer polyethylene composition is formed via solution polymerization in the presence of a catalyst composition comprising a multi-metallic procatalyst. In further embodiments, the release layer polyethylene composition may have a CDBI of less than 60% or 40% to 60%. The LLDPE can have a density in the range of 0.912 to 0.940 g/cc and a melt index in the range of 0.5 to 30g/10 min. Exemplary LLDPE for the release layer of the multilayer film is sold under the trade name ELITE^TM、TUFLIN^TMAnd DOWLEX^TMPurchased from the dow chemical company.

In some embodiments, the release layer comprises LLDPE in an amount of 0 to 100%, 50 to 100%, 75 to 100%, 85 to 100%, or 95 to 100% by weight of the polymer present in the release layer. In other embodiments, the release layer comprises a release layer polyethylene composition in an amount from 0 to 100%, 50 to 100%, 75 to 100%, 85 to 100%, or 95 to 100% by weight of the polymer present in the release layer. In further embodiments, the release layer may comprise LLDPE and release layer polyethylene composition in a weight ratio in the range of 1:4 to 4:1 or 1:3 to 3: 4. The release layer may further comprise one or more additives such as pigments, inorganic fillers, UV stabilizers, antioxidants, and the like.

The multilayer films described herein can be made by various techniques, such as cast film techniques, including uniaxial and biaxial orientation, as is generally known in the art. The multilayer films described herein may also be advantageously stretched in the machine and/or cross direction by at least 50%, preferably 100%. In some embodiments, a multilayer cast film can be made by coextruding an adhesion layer composition, a core layer composition, and a release layer composition to form a multilayer cast film. The adhesion layer composition comprises a propylene interpolymer as previously described herein, and may optionally comprise an adhesion layer polyethylene composition as previously described herein; the core layer composition comprises a core layer polyethylene composition as previously described herein; and the release layer composition comprises a linear low density polyethylene or a release layer polyethylene composition as previously described herein. The core layer polyethylene composition, the tie layer polyethylene composition and the release layer polyethylene composition used in the multilayer cast film may be the same or different independently of each other.

Embodiments of multilayer cast films will now be described further in the illustrative examples below.

Test method

Density of

Density can be measured in accordance with ASTM D-792 in grams per cubic centimeter (g/cc or g/cm)³) And (6) reporting.

Melt index/melt flow Rate

For ethylene-based polymers, the melt index (I2) was measured according to ASTM D1238-10, condition, 190 ℃/2.16kg and is reported in grams eluted per 10 minutes. For ethylene-based polymers, the melt index (I10) was measured according to ASTM D1238-10, condition, 190 ℃/10kg and is reported in grams eluted per 10 minutes. For propylene-based polymers, melt flow rate MFR2 was measured according to ASTM D1238-10, Condition, 230 ℃/2.16kg and is reported in grams eluted per 10 minutes. For propylene-based polymers, melt flow rate MFR10 was measured according to ASTM D1238-10, Condition, 230 ℃/10kg, and is reported in grams eluted per 10 minutes.

High temperature gel permeation chromatography (HT-GPC)

Propylene interpolymers

The polymers were analyzed by Gel Permeation Chromatography (GPC) on a Polymer laboratory (Polymer Laboratories) PL-GPC-220 high temperature chromatography apparatus equipped with three linear mixed bed columns, 300X 7.5mm (Polymer laboratory PLgel mix B (10 micron particle size)). The oven temperature was 160 ℃, with the autosampler hot zone at 160 ℃ and the warm zone at 145 ℃. The solvent was 1,2, 4-trichlorobenzene containing 200ppm of 2, 6-di-tert-butyl-4-methylphenol (BHT). The flow rate was 1.0ml/min and the injection size was 100 microliters. A0.15 wt% sample solution was prepared for injection by dissolving the sample in nitrogen purged 1,2, 4-trichlorobenzene containing 200ppm 2, 6-di-tert-butyl-4-methylphenol for 2.5 hours with gentle stirring at 160 ℃.

The determination of the molecular weight was deduced by using 10 narrow molecular weight distribution polystyrene standards (from polymer laboratories, EasiCal PS1 range 580-7,500,000 g/mol) and their elution volumes. BHT was used as a relative flow rate marker that was run back to the polystyrene narrow standard calibration curve with reference to each chromatogram.

