Low acid ethylene acid copolymers and ionomers thereof with improved adhesion to metal substrates

Abstract

The present disclosure is directed to a composition comprising 1 to 99 wt.% of a first ethylene acid copolymer having a melt strength (MS) ≤ 1.5 cN, the first ethylene acid copolymer comprising the polymerized reaction product of: 60 to 99 wt.% ethylene monomer; and carboxylic acid comonomer. The composition also comprises: 1 wt.% to 30 wt.% of a second ethylene acid copolymer comprising the polymerized reaction product of: 60 wt.% to 99 wt.% ethylene monomer; and carboxylic acid comonomer; wherein: the second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer; the composition comprises a greater wt.% of the first ethylene acid copolymer than the second ethylene acid copolymer; and the composition comprises a total acid content of less than or equal to 6.5 wt.%, based on the total weight of carboxylic acid comonomer in the composition.

Description

LOW ACID ETHYLENE ACID COPOLYMERS AND IONOMERS THEREOF WITH IMPROVED ADHESION TO METAL SUBSTRATESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 594,795 filed October 31, 2023, the contents of which are incorporated in their entirety herein.TECHNICAL FIELD

[0002] The present disclosure generally relates to low acid ethylene acid copolymers and ionomers thereof, and specifically relates to low acid ethylene acid copolymers and ionomers thereof that provide improved adhesion to metal substrates.BACKGROUND

[0003] Ethylene acid copolymers and ionomers thereof are commonly used materials in various applications, such as food packaging. For example, ethylene acid copolymers and ionomers thereof have found utility in condiment packaging, where ethylene acid copolymers or ionomers thereof are incorporated into multilayer flexible packaging that includes a metal substrate such as aluminum to minimize the permeation of oxygen and moisture into the packaging and extend the shelf life of the food product.SUMMARY

[0004] The ethylene acid copolymers and ionomers thereof used for condiment packaging, and other similar applications are typically high acid ethylene acid copolymers and ionomers thereof. The high acid ethylene acid copolymers and ionomers thereof exhibit strong bonds and high adhesion strength to the metal substrate due to the reaction between the acid functional groups of the ethylene acid copolymers and metal oxide on the surface of the metal substrate. This bonding is also known to reflect high acid resistance. The high acid resistance prevents the delamination between ethylene acid copolymers and ionomers thereof and the metal substrate when the foodproduct has acidic ingredients. However, using high acid ethylene acid copolymers and ionomers thereof often leads to issues during the extrusion, such as corrosion of extrusion lines, die build up, tearing of the melt curtain, and long purge times during resin transition. Therefore, low acid ethylene acid copolymers and ionomers thereof with improved adhesion to metal substrates are needed.

[0005] Embodiments of the present disclosure address this need for low acid ethylene acid copolymers and ionomers thereof with improved adhesion to metal substrates.

[0006] According to one embodiment, a composition includes 1 to 99 wt.% of a first ethylene acid copolymer melt strength (MS) < 1.5 cN, the first ethylene acid copolymer including the polymerized reaction product of 60 to 99 wt.% ethylene monomer and carboxylic acid comonomer, 1 wt.% to 30 wt.% of a second ethylene acid copolymer comprising the polymerized reaction product of 60 wt.% to 99 wt.% ethylene monomer; and carboxylic acid comonomer; wherein the second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer, the composition comprises a greater wt.% of the first ethylene acid copolymer than the second ethylene acid copolymer, and the composition comprises a total acid content of less than or equal to 6.5 wt.%, based on the total weight of carboxylic acid comonomer in the composition.

[0007] These and other features, aspects, and advantages will become better understood with reference to the following description and the appended claims.

[0008] Additional features and advantages of the examples described herein will be set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the examples described herein, including the detailed description that follows, and the claims.

[0009] It is to be understood that both the foregoing general description and the following detailed description describe various examples and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter.DETAILED DESCRIPTION[0010J Specific embodiments of the present application will now be described. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the subject matter to those skilled in the art.

[0011] The term “polymer” refers to a polymeric compound prepared by polymerizing monomers, whether of a same or a different type. The generic term polymer thus embraces the term “homopolymer,” which usually refers to a polymer prepared from only one type of monomer as well as “copolymer,” which refers to a polymer prepared from two or more different monomers. The term “interpolymer,” as used herein, refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes a copolymer or polymer prepared from more than two different types of monomers, such as terpolymers.

