WO2007136460A1

WO2007136460A1 - Elastomeric modifier and process for manufacture

Info

Publication number: WO2007136460A1
Application number: PCT/US2007/008071
Authority: WO
Inventors: Guy Joseph Wouters; Jean-Roch Schauder
Original assignee: Exxonmobil Chemical Patents Inc.
Priority date: 2006-05-23
Filing date: 2007-04-03
Publication date: 2007-11-29

Abstract

The instant disclosure is directed to an elastomeric modifier comprising about 5 to about 95 wt% of a functionalized polymer comprising ethylene, a C4-C30 alpha-olefin, and a functional group; and about 5 to about 95 wt% of an unfunctionalized polymer comprising ethylene and a C4-C30 alpha-olefin, wherein the functionalized polymer, the unfunctionalized polymer, or both, have a density less than or equal to about 0.865 g/ml. Thermoplastic polymer compositions comprising the elastomeric modifier, and processes for making the same are also disclosed.

Description

Elastomeric Modifier and Process for Manufacture

Field of the Invention

[0001] The instant disclosure is directed to elastomeric modifiers suitable for producing impact modifier compositions for engineering thermoplastic polymers, with processes to prepare elastomeric modifier compositions, and with processes to prepare thermoplastic polymer compositions comprising the instant elastomeric modifiers.

Background of the Invention

[0002] Elastomeric modifiers may include a grafted polymer, also referred to herein as a functionalized polymer, or a blend comprising both a functionalized polymer and an unfunctionalized (ungrafted) polymer. Examples of elastomeric modifier compositions include:

[0003] US 4,174,358, directed to blends of polyamide with carboxylic acid grafted and ungrafted ethylene copolymers, where the ethylene copolymers are ethylene-acrylates, EVA, EPDM and ethylene copolymers with carbon monoxide; [0004] WO 93/20149, directed to blends of polyamide with maleic anhydride grafted and ungrafted EP and EPDM;

[0005] US 4,594,386, directed to blends of polyamide with grafted EPM, where the base EPM is a liquid or semi-liquid;

[0006] US 5,525,668, directed to blends of polyamide with maleic anhydride grafted EPM or EPDM and ungrafted EPM or EPDM, where the rubber is cross- linked after dispersion in the polyamide matrix;

[0007] Machado et al. (J. Polym. Sci. vol. 37, p.1311, 1999), directed to development of the morphology of blends of polyamide-6 with ungrafted and grafted EP copolymers;

[0008] WO 90/03418, directed to blends of polyamide with rubber and carboxylic acid modified rubber, where the rubber is a C2-C₄ or a hydrogenated styrene butadiene block polymer;

[0009] WO 91/07467, directed to blends of polyamide with maleic anhydride grafted EP rubber (MA-g-EP-rubber) and an ungrafted EP rubber, such that the blend has a dispersed phase particle size of at least 2 microns and 15-60 % of the particles have a diameter greater that 1 micron;

[0010] WO 94/13740, directed to a blow molding or extrusion process of a polyamide composition comprising a polyamide and polymer selected from the group consisting of grafted polymers and mixtures of grafted polymers, and ungrafted polymers;

[0011] WO 97/12919 directed to branched block ethylene polymers comprising an ethylene polymer, an ethylenically unsaturated functionalized organic compound and a reactive thermoplastic polymer capable of reacting with the unsaturated functionalized organic compound;

[0012] US 5,346,963 directed to maleic anhydride grafted substantially linear ethylene polymers;

[0013] US 5,705,565, and related cases WO 9425526, and EP 0 696 303, which are directed to blends of thermoplastic polymers like polyamide with MA- grafted substantially linear ethylene polymers that may also contain ungrafted substantially linear ethylene polymers;

[0014] WO 0077078, directed to a process using blends of a polyamide with a preblend made of polyamide with both MA-grafted rubber and an unmodified rubber;

[0015] WO 03087216, directed to blends comprising a functionalized polyolefin, a reactive thermoplastic like polyamide, and a base polymer comprising at least 55% of a single site catalyst polymerized polyolefin, where the base polymer represents more than 50% of the total blend;

[0016] US 6,548,181, directed to flexible blends of low molecular weight polyamide with a rubber composition comprising a functionalized rubber that can react with the polyamide and a non functionalized rubber, where the Mooney viscosity of the rubber composition is at least 40; and

[0017] Li et al. in Polymer Engineering and Science (2001, vol. 41, No 12 p.