The equivalent polypropylene molecular weight was determined by: suitable Mark-Houwink coefficients for polypropylene (e.g., Th. G. Scholte, N.L. J. Meijerink, H.M. Schofelers and A.M. G. Brands, J.Appl. Polymer. Sci.), 29, 3763-42 3782(1984), which is incorporated herein by reference), and for polystyrene (e.g., E.P.Otokka, R.J.roe, N.Y.Hellman, P.M.Muglia, Macromolecules (Macromolecules) 4,507(1971), which is incorporated herein by reference) are used in the Mark-Houwink (Mark-Houwink) equation (EQ 1) relating intrinsic viscosity to molecular weight. The instantaneous molecular weight (M) of each chromatographic point was determined by EQ 2 using the universal calibration and Mark-Houwink coefficients defined in EQ 1_(PP)). Number average, weight average and z-average molecular weight moments Mn, Mw and Mz were calculated from EQ 3, EQ 4 and EQ 5, respectively, where RI is the refractometer signal height of the polymer elution peak at each chromatographic point (i) minus the baseline.

{η}＝KM^a (EQ 1)

Wherein K_pp＝1.90E-04，a_pp0.725 and K_ps＝1.26E-04，a_ps＝0.702。

Ethylene-based polymers

MW and MWD measurements were performed using a pelimo corporation (PolymerChar) (Valencia, Spain) high temperature gel permeation chromatography system consisting of an infrared concentration detector (IR-5). The solvent delivery pump, in-line solvent degasser, autosampler, and column oven were from Agilent (Agilent). The column compartment and the detector compartment were operated at 150 ℃. The columns were three PLgel 10 μm mix-B columns (Agilent). The carrier solvent was 1,2, 4-Trichlorobenzene (TCB) with a flow rate of 1.0 mL/min. The solvent source used for chromatography and sample preparation contained 250ppm of Butylated Hydroxytoluene (BHT) and was sparged with nitrogen. Polyethylene samples were prepared at a target polymer concentration of 2mg/mL by dissolving in TCB at 160 ℃ for 3 hours on an autosampler just prior to injection. The injection volume was 200. mu.L.

Calibration of GPC column sets was performed using 21 narrow molecular weight distribution polystyrene standards. The molecular weights of the standards ranged from 580 to 8,400,000g/mol and were arranged in 6 "cocktail" mixtures with at least ten times the separation between the individual molecular weights. The peak molecular weight of polystyrene standards was converted to polyethylene molecular weight using the following equation (as described in Williams and Ward, journal of polymer science: polymer press (j.polym. sci., polym.let.) -Let.) -6, 621 (1968):

M_polyethylene＝A(M_Polystyrene)^B (1)

Here the value of B is 1.0 and the experimentally determined value of a is about 0.42.

The corresponding polyethylene equivalent calibration points obtained from equation (1) were fitted to their observed elution volumes using a third order polynomial. A realistic polynomial fit was obtained to relate the logarithm of polyethylene equivalent molecular weights to the observed elution volumes (and associated powers) for each polystyrene standard.

The number average molecular weight, weight average molecular weight, and z average molecular weight were calculated according to the following equations:

wherein, Wf_iIs the weight fraction of the ith component, and M_iIs the molecular weight of the ith component. MWD is expressed as the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn).

The exact A value is determined by adjusting the A value in equation (1) until the weight average molecular weight Mw, calculated using equation (3) and the corresponding hold-up volume polynomial, is consistent with an independent determination of Mw obtained from a linear homopolymer reference with a known weight average molecular weight of 120,000 g/mol.

Neutron activation method for metals

Two replicate samples were prepared by transferring approximately 3.5 grams of pellets into pre-cleaned 2 dram polyethylene vials. Standards were prepared in 2-dram polyethylene vials for each metal tested from NIST traceable standard solution (certi. It was diluted to 6ml with milli-Q purified water, and the vial was heat sealed. Samples and standards for these elements were then analyzed using a Mark I TRIGA nuclear reactor. The reaction and experimental conditions for these elements are summarized in the table below. The samples were transferred to unirradiated vials prior to gamma-spectroscopy. Elemental concentrations were calculated using CANBERRA software and standard comparison techniques. Table 1 provides the measurement parameters for the metal determination.

Table 1: reaction and experimental conditions for the elements during neutron activation.