[0012] “Ethylene polymer” or “polyethylene” shall mean polymers comprising greater than 50% by weight of units derived from ethylene monomer. This includes ethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene polymers known in the art include, but are not limited to, Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m- LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).

[0013] “Ethylene acid copolymer” is a polymerized reaction product of ethylene and one or more unsaturated carboxylic acids.

[0014] “High acid copolymer” refers to a copolymer with greater than or equal to 8 weight percent (wt.%) carboxylic acid comonomer.

[0015] “Low acid copolymer” refers to a copolymer with less than 8 wt.% carboxylic acid comonomer.

[0016] Reference will now be made in detail to examples of compositions including 1 to 99 wt.% of a first ethylene acid copolymer melt strength (MS) < 1.5 cN, the first ethylene acid copolymer including the polymerized reaction product of 60 to 99 wt.% ethylene monomer and carboxylic acid comonomer, 1 wt.% to 30 wt.% of a second ethylene acid copolymer comprising the polymerized reaction product of 60 wt.% to 99 wt.% ethylene monomer; and carboxylic acid comonomer; wherein the second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer, the composition comprises a greater wt.% of the first ethylene acid copolymer than the second ethylene acid copolymer, and the composition comprises a total acid content of less than or equal to 6.5 wt.%, based on the total weight of carboxylic acid comonomer in the composition.

[0017] The composition includes 1 to 99 wt.% of a first ethylene acid copolymer. In some examples, the composition may include 1 to 99 wt.%, 25 to 99 wt.%, 50 to 99 wt.%, 60 to 99 wt.%, 70 to 99 wt.%, 1 to 95 wt.%, 25 to 95 wt.%, 50 to 95 wt.%, 60 to 95 wt.%, or 70 to 95 wt.% of a first ethylene acid copolymer.

[0018] The first ethylene acid copolymer includes the polymerized reaction product of ethylene monomer, and carboxylic acid comonomer. The carboxylic acid monomers can be, for example, acrylic acid, methacrylic acid, or combinations thereof. In some examples, the first ethylene acid copolymer includes the polymerized reaction product of 60 to 99 wt.%, 65 to 99 wt.%, 70 to 99 wt.%, 75 to 99 wt.%, 80 to 99 wt.%, 60 to 95 wt.%, 65 to 95 wt.%, 70 to 95 wt.%, 75 to 95 wt.%, 80 to 95 wt.% ethylene monomer, and 1 to 6 wt.%, 2 to 6 wt.%, 3 to 6 wt.%, 1 to 5 wt.%, 2 to 5 wt.%, 3 to 5 wt.%, 1 to 4 wt.%, 2 to 4 wt.%, or 3 to 4 wt.% carboxylic acid comonomer.

[0019] The first ethylene acid copolymer may have a melt strength (MS) < 1.5 cN, from 0.1 to 1.5 cN, from 0.3 to 1.2 cN, or from 0.5 to 1.0 cN.

[0020] In additional embodiments, the first ethylene acid copolymer has a melt index (h) of at least 9 g / 10 min as measured according to ASTM DI 238 (190 °C, 2.16 kg), the entire protocol of which is hereby incorporated by reference. Unless otherwise stated, melt index was measured in grams per 10 minutes (g / 10 min). In some examples, the first ethylene acid copolymer has a melt index (I2) of at least 5 g / 10 min, 7 g / 10 min, or at least 9 g / 10 min. In some examples, thefirst ethylene acid copolymer has a melt index (I2) of from 5 to 100 g / 10 min, 7 to 50 g / 10 min, or 9 to 20 g / 10 min.

[0021] The composition also includes a second ethylene acid copolymer. The second ethylene acid copolymer is different from the first ethylene acid copolymer. The composition includes 1 wt.% to 30 wt.% of a second ethylene acid copolymer. In some examples, the composition includes 1 wt.% to 30 wt.%, 1 wt.% to 20 wt.%, or 1 wt.% to 15 wt.% of a second ethylene acid copolymer.

[0022] The second ethylene acid copolymer includes the polymerized reaction product of ethylene monomer, and carboxylic acid comonomer. The second ethylene acid copolymer includes the polymerized reaction product of 60 to 99 wt.%, 65 to 99 wt.%, 70 to 99 wt.%, 75 to 99 wt.%, 80 to 99 wt.%, 60 to 95 wt.%, 65 to 95 wt.%, 70 to 95 wt.%, 75 to 95 wt.%, 80 to 95 wt.% ethylene monomer, and 9 to 15 wt.%, 10 to 15 wt.%, 11 to 15 wt.%, 12 to 15 wt.%, 9 to 14 wt.%, 10 to 14 wt.%, 11 to 14 wt.%, 12 to 14 wt.%, 9 to 13 wt.%, 10 to 13 wt.%, 11 to 13 wt.%, or 12 to 13 wt.% carboxylic acid comonomer.

