Tie layers comprising functionalized polyethylene and multilayer structures incorporating same

Abstract

A multilayer structure includes an aluminum substrate, a polymer layer, and at least one tie layer adhering the polymer layer to the aluminum substrate, wherein the tie layer includes a polyethylene comprising one or more linear low density polyethylene resins and having a melt index (I2) of 0.5 to 10 dg / min as determined according to ASTM D1238 (190 oC / 2.16 kg), functionalized polyethylene having a melt index (I2) of 1.0 to 10.0 dg / min, wherein the functionalized polyethylene comprises a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof, a polystyrene with a VICAT softening temperature above 90 oC, and a modifier including one or more of very low density polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer.

Description

TIE LAYERS COMPRISING FUNCTIONALIZED POLYETHYLENE AND MULTILAYER STRUCTURES INCORPORATING SAMECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 627,391 filed January 31, 2024, the contents of which are incorporated in their entirety herein.TECHNICAL FIELD

[0002] The present disclosure generally relates to tie layers effective at higher temperatures and specifically relate to multilayer structures that utilizes these tie layers to maintain adhesion between an aluminum substrate and a polymer layer at higher temperatures.BACKGROUND

[0003] Specialty multilayer structures serve multiple applications and market segments across the food, specialty packaging, infrastructure, and transportation industries. These multilayer structures may include tie layers to adhere dissimilar layers within the multilayer structures. The tie layers strongly adhere to the layers on each side of the tie layer, thus helping bind together those layers in the multilayer composite structure.

[0004] However, conventional tie layers are often unable to withstand high temperatures (i.e., temperatures greater than 100 °C), which may result in poor adhesion and delamination of the multilayer structure. Therefore, a need exists for improved tie layers that resist delamination at high temperatures.SUMMARY

[0005] Possibly the most vulnerable point in multilayered aluminum pipes is the adhesion between the adhesive layer and aluminum. During heating, the multilayered aluminum pipes may blister, which results in a delamination between the tie layer and the aluminum layer. This delamination is detrimental to the integrity and longevity of the pipes.

[0006] Embodiments of the present disclosure address these and other issues by utilizing a tie layer including polyethylene, functionalized polyethylene, polystyrene, and a modifier. The formulated tie resins will not only deliver strong bond between aluminum and polyethylene core layer, but also provide improved heat resistance for high-temperature applications such as hot water pipes.

[0007] In one embodiment, a multilayer structure comprises an aluminum substrate, a polymer layer such as polyethylene layer, and at least one tie layer adhering the polymer layer to the aluminum substrate, wherein the tie layer includes a polyethylene comprising one or more linear low density polyethylene resins and having a melt index (E) of 0.5 to 10 dg / min as determined according to ASTM D1238 (190 °C / 2.16 kg), functionalized polyethylene having a melt index (I2) of 1.0 to 10.0 dg / min, wherein the functionalized polyethylene comprises a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof, a polystyrene with a VICAT softening temperature above 90 °C, and a modifier including one or more of very low density polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer.

[0008] According to one or more embodiments of the present disclosure, an article may be produced from the above multilayer structures.

[0009] According to one or more embodiments of the present disclosure, a tie layer includes a polyethylene comprising one or more linear low density polyethylene resins and having a melt index (I2) of 0.5 to 10 dg / min as determined according to ASTM D1238 (190 °C / 2.16 kg), functionalized polyethylene having a melt index (I2) of 1.0 to 10.0 dg / min, wherein the functionalized polyethylene comprises a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof, a polystyrene with a VICAT softening temperature above 90 °C, and a modifier including one or more of very low density polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer.

[0010] Additional features and advantages 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 orrecognized by practicing the embodiments described herein, including the detailed description which follows in addition to the claims.

[0011] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter.DETAILED DESCRIPTION

[0012] DEFINITIONS

[0013] As used in this disclosure, the term “polymer” may refer to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term “homopolymer,” usually employed to refer to polymers prepared from only one type of monomer as well as “copolymer,” which refers to polymers 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 copolymers, and polymers prepared from more than two different types of monomers, such as terpolymers.

[0014] “Blend”, “polymer blend” and like terms mean a composition of two or more polymers. Such a blend may or may not be miscible. Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and any other method known in the art. Blends are not laminates, but one or more layers of a laminate may contain a blend. Such blends can be prepared as dry blends, formed in situ (e.g., in a reactor), melt blends, or using other techniques known to those of skill in the art.

[0015] “Polyolefin”, “polyolefin polymer”, “polyolefin resin” and like terms mean a polymer produced from a simple olefin (also called an alkene with the general formula Cnfhn) as a monomer. Polyethylene is produced by polymerizing ethylene with or without one or more comonomers, polypropylene by polymerizing propylene with or without one or morecomonomers, etc. Thus, polyolefins include interpolymers such as ethylene / a-olefin copolymers, propylene / a-olefin copolymers, etc.

[0016] As used in this disclosure, the term “polyethylene” or “ethylene -based polymer” may refer to polymers comprising greater than 50% by mole of units, which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene-based polymer known in the art include low density polyethylene (TDPE); linear low density polyethylene (TTDPE); 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).

[0017] The term “functionalized polyethylene” means a polyethylene incorporating at least one functional group in its polymer structure. Exemplary functional groups may include, for example, ethylenically unsaturated mono- and di-functional carboxylic acids, ethylenically unsaturated mono- and di-functional carboxylic acid anhydrides, salts thereof and esters thereof. Such functional groups can be grafted to an ethylene homopolymer or an ethylene / a-olefin interpolymer, or it may be copolymerized with ethylene and an optional additional comonomer to form an interpolymer of ethylene, the functional comonomer and optionally other comonomer(s).

[0018] “Ethylene acid copolymer” is a polymerized reaction product of ethylene and one or more unsaturated carboxylic acids.

[0019] The term “TTDPE”, includes both resins made using the traditional Ziegler-Natta catalyst systems and chromium-based catalyst systems as well as single-site catalysts, including, but not limited to, bis -metallocene catalysts (sometimes referred to as “m- LLDPE”), constrained geometry catalysts (CGC), and molecular catalysts. Resins include linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPEs contain less long chain branching than LDPEs and includes the substantially linear ethylene polymers which are further defined in U.S. Patent 5,272,236, U.S. Patent 5,278,272, U.S. Patent 5,582,923 and US Patent 5,733,155; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992; the heterogeneously branched ethylene polymers such as thoseprepared according to the process disclosed in U.S. Patent No. 4,076,698; and / or blends thereof (such as those disclosed in US 3,914,342 or US 5,854,045). The LLDPEs can be made via gasphase, solution-phase or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0020] “Low density polyethylene” or “LDPE” refers polyethylene having a density from about 0.910 to 0.940 g / cm3produced in radical polymerization reactions under high pressure such that branching occurs and non-linear polyethylene is formed.

[0021] “Very low density polyethylene” or “VLDPE” refers to refers polyethylene having a density from about 0.885 to 0.915 g / cm3.

[0022] “Eligh density polyethylene” or “EIDPE” refers to polyethylene having a density from about 0.940 usually to about 0.970 g / cm3.

[0023] The term "olefin block copolymer" refers to a copolymerized polymer of ethylene or propylene with a-olefins, wherein the copolymer comprises a plurality of repeating unit blocks or segments that are distinguishable from one another as they differ in at least one of their physical or chemical properties; for example, the content (mole fraction) of the repeating units derived from ethylene (or propylene) and the a-olefins, respectively, a degree of crystallization, a density, or a melting temperature.

[0024] EMBODIMENTS

[0025] Reference will now be made in detail to embodiments of multilayer structures an aluminum substrate, a polymer layer, and at least one tie layer adhering the polymer layer to the aluminum substrate, wherein the tie layer includes a polyethylene comprising one or more linear low density polyethylene resins and having a melt index (L) of 0.5 to 10 dg / min as determined according to ASTM D1238 (190 °C / 2.16 kg), functionalized polyethylene having a melt index (I2) of 1.0 to 10.0 dg / min, wherein the functionalized polyethylene comprises a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof, a polystyrene with a VICAT softening temperature above 90 °C, and a modifier including one or more of very lowdensity polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer.

[0026] Various compositions are considered suitable for the polyethylene including one or more linear low density polyethylene resins. In embodiments, the polyethylene including one or more linear low density polyethylene resins may have a melt index (I2) of from 0.5 to 10.0 dg / min as measured according to ASTM D-1238 (190 °C / 2.16 Kg). In embodiments, the ethylene-based polymer may have a melt index of from 0.5 to 10.0 dg / min, 0.5 to 8.0 dg / min, from 0.5 to 5.0 dg / min, from 0.5 to 2.5 dg / min, 1.0 to 10.0 dg / min, from 1.0 to 8.0 dg / min, from 1.0 to 5.0 dg / min, or from 1.0 to 2.5 dg / min. In further embodiments, the polyethylene including one or more linear low density polyethylene resins may have a density from 0.900 to 0.960 g / cm3, from 0.905 to 0.960 g / cm3, from 0.910 to 0.960 g / cm3, from 0.915 to 0.960 g / cm3, from 0.900 to 0.955 g / cm3, from 0.905 to 0.955 g / cm3, from 0.910 to 0.955 g / cm3, from 0.915 to 0.955 g / cm3, from 0.900 to 0.950 g / cm3, from 0.905 to 0.950 g / cm3, 0.910 to 0.950 g / cm3, from 0.915 to 0.950 g / cm3, from 0.900 to 0.945 g / cm3, from 0.905 to 0.945 g / cm3, 0.910 to 0.945 g / cm3, or from 0.915 to 0.945 g / cm3.

[0027] In various embodiments, the tie layer may include from 50 to 80 wt.% polyethylene, such as from 50 to 80 wt.%, from 55 to 80 wt.%, from 60 to 80 wt.%, from 65 to 80 wt.%, from 50 to 75 wt.%, from 55 to 75 wt.%, from 60 to 75 wt.%, from 65 to 75 wt.%, from 50 to 70 wt.%, from 55 to 70 wt.%, from 60 to 70 wt.%, or from 65 to 70 wt.% polyethylene.

[0028] Various compositions are considered suitable for the functionalized polyethylene. The functionalized polyethylene may be a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof. The ethylenically unsubstituted dicarboxylic acid or derivative thereof may be selected from maleic anhydride, itaconic anhydride, maleic acid diesters, fumaric diesters, maleic acid monoesters or fumaric acid monoesters, esters of Ci to C4 alcohols, maleic acid, itaconic acid, fumaric acid, or mixtures thereof. In some embodiments, the functionalized polyethylene may be a functionalized high density polyethylene. For example, the functionalized polyethylene may include maleic anhydride grafted high density polyethylene.

[0029] The functionalized polyethylene may have a melt index of from 0.5 to 10.0 dg / min as measured according to ASTM D-1238 (190° C / 2.16 kg). In embodiments, the functionalizedpolyethylene may have a melt index of from 0.5 to 10.0 dg / min, from 0.5 to 8.0 dg / min, from 0.5 to 5.0 dg / min, 1.0 to 10.0 dg / min, from 1.0 to 8.0 dg / min, from 1.0 to 5.0 dg / min, 1.5 to 10.0 dg / min, from 1.5 to 8.0 dg / min, from 1.5 to 5.0 dg / min, from 2.0 to 10.0 dg / min, from 2.0 to 8.0 dg / min, or from 2.0 to 5.0 dg / min. In further embodiments, the functionalized polyethylene may have a density from 0.910 to 0.965 g / cm3, from 0.915 to 0.965 g / cm3, from 0.920 to 0.965 g / cm3, from 0.925 to 0.965 g / cm3, from 0.930 to 0.965 g / cm3, from 0.935 to 0.965 g / cm3, or from 0.940 to 0.965 g / cm3.

[0030] In some embodiments, the functionalized polyethylene may be grafted with 0.1 to 3.0 wt.%, such as from 0.1 to 3.0 wt.%, from 0.5 to 3.0 wt.%, from 0.8 to 3.0 wt.%, from 0.1 to 2.5 wt.%, from 0.5 to 2.5 wt.%, 0.8 to 2.5 wt.%, from 0.1 to 2.0 wt.%, from 0.5 to 2.0 wt.%, from 0.8 to 2.0 wt.%, from 0.1 to 1.8 wt.%, from 0.5 to 1.8 wt.%, or from 0.8 to 1.8 wt.% ethylenically unsubstituted dicarboxylic acid or derivative thereof, for example, maleic anhydride.

[0031] In one or more embodiments, the tie layer may include from 5 wt.% to 20 wt.% functionalized polyethylene. In one or more embodiments, the tie layer may include from 5 wt.% to 20 wt.%, from 8 wt.% to 20 wt.%, from 10 wt.% to 20 wt.%, from 12 wt.% to 20 wt.%, from 5 wt.% to 15 wt.%, from 8 wt.% to 15 wt.%, from 10 wt.% to 15 wt.%, or from 12 wt.% to 15 wt.% functionalized polyethylene.

[0032] Various compositions are considered suitable for the polystyrene. In some embodiments, the polystyrene may include high impact polystyrene. The polystyrene may have a VICAT softening temperature of at least 90 °C, at least 92 °C, at least at least 95 °C, at least 97 °C, or at least 99 °C. VICAT softening temperature may be determined in according to ASTM D- 1525. Without being bound by theory, it is believed that using a polystyrene with a VICAT softening temperature of at least 90 °C may improve adhesion performance and improved delamination resistance of the tie layers at high temperature (i.e. temperatures of at least 100 °C). Without being bound by theory, it is believed that using a polystyrene with a VICAT softening temperature of at least 90 °C may improve adhesion performance and improved delamination resistance of the tie layer at high temperatures (i.e. temperatures of at least 100 °C).

[0033] In one or more embodiments, the tie layer may include from 5 wt.% to 25 wt.% polystyrene. In one or more embodiments, the tie layer may include from 5 wt.% to 25 wt.%, from8 wt.% to 25 wt.%, from 10 wt.% to 25 wt.%, from 12 wt.% to 25 wt.%, from 5 wt.% to 20 wt.%, from 8 wt.% to 20 wt.%, from 10 wt.% to 20 wt.%, or from 12 wt.% to 20 wt.% polystyrene.

[0034] In one or more embodiments, the modifier may include one or more of very low density polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer, ethylene alkyl acrylate.

[0035] In one or more embodiments, polyolefin elastomers may be a homogeneously branched ethylene / alpha-olefin copolymer. These copolymers can be made with a single-site catalyst, including but not limited to metallocene catalyst or constrained geometry catalyst, and typically have a melting point of less than 105, preferably less than 90, more preferably less than 85, even more preferably less than 80 and still more preferably less than 75°C. The melting point is measured by differential scanning calorimetry (DSC) as described, for example, in USP 5,783,638. The alpha-olefin is preferably a C3-20 linear, branched or cyclic alpha -olefin. Examples of C3-20 alpha-olefins include propene, 1 butene, 4-methyl-l -pentene, 1 -hexene, 1 octene, 1 -decene, 1 -dodecene, 1 tetradecene, 1 hexadecene, and 1 -octadecene. The alpha olefins can also contain a cyclic structure such as cyclohexane or cyclopentane, resulting in an alpha - olefin such as 3 cyclohexyl- 1 -propene (allyl cyclohexane) and vinyl cyclohexane. Although not alpha olefins in the classical sense of the term, for purposes of this invention certain cyclic olefins, such as norbornene and related olefins, are alpha -olefins and can be used in place of some or all of the alpha olefins described above. Similarly, styrene and its related olefins (for example, alpha methylstyrene, etc.) are alpha-olefins for purposes of this invention. Illustrative homogeneously branched ethylene / alpha-olefin copolymers include ethyl ene / propylene, ethylene / butene, ethylene / 1 hexene, ethylene / 1 octene, ethylene / styrene, and the like. Illustrative terpolymers include ethylene / propylene / 1 -octene, ethylene / propylene / butene, ethylene / butene / 1 octene, and ethylene / butene / styrene .

[0036] More specific examples of homogeneously branched ethylene / alpha-olefin interpolymers useful in this invention include homogeneously branched, linear ethylene / alpha olefin copolymers (e.g. TAFMER® by Mitsui Petrochemicals Company Limited and EXACT® by Exxon Chemical Company), and the homogeneously branched, substantially linear ethylene / alpha -olefin polymers (e.g., AFFINITY™ and ENGAGE™ polyethylene available from TheDow Chemical Company). The substantially linear ethylene copolymers are especially preferred, and are more fully described in USP 5,272,236, 5,278,272 and 5,986,028. Blends of any of these interpolymers can also be used in the practice of this invention.

[0037] In one or more embodiments, the tie layer may include from 5 wt.% to 25 wt.% modifier. In one or more embodiments, the tie layer may include from 5 wt.% to 25 wt.%, from 8 wt.% to 25 wt.%, from 10 wt.% to 25 wt.%, from 12 wt.% to 25 wt.%, from 5 wt.% to 20 wt.%, from 8 wt.% to 20 wt.%, from 10 wt.% to 20 wt.%, or from 12 wt.% to 20 wt.% modifier.

[0038] Various compositions are considered suitable for the ethylene alkyl acrylate copolymer. In one or more embodiments, the ethylene alkyl acrylate copolymer includes from 15 to 35 wt.%, from 20 to 35 wt.%, or from 25 to 35 wt.% of the acrylate comonomer. In some embodiments, the ethylene alkyl acrylate copolymer may include ethylene methyl acrylate copolymers, ethylene ethyl acrylate copolymers, ethylene propyl acrylate copolymers, or ethylene butyl acrylate copolymers.

[0039] Various compositions are considered suitable for the olefin block copolymer. In one or more embodiments, the olefin block copolymer may be an ethylene copolymer-based elastomer with a C3 to C20 hydrocarbon comonomer such as 1 -butene, 1 -hexene, or 1 -octene. For example, the olefin block copolymer may include an ethylene / C3-Ci2-alpha-olefin copolymer.

[0040] The olefin block copolymer may have a melt index (I2) of from 0.1 to 5.0 dg / min (2.16 kg / 190 °C). The olefin block copolymer may have a melt index (I2) of from 0.1 to 5.0 dg / min, from 0.1 to 4.0 dg / min, from 0.1 to 3.0 dg / min, from 0.1 to 2.0 dg / min, from 0.1 to 1.5 dg / min, from 0.5 to 5.0 dg / min, from 0.5 to 4.0 dg / min, from 0.5 to 3.0 dg / min, from 0.5 to 2.0 dg / min, or from 0.5 to 1.5 dg / min. The olefin block copolymer may have a melting temperature of at least 115 °C, at least 116 °C, at least 117 °C, or at least 118 °C. The olefin block copolymer may have a density of from 0.850 to 0.900 g / cm3, such as from 0.850 to 0.900 g / cm3, from 0.850 to 0.895 g / cm3, from 0.850 to 0.890 g / cm3, from 0.850 to 0.885 g / cm3, from 0.850 to 0.880 g / cm3, from 0.860 to 0.900 g / cm3, such as from 0.860 to 0.900 g / cm3, from 0.860 to 0.895 g / cm3, from 0.860 to 0.890 g / cm3, from 0.860 to 0.885 g / cm3, from 0.860 to 0.880 g / cm3, 0.865 to 0.900 g / cm3, such as from 0.865 to 0.900 g / cm3, from 0.865 to 0.895 g / cm3, from 0.865 to 0.890 g / cm3, from 0.865 to 0.885 g / cm3, or from 0.865 to 0.880 g / cm3.

[0041] In one or more embodiments, the ethylene propylene diene terpolymers may have a density of from 0.850 to 0.890 g / cm3, from 0.860 to 0.890 g / cm3, from 0.870 to 0.890 g / cm3, from 0.875 to 0.890 g / cm3, from 0.850 to 0.885 g / cm3, from 0.860 to 0.885 g / cm3, from 0.870 to 0.885 g / cm3, or from 0.875 to 0.885 g / cm3.

[0042] In one or more embodiments, the ethylene propylene diene terpolymers may have an ethylene content of from 50 to 90 wt.%, from 55 to 90 wt.%, from 60 to 90 wt.%, from 65 to 90 wt.%, from 50 to 85 wt.%, from 55 to 85 wt.%, from 60 to 85 wt.%, from 65 to 85 wt.%, from 50 to 80 wt.%, from 55 to 80 wt.%, 60 to 80 wt.%, 65 to 80 wt.%, from 50 to 75 wt.%, from 55 to 75 wt.%, from 60 to 75 wt.%, or from 65 to 75 wt.%.

[0043] In one or more embodiments, the ethylene propylene diene terpolymers may have an ethylidene norbornene (ENB) content of from 0.1 to 5.0 wt.%, from 0.1 to 4.0 wt.%, from 0.1 to 3.0 wt.%, from 0.1 to 2.0 wt.%, from 0.1 to 1.0 wt.%, from 0.2 to 1.0 wt.%, from 0.3 to 1.0 wt.%, from 0.4 to 1.0 wt.%, from 0.1 to 0.9 wt.%, from 0.2 to 0.9 wt.%, 0.3 to 0.9 wt.%, from 0.4 to 0.9 wt.%, from 0.1 to 0.8 wt.%, from 0.2 to 0.8 wt.%, from 0.3 to 0.8 wt.%, from 0.4 to 0.8 wt.%, from 0.1 to 0.7 wt.%, from 0.2 to 0.7 wt.%, from 0.3 to 0.7 wt.%, from 0.4 to 0.7 wt.%, from 0.1 to 0.6 wt.%, from 0.2 to 0.6 wt.%, from 0.3 to 0.6 wt.%, or from 0.4 to 0.6 wt.%.

[0044] In one or more embodiments, the ethylene propylene diene terpolymers may have a propylene content of from 10 to 50 wt.%, from 15 to 50 wt.%, from 20 to 50 wt.%, from 25 to 50 wt.%, from 10 to 50 wt.%, from 15 to 50 wt.%, from 20 to 50 wt.%, from 25 to 50 wt.%, from 10 to 45 wt.%, from 15 to 45 wt.%, from 20 to 45 wt.%, from 25 to 45 wt.%, from 10 to 45 wt.%, from 15 to 45 wt.%, from 20 to 45 wt.%, from 25 to 45 wt.%, from 10 to 40 wt.%, from 15 to 40 wt.%, from 20 to 40 wt.%, from 25 to 40 wt.%, from 10 to 40 wt.%, from 15 to 40 wt.%, from 20 to 40 wt.%, from 25 to 40 wt.%, from 10 to 35 wt.%, from 15 to 35 wt.%, from 20 to 35 wt.%, from 25 to 35 wt.%, from 10 to 35 wt.%, from 15 to 35 wt.%, from 20 to 35 wt.%, or from 25 to 35 wt.%.

[0045] In one or more embodiments, the ethylene propylene diene terpolymers may have a Mooney viscosity (ML l+4@ 125 °C) greater than 10 Mooney Units (MU). The ethylene propylene diene terpolymers may have a Mooney viscosity of from 10 to 50 MU, from 15 to 50 MU, from 18 to 50 MU, from 10 to 45 MU, from 15 to 45 MU, from 18 to 45 MU, from 10 to 40MU, from 15 to 40 MU, from 18 to 40 MU, from 10 to 35 MU, from 15 to 35 MU, from 18 to 35MU, from 10 to 30 MU, from 15 to 30 MU, from 18 to 30 MU, from 10 to 25 MU, from 15 to 25MU, from 18 to 25 MU, from 10 to 22 MU, from 15 to 22 MU, or from 18 to 22 MU.

[0046] The ethylene acid copolymer includes or is derived from 60 weight percent (wt.%) to99 wt.% ethylene monomer. In some examples, the polymerized reaction product includes from 60 wt.% to 99 wt.% ethylene, from 60 wt.% to 95 wt.% ethylene, from 60 wt.% to 90 wt.% ethylene, 70 wt.% to 99 wt.% ethylene, from 70 wt.% to 95 wt.% ethylene, from 70 wt.% to 90 wt.% ethylene, 80 wt.% to 99 wt.% ethylene, from 80 wt.% to 95 wt.% ethylene, or from 80 wt.% to 90 wt.% ethylene.

[0047] The ethylene acid copolymer includes from 1 wt.% to 40 wt.% carboxylic acid monomers. The carboxylic acid monomers can be, for example, acrylic acid, methacrylic acid, or combinations thereof. In some examples, ethylene acid copolymer includes from 1 wt.% to 40 wt.% carboxylic acid monomers, from 1 wt.% to 30 wt.% carboxylic acid monomers, from 1 wt.% to 20 wt.% carboxylic acid monomers, from 1 wt.% to 10 wt.% carboxylic acid monomers, from 1 wt.% to 5 wt.% carboxylic acid monomers.

[0048] The ethylene acid copolymer 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 acid copolymer 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. In some embodiments, blends of two or more ethylene acid copolymers may be used, provided that the aggregate components and properties of the blend fall within the limits described above for the ethylene acid copolymers.

[0049] In one or more embodiments, the tie layer may further include zeolite. Without being bound by theory, zeolite is believed to absorb moisture that may become trapped between the aluminum substrate and the polymer layer. Absorbing moisture between the aluminum substrate and the polymer layer may help increase the lifespan of the multilayer structure and may help to prevent delamination. Various zeolites are considered suitable, such as framework type MFIzeolites. In one or more embodiments, the zeolite may be present in the tie layer at from 0.1 to 5 wt.%, such as from 0.2 to 1.0 wt.%.

[0050] In one or more embodiments, the tie layer may include from 0.05 to 3.0 wt.% maleic anhydride, such as from 0.05 to 3.0 wt.%, from 0.1 to 3.0 wt.%, from 0.5 to 3.0 wt.%, from 1.0 to 3.0 wt.%, from 1.5 to 3.0 wt.%, from 2.0 to 3.0 wt.%, from 0.05 to 2.0 wt.%, from 0.1 to 2.0 wt.%, from 0.5 to 2.0 wt.%, from 1.0 to 2.0 wt.%, from 1.5 to 2.0 wt.%, from 0.05 to 1.5 wt.%, from 0.1 to 1.5 wt.%, from 0.5 to 1.5 wt.%, from 1.0 to 1.5 wt.%, 0.05 to 1.0 wt.%, from 0.1 to 1.0 wt.%, from 0.5 to 1.0 wt.%, 0.05 to 0.5 wt.%, or from 0.1 to 0.5 wt.% maleic anhydride.

[0051] Without being bound by theory, it is believed that using polyethylene including one or more linear low density polyethylene resins, functionalized polyethylene, polystyrene, and a modifier may improve adhesion at higher temperatures compared to conventional tie layers.

[0052] ADDITIVES

[0053] It should be understood that any of the foregoing layers can further comprise one or more additives as known to those of skill in the art such as, for example, antioxidants, rheology modifiers, moisture absorbents, ultraviolet light stabilizers, thermal stabilizers, slip agents, antiblock agents, antistatic agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers and foaming agents. The layer may contain any amounts of such additives, such as from 0 wt. % to 10 wt. %, from 0 wt. % to 5 wt. %, from 0 wt. % to 1 wt. %, from 0 wt. % to 0.1 wt. %, from 0 wt. % to 0.001 wt. %, or any subset thereof, based on a weight of the layer.

[0054] ARTICEES

[0055] In various embodiments, the multilayer structure may be a laminate or an extrusion coated substrate.

[0056] The multilayer structure may be constructed from two or more layers by any lamination and / or coextrusion technique and using any blown or cast extrusion and lamination equipment known in the art. For example, multilayer structure may be prepared using coextrusion techniques, such as, by cast coextrusion techniques.

[0057] In one or more embodiments, an article may be produced from the multilayer structures described herein. The articles may include aluminum composite pipe, aluminum composite sheet, or aluminum composite panel.

[0058] TEST METHODS

[0059] Melt index was measured according to ASTM D1238 and / or ISO 1133, under selected conditions of temperature (T) and load (E), noted as MI (T(°C) / L(kg)) and expressed in units of gram per 10 minutes or simplified to dg / min. Conditions used are (190 °C / 2.16 kg) so the melt index is also referred to as “I2”.

[0060] Mooney viscosity was measured following ASTM DI 646 with conditions ME 1+4(125 °C).

[0061] The melting temperature (Tm) of different polymers was measured by differential scanning calorimetry (DSC) with a heat / cool / heat method, where the reported Tm was the peak temperature determined from the second heat based on ASTM D3418.

[0062] Density measurements were performed on test specimen from compression-molded plaques prepared according to ASTM D4703. Measurements were made within one hour of sample pressing, according to ASTM D792, Method B, within one hour of sample pressing.

[0063] VICAT softening temperature was determined according to ASTM-D1525, the entirety of which is hereby incorporated by reference.

[0064] An adhesion test to determine bonding strength was performed using an Instron 5966 test frame with a 3199-6000 custom environmental chamber. The adhesion peel force was measured at 23 °C or 95 °C at peel rate of 10 inch per minute, and average peel-force was recorded between a displacement of 1 inch and 4 inches.EXAMPLES

[0065] 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.

[0066] The following compositions is listed in Table 1 were used in the Examples below.Table 1: Chemical Compositions

[0067] FP-1 was prepared according to Example 1 of U.S. Patent No 4950541 , the entirety of which is hereby incorporated by reference.

[0068] N d )PE-1 was prepared in a loop reactor, using the conditions shown in Table 2, according to Inventive Composition 1 in United States Patent No. 10800908, the entirety of which is hereby incorporated by reference.Table 2: Loop Reactor Conditions

[0069] EXAMPLE 1

[0070] Example tie layers were prepared according to the formulations shown in Table 3. Different formulations of tie resins were compounded through a 26 mm diameter co-rotating, intermeshing twin-screw extruder (26MC18 from Coperion). The extruder was configured with 11 barrels (44 L / D). The extruder was equipped with loss-in- weight feeders. All the raw materials were fed through the main feed port. Nitrogen at 10 SCFH was used to purge first barrel section to maintain an inert atmosphere and minimize oxidation. A two-hole die and three-blades hub were used for underwater pelletization process. Cooling water temp is at 13 °C. A run rate of 20Ibs / hr and a screw speed of 300 rpm was used. Barrel 1 was water cooled, Barrels 2-3 were maintained at 130-180 °C, Barrels 4-11 were maintained at 220 °C.Table 3: Example Tie Layer Formulations

[0071] Tie resins were fabricated into monolayer fdms with 3 mils (75 micron) thickness from a Collin blown fdm line with a 30 mm diameter screw extruder and 30 L / D ratio. The extrusion temperature profde was: 160 °C / 185 °C / 185 °C / 185 °C / Adapter = 185 °C / Die = 185 °C with a 24 inch lay flat and blow up ratio around 2.5.

[0072] DOWLEX 2388 (12=0.55, density = 0.941 g / cc) HDPE was fabricated into an 80 mil (2 mm) sheet through a monolayer Collin cast sheet line and cut into 9 inches by 12 inches sheets to form a core sheet.

[0073] A roll of soft aluminum (zero temper) was cut into 9 inches by 12 inches sheets and wiped with isopropanol to clean the surface. The laminates were pre-assembled in the order of [aluminum sheets / / adhesive film / / HDPE core / / adhesive film / / aluminum sheet]. One side of the adhesive fdms was same size as the aluminum sheet (9 inches by 12 inches), and the other was half the length of the aluminum sheet (9 inch by 6 inch), which generates peel tabs for adhesiontests. The assembled panels were taped on the edge and placed under a hot platen press, pre-heated at 70 °C for 4 minutes, and then laminated at 180 °C, 50 psi for 20 seconds. The laminated structure was cooled down to room temperature and then sized into 1-inch strips by a hydraulic press die cut for peel test.

[0074] An adhesion test was performed using an Instron 5966 test frame with a 3199-6000 custom environmental chamber. The adhesion peel force was measured at 23 °C and 95 °C for 5 specimen per sample at peel rate of 10 inch per minute, and average peel-force between displacement of 1 inch to 4 inches was reported for each sample. The results were as shown in Table 4.Table 4: Results of the Peel Test

[0075] Though examples CE1 and CE2 both had good adhesion (i.e. adhesion of greater than 2 newtorns per mm (N / mm)) at room temperature (23 °C), examples CE1 and CE2 failed to have good adhesion at 95 °C. However, examples IE1-IE7, which included polystyrene, all had good adhesion at both 23 °C and 95 °C. The good adhesion of examples IE1-IE7 show that the tie layers may be suitable for high temperature applications such as hot water aluminum composite pipes.

[0076] The subject matter of the present disclosure has been described in detail and by reference to specific embodiments. It should be understood that any detailed description of a component or feature of an embodiment does not necessarily imply that the component or feature is essential to the particular embodiment or to any other embodiment. Further, it should be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

[0077] It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce arecitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”

[0078] It should be understood that where a first component is described as “comprising” a second component, it is contemplated that, in embodiments, the first component “consists” or “consists essentially of’ that second component. It should further be understood that where a first component is described as “comprising” a second component, it is contemplated that, in embodiments, the first component comprises at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even at least 99% that second component (where % can be weight % or molar %).

[0079] It is also noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc.

Claims

CLAIMS1. A multilayer structure comprising an aluminum substrate, a polymer layer, and at least one tie layer adhering the polymer layer to the aluminum substrate, wherein the tie layer comprises: a polyethylene comprising one or more linear low density polyethylene resins and having a melt index (I2) of 0.5 to 10 dg / min as determined according to ASTM D1238 (190 °C / 2.16 kg); functionalized polyethylene having a melt index (I2) of 1.0 to 10.0 dg / min, wherein the functionalized polyethylene comprises a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof; a polystyrene with a VICAT softening temperature above 90 °C; and a modifier comprising one or more of very low density polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer.

2. The multilayer structure of claim 1, wherein the tie layer comprises from 0.05 to 0.3 wt.% malefic anhydride.

3. The multilayer structure of claims 1 or 2, wherein the tie layer further comprises zeolite.

4. The multilayer structure of any one of claims 1 to 3, wherein the modifier comprises the ethylene alkyl acrylate copolymer, the ethylene alkyl acrylate copolymer having an acrylate comonomer comprising one or more of methyl acrylate, ethyl acrylate, or butyl acrylate.

5. The multilayer structure of any one of claims 1 to 4, wherein the ethylene alkyl acrylate copolymer comprises from 15 to 35 wt.% of the acrylate comonomer.

6. The multilayer structure of any one of claims 1 to 5, wherein the modifier comprises the ethylene propylene diene terpolymer having a Mooney viscosity (MT 1+4, 125 °C) greater than 10 Mooney Units (MU).

7. The multilayer structure of any one of claims 1 to 6, wherein the ethylenically unsubstituted dicarboxylic acid is selected from the group consisting of maleic anhydride, itaconic anhydride, maleic acid diesters, fumaric diesters, maleic acid monoesters orfumaric acid monoesters, esters of Ci to C4 alcohols, maleic acid, itaconic acid, fumaric acid, or mixtures thereof.

8. The multilayer structure of any one of claims 1 to 7, wherein the ethylenically unsubstituted dicarboxylic acid comprises maleic anhydride.

9. The multilayer structure of any one of claims 1 to 8, wherein the modifier comprises the olefin block copolymer, the olefin block copolymer being an ethylene / C3-Ci2 alpha-olefin copolymer having a density of 0.850 to 0.900 g / cm3, a melt index (I2) of 0.5 to 5.0 dg / min (190 °C / 2.16 kg), and a melting temperature of at least 115 °C.

10. The multilayer structure of any one of claims 1 to 9, wherein the polyethylene comprises a density of 0.910 to 0.945 g / cm3and a melt index (I2) of 0.5 to 8.0 dg / min (190 °C / 2.16 kg).

11. The multilayer structure of any one of claims 1 to 10, wherein the tie layer comprises: from 50 to 80 wt.% polyethylene; from 5 to 20 wt.% functionalized polyethylene; from 5 to 25 wt.% polystyrene; and from 5 to 25 wt.% modifier.

12. The multilayer structure of any one of claims 1-11, wherein the multilayer structure is a laminate or an extrusion coated substrate.

13. An article comprising the multilayer structure of any one of claims 1 to 12.

14. The article of claim 13, wherein the article comprises aluminum composite pipe, aluminum composite sheet, or aluminum composite panel.

15. A composition comprising: a polyethylene comprising one or more linear low density polyethylene resins and having a melt index (I2) of 0.5 to 10 dg / min as determined according to ASTM D1238 (190 °C / 2.16 kg);functionalized polyethylene having a melt index (h) of 1.0 to 10.0 dg / min (190 °C / 2.16 kg), wherein the functionalized polyethylene comprises a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid; a polystyrene with a VICAT softening temperature above 90 °C; and a modifier comprising one or more of very low density polyethylene, polyolefin elastomer, ethylene acid copolymer, olefin block copolymer, ethylene alkyl acrylate copolymer, and ethylene propylene diene terpolymer.

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