Ethylene acid copolymer ionomers with improved creep resistance.

Abstract

According to one embodiment, the ionomer comprises a neutralized blend of an ethylene acid copolymer and an aliphatic monofunctional organic acid. The blend comprises 60 to 95 wt % of the aliphatic monofunctional organic acid, based on the total weight percent of the blend, and 5 to 40 wt % of the aliphatic monofunctional organic acid, based on the total weight percent of the blend. The ethylene acid copolymer is the polymerization reaction product of ethylene, an alkyl acrylate, and optionally a monocarboxylic acid monomer and an unsaturated dicarboxylic acid monomer. At least 30 mole percent of the total acid units of the blend are neutralized with magnesium cations of a magnesium neutralization salt. [Selection diagram] None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 712,591, filed July 31, 2018, the entire disclosure of which is incorporated herein by reference.

[0002] Embodiments of the present disclosure relate generally to ionomer resins, and specifically to ionomers comprising the polymerization reaction products of ethylene, monocarboxylic acid monomers, unsaturated dicarboxylic acid monomers, alkyl acrylate monomers, aliphatic monofunctional organic acids, and combinations thereof, which are at least partially neutralized with magnesium cations. [Background technology]

[0003] Ionomers are commonly used materials in a variety of applications because they have higher tensile strength, excellent clarity, good abrasion resistance, and high stiffness than their precursor acid copolymers. For example, ionomers of ethylene acid copolymers have found utility in many applications, such as food packaging, foam parts, injection molded parts (e.g., cosmetic containers), and golf ball components.

[0004] Although ionomers can be used in many applications, their limited service temperature limits their use in applications requiring creep resistance at temperatures above 60° C. For example, ionomers may deform under stress at temperatures above 60° C. Dynamic mechanical thermal analysis reveals a significant decrease in the mechanical strength of ionomers at approximately 60° C., which correlates with the onset of dissociation of ionic aggregates. Summary of the Invention

[0005] Therefore, it would be beneficial to develop alternative ionomers that have improved creep resistance while maintaining the physical and chemical properties of ionomers, such as optical clarity and toughness.

[0006] In an embodiment, the ionomer of the present disclosure comprises a neutralized blend of an ethylene acid copolymer and an aliphatic monofunctional organic acid. The blend comprises 60 to 95 weight percent of the ethylene acid copolymer, based on the total weight percent of the blend, and 5 to 40 weight percent of the aliphatic monofunctional organic acid, based on the total weight percent of the blend, where the aliphatic monofunctional organic acid has fewer than 36 carbon atoms. At least 30 mole percent of the total acid units of the blend are neutralized with the magnesium cation of a magnesium neutralization salt. The ethylene acid copolymer in the blend comprises the polymerization reaction product of ethylene, 1 to 40 weight percent of an alkyl acrylate, based on the total weight percent of the monomers present in the ethylene acid copolymer, 2 to 15 weight percent of an unsaturated dicarboxylic acid monomer, based on the total weight percent of the monomers present in the ethylene acid copolymer, and optionally 0 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of the monomers present in the ethylene acid copolymer.

[0007] In one or more embodiments, an ionomer of the present disclosure comprises a neutralized blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid, wherein the aliphatic monofunctional organic acid has fewer than 36 carbon atoms. The ratio of the first ethylene acid copolymer to the second ethylene acid copolymer in the blend is 90 / 10 wt% to 10 / 90 wt%, based on the total weight percent of the blend, 5 to 40 wt% of the aliphatic monofunctional organic acid, and at least 30 mole percent of the total acid units of the blend are neutralized with magnesium cations of the magnesium neutralization salt.

[0008] In one or more embodiments of the blend, the first ethylene acid copolymer of the blend is the polymerization reaction product of ethylene and 2 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of monomers present in the first ethylene acid copolymer, and 0 to 40 weight percent of an alkyl acrylate, based on the total weight percent of monomers present in the first ethylene acid copolymer.

[0009] In various embodiments of the blend, the second ethylene acid copolymer is the polymerization reaction product of ethylene, 1 to 40 weight percent, based on the total weight percent of monomers present in the second ethylene acid copolymer, of an alkyl acrylate, 0 to 20 weight percent, based on the total weight percent of monomers present in the second ethylene acid copolymer, of a monocarboxylic acid monomer, and 2 to 15 weight percent, based on the total weight percent of monomers present in the ethylene acid copolymer, of an unsaturated dicarboxylic acid monomer. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 present specification, including definitions, will control.

[0011] Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of various embodiments, suitable methods and materials are described herein.

[0012] Unless otherwise specified, all percentages, parts, ratios, etc. are by weight. When an amount, concentration, or other value or parameter is given as either a range, a preferred range, or a list of lower and higher preferred values, this should be understood to specifically disclose all ranges formed from any pairing of any lower range limit or preferred value with any higher range limit or preferred value, regardless of whether the ranges are separately disclosed. When a range of numerical values ​​is recited herein, unless otherwise indicated, the range is intended to include its endpoints, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values ​​recited when defining the range.

[0013] When the term "about" is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

[0014] 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 includes a list of elements is not necessarily limited to those elements and may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated otherwise, "or" refers to an inclusive or, not an exclusive or.

[0015] The transitional phrase "consisting essentially of" limits the scope of a claim to certain materials or steps and to those that do not materially affect the basic and novel characteristic(s) of the disclosure. If applicant has defined an embodiment or portion thereof with open-ended terms such as "comprising," the description should be construed as also describing such embodiments using the term "consisting essentially of," unless otherwise indicated.

[0016] The use of "a" or "an" is used to describe elements and components of various embodiments. This is merely for convenience and to give a general sense of the various embodiments. This description should be read to include one or at least one, and it also includes the plural unless it is clear that the singular means otherwise.