[0023] The second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer. In some examples, the second ethylene acid copolymer has at least 8 wt.%, at least 9 wt.%, or at least 10 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer. In some examples, the second ethylene acid copolymer has 8 to 30 wt.%, 9 to 30 wt.%, or 10 to 30 wt.% carboxylic acid comonomer.

[0024] The composition may include a greater wt.% of the first ethylene acid copolymer than the second ethylene acid copolymer. Additionally, the composition may also include a total acid content of less than or equal to 6.5 wt.%, less than or equal to 5.5 wt.%, or less than or equal to 5.0 wt.% based on the total weight of carboxylic acid comonomer in the composition.

[0025] The ethylene acid copolymers can be prepared by standard free-radical copolymerization methods, using high pressure, operating in a continuous manner. Monomers are fed into the reaction mixture in a proportion which relates to the monomer’s activity, and the amount desired to be incorporated. In this way, uniform, near-random distribution of monomer units along the chain is achieved. Unreacted monomers may be recycled. The ethylene acidcopolymers may be polymerized according to processes disclosed in U.S. Pat. Nos. 3,404,134; 5,028,674; 6,500,888; and 6,518,365.

[0026] The composition may have a melt index (h) of from 4 g / 10 min to 12 g / 10 min as measured according to ASTM DI 238 (190 °C, 2.16 kg), the entire protocol of which is hereby incorporated by reference. Unless otherwise stated, melt index was measured in grams per 10 minutes (g / 10 minutes). In some examples, the composition has a melt flow from 4 g / 10 min to 12 g / 10 minutes, 5 g / 10 min to 12 g / 10 minutes, 4 g / 10 min to 10 g / 10 minutes, 5 g / 10 min to 12 g / 10 minutes, 4 g / 10 min to 9 g / 10 minutes, or 5 g / 10 min to 9 g / 10 minutes.

[0027] If the composition has a melt index (I2) below 4 g / 10 minutes, the composition may not have sufficient melt flow for processability, for example, extrusion coating process. Conversely, if the composition has a melt flow above 12 g / 10 minutes, the mechanical properties of the composition may cause undesirable qualities during extrusion coating processing such as “necking in” where the outer edges of the composition contracts around the outer edges after it have been extruded from the die exit and drawn down to the nip rollers.

[0028] In some examples, the first ethylene acid copolymer, the second ethylene acid copolymer, or both are at least partially neutralized with metal cations (to form an ionomer). In some examples, the metal cations include zinc cations or sodium cations. In some examples, the metal cations neutralize from 1 wt.% to 100 wt.%, from 10 wt.% to 100 wt.%, from 15 wt.% to 75 wt.%, or from 15 wt.% to 65 wt.% carboxylic acid comonomers.

[0029] The composition can additionally include small amounts of additives including plasticizers, stabilizers including viscosity stabilizers and UV stabilizers, hydrolytic stabilizers, primary and secondary antioxidants, anti-static agents, dyes, pigments or other coloring agents, inorganic fillers, fire-retardants, lubricants, reinforcing agents such as glass fiber and flakes, synthetic (for example, aramid) fiber or pulp, foaming or blowing agents, processing aids, slip additives, slip agents, antiblock agents such as silica or talc, release agents, tackifying resins, or combinations of two or more thereof. Inorganic fillers, such as calcium carbonate, and the like can also be incorporated into the blend. These additives may be present in the blends in quantities ranging from 0.01 to 40 wt%, 0.01 to 25 wt%, 0.01 to 15 wt%, 0.01 to 10 wt%, or 0.01 to 5 wt%. The incorporation of the additives can be carried out by any known process such as, for example,by dry blending, by extruding a mixture of the various constituents, by the conventional masterbatch technique, or the like.

[0030] Additional embodiments may be directed to methods of producing an extrusion-coated metal substrate. The method may include melt blending the composition as described herein in an extruder to produce extrusion coating material and applying the extrusion coating material onto a metal substrate to produce the extrusion-coated metal substrate. In one or more examples, the first ethylene acid copolymer and the second ethylene acid copolymer are neutralized with metal cations during the melt blending. The melt blending may include mixing the components of the composition under heat to form a melt. The melt blending may occur at a temperature of from 180 °C to 270 °C. The components may be mixed and blended using any technique known and used in the art, including Banbury mixers, continuous mixers, intensive mixers, two-roll mills, and extruders.