Element(s)	Nuclear reaction	Isotope of carbon monoxide	Half life	Reactor power
					Al	²⁷Al(n,γ)²⁸Al	²⁸Al	2.24m	250kW
Cl	³⁷Cl(n,γ)³⁸Cl	³⁸Cl	37.2m	250kW
					Cr	⁵⁰Cr(n,γ)⁵¹Cr	⁵¹Cr	27.7d	250kW
Hf	¹⁸⁰Hf(n,γ)¹⁸¹Hf	¹⁸¹Hf	42.4d	250kW
					Mg	²⁶Mg(n,γ)²⁷Mg	²⁷Mg	9.46m	250kW
Mo	⁹⁸Mo(n,γ)⁹⁹Mo	⁹⁹Mo	66.0 hours	250kW
					Nb	⁹³Nb(n,γ)^94mNb	^94mNb	6.26m	250kW
Ta	¹⁸¹Ta(n,γ)¹⁸²Ta	¹⁸²Ta	114.4d	250kW
					Ti	⁵⁰Ti(n,γ)⁵¹Ti	⁵¹Ti	5.76m	250kW
W	¹⁸⁶W(n,γ)¹⁸⁷W	¹⁸⁷W	23.7 hours	250kW
					V	⁵¹V(n,γ)⁵²V	⁵²V	3.75m	250kW
Zr	⁹⁶Zr(n,γ)⁹⁷Zr	⁹⁷Zr	16.91 hours	250kW

TABLE 1 continuation

Element(s)	Time of irradiation	Waiting time	Calculating time	Gamma energy, keV
					Al	2m	4m	4.5 minutes	1778.5
Cl	2m	4m	4.5 minutes	1642.5、2166.5
					Cr	90m	5 hours	1.6 hours	320
Hf	90m	5 hours	1.6 hours	133、482
					Mg	2m	4m	4.5 minutes	843.8、1014
Mo	90m	5 hours	1.6 hours	181、739.7、141
					Nb	2m	4m	4.5 minutes	871
Ta	90m	5 hours	1.6 hours	1121、1222
					Ti	2m	4m	4.5 minutes	320
W	90m	5 hours	1.6 hours	135、481
					V	2m	4m	4.5 minutes	1434
Zr	90m	5 hours	1.6 hours	743.4

Differential Scanning Calorimetry (DSC)

DSC is used to measure the melting and crystallization behavior of polymers over a wide temperature range. This analysis is performed, for example, using a TA instrument (TA Instruments) Q1000DSC equipped with an RCS (refrigerated cooling system) and an autosampler. During the test, a nitrogen purge stream of 50ml/min was used. Melt pressing each sample into a film at about 175 ℃; the molten sample was then air cooled to room temperature (about 25 ℃). The film samples were formed by pressing the "0.1 to 0.2 gram" samples at 1,500psi at 175 ℃ for 30 seconds to form "0.1 to 0.2 mil thick" films. 3 to 10mg of a 6mm diameter sample was extracted from the cooled polymer, weighed, placed in a light aluminum pan (approximately 50mg), and crimped shut. And then analyzed to determine its thermal properties.

The thermal properties of the sample were determined by slowly raising and slowly lowering the sample temperature to produce a heat flow versus temperature curve. First, the sample was rapidly heated to 180 ℃ and held isothermal for five minutes to remove its thermal history. Next, the sample was cooled to-40 ℃ at a cooling rate of 10 ℃/minute and held isothermally at-40 ℃ for five minutes. The sample was then heated to 150 deg.C (this is a "second heat" ramp) at a 10 deg.C/minute heating rate. Recording the cooling curve anda second heating profile. The cooling curve was analyzed by setting the baseline endpoint from the onset of crystallization to-20 ℃. The heating curve was analyzed by setting the baseline end point from-20 ℃ to the end of melting. The value measured is the peak melting temperature (T)_m) Peak crystallization temperature (T)_c) Initial crystallization temperature (Tc onset), heat of fusion (H)_f) (in joules/gram), and the calculated% crystallinity for the polyethylene samples used the following: the% crystallinity for PE ═ ((Hf)/(292J/g)) x 100, and the calculated% crystallinity for the polypropylene samples used the following: the% crystallinity for PP is ((Hf)/165J/g)) x 100. Heat of fusion (H)_f) And peak melting temperatures are reported from the second heating curve. The peak crystallization temperature and the onset crystallization temperature were determined from the cooling curve.

Dynamic Mechanical Spectroscopy (DMS)

The resin was compression molded into "3 mm thick by 1 inch" circular panels at 350 ° f in air at 1500psi pressure for 5 minutes. The sample was then removed from the press and placed on a counter to cool.