[0017] The term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the general term polymer encompasses the terms "homopolymer" and "copolymer." The term "homopolymer" refers to a polymer prepared from only one type of monomer, while the term "copolymer" refers to a polymer prepared from two or more different monomers, and for purposes of this disclosure, may include "terpolymer" and "interpolymer."

[0018] The term "monocarboxylic acid monomer" refers to a molecule having a reactive moiety, such as vinyl or vinylene, which can combine with other monomers to form a carboxylic acid (-C(O)OH) moiety that is not included in the polymer and the reactive moiety is not included. For example, (meth)acrylic acid is a monocarboxylic acid monomer in which vinylene is the reactive moiety and a carboxylic acid is present. The term "(meth)acrylic acid" includes methacrylic acid and / or acrylic acid, and "(meth)acrylate" includes methacrylate, acrylate, or a combination of methacrylate and acrylate.

[0019] The term "unsaturated dicarboxylic acid monomer" as used in this disclosure means a molecule having a reactive moiety, such as vinyl or vinylene, which can combine with other monomers to form a polymer and two carboxylic acid (-C(O)OH) moieties that are not included in the reactive moiety. Additionally, "unsaturated dicarboxylic acid monomer" includes unsaturated dicarboxylic acid derivative monomers (half esters and anhydrides).

[0020] Various embodiments are directed to ionomers comprising a neutralized blend of an ethylene acid copolymer and an aliphatic monofunctional organic acid. In one or more embodiments, the neutralized blend may comprise an amount of ethylene acid copolymer in the range of 60 to 95 wt%, based on the total weight percent (wt%) of the blend, and an amount of aliphatic monofunctional organic acid in the range of 5 to 40 wt%, based on the total weight percent of the blend. In some embodiments, the ionomer comprises a neutralized blend of an ethylene acid copolymer and an aliphatic monofunctional organic acid, wherein the amount of ethylene acid copolymer is 65 to 80 wt%, 70 to 85 wt%, or 70 to 80 wt%. In some embodiments, the amount of aliphatic monofunctional organic acid is 10 to 40 wt%, 15 to 40 wt%, or 20 to 40 wt%.

[0021] In some embodiments, at least 30 mole percent (mol%) of the total acid units of the blend are neutralized with the magnesium cations of the magnesium neutralizing salt, hi some embodiments, 35-50 mol%, 45-70 mol%, 60-80 mol%, or 80-100 mol% of the total acid units of the blend are neutralized with the magnesium cations of the magnesium neutralizing salt.

[0022] In some embodiments, the ionomer may contain cations other than magnesium cations in addition to the magnesium cations in the blend. The blend may be neutralized with at least one additional metal cation of a neutralizing salt. The neutralizing salt of the at least one additional metal cation may be selected from the group consisting of zinc salts, lithium salts, and sodium salts. In some embodiments, the ionomer may contain 0% to 10%, 1% to 10%, 5% to 20%, 5% to 30%, or 10% to 50% of the total acid units of the blend neutralized with sodium cations of the neutralizing salt, lithium cations of the neutralizing salt, zinc cations of the neutralizing salt, or combinations thereof. In one or more embodiments, at least 70 mole percent of the total acid units of the blend are neutralized with metal cations of the neutralizing salt, and at least 30 mole percent of the at least 70 mole percent of the total acid units of the blend are neutralized with magnesium cations of the magnesium salt.

[0023] In one or more embodiments, the ethylene acid copolymer is the polymerization product of ethylene, an alkyl acrylate, a monocarboxylic acid monomer, and an unsaturated dicarboxylic acid monomer. In some embodiments of the blended ethylene acid copolymer, the alkyl acrylate may be present in an amount of 1 to 40 wt%, based on the total weight percent of monomers present in the ethylene acid copolymer. All individual values ​​and subranges encompassed by "1 wt% to 40 wt%" are disclosed as separate embodiments. The ethylene acid copolymer may, for example, comprise 1 wt% to 20 wt%, 2 wt% to 10 wt%, or 10 wt% to 30 wt% alkyl acrylate, based on the total weight percent of monomers present in the ethylene acid copolymer.

[0024] In various embodiments of the ethylene acid copolymer, the monocarboxylic acid monomer is optional and may be present in an amount of 0 to 20 wt%. All individual values ​​and subranges encompassed by "0 to 20 wt%" are disclosed as separate embodiments. For example, the monocarboxylic acid monomer may be absent or present in an amount of greater than 0 to 10 wt%, 5 to 10 wt%, 10 to 20 wt%, or 15 to 20 wt%, based on the total weight of monomers present in the ethylene acid copolymer.

[0025] In one or more embodiments of the ethylene acid copolymer, the unsaturated dicarboxylic acid monomer may be present in an amount of 2 to 15 wt%, based on the total weight percent of monomers present in the ethylene acid copolymer. All individual values ​​and subranges encompassed by "2 to 15 wt%" are disclosed as separate embodiments. For example, the unsaturated dicarboxylic acid monomer may be present in an amount of 5 to 15 wt%, 3 to 10 wt%, or 4 to 10 wt%, based on the total weight of monomers present in the ethylene acid copolymer.

[0026] In an embodiment of the ionomer of the present disclosure, the ionomer may comprise a blend of two ethylene acid copolymer resins, a first ethylene acid copolymer polymer, and a second ethylene acid copolymer, wherein one of the first ethylene acid copolymer or the ethylene acid copolymer polymer contains an unsaturated dicarboxylic acid monomer.

[0027] In various embodiments, the ionomers of the present disclosure can comprise a neutralized blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid. The first ethylene acid copolymer is the polymerization reaction product of ethylene, a monocarboxylic acid monomer, and optionally an alkyl acrylate. The second ethylene acid copolymer is the polymerization reaction product of ethylene, an alkyl acrylate, an unsaturated dicarboxylic acid monomer, and optionally a monocarboxylic acid monomer. In some embodiments, at least 30 mole percent (mol%) of the total acid units of the blend are neutralized with the magnesium cation of a magnesium neutralization salt. In one or more embodiments, 35-50 mol%, 45-70 mol%, 60-80 mol%, or 80-100 mol% of the total acid units of the blend are neutralized with the magnesium cation of a magnesium neutralization salt.