[0031] In various embodiments, the extrusion coating material may be extruded at a drawn down of greater than or equal to 1400 feet per min, greater than or equal to 1450 feet per min, or greater than or equal to 1500 feet per min. In one or more embodiments, the extrusion coating material may be extruded at a draw rate of greater than or equal to 1400 feet per min, greater than or equal to 1450 feet per min, or greater than or equal to 1500 feet per min.

[0032] According to various examples, the composition may be used to form various articles. As stated above, one article is an extrusion-coated metal substrate. In one or more examples, the metal substrate is aluminum. In one or more examples, the metal substrate is a metalized film.

[0033] The composition described herein provides a peel strength to a metal substrate of greater than or equal to 425 g / inch when the composition is extrusion coated on to a metal substrate.

[0034] Without being bound by theory, the large polarity difference between the first ethylene acid copolymer and the second ethylene acid copolymer when the second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer, is believed to result in the segregation of the second ethylene copolymer to the surface of the metal substrate due to low compatibility between the first and the second acid copolymers and high shearforce of extrusion coating process. This segregation allows for strong adhesion between the composition and the metal substrate Additionally, the use of a first ethylene acid copolymer having a melt strength (MS) < 1.5 cN is believed to result in a composition with less chain entanglement, which allows the composition to deliver a high draw down and draw rate in the extrusion coating process. Furthermore, the melt index (I2) of at least 9 g / 10 min of the first ethylene acid copolymer is also believed to contribute to the high draw down and draw rate of the composition.TEST METHODS

[0035] Melt Strength

[0036] Melt Strength testing was conducted on either Rheotester 2000 or Rheograph 25 capillary rheometers paired with a Rheotens model 71.97, all of which were manufacture by Gottfert. The die used for testing has a diameter of 2 mm, length of 30 mm and entry angle of 180 degrees. Each test was performed isothermally at 190 °C.

[0037] During the test, the sample, in pellet form, was loaded into the capillary barrel and allowed to equilibrate at the testing temperature for 10 min. After which, the piston inside the barrel applies a steady force on the molten sample to achieve an apparent wall shear rate of 38.2 s1, and the melt is extruded through the die with an exit velocity of approximately 9.5 mm / s. Located 100 mm below the die exit, the extrudate is guided through the wheel pairs of the rheotens, which both accelerate at a constant rate of 2.4 mm / s2and measures the extrudate response to the applied extensional force. The Rheotens wheel pairs are serrated and are spaced 0.4 mm apart. The results of this testing were documented into plots of force with respect to rheotens wheel speed. For analysis, the force at which fracture occurred in the melt or the force at 130 mm / s if the fracture does not occur is referred to as the melt strength of the material or resin.

[0038] Melt Index (I2)

[0039] Melt index (I2) was measured in accordance with ASTM D-1238, Procedure B (condition 190°C / 2.16 kg), the entirety of which is hereby incorporated by reference, and reported in grams eluted per 10 minutes (g / 10 min).

[0040] Peel Strength

[0041] The polymer or polymer blend is extrusion-coated on an aluminum foil sheet (laminated with PET) via an extrusion coating process. The coating is applied to the aluminum side and has a thickness of 1.25 mil. Masking tape is placed on a portion of the aluminum foil sheet before the polymer is extruded and coated onto the aluminum foil sheet. Since there is weak adhesion between the masking tape and coating, the masking tape can be peeled-off the coating prior to the Peel Test. Then, the Peel Test is used to obtain the peel strength between the coating and the aluminum foil sheet. Prior to testing of the peel strength, the samples are conditioned for a minimum of 40 hrs at 23 °C (± 2°C) and 50% (± 10%) relative humidity (R.H).

[0042] The extrusion-coated sheet to be tested is cut into 1 inch wide strips along the machine direction with the longer side oriented along the machine direction. The coating is peeled off from the aluminum foil sheet (starting from the location with the masking tape), and then the two jaws of the tensile test machine grips the ends of the peeled-off coating and aluminum foil sheet. Then the whole sample is slowly pulled at 1 in / min to remove the slack. The sample is then tested at 12 in / min, five specimens are tested and the average peak load and average load over 3 inches (from 1 inch to 4 inches) are reported.EXAMPLES

[0043] The following examples are offered by way of illustration and are presented in a manner such that one skilled in the art should recognize are not meant to be limiting to the present disclosure as a whole or to the appended claims.