A constant temperature frequency sweep was performed under a nitrogen purge using a TA instrument "Advanced Rheology Extension System (ARES)" equipped with 25mm (diameter) parallel plates. The sample was placed on a plate and allowed to melt at 190 ℃ for five minutes. The plate was then brought close to the 2mm gap, the sample trimmed (removing additional sample extending beyond the perimeter of the "25 mm diameter" plate), and the test was then started. The process had an additional five minute delay built in to allow for temperature equilibration. The experiments were carried out at 190 ℃ in the frequency range from 0.1 to 100 rad/s. The strain amplitude was constant at 10%. From these data, the complex viscosity η ·, tan (δ) or tan δ, the viscosity at 0.1rad/s (V0.1), the viscosity at 100rad/s (V100) and the viscosity ratio (V0.1/V100) were calculated.

Crystallization Elution Fractionation (CEF) process

The Crystallization Elution Fractionation (CEF) technique is performed according to Monrabal et al, proceedings of the macromolecular symposium (Macromol. Symp.) (257, 71-79 (2007)). CEF instruments are equipped with IR-4 or IR-5 detectors (such as those commercially available from Perry Moire, Spain)) And 2040 type dual angle light scatter Detectors (such as those commercially available from Precision Detectors). A50 mm by 4.6mm 10 micron protective column (such as those commercially available from Polymer laboratories) was installed in front of the IR-4 or IR-5 detectors in the detector oven. Ortho-dichlorobenzene (ODCB, 99% anhydrous grade) and 2, 5-di-tert-butyl-4-cresol (BHT) (as commercially available from Sigma-Aldrich) were obtained. Silica gel 40 (particle size) was also obtained

) (as commercially available from EMD Chemicals). The silica gel was dried in a vacuum oven at 160 ℃ for at least two hours before use. ODBC were treated with dry nitrogen (N) prior to use₂) Bubbling for one hour. By passing through<90psig conveying nitrogen through CaCO₃And

molecular sieves to obtain dried nitrogen. The ODCB was further dried by adding 5 grams of dried silica to two liters of ODCB or by pumping through a column or columns filled with dried silica at a rate between 0.1ml/min and 1.0 ml/min. If no use is made of e.g. N when purging the sample vial₂Eight hundred milligrams of BHT was added to two liters of ODCB. The dried ODCB with or without BHT is hereinafter referred to as "ODCB-m. "sample solutions were prepared by dissolving polymer samples at 4mg/ml in ODCB-m at 160 deg.C for 2 hours with shaking using an autosampler. 300 μ L of sample solution was injected into the column. The temperature profile of CEF is: and (3) crystallization: at 3 ℃/min, from 110 ℃ to 30 ℃; heat balance: at 30 ℃ for 5 minutes (including soluble fraction elution time set to 2 minutes); and elution: from 30 ℃ to 140 ℃ at 3 ℃/min. The flow rate during crystallization was 0.052 ml/min. The flow rate during elution was 0.50 ml/min. IR-4 or IR-5 signal data was collected at one data point/second.

The CEF column was packed at 125 μm. + -. 6% with glass beads (such as those available from MO-SCI Specialty Products with acid wash) having 1/8 inch stainless steel tubing according to U.S.8,372,931. The internal liquid volume of the CEF column is between 2.1ml and 2.3 ml. Temperature calibration was performed by using a mixture of NIST standard reference materials linear polyethylene 1475a (1.0mg/ml) and eicosane (2mg/ml) in ODCB-m. The calibration consists of the following four steps: (1) calculating a delay volume defined as the measured eicosane peak elution temperature minus the temperature shift between 30.00 ℃; (2) CEF raw temperature data minus the temperature offset of the elution temperature. It should be noted that this temperature shift is a function of experimental conditions, such as elution temperature, elution flow rate, etc.; (3) a linear calibration line was generated to convert elution temperatures in the range of 30.00 ℃ and 140.00 ℃ such that NIST linear polyethylene 1475a had a peak temperature at 101.00 ℃ and eicosane had a peak temperature of 30.00 ℃, (4) for soluble fractions measured isothermally at 30 ℃, the elution temperature was extrapolated linearly by using an elution heating rate of 3 ℃/min. The reported elution peak temperatures were obtained such that the observed comonomer content calibration curves were consistent with those previously reported in USP 8,372,931.