[0028] In some embodiments, the ionomers of the present disclosure, comprising a neutralized blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid, may contain cations other than magnesium cations in addition to the magnesium cations in the blend. The blend may be neutralized with at least one additional metal cation of a neutralizing salt. The neutralizing salt of the at least one additional metal cation may be selected from the group consisting of zinc salts, lithium salts, and sodium salts. In some embodiments, the ionomer may comprise 0% to 10%, 1% to 10%, 5% to 20%, 5% to 30%, or 10% to 50% of the total acid units of the blend neutralized with sodium cations of the neutralizing salt, lithium cations of the neutralizing salt, zinc cations of the neutralizing salt, or combinations thereof. In one or more embodiments, at least 70 mole percent of the total acid units of the blend are neutralized with metal cations of the neutralizing salt, and at least 30 mole percent of the at least 70 mole percent of the total acid units of the blend are neutralized with magnesium cations of the magnesium salt.

[0029] In one or more embodiments, the ratio of the first ethylene acid copolymer to the second ethylene acid copolymer in the blend is from 90 / 10 to 10 / 90 weight percent, and the aliphatic monofunctional organic acid in the blend is in an amount of from 5 to 40 weight percent, based on the total weight percent of the blend. In some embodiments, the ratio of the first ethylene acid copolymer to the second ethylene acid copolymer in the blend is from 50 / 50 to 80 / 20 weight percent, or from 90 / 10 to 60 / 40 weight percent.

[0030] In various embodiments, the ionomers of the present disclosure may comprise a neutralized blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid. In one or more embodiments, the first ethylene acid copolymer is the polymerization reaction product of ethylene, 2 to 20% or 5 to 10% by weight of a monocarboxylic acid, based on the total weight percent of monomers present in the first ethylene acid copolymer, and 0 to 40%, 1 to 20%, or 5 to 15% by weight of an alkyl acrylate, based on the total weight percent of monomers present in the first ethylene acid copolymer.

[0031] In one or more embodiments, the second ethylene acid copolymer is the polymerization product of ethylene, an alkyl acrylate, and optionally a monocarboxylic acid monomer and an unsaturated dicarboxylic acid monomer. The alkyl acrylate may be present in an amount of 1 to 40%, 5 to 30%, 10 to 20%, or 20 to 30% by weight, based on the total weight percent of monomers present in the second ethylene acid copolymer. The monocarboxylic acid monomer may be present in an amount of 0 to 20%, 1 to 20%, or 5 to 15% by weight, based on the total weight percent of monomers present in the second ethylene acid copolymer. The unsaturated dicarboxylic acid monomer may be present in the second ethylene acid copolymer in an amount of 2 to 15%, or 5 to 10% by weight, based on the total weight percent of monomers present in the second ethylene acid copolymer.

[0032] In some embodiments of the ethylene acid copolymer, first ethylene acid copolymer, or second ethylene acid copolymer, the alkyl acrylate can be, by way of example and not limitation, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, or a combination thereof. In various embodiments, the alkyl acrylate has an alkyl group having 1 to 8 carbons. This is referred to as a C2-C8 alkyl acrylate. In certain embodiments, the alkyl acrylate is n-butyl acrylate.

[0033] In one or more embodiments of the ethylene acid copolymer, the first ethylene acid copolymer, or the second ethylene acid copolymer, the monocarboxylic acid monomer may include, for example, one or more of acrylic acid, methacrylic acid, or a combination thereof.

[0034] In one or more embodiments of the ethylene acid copolymer or second ethylene acid copolymer, the unsaturated dicarboxylic acid monomer comprises an unsaturated dicarboxylic acid or a reaction product of an unsaturated dicarboxylic acid derivative in the precursor acid copolymer. The unsaturated dicarboxylic acid monomer may include maleic acid monoethyl ester (MAME), maleic anhydride monopropyl ester, maleic anhydride monoethyl ester, maleic anhydride monobutyl ester, or combinations thereof, as well as C1-C4 alkyl half esters of these acids, and anhydrides of these acids, including maleic anhydride, maleic anhydride monomethyl ester, maleic anhydride monoethyl ester, and itaconic anhydride. The carboxylic acid or anhydride units of these monomers can be neutralized with metal ions in much the same way as the monocarboxylic acid carboxylic acid units are shown, although neutralization of unsaturated dicarboxylic acid monomers may have different effects on polymer properties, including their nature and melting behavior. Unsaturated dicarboxylic acids can dehydrate to form intrachain anhydride units within the polymer (i.e., within the chain, rather than crosslinking interchain anhydride units).

[0035] In various embodiments described herein, the ionomer is a fatty acid modified ionomer (FAMI). In particular, according to various embodiments, the ethylene acid copolymer is blended with an aliphatic monofunctional organic acid. In one or more embodiments, the aliphatic monofunctional organic acid has fewer than 36 carbon atoms. In some embodiments, the aliphatic monofunctional organic acid comprises a fatty acid having 4 to 36 carbon atoms, optionally substituted with 1 to 3 substituents independently selected from the group consisting of C1 to C8 alkyl groups. For example, the aliphatic monofunctional organic acid may be a C 34 , C 4~26 , C 6~22 , or C 12~22 C4 to C 36 The fatty acid may comprise at least one of behenic acid, steric acid, oleic acid, erucic acid, 12-hydroxystearic acid, and isostearic acid. At high neutralizations, such as greater than 80% up to 100%, nominal neutralization (e.g., sufficient metal compound is added so that all acid moieties in the copolymer and the aliphatic monofunctional organic acids of the blend are nominally neutralized), volatility is not an issue, and aliphatic monofunctional organic acids with low carbon content may be used. In some embodiments, the aliphatic monofunctional organic acid (or salt) is nonvolatile (does not volatilize at the temperature of the melt blend of the drug and acid copolymer) and non-migratory (does not bloom to the surface of the polymer under normal storage conditions (ambient temperature)).