[0044] The following commercial compositions were used in the Examples below:

[0045] EAC 1 is an ethylene / methacrylic acid (MAA) copolymer that has an MAA content of 4 wt.% and a melt index of 11 g / 10 min. The melt strength of EAC 1 is 1.0 cN.

[0046] EAC2 is an ethylene / MAA copolymer that has an MAA content of 8.7 wt.% and a melt index of 10 g / 10 min. The melt strength of EAC 2 is 2.3 cN.

[0047] EAC3 is ethylene / MAA copolymer that has an MAA content of 12 wt.% and a melt index of 13.5 g / 10 min. The melt strength of EAC3 is less than 0.5 cN.

[0048] EAC4 is ethylene / MAA copolymer that has an MAA content of 15 wt.% and a melt index of 25 g / 10 min. The melt strength of EAC4 is less than 0.5 cN.

[0049] All ethylene / MAA copolymers were prepared by standard free-radical copolymerization methods, using high pressure, operating in a continuous manner. Monomers are fed into the reaction mixture in a proportion, which relates to the monomer's reactivity, and the amount desired to be incorporated. In this way, uniform, near-random distribution of monomer units along the chain is achieved. Polymerization in this manner is well known, and is described in U.S. Pat. No. 4,351,931 (Armitage), which is hereby incorporated by reference. Other polymerization techniques are described in U.S. Pat. No. 5,028,674 (Hatch et al.) and U.S. Pat. No. 5,057,593 (Statz), both of which are also hereby incorporated by reference. The composition of each sample was a shown in Table 1.Table 1: Sample Composition

[0050] The ethylene / MAA copolymers were all neutralized with 1.57 wt.% zinc oxide during extrusion and compounding. Extrusion and compounding were performed on a Krauss Maffei ZE42 co-rotating intermeshing twin-screw extruder. The screw diameter was 42 mm, and the total extruder length: diameter ratio was 48:1. The raw material pellets were fed into the extruder byloss-in- weight feeders. A 20 HP Wintek vacuum pump was used to enforce devolatilization on the vent port of the extruder to remove the water generated by the neutralization reaction as well as other volatiles. The neutralized polymer melt was pelletized by a GALA underwater pelletization system. Pellets were dried under desiccated air overnight, and finally packaged into moisture-proof bags. The extrusion and compounding parameters used by the extruder are as provided in Table 2.

[0051] Extrusion coating trials are performed using a Black-Clawson line following standard coating procedures. In brief, single-layer films are extruded using a the 3 -layer extrusion coating (EC) line, utilizing the 3.5 inch (88.9 mm) diameter extruder. The barrel has six heater zones with a temperature profile Al-6 = 365 °F, 455 °F, 500 °F, 560 °F, 560 °F, 560 °F and melt temperature of 550 °F measured at the adapter pipe entry into feed block. A Nordson EDI 36 inch Autoflex™ Die is used, and a 0.5-0.6 mm (0.020”) die gap. The line is equipped with a 30 inch chill roll, nip roll, backing roll, and shear slitter.

[0052] The air gap was set at 9 inches (229 mm) and samples were collected at 440 ft / min (134 meter / min) with a time-in-the-air-gap (TIAG) around 100 ms. Pre-laminated aluminum foil / / PET sheet was dropped onto the kraft paper substrate at the main nip / chill roll, and the coated slip sheets were collected for adhesion test. Process stability assessments (drawdown and draw rate) were conducted to assess extensibility of the extrudate. The drawdown test was performed by maintaining a constant material output (90 rpm at extrusion screw) while increasing line rate (ft / min) until web failure or maximum speed of 1500 ft / min. The draw rate test is performed by maintaining constant extrusion coat weight (7.5 Ibs. / ream) while increasing line rate (ft / min) until web failure or maximum speed of 1500 ft / min.Table 2: Extrusion and Compounding Parameters

[0053] The properties of the extrusion-coated metal substrate for the various samples are as shown in Table 3.Table 3: Properties of the Extrusion-Coated Metal Substrate

[0054] As demonstrated by samples IE A-IE D, the peel strength is greater than the peel strength of other samples when the second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer, the sample included a greaterwt.% of the first ethylene acid copolymer than the second ethylene acid copolymer, and the sample included a total acid content of less than or equal to 6.5 wt.%, based on the total weight of carboxylic acid comonomer in the composition.