Comonomer Distribution Breadth Index (CDBI)

CDBI was calculated using the method described in WO/93/03093 for data obtained from CEF. CDBI is defined as the weight% of polymer molecules having a comonomer content within 50% of the median total molar comonomer content. It represents a comparison of the comonomer distribution in the polymer with that expected from a Bernoullian distribution.

CEF was used to measure the Short Chain Branching Distribution (SCBD) of polyolefins. CEF molar comonomer content calibration was performed using 24 reference materials (e.g., polyethylene octene random copolymer and ethylene butene copolymer) with a narrow SCBD of comonomer mole fraction in the range of 0 to 0.108 and Mw of 28,400 to 174,000 g/mole. Ln (mole fraction of ethylene) is obtained, which is ln (comonomer mole fraction) relative to 1/T (k), where T is the elution temperature in Kelvin (Kelvin) for each reference material. Comonomer distribution of the reference material was determined using 13C NMR analysis according to techniques described, for example, in U.S. patent No. 5,292,845 (Kawasaki et al) and j.c. Randall in polymer chemistry physical reviews (Randall in rev. macro. chem. phys.), C29, 201-317.

13C-NMR

Sample preparation

Samples were prepared by adding approximately 2.7g of a 50/50 mixture of tetrachloroethane-d 2/o-dichlorobenzene containing 0.025M Cr (AcAc)3 to 0.25g of sample in a Norell 1001-710 mm NMR tube. The sample was dissolved and homogenized by heating the test tube and its contents to 150 ℃ using a heating block and vortex mixer. Each sample was visually inspected to ensure homogeneity.

Data acquisition parameters

Data were collected using a Bruker 400MHz spectrometer equipped with a Bruker Dual DUL high temperature CryoProbe. Data were acquired using 320 transients per data file, 6 second pulse repetition delay, 90 degree flip angle, and back-gated decoupling, with the sample temperature at 120 ℃. All measurements were performed on non-rotating samples in the locked mode. The samples were allowed to thermally equilibrate for 7 minutes prior to data acquisition.¹³The C NMR chemical shifts were internally referenced to mmmm pentads (pentads) at 21.90ppm or EEE triads at 30.0 ppm.

Data analysis

Compositions were determined Using 13C-NMR Spectroscopy from S.Di Martino and M.Keclchtermans, Determination of the Composition of Ethylene-Propylene Rubbers Using 13C-NMR Spectroscopy, C13NMR Spectroscopy Using the distribution and integration of Journal of Polymer Science (Journal of Applied Polymer Science), Vol.56, 1781 & 1787(1995) to solve the vector equation s.fM, where M is the distribution matrix, s is the row vector representation of the spectra and f is the mole fraction Composition vector. The elements of f are taken as triads of E and O, with all permutations of E and O. An assignment matrix M is created in which for each triad in f, one row is created and for each integrated NMR signal, one column is created. The elements of the matrix are the integrated values determined by referring to the assignments in reference 1. The equation is solved by changing the element of f as needed to minimize the error function between s and the integrated C13 data for each sample. This can be easily performed in Microsoft Excel using the Solver function.

Final stretching

The final tensile was tested on a Highlight film test system from Highlight Industries. The film rolls are placed on the unwind section of the machine and the film is passed through a set of rolls. The film then unfolds with increasing force until it reaches its final stretch point. The force gauge measures the amount of force applied and makes a calculation to determine the amount of stretch present in the film, measured in%. Three measurements were made and averaged together to obtain an average final stretch value. The film width was 20 inches.

Tear on tray test

This test uses the Bruceton ladder method to determine the maximum force that a film can be loaded through a test probe for three wraps without failure. The test probes are inserted into the test station at the desired protrusion distance. The membrane is positioned so that the test probe is aligned with the center of the membrane. The film was attached to the test station and the wrapper was started. Once the wrapper reached 250% pre-stretch, the film was passed through the probe for a maximum of three wraps. Any rupture of the film during any wrapping is considered to be a failure at the force set by the load. Depending on the performance of the membrane at the load setting (i.e., pass or fail), the load force can be adjusted up or down and the test repeated at the new load setting. This continues until the maximum force is found at which no failure occurs. The following table provides the equipment and settings used in this process.