2156), which is directed to blends of polyamide with MA grafted and ungrafted ethylene-octene copolymer of 0.868 density. [0018] While previously developed thermoplastic polymer compositions have provided markedly improved toughness, the retention of high toughness at low temperatures has been difficult to attain.

Summary of the Invention

[0019] In an embodiment, an elastomeric modifier comprises: a) about 5 to about 95 wt% of a functionalized polymer comprising ethylene, a C₄-C₃₀ alpha-olefin, and a functional group; and b) about 5 to about 95 wt% of an unfunctionalized polymer comprising ethylene and a C₄-C₃0 alpha-olefin, wherein the functionalized polymer, the unfunctionalized polymer, or both, have a density less than or equal to about 0.865 g/ml.

[0020] In another embodiment, a thermoplastic composition comprises an elastomeric modifier dispersed within a thermoplastic polymer, wherein the elastomeric modifier comprises: a) about 5 to about 95 wt% of a functionalized polymer comprising ethylene, a C4-C₃₀ alpha-olefin, and a functional group; and b) about 5 to about 95 wt% of an unfunctionalized polymer comprising ethylene and a C₄-C₃₀ alpha-olefin, wherein the functionalized polymer, the unfunctionalized polymer, or both, have a density less than or equal to about 0.865 g/ml, and wherein the thermoplastic polymer is capable of reacting with the functionalized polymer.

[0021] In yet another embodiment, a process to produce an elastomeric modifier comprises the steps of combining about 5 to about 95 wt% of a functionalized polymer comprising ethylene, a C₄-C₃₀ alpha-olefin, and a functional group with about 5 to about 95 wt% of an unfunctionalized polymer comprising ethylene and a C4-C3₀ alpha-olefin, wherein the functionalized polymer, the unfunctionalized polymer, or both, have a density less than or equal to about 0.865 g/ml, to produce the elastomeric modifier. [0022] In yet another embodiment, a process to produce a thermoplastic composition comprises the steps of dispersing an elastomeric modifier within a thermoplastic polymer, preferably under melt conditions, to produce the thermoplastic composition, wherein the elastomeric modifier comprises: a) about 5 to about 95 wt% of a functionalized polymer comprising ethylene, a C4-C₃₀ alpha-olefin, and a functional group; and b) about 5 to about 95 wt% of an unfunctionalized polymer comprising ethylene and a C₄-C₃₀ alpha-olefin, wherein the functionalized polymer, the unfunctionalized polymer, or both, have a density less than or equal to about 0.865 g/ml, and wherein the thermoplastic polymer is capable of reacting with the functionalized polymer, preferably under the melt conditions.

Detailed Description of the Invention

[0023] Various specific embodiments, versions and examples of the present disclosure will now be described, including preferred embodiments and definitions that are adopted herein for purposes of understanding the claimed invention.

[0024] As used herein, the phrase "suitable polymerization conditions" relates to the selection of polymerization conditions and components, which are necessary to obtain the production of a desired polymer in light of process parameters and component properties. There are numerous permutations of polymerization processes to produce the polymers disclosed herein, as well as numerous variations in the polymerization components available to produce such polymers having one or more of the desired attributes.

[0025] The term "alkyl" refers to a hydrocarbon group having from 1 to 20 carbon atoms, which may be derived from the corresponding alkane, alkene, or alkyne, by removing one or more hydrogens from the formula. Examples include a methyl group (CH₃), which is derived from methane (CH₄), and an ethyl group

(CH₃CH₂), which is derived from ethane (CH₃CH₃). [0026] The term "aryl" refers to a hydrocarbon group comprising 5 to 20 carbon atoms that form a conjugated ring structure characteristic of aromatic compounds. Examples of aryl groups or substituents include benzene, naphthalene, phenanthrene, anthracene, and the like, which possess alternating double bonding ("unsaturation") within a cyclic structure. An aryl group is derived from an aromatic compound by dropping one or more hydrogens from the formula.

[0027] The term "substituted alkyl group(s)" refers to replacement of at least one hydrogen atom on an alkyl, alkene, alkyne, or aryl group having 1 to 20 carbon atoms, by at least one substituent. Examples of substituents include halogen (chlorine, bromine, fluorine, or iodine), amino, nitro, sulfoxy (sulfonate or alkyl sulfonate), thiol, alkylthiol, hydroxy, alkoxy, and straight, branched, or cyclic alkyls, alkenes, or alkynes having 1 to 20 carbon atoms. Examples of alkyl substituents include methyl, ethyl, propyl, tert-butyl, isopropyl, isobutyl, and the like. Examples of alkoxy substituents include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, secondary butόxy, tertiary butoxy, pentyloxy, isopentyloxy, hexyloxy, heptryloxy, octyloxy, nonyloxy, and decyloxy. The term haloalkyl refers to straight or branched chain alkyl groups having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted by at least one halogen.

Elastomeric Modifier

[0028] The elastomeric modifier of the instant disclosure comprises a blend comprising a non-functionalized (unfunctionalized) polymer and a functionalized polymer. In an embodiment, the unfunctionalized polymer may comprise essentially the same monomers, in the same relative proportions as the functionalized polymer, except for the presence of the functional group or groups of the functionalized polymer. In another embodiment, the functionalized polymer may be different than the unfunctionalized polymer of the instant elastomeric modifier.

[0029] The unfunctionalized polymer and the functionalized polymer (the polymer(s)) of the elastomeric modifier of the instant disclosure comprise ethylene (C₂), and one or more C4 to C₃₀ olefin monomers, preferably C₄ to C₂₀ olefin monomers, more preferably C₄ to C ₁₂ olefin monomers. The olefin monomers may be linear, branched and/or cyclic alpha-olefins, internal olefins, or multiolefins. Examples of alpha-olefins include butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, and branched olefins including 3-methylbutene-l, 3-methylepentene-l, 4- methylpentene-1, 3,5,5-trimethylhexene-l, 5-ethyl-l-nonene, and 4,4- dimethylpentene-1.

[0030] In an embodiment, the polymers of the elastomeric modifier may comprise one or more linear or branched C4 to C₃₀ prochiral alpha-olefins, and/or C₅ to C₃0 ring containing olefins, or combinations thereof capable of being polymerized by either stereospecific and non-stereospecific catalysts. Prochiral, as used herein, refers to monomers that favor the formation of isotactic or syndiotactic polymer when polymerized using stereospecific catalyst(s). [0031] In an embodiment, the polymers of the elastomeric modifier may comprise aromatic-group-containing monomers containing up to about 30 carbon • atoms. Suitable aromatic-group-containing monomers comprise at least one aromatic structure, preferably from one to three, more preferably a phenyl, indenyl, fluorenyl, or naphthyl moiety. The aromatic-group-containing monomer may further comprise at least one polymerizable double bond such that after polymerization, the aromatic structure will be pendant from the polymer backbone. The aromatic-group containing monomer may further be substituted with one or more alkyl groups including, but not limited to, Ci to Cio alkyl groups. Additionally, two adjacent substitutions may be joined to form a ring structure. Preferred aromatic-group-containing monomers contain at least one aromatic structure appended to a polymerizable olefinic moiety. Particularly preferred aromatic monomers include styrene, alpha-methylstyrene, para-alkylstyrenes, vinyltoluenes, vinylnaphthalene, allyl benzene, and indene, especially styrene, paramethyl styrene, 4-phenyl- 1 -butene, and allyl benzene.

[0032] Non-aromatic-cyclic-group-containing monomers may also be included in the polymers of the elastomeric modifier. These monomers may contain up to about 30 carbon atoms. Suitable non-aromatic cyclic group containing monomers preferably have at least one polymerizable olefϊnic group that is either pendant on the cyclic structure or is part of the cyclic structure. The cyclic structure may also be further substituted by one or more alkyl groups or substituted alkyl groups such as, but not limited to, Ci to Cio alkyl groups. Preferred non-aromatic cyclic group containing monomers include vinylcyclohexane, vinyl cyclohexene, vinylnorbornene, ethylidene norbomene, cyclopentadiene, cyclopentene, cyclohexene, cyclobutene, vinyladamantane, and the like.

[0033] The polymers of the elastomeric modifier may further comprise polyene monomers, e.g., dienes, preferably C₄ to C₃₀ olefins having at least two unsaturated bonds, wherein at least two of the unsaturated bonds are readily incorporated into a polymer by either a stereospecific or a non-stereospecific catalyst(s). It is further preferred that the diolefin monomers be selected from alpha, omega-diene monomers (i.e. di-vinyl monomers). More preferably, the diolefin monomers are linear di-vinyl monomers, most preferably those containing from 4 to 30 carbon atoms. Examples of preferred dienes include butadiene, pentadiene, hexadiene, heptadiene, octadiene, nonadiene, decadiene, undecadiene, dodecadiene, tridecadiene, tetradecadiene, pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene, nonadecadiene, icosadiene, heneicosadiene, docosadiene, tricosadiene, tetracosadiene, pentacosadiene, hexacosadiene, heptacosadiene, octacosadiene, nonacosadiene, and triacontadiene. Particularly preferred dienes include 1 ,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9- decadiene, 1,10-undecadiene, 1,11 -dodecadiene, 1,12-tridecadiene, 1,13- tetradecadiene, and low molecular weight polybutadienes (Mw less than 1000 g/mol). Preferred cyclic dienes include cyclopentadiene, vinylnorbornene, norbornadiene, ethylidene norbornene, divinylbenzene, dicyclopentadiene or higher ring containing diolefins, with or without substituents at various ring positions.

[0034] In another embodiment, the unfunctionalized polymer, the functionalized polymer, or both, of the instant elastomeric modifier may each comprise a blend, combination, or mixture of polymers, wherein each of the polymers comprises ethylene and a C4-C₃0 olefin. [0035] By "functionalized polymer" it is meant that the polymer comprises at least one functional group. In an embodiment, the functionalized polymer may be produced by copolymerizing the monomers from which the functionalized polymer is produced (e.g., ethylene, C₄-C₃₀ alpha-olefin(s), and the like), along with a functional group monomer, or a monomer which is a precursor to the functional group, under suitable polymerization conditions, to produce the functionalize polymer. In another embodiment, the functionalized polymer may be produced by contacting the polymer to be functionalized with a functional group, or a functional group precursor, and optionally a catalyst, an initiator, and/or free radical source, under suitable conditions to cause all or part of the functional group to incorporate, graft, bond to, physically attach to, and/or chemically attach to the polymer to be functionalized, and thus produce the functionalized polymer. Such functionalization of the polymer may be referred to herein as grafting. Accordingly, a functional group may be referred to herein as a grafting monomer.

[0036] For ease of reference herein, any functionalized polymer may be abbreviated herein using the format "AA-g-FG", wherein AA represents the specific type of polymer being functionalized (e.g., ethylene-alpha-olefin polymer such as EO representing ethylene-octene copolymer, and the like), wherein FG refers to the functional group or compounds with which the polymer was functionalized (e.g., MA represents maleic anhydride), and wherein "-g-" represents grafting (i.e., attachment) between the two moieties. Accordingly, EO- g-MA represents a functionalized polymer comprising an ethylene-octene- copolymer functionalized with maleic anhydride.

[0037] The term "functional group" represents any compound with a weight average molecular weight of 1000 g/mol or less, that contains a heteroatom and/or an unsaturation, and where the unsaturation allows grafting or copolymerization to produce the functionalized polymer. Preferred functional groups (preferred grafting monomers) include any compound with a weight average molecular weight of 750 or less, that contain one or more heteroatoms and/or one or more sites of unsaturation. Preferably, the functional group is a compound containing a heteroatom and an unsaturation, such as maleic anhydride. Preferred functional groups include organic acids and salts thereof, organic amides, organic imides, organic amines, organic esters, organic anhydrides, organic alcohols, organic thiols, organic epoxides, organic acid halides (such as acid chlorides, acid bromides, and the like), organic peroxides, organic silanes, and the like, each comprising from 1 to 20 carbon atoms.

[0038] Examples of preferred functional groups useful in the instant elastomeric modifier include compounds comprising a carbonyl bond such as caxboxylic acids, esters of carboxylic acids, acid anhydrides, di-esters, salts, amides, and imides. Aromatic vinyl compounds, hydrolyzable unsaturated silane compounds, saturated halogenated hydrocarbons, and unsaturated halogenated hydrocarbons may also be used.

[0039] Examples of particularly preferred functional groups useful in the instant elastomeric modifier include, but are not limited to, maleic anhydride, citraconic anhydride, 2-methyl maleic anhydride, 2-chloromaleic anhydride, 2,3- dimethylmaleic anhydride, bicyclo[2,2,l]-5-heptene-2,3-dicarboxylic anhydride, 4-methyl-4-cyclohexene-l,2-dicarboxylic anhydride, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, crotonic acid, bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic acid anhydride, 1,2,3,4,5,8,9,10- octahydronaphthalene-2,3-dicarboxylic acid anhydride, 2-oxa- l,3-diketospiro(4.4)non-7-ene, bicyclo(2.2.1)hept- 5-ene-2,3- dicarboxylic acid anhydride, maleopimaric acid, tetrahydrophtalic anhydride, norborn-5-ene-2,3- dicarboxylic acid anhydride, nadic anhydride, methyl nadic anhydride, himic anhydride, methyl himic anhydride, and x-methyl-bicyclo(2.2.1)hept-5-ene-2,3- dicarboxylic acid anhydride (XMNA).

[0040] Examples of esters of unsaturated carboxylic