[0036] The ionomers of the present disclosure include neutralized blends of ethylene acid copolymers and aliphatic monofunctional organic acids, or neutralized blends of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid. The term "neutralized blend" includes fully or partially neutralized ethylene acid copolymers. The ethylene acid copolymers may contain neutralized and non-neutralized monocarboxylic acid units, neutralized, mono-neutralized, and non-neutralized unsaturated dicarboxylic acid units, and in-chain anhydride units.

[0037] When referring to total neutralized acid units, monocarboxylic acids contribute one acid unit, dicarboxylic acids contribute two acid units, anhydrides such as maleic anhydride are considered to contribute two acid units, and half esters are considered to contribute one acid unit. The calculation of the neutralization percentage is based on the number of acid units considered to be present as described above and the number of metal equivalents added. In fact, anhydride units may remain as anhydride units rather than converting to acid units. Upon neutralization, the anhydride monomer units may form dimetal salts, monometal salts, or unneutralized dicarboxylic acid monomers, or the anhydride units may function as if they had no acid functionality, remaining unchanged as an anhydride unit. Half esters of dicarboxylic acid monomers are counted as having only one acid, but may actually be converted to dicarboxylic acid monomers or anhydrides, with various possibilities related to neutralization described above. However, as previously mentioned, regardless of the number of acid groups (free or neutralized) actually present, the calculated neutralization percentage is based on the number of acid units based on the known molar amounts of monocarboxylic acid and dicarboxylic acid comonomers. Therefore, considering the various variations in possible dicarboxylic acid monomers and salts, the actual percent of neutralized acid groups as a percent of the total neutralized and unneutralized free acid groups may differ from the calculated neutralization percentage, which is based on the amount of monocarboxylic acid or dicarboxylic acid monomer in the ionomer. The difference is due to the anhydride units counting as two acid units rather than one acid unit.

[0038] Ethylene acid copolymers can be prepared by standard free-radical copolymerization methods using high pressure and operating continuously. Monomers are fed to the reaction mixture in proportions related to the activity of the monomers and the amount desired to be incorporated. In this way, a uniform, nearly random distribution of monomer units along the chain is achieved. Unreacted monomers can be recycled. Additional information regarding the preparation of ethylene acid copolymers containing softening monomers can be found in U.S. Pat. Nos. 3,264,272 and 4,766,174, each of which is incorporated herein by reference in its entirety.

[0039] The blend can be produced by any means known to those skilled in the art. It is substantially melt-processible and can be prepared by combining one or more ethylene acid copolymers or ionomers of ethylene acid copolymers, one or more fatty acids or salts thereof, a basic metal compound, and a neutralization composition containing a trivalent metal cation to form a mixture and heating the mixture under conditions sufficient to produce the composition. Heating can be carried out at temperatures ranging from 80°C to 350°C, 120°C to 300°C, or 160°C to 260°C, and at pressures corresponding to the temperature, for periods ranging from 30 seconds to 2 or 3 hours. The blend can be prepared by melt-blending the ethylene acid copolymer and / or ionomers thereof with one or more fatty acids or salts thereof, and simultaneously or subsequently combining sufficient amounts of a basic metal compound and a trivalent metal cation. A salt blend of the components can be prepared, or the components can be melt-blended in an extruder. For example, a Werner & Pfleiderer twin-screw extruder can be used to simultaneously mix and process the ethylene acid copolymer and the aliphatic monofunctional organic acid (or salt) with the metal compound.

[0040] The blends may further contain minor amounts of additives including plasticizers, stabilizers including viscosity stabilizers, hydrolysis stabilizers, primary and secondary antioxidants, ultraviolet absorbers, antistatic agents, dyes, pigments or other colorants, inorganic fillers, flame retardants, lubricants, reinforcing agents such as glass fibers and flakes, synthetic (e.g., aramid) fibers or pulp, foaming or blowing agents, processing aids, slip additives, antiblocking agents such as silica or talc, release agents, tackifying resins, or combinations of two or more thereof. Inorganic fillers such as calcium carbonate may also be incorporated into the blends.

[0041] These additives can be present in the blend in amounts ranging from 0.01% to 40%, 0.01 to 25%, 0.01 to 15%, 0.01 to 10%, or 0.01 to 5% by weight. Incorporation of the additives can be by any known process, such as, for example, dry blending, extrusion of a mixture of the various components, conventional masterbatch techniques, etc.

[0042] In one or more embodiments, the ionomers of the present disclosure have a melt index of 0.1 to 10.0 g / 10 min, as determined according to ASTM D1238 (210°C, 2.16 kg). In other embodiments, the ionomers have a melt index of 1.0 to 10.0 g / 10 min, as determined according to ASTM D1238 (210°C, 2.16 kg). Additionally, in some embodiments of the present disclosure, the ionomers have a density of 0.920 to 0.980 g / cc, as measured according to ASTM D792.

[0043] In some embodiments, ionomers according to the present disclosure exhibit load-bearing capability at temperatures above the melting temperature of the ionomer, as measured by differential scanning calorimetry (DSC).

[0044] According to various embodiments, ionomers can be used to form foams or molded articles. For example, in embodiments, ionomers can be combined with additives used to control foam properties to form foams of various shapes. In some embodiments, foams can be extruded from a twin-screw extruder or the like, as known to those skilled in the art.