Equipment:	lantech SHC film test wrapper
		Pre-stretching:	250％
speed of the turntable:	10rpm
		load force (F2):	variables of
Probe type	1 "Metal Square tubes with 1/2" razor blades attached thereto
		Probe protrusion distance	1 inch

Tensile, spreading, sound level：

Tensile force, deployment force, sound level were tested on a Highlight film test system from Highlight Industries. The film rolls are placed on the unwind section of the machine and the film is passed through a set of rolls. The film then unfolds with increasing force until it reaches its final stretch point. The load cell measures the force applied by stretching (tensile force) and the force required for deployment (deployment force). During this test, the sound level was measured using a built-in sound level meter (in decibels). Three measurements were taken for each test and the tensile, deployment and sound level values were averaged. The film width for these tests was 20 inches.

Puncturing on the tray:

Equipment:	lantech SHC film test wrapper
		Pre-stretching:	250％
speed of the turntable:	10rpm
		load force (F2):	variables of
Probe type	4 'X4' blunt rod
		Probe protrusion distance	12 inch

Adhesion

The tensile adhesion (for tensile adhesion performance) on the tray can be measured by the Lantech SHS test equipment. The test consisted of: with the turntable running at 10rpm, the film was stretched to 250% with a constant force F2 of 12lbs for 5 wraps. The end of the film is then attached to a force gauge, which measures the amount of force (in grams) required to separate the film from the roll.

Examples of the invention

The resins used in the multilayer cast films are shown in tables 2, 3& 5. The propylene interpolymers of the present invention are propylene-ethylene copolymers and are prepared via the processes in paragraphs [0018] to [0020] above. Additional properties of the propylene interpolymers are summarized in table 3 below. The PE resin 1 was produced by the following method. Additional properties of PE resin 1 and the comparative polyethylene composition are summarized in table 5.

Table 2: resin Properties

Table 3: resin Properties

PE resin 1

PE resin 1 was prepared as follows: a multi-metal catalyst (catalyst 1) was prepared. Catalyst 1 was then used to prepare PE resin 1 polymerized in solution.

Preparation of catalyst 1

7.76kg of EADC solution (15% by weight in heptane) was added to about 109kg of 0.20M MgCl₂The slurry was then stirred for 8 hours. Then, TiCl was added₄/VOCl₃(85 mL and 146mL, respectively), followed by addition of Zr (TMHD)₄0.320kg of Isopar E solution (0.30M). These two additions were carried out sequentially within 1 hour of each other. The resulting catalyst premix was aged for a further 8 hours with stirring before use.

Production of PE resin 1

PE resin 1 was produced according to the following procedure: all of the starting materials (ethylene, 1-hexene) and the process solvent (an isoparaffinic solvent under the trade name ISOPAR E, available from ExxonMobil Corporation) were purified with molecular sieves prior to introduction to the reaction environment. Hydrogen was supplied in pressurized cylinders at high purity grade and was not further purified. The reactor monomer feed (ethylene) stream is pressurized via a mechanical compressor to a pressure above the reaction pressure (e.g., 750 psig). The solvent and comonomer (1-hexene) feeds were pressurized via a mechanical positive displacement pump to a pressure above the reaction pressure (e.g., 750 psig). The individual catalyst components are manually batch diluted with purified solvent (ISPAR E) to the specified component concentrations and pressurized to a pressure above the reaction pressure (e.g., 750 psig). All reaction feed flows were measured with mass flow meters and independently controlled with a computer automated valve control system.

The continuous solution polymerization reactor consists of a liquid-filled, non-adiabatic, isothermal, circulating loop. It is possible to independently control all fresh solvent, monomer, comonomer, hydrogen and catalyst component feeds. The combined solvent, monomer, comonomer and hydrogen feed is temperature controlled to between 5 ℃ and 50 ℃ and typically 40 ℃ by passing the feed stream through a heat exchanger. Fresh comonomer feed to the polymerization reactor is aligned to add comonomer to the recycled solvent. The total fresh feed to the polymerization reactor was injected into the reactor at two locations, with the reactor volume between each injection location being approximately equal. Fresh feed is typically controlled with each injector receiving half of the total fresh feed mass flow. The catalyst components are injected into the polymerization reactor through specially designed injection inlet devices and combined into a mixed procatalyst/cocatalyst feed stream prior to injection into the reactor. The co-catalyst component is fed based on a calculated value of the specified molar ratio to the main catalyst component. Immediately after each fresh injection site (feed or catalyst), the feed stream was mixed with the circulating polymerization reactor contents using a Kenics static mixing element. The contents of the reactor are continuously circulated through a heat exchanger responsible for removing much of the heat of reaction, and where the temperature of the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. Circulation around the reactor loop is provided by a screw pump. The effluent from the polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst components and molten polymer) exits the reactor loop and enters a zone of contact with a deactivating and acid scavenger (typically calcium stearate and accompanying water of hydration) to stop the reaction and scavenge hydrogen chloride. Further, various additives such as an antioxidant may be added at this time. The stream then passes through another set of knins static mixing elements to uniformly disperse the catalyst deactivator and additive.