[0055] In samples CE 1 - CE 3, where the samples included a greater or equal weight percentages of the second ethylene acid copolymer than first copolymer, and wherein the second ethylene acid copolymer had less than 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer, the peel strength was not as great as the peel strength for samples IE A- IE D.

[0056] Similarly, even in CE 4 and CE 5, where the samples included a lower weight percentage of the second ethylene acid copolymer than first copolymer, the second ethylene acid copolymer had less than 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer, the peel strength was still not as great as the peel strength for samples IE A-IE D.

[0057] Additionally, samples CE 1, CE 2, and CE 6 - CE 9 all included a total acid content of greater than 6.5 wt.%, based on the total weight of carboxylic acid comonomer in the composition, and all had a peel strength below the peel strength of the peel strength for samples IE A-IE D.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of conflict, the specification, including definitions, will control.

[0059] Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of various examples, suitable methods and materials are described herein.

[0060] Unless stated otherwise, all percentages, parts, ratios, etc., are by weight. When an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of lower preferable values and upper preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any lower range limit or preferred value and any upper range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended toinclude the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the present disclosure be limited to the specific values recited when defining a range.

[0061] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “containing,” “characterized by,” “has,” “having,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or.

[0062] The transitional phrase “consisting essentially of’ limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the disclosure. Where applicants have defined an embodiment or a portion thereof with an open-ended term such as “comprising,” unless otherwise stated, the description should be interpreted to also describe such an embodiment using the term “consisting essentially of.”

[0063] Use of “a” or “an” are employed to describe elements and components of various examples. This is merely for convenience and to give a general sense of the various examples. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Claims

CLAIMS1. A composition comprising:1 to 99 wt.% of a first ethylene acid copolymer having a melt strength (MS) < 1.5 cN, the first ethylene acid copolymer comprising the polymerized reaction product of:60 to 99 wt.% ethylene monomer; and carboxylic acid comonomer;1 wt.% to 30 wt.% of a second ethylene acid copolymer comprising the polymerized reaction product of:60 wt.% to 99 wt.% ethylene monomer; and carboxylic acid comonomer; wherein: the second ethylene acid copolymer has at least 8 wt.% more carboxylic acid comonomer than the first ethylene acid copolymer; the composition comprises a greater wt.% of the first ethylene acid copolymer than the second ethylene acid copolymer; and the composition comprises a total acid content of less than or equal to 6.5 wt.%, based on the total weight of carboxylic acid comonomer in the composition.

2. The composition of claim 1, wherein the composition has a melt index (L) of from 4 g / 10 min to 12 g / 10 min as measured according to ASTM D1238 (190 °C, 2.16 kg).

3. The composition of claim 1 or claim 2, wherein the first ethylene acid copolymer has a melt index (I2) of at least 5 g / 10 min.

4. The composition of any one of claims 1-3, wherein the composition comprises 70 to 95 wt.% of the first ethylene acid copolymer, and 1 to 20 wt.% of the second ethylene acid copolymer.

5. The composition of any one of claims 1-4, wherein the first ethylene acid copolymer comprises 1 to 6 wt.% carboxylic acid comonomer, and the second ethylene acid copolymer comprises 9 to 25 wt.% carboxylic acid comonomer.

6. The composition of any one of claims 1-5, wherein the MS of the first ethylene acid copolymer is from 0.3 to 1.2 cN.

7. The composition of any one of claims 1-6, wherein the first ethylene acid copolymer, the second ethylene acid copolymer or both of the composition are at least partially neutralized with metal cations.

8. A method of producing an extrusion-coated metal substrate, the method comprising: melt blending the composition of any one of the preceding claims in an extruder to produce extrusion coating material; and applying the extrusion coating material onto a metal substrate to produce the extrusion- coated metal substrate.

9. The method of claim 6, wherein the first ethylene acid copolymer and the second ethylene acid copolymer are neutralized with metal cations during the melt blending.

10. The method of claim 9 or the composition of claim 7, wherein the metal cations comprise zinc or sodium.

11. An article comprising the composition of any of claims 1-7.

12. The article of claim 11, wherein the article is an extrusion-coated metal substrate, a film, or a laminate.

13. The article of claim 12, wherein the metal substrate is aluminum.

14. The article of claim 12, wherein the metal substrate is a metalized film.

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