[0045] The blowing agents (also called blowing agents) used to produce foams can be physical or chemical blowing agents. As used herein, a "physical blowing agent" is a low-boiling liquid that volatilizes under curing conditions to form a foaming gas. Exemplary physical blowing agents include hydrocarbons, fluorocarbons, hydrofluorocarbons, hydrofluoroolefins, hydrochlorofluoroolefins, and other halogenated compounds. Other suitable chemical blowing agents may include, for example, sodium bicarbonate, ammonium bicarbonate, azodicarbonamide, dinitrosopentamethylenediamine, and sulfonylhydrazides. Blowing agents such as water or carbon dioxide, added as a gas or liquid or generated in situ by the reaction of water with polyisocyanate, can also be used. Blowing agents can be used in mixtures of two or more, and chemical and physical blowing agents can be used together to adjust the expansion decomposition temperature and foaming process.

[0046] The foam composition may further include free radical initiators or crosslinkers, co-curatives, activators, and any other type of additives typically used in similar compositions, including, but not limited to, pigments, adhesion promoters, fillers, nucleating agents, rubbers, stabilizers, and processing aids.

[0047] The free radical initiator or crosslinker can include, by way of example and without limitation, an organic peroxide, such as a dialkyl organic peroxide. Examples of organic peroxides suitable for use include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butyl-cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butyl-peroxyl)hexane, 1,3-bis(tert-butyl-peroxyl-isopropyl)benzene, or a combination of two or more thereof.

[0048] Co-curing agents include trimethylolpropane triacrylate (and similar compounds), N,Nm-phenylene dimaleimide, triallyl cyanurate, or a combination of two or more thereof.

[0049] The activator may include a blowing agent activator and may include one or more metal oxides, metal salts, or organometallic complexes. Examples include ZnO, Zn stearate, MgO, or a combination of two or more thereof.

[0050] Foams can be produced by many methods, such as compression molding, injection molding, and a combination of extrusion and molding. This process can include mixing the components of the foam composition under heat to form a melt. The components can be mixed and blended using any technique known and used in the art, including Banbury, intensive mixer, two-roll mill, and extruder. Time, temperature, and shear rate can be adjusted to ensure dispersion without premature crosslinking or foaming.

[0051] After mixing, molding can be carried out. Sheeting or calendaring rolls can be used to create sheets of appropriate dimensions for foaming. An extruder can be used to form the composition into pellets.

[0052] Foaming can be achieved by compression molding at a temperature and time to complete the decomposition of the peroxide and blowing agent. Pressure, molding temperature, and heating time can be controlled. Foaming can be achieved using an injection molding machine by using pellets made from the foaming composition. The resulting foam can be further molded to the dimensions of the final product by any means known in the art, including thermoforming and compression molding.

[0053] In various embodiments, the resulting polymer foam composition can be substantially closed-cell and can be useful in a variety of articles, for example, footwear applications, including midsoles or insoles.

[0054] In embodiments, the molded article exhibits improved creep resistance at least at 80°C, where the molded article exhibits a dimensional change of less than 25%, less than 20%, less than 18%, or less than 15% at 80°C for 30 minutes under a stress of 20 psi.

[0055] The ionomers of the present invention can be prepared by standard neutralization techniques, as disclosed in U.S. Pat. No. 3,264,272 (Rees), which is incorporated herein by reference. The resulting ionomer compositions of the present invention can have a MI of 0.01 to 100 grams / 10 minutes, preferably 0.1 to 30 grams / 10 minutes, as determined according to ASTM D1238 (190°C, 2.16 kg). The total percent neutralization, as defined in the preceding paragraph, is about 5 to 90 percent, preferably 10 to 70 percent, and most preferably 25 to 60 percent. Lower neutralization levels result in reduced ionomer properties, while higher levels reduce ionomer flow. [Example]

[0056] Test Procedure Melt index (MI) is measured using ASTM D-1238 using a 2160 gram weight.

[0057] Melting points (Tm) were measured using differential scanning calorimetry (DSC). Differential scanning calorimetry (DSC) was measured on a TA Instruments Q1000 DSC equipped with an RCS cooling attachment and an autosampler. The melting points (Tm) of the samples were measured according to ASTM D3418.

[0058] The composition of the ionomers was determined using Perkin-Elmer Fourier Transform Infrared Spectroscopy (FTIR). Five mil thick compression molded films were used for FTIR analysis.

[0059] The following examples are provided to illustrate various embodiments, but are not intended to limit the scope of the claims. All parts and percentages are by weight unless otherwise indicated. Approximate properties, characteristics, parameters, etc. are provided below for various examples, comparative examples, and materials used in the examples and comparative examples. Additionally, a description of the raw materials used in the examples is as follows:

[0060] Comparative C1 is a magnesium ionomer blend of 65 weight percent ethylene acid copolymer and 35 weight percent oleic acid. The ethylene acid copolymer contains ethylene, 6.2 weight percent acrylic acid, and 28.0 weight percent n-butyl acrylate having an MI of 60-300 g / 10 min as determined according to ASTM D1238 (190°C, 2.16 kg). Nominally 100% of the total acid units in the neutralized blend of ethylene copolymer and oleic acid are neutralized with magnesium cations. Mg(OH)2 was used as the magnesium cation source for neutralization in an amount that resulted in 145% neutralization of all carboxylic acid moieties.

[0061] Comparative C2 is a Mg ionomer derived from a blend of 65 wt% ethylene copolymer and 22.5 wt% erucic acid, where the acid copolymer has 6.2 wt% acrylic acid and 28.0 wt% n-butyl acrylate, and is an ethylene / acrylic acid / n-butyl acrylate terpolymer with an MI of 85 g / 10 min as measured according to ASTM D1238 (190°C, 2.16 kg). Nominally 100% of the available carboxylic acid moieties of both the ethylene copolymer and the oleic acid are neutralized with Mg cations. Mg(OH)2 was used as the Mg cation source for neutralization in an amount that neutralized 120% of all carboxylic acid moieties.

[0062] Comparative C3 has a hardness of 0.950 g / cm as measured in accordance with ASTM D792 3and a melt index, I2, of 0.7 g / 10 min, as measured according to ASTM D1238 (190°C, 2.16 kg).

[0063] Comparative C4 has a hardness of 0.950 g / cm as measured in accordance with ASTM D792 3 and a melt index, I2, of 0.9 g / 10 min, as measured in accordance with ASTM D1238 (190°C, 2.16 kg).

[0064] Creep resistance data are shown in Tables 1, 2, and 3. Creep tests were performed by measuring the dimensional change (vertical) of a press-formed film mounted under dead load in a heated oven. Creep resistance is a function of time, temperature, and load (stress), so the tests include these variables.

[0065] Creep resistance is a function of time, temperature, and load weight (stress). A simple test was employed to differentiate the creep resistance of ionomers with and without MAME, an unsaturated dicarboxylic acid comonomer neutralized with various metal cations. Creep tests were performed by measuring the dimensional change (vertical) of film specimens attached to a dead load in a cross-flow air oven equipped with a shelf rack to hold the specimen holder. Creep tests were performed on 10-mil-thick, 1-inch-wide, and 3-inch-long press-molded film strips cut from 10-mil-thick compression-molded film. The films were suspended from the specimen holder under a 200-gram dead load and in the oven initially set at the desired temperature.

[0066] Example 1 - Creep Resistance of Ethylene Acid Copolymers Containing Dicarboxylic Acid Monomers

[0067] The results, summarized in Table 1, include data obtained from Inventive Example 1 and Comparative C1, the compositions of which are described above.

[0068] The copolymer composition of Example 1 is a blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid. Example 1 is a blend of (a) 80% by weight of the first ethylene acid copolymer and (b) 20% by weight of the second ethylene acid copolymer. First ethylene acid copolymer, Comparative Example C1. The second ethylene acid copolymer, E / iBA / MAME terpolymer, contains 10 weight percent isobutyl acrylate and 12 weight percent MAME. The E / iBA / MAME terpolymer has a melt index (MI) of 95 g / 10 min according to ASTM D1238, measured at 190°C using a 2160 gram load.

[0069] Example 1 was prepared in a Haake Rheocord 90 melt mixer at 150 rpm for 5 minutes at a temperature of about 210° C. The melt flow index of Example 1 is 1.0 g / 10 min as measured according to ASTM D1238 using 2160 grams at 210° C.

[0070] Creep test results, summarized in Table 1, were generated by measuring the dimensional change (vertical) of film specimens mounted under a dead load in a cross-flow air oven equipped with a shelf rack to hold the specimen holder. Creep tests were performed on 10 mil thick, 1 inch wide, and 3 inch long press-molded film strips cut from 10 mil thick compression-molded film. The film was suspended from the specimen holder under a 200 gram dead load and with the oven initially set at the desired temperature. The deformation of the film specimens was measured after the specified time and temperature in the oven, as shown in Table 1. [Table 1]

[0071] The creep resistance of the two polymer samples is summarized in Table 1. Creep resistance was measured over a 24-hour period at various temperatures: room temperature (approximately 22.0°C), 40°C, 50°C, 60°C, 70°C, and 80°C. In Comparative Example C1, the ionomer containing no unsaturated dicarboxylic acid monomer deformed between 40°C and 50°C. In comparison, in Example 1, the ionomer containing the unsaturated dicarboxylic acid MAME exhibited less deformation at a temperature of 80°C. In comparison, in Example 1, the ionomer containing the unsaturated dicarboxylic acid MAME exhibited significantly less deformation between 40°C and 50°C.

[0072] Example 2 - Creep Resistance of Ethylene Acid Copolymers Containing Aliphatic Monofunctional Organic Acids The results, summarized in Table 2, include data obtained from Inventive Example 2, which is a blend of a first ethylene acid copolymer and a second ethylene acid copolymer. Example 2 includes (a) 70 wt. % of the first ethylene acid copolymer, Comparative Example C1, and (b) an E / iBA / MAME terpolymer containing 30 wt. % of the second ethylene acid copolymer, 10 wt. % iBA, and 12 wt. % MAME, and having a MI of 95 g / 10 min when measured at 190° C.

[0073] Example 2 was prepared in a Haake Rheocord 90 melt mixer at 150 rpm for 6 minutes at a temperature of about 210° C. The melt flow index of Example 2 is 0.9 g / 10 min as measured according to ASTM D1238 using 2160 grams at 210° C. [Table 2]

[0074] The creep resistance of three examples is summarized in Table 2. Creep tests were performed on 10 mil thick, 1 inch wide, and 3 inch long press-molded film strips cut from 10 mil thick compression-molded film. The films were hung with a dead load of 110 grams in an oven initially set at 50°C. The deformation of the film specimens was measured after 30 minutes in the oven, and then the oven temperature was increased by 10°C. Temperatures were measured at 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, and 120°C. Comparative Examples C1-C2, ionomers containing no unsaturated dicarboxylic acid monomer or aliphatic monofunctional organic acid ("fatty acid"), failed at 90°C and 100°C. Comparative Example C4 is an ionomer containing a fatty acid salt but no unsaturated dicarboxylic acid. Comparative Example C4 did not fail the creep test, but it deformed 750.0%. In comparison, in Example 2, the ionomer containing the dicarboxylic acid MAME and fatty acid exhibited less deformation in the temperature range of 80°C to 100°C than the comparative sample.