After the additives are added, the effluent (containing solvent, monomer, comonomer, hydrogen, catalyst components, and molten polymer) is passed through a heat exchanger to raise the temperature of the stream in production, thereby separating the polymer from the other lower boiling reaction components. The flow is then passed through a pressure let down control valve (responsible for maintaining the pressure of the reactor at the specified target). The stream then enters a two stage separation and devolatilization system where the polymer is removed from the solvent, hydrogen, and unreacted monomer and comonomer. Impurities are removed from the recycle stream before re-entering the reactor. The separated and devolatilized polymer melt is pumped through a die specifically designed for underwater pelletization, cut into uniform solid pellets, dried and transferred into a hopper. After verifying the initial polymer properties, the solid polymer pellets were transferred to a storage device.

The portion removed in the devolatilization step may be recycled or destroyed. For example, most of the solvent is recycled back to the reactor after passing through the purification bed. The recycled solvent may still have unreacted comonomer which is enriched with fresh comonomer before re-entering the reactor. The recycled solvent may still have some hydrogen, which is then enriched with fresh hydrogen. Table 4 summarizes the polymerization conditions of PE resin 1

Table 4: reactor data

Table 5: resin Properties of PE composition

Table 5: neutron activation data

In any of the examples, niobium (Nb) (5ppm), tantalum (Ta) (50ppb), chromium (Cr) (0.5ppm), molybdenum (Mo) (50ppb), and tungsten (W) (5ppm) were not detected at their respective detection limits as indicated in parentheses after each element.

Example 1

A three layer cast film was made using a Dolci 7 layer casting line with 5 extruders. The layer ratio of the adhesive layer was 12%, the layer ratio of the core layer was 76%, and the layer ratio of the release layer was 12%. The extrusion melt temperature for extruder 1 was 251 deg.C, for extruder 2 was 197 deg.C, for extruder 3 was 253 deg.C, for extruder 4 was 235 deg.C, for extruder 5 was 181 deg.C, and the die temperature was 235 deg.C. The output rate was 1,000 kg/hr. The chill roll temperature was 17 ℃. The air gap was 5 ml. The film thickness was 25 μm. The membrane structure and membrane properties are further summarized in table 6 below.

Table 6: cast film structure

As shown in table 6, even if the amount of the adhesive was reduced from 18% for the comparative film 1 to 13% for the film 1 of the present invention, a higher adhesion value could be obtained.

Example 2

A three-layer cast film was made using a 5-layer casting line with 4 extruders. The layer ratio of the adhesive layer was 10%, the layer ratio of the core layer was 80%, and the layer ratio of the release layer was 10%. The melting temperature of the extruder ranged from 200 ℃ to 250 ℃. The output rate was 860 kg/hr. The mold temperature was 250 ℃. The air gap was 3 cm. Inventive film 2 was made using the following extruder pressures: 194/213/224/195 bar. Comparative film 2 was made using the following extruder pressures: 221/222/240/215 bar. The film thickness was 20 microns. The membrane structure and membrane properties are further summarized in table 7 below.

Table 7: cast film structure

As shown in table 1, higher adhesion values were achieved for the inventive film 2 using the inventive polyethylene composition in the adhesion layer, the core layer and the release layer as compared to the comparative film 2 using other LLDPE resins.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Indeed, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm".

Unless expressly excluded or otherwise limited, each document cited herein, if any, including any cross-referenced or related patents or applications and any patent applications or patents to which this application claims priority or benefit, is hereby incorporated by reference in its entirety. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it teaches, teaches or discloses any such invention alone or in combination with any other reference or references above. Furthermore, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to the term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A multilayer cast film comprising an adhesion layer, a core layer, and a release layer, wherein:

the adhesion layer comprises a propylene interpolymer comprising at least 60 weight percent units derived from propylene and between 1 and 40 weight percent units derived from ethylene, wherein the propylene interpolymer has 0.840g/cm³To 0.900g/cm³(ii) a density of 50.0 ℃ to 120.0 ℃, a highest DSC melting peak temperature, a melt flow rate MFR2 of 1 to 100g/10min when measured according to ASTM D1238 at 230 ℃ and 2.16kg load, and a molecular weight distribution MWD of less than 4.0; and is

The core layer comprises a core layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the core layer polyethylene composition is characterized by the following properties:

(a) melt index I of 2.5 to 12.0g/10min₂；

(b) A density of 0.910 to 0.925 g/cc;

(c) melt flow ratio I of 6.0 to 7.6₁₀/I₂(ii) a And

(d) a molecular weight distribution Mw/Mn of from 2.25 to 4.0.

2. The multilayer cast film of claim 1, wherein the propylene interpolymer has a% crystallinity in the range of from 0.5% to 45%.

3. The multilayer cast film of claim 1 or 2, wherein the propylene interpolymer has a weight average molecular weight, Mw, of at least 50,000 g/mole.

4. The multilayer cast film of claim 1 or 2, wherein the adhesion layer further comprises an adhesion layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the adhesion layer polyethylene composition is characterized by one or more of the following properties:

(a) melt index I of 2.5 to 12.0g/10min₂；

(b) A density of 0.910 to 0.925 g/cc;

(c) melt flow ratio I of 6.0 to 7.6₁₀/I₂(ii) a And

(d) a molecular weight distribution Mw/Mn of from 2.25 to 4.0.

5. The multilayer cast film of claim 1 or 2, wherein the release layer comprises a linear low density polyethylene or release layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the release layer polyethylene composition is characterized by one or more of the following properties:

(a) melt index I of 2.5 to 12.0g/10min₂；

(b) A density of 0.910 to 0.925 g/cc;

(c) melt flow ratio I of 6.0 to 7.6₁₀/I₂(ii) a And

(d) a molecular weight distribution Mw/Mn of from 2.25 to 4.0.

6. Multilayer cast film according to claim 1 or 2, wherein the core layer polyethylene composition is formed via solution polymerization in the presence of a catalyst composition comprising a multi-metallic procatalyst.

7. The multilayer cast film of claim 1 or 2, wherein the core layer polyethylene composition has a CDBI of less than 60% or from 40% to 60%.

8. Multilayer cast film according to claim 1 or 2, wherein the core layer polyethylene composition has a molecular weight distribution Mw/Mn from 2.6 to 3.5.

9. The multilayer cast film according to claim 1 or 2, wherein the core layer polyethylene composition has a viscosity ratio of 2 to 6 of viscosity at 0.1rad/s viscosity at 100rad/s, both measured at 190 ℃ using dynamic mechanical spectroscopy.

10. The multilayer cast film of claim 9, wherein the core layer polyethylene composition has a viscosity ratio of 2.0 to 2.9.

11. A method of making a multilayer cast film, the method comprising:

coextruding an adhesion layer composition, a core layer composition, and a release layer composition to form a multilayer cast film;

wherein the adhesion layer composition comprises a propylene interpolymer comprising at least 60 weight percent units derived from propylene and between 1 and 40 weight percent units derived from ethylene, wherein the propylene interpolymer has 0.840g/cm³To 0.900g/cm³(ii) a density of 50.0 ℃ to 120.0 ℃, a highest DSC melting peak temperature, a melt flow rate MFR2 of 1 to 100g/10min when measured according to ASTM D1238 at 230 ℃ and 2.16kg load, and a molecular weight distribution MWD of less than 4.0;

wherein the core layer composition comprises a core layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the core layer polyethylene composition is characterized by the following properties:

(a) melt index I of 2.5 to 12.0g/10min₂；

(b) A density of 0.910 to 0.925 g/cc;

(c) melt flow ratio I of 6.0 to 7.6₁₀/I₂(ii) a And

(d) a molecular weight distribution Mw/Mn of from 2.25 to 4.0; and is

Wherein the release layer composition comprises a linear low density polyethylene or release layer polyethylene composition comprising the reaction product of ethylene and optionally one or more alpha-olefin comonomers, wherein the release layer polyethylene composition is characterized by one or more of the following properties:

(a) melt index I of 2.5 to 12.0g/10min₂；

(b) A density of 0.910 to 0.925 g/cc;

(c) melt flow ratio I of 6.0 to 7.6₁₀/I₂(ii) a And

(d) a molecular weight distribution Mw/Mn of from 2.25 to 4.0.