[0075] Example 3 - Creep Resistance of Two Polymer Resins and an Ethylene Acid Copolymer Containing an Aliphatic Monofunctional Organic Acid The results include data obtained from inventive Examples 3-7, as summarized in Table 3. The copolymer compositions of Examples 3-7 are recorded in Table 3. Examples 3, 4, 5, 6, and 7 were prepared in a 26 mm twin-screw extruder equipped with a mixing screw using melt temperatures of 220°C to 250°C.

[0076] Example 3 is a blend of 80 wt. % Comparative Example C1 with 20 wt. % ethylene / isobutyl acrylate / monoethyl maleate (E / iBA / MAME) terpolymer, in which 10 wt. percent iBA and 12 wt. percent MAME are present, and has a MI of 95 g / 10 min according to ASTM D1238 measured at 190° C. using 2160 grams.

[0077] Examples 4, 5, and 6 include blends of Comparative Example C1 with E / iBA / MAME terpolymer, as outlined in Table 3 below. The E / iBA / MAME terpolymer has 15 weight percent iBA and 12 weight percent MAME and has a MI of 173 g / 10 min when measured at 190° C. according to ASTM D1238 using 2160 grams. The weight percent of Comparative Example C1 and the percentage of the terpolymer are recorded in Table 3 for each example.

[0078] Example 7 is a blend of 80 wt. % Comparative Example C2 with an E / nBA / MAME terpolymer having 15 wt. percent iBA and 12 wt. percent MAME, and has a MI of 173 g / 10 min as measured according to ASTM D1238 using 2160 grams at 190°C.

[0079] Comparative C1 is the same composition as above.

[0080] Comparative C2 is the same composition as above. [Table 3]

[0081] In Table 3, the creep temperature for each sample was measured when the sample showed a 25% change in dimension. Each polymer resin containing unsaturated dicarboxylic acid monomer (MAME) (Examples 3-7) exhibited creep resistance approximately 30-40°C greater than Comparative Example C1. The present invention includes the following aspects. Section 1. 1. An ionomer comprising a neutralized blend of an ethylene acid copolymer and an aliphatic monofunctional organic acid, said blend comprising: 60 to 95 weight percent of the ethylene acid copolymer, based on the total weight percent of the blend; Ethylene and 1 to 40 weight percent of an alkyl acrylate, based on the total weight percent of the monomers present in the ethylene acid copolymer; 0 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of the monomers present in the ethylene acid copolymer; an ethylene acid copolymer that is the polymerization reaction product of 2 to 15 weight percent of an unsaturated dicarboxylic acid monomer, based on the total weight percent of the monomers present in the ethylene acid copolymer; and 5 to 40 weight percent of an aliphatic monofunctional organic acid, based on the total weight percent of the blend, wherein the aliphatic monofunctional organic acid has fewer than 36 carbon atoms; an ionomer wherein at least 30 mole percent of the total acid units of said blend are neutralized with magnesium cations of the magnesium neutralization salt. Section 2. Item 2. The ionomer according to item 1, wherein the ethylene acid copolymer contains 1 to 20% by weight of an alkyl acrylate. Section 3. 1. An ionomer comprising a neutralized blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid, said blend comprising: the first ethylene acid copolymer comprising: Ethylene and; 2 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of monomers present in the first ethylene acid copolymer; and 0 to 40 weight percent alkyl acrylate, based on the total weight percent of monomers present in the first ethylene acid copolymer; the second ethylene acid copolymer is Ethylene and; 1 to 40 weight percent of an alkyl acrylate, based on the total weight percent of the monomers present in the second ethylene acid copolymer; 0 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of the monomers present in the second ethylene acid copolymer; and 2 to 15 weight percent of an unsaturated dicarboxylic acid monomer, based on the total weight percent of the monomers present in the second ethylene acid copolymer; the ratio of the first ethylene acid copolymer to the second ethylene acid copolymer is 90 / 10 wt% to 10 / 90 wt%; and 5 to 40 weight percent of an aliphatic monofunctional organic acid, based on the total weight percent of the blend, wherein the aliphatic monofunctional organic acid has fewer than 36 carbon atoms; an ionomer wherein at least 30 mole percent of the total acid units of said blend are neutralized with magnesium cations of the magnesium neutralization salt. Section 4. Item 4. The ionomer according to item 1 or 3, wherein at least 70 mole percent of the total acid units of the blend are neutralized with the magnesium cations of the magnesium salt. Section 5. Item 4. The ionomer according to item 1 or 3, wherein the blend is further neutralized with at least one additional cation of the neutralization salt selected from zinc salts, lithium salts, and sodium salts. Section 6. Item 4. The ionomer according to Item 3, wherein the total acid units of the blend are neutralized in the range of 80 to 100 mole percent, and 30 to 80 mole percent of the total acid units of the blend are neutralized with the magnesium cations of the magnesium salt. Section 7. Item 2. The ionomer according to item 1, wherein the second ethylene acid copolymer contains 20 to 30% by weight of alkyl acrylate. Section 8. Item 8. The ionomer according to any one of items 1 to 7, wherein the unsaturated monocarboxylic acid monomer comprises one or more of acrylic acid, methacrylic acid, or a combination thereof. Section 9. Item 4. The ionomer according to any one of Items 1 to 3, wherein 80 to 100% of the total acid units of the blend are neutralized with magnesium cations. Section 10. Item 10. The ionomer according to any one of items 1 to 9, wherein the unsaturated dicarboxylic acid monomer comprises maleic anhydride, maleic anhydride monomethyl ester, maleic anhydride monoethyl ester, maleic anhydride monopropyl ester, maleic anhydride monobutyl ester, or a combination thereof. Section 11. Item 11. The ionomer according to any one of items 1 to 10, wherein the alkyl acrylate comprises methyl acrylate, ethyl acrylate, n-butyl acrylate, or isobutyl acrylate, or a combination thereof. Section 12. Item 12. The ionomer according to any one of Items 1 to 11, wherein the aliphatic monofunctional organic acid is a fatty acid having 4 to 36 carbon atoms, optionally substituted with 1 to 3 substituents independently selected from the group consisting of C1 to C8 alkyl groups. Section 13. Item 13. The ionomer according to item 12, wherein the fatty acid comprises at least one of behenic acid, stearic acid, oleic acid, erucic acid, 12-hydroxystearic acid, and isostearic acid. Section 14. Item 16. The ionomer according to any one of items 3 to 15, wherein the ratio of the first ethylene acid copolymer to the second ethylene acid copolymer is 90 / 10 wt % to 60 / 40 wt %. Section 15. Item 15. A molded article or foam comprising the ionomer according to any one of items 1 to 14. Section 16. Item 16. The molded article according to item 15, wherein the molded article exhibits improved creep resistance at least at 80 ° C, and the molded article exhibits a dimensional change of less than 25% under a stress of 20 psi at 80 ° C for 30 minutes.

Claims

1. 1. A blend of an ethylene acid copolymer and an aliphatic monofunctional organic acid, said blend comprising: 60 to 95 weight percent of said ethylene acid copolymer, based on the total weight percent of said blend; Ethylene and 1 to 40 weight percent of an alkyl acrylate, based on the total weight percent of monomers present in the ethylene acid copolymer; 0 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of monomers present in the ethylene acid copolymer; an ethylene acid copolymer that is the polymerization reaction product of 5 to 15 weight percent of an unsaturated dicarboxylic acid monomer, based on the total weight percent of monomers present in said ethylene acid copolymer; 15 to 40 weight percent of an aliphatic monofunctional organic acid, based on the total weight percent of the blend, wherein the aliphatic monofunctional organic acid has 36 or fewer carbon atoms; A blend wherein at least 30 mole percent of the total acid units of said blend are neutralized with magnesium cations of the magnesium neutralization salt.

2. 10. The blend of claim 1, wherein the ethylene acid copolymer comprises 1 to 20 weight percent alkyl acrylate.

3. A blend of a first ethylene acid copolymer, a second ethylene acid copolymer, and an aliphatic monofunctional organic acid, said blend comprising: The first ethylene acid copolymer, Ethylene and 2 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of monomers present in said first ethylene acid copolymer; a first ethylene acid copolymer that is the polymerization reaction product of 0 to 40 weight percent of an alkyl acrylate, based on the total weight percent of monomers present in said first ethylene acid copolymer; The second ethylene acid copolymer, Ethylene and 1 to 40 weight percent of an alkyl acrylate, based on the total weight percent of monomers present in said second ethylene acid copolymer; 0 to 20 weight percent of a monocarboxylic acid monomer, based on the total weight percent of monomers present in said second ethylene acid copolymer; a second ethylene acid copolymer that is the polymerization reaction product of 5 to 15 weight percent of an unsaturated dicarboxylic acid monomer, based on the total weight percent of monomers present in said second ethylene acid copolymer; 15 to 40 weight percent of an aliphatic monofunctional organic acid, based on the total weight percent of the blend, wherein the aliphatic monofunctional organic acid has 36 or fewer carbon atoms; the weight ratio of the first ethylene acid copolymer to the second ethylene acid copolymer is from 90 / 10 to 10 / 90; and A blend wherein at least 30 mole percent of the total acid units of said blend are neutralized with magnesium cations of the magnesium neutralization salt.

4. 4. The blend of claim 1 or claim 3, wherein at least 70 mole percent of the total acid units of the blend are neutralized with magnesium cations of the magnesium neutralization salt.

5. 4. The blend of claim 1 or claim 3, wherein the blend is further neutralized with at least one additional cation of a neutralizing salt selected from zinc salts, lithium salts, and sodium salts.

6. 4. The blend of claim 1 or claim 3, wherein the total acid units of the blend are neutralized in the range of 80 to 100 mole percent, and 30 to 80 mole percent of the total acid units of the blend are neutralized with magnesium cations of a magnesium neutralization salt.

7. 4. The blend of claim 3, wherein the second ethylene acid copolymer comprises 20 to 30 weight percent alkyl acrylate.

8. 8. The blend of any one of claims 1 to 7, wherein the monocarboxylic acid monomer comprises one or more of acrylic acid, methacrylic acid, or a combination thereof.

9. The blend of any one of claims 1 to 8, wherein 80 to 100 mole percent of the total acid units of the blend are neutralized with magnesium cations.

10. 10. The blend of any one of claims 1 to 9, wherein the unsaturated dicarboxylic acid monomer comprises maleic anhydride, maleic anhydride monomethyl ester, maleic anhydride monoethyl ester, maleic anhydride monopropyl ester, maleic anhydride monobutyl ester, or a combination thereof.

11. 11. The blend of any one of claims 1 to 10, wherein the alkyl acrylate comprises methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, or a combination thereof.

12. The aliphatic monofunctional organic acid is a fatty acid having 4 to 36 carbon atoms, and optionally １ ~C ８ 12. The blend of any one of claims 1 to 11, substituted with 1 to 3 substituents independently selected from the group consisting of alkyl groups.

13. 13. The blend of claim 12, wherein the fatty acids include at least one of behenic acid, stearic acid, oleic acid, erucic acid, 12-hydroxystearic acid, and isostearic acid.

14. 4. The blend of claim 3, wherein the weight ratio of said first ethylene acid copolymer to said second ethylene acid copolymer is from 90 / 10 to 60 / 40.

15. A molded article or foam comprising a blend according to any one of claims 1 to 14.

16. 16. The molded article of claim 15, wherein the molded article exhibits creep resistance of at least 80°C, and wherein the molded article exhibits a dimensional change of less than 25% at 80°C for 30 minutes under a stress of 20 psi.

17. 4. The blend of claim 1 or claim 3, comprising 20 to 40 weight percent of an aliphatic monofunctional organic acid, based on the total weight percent of the blend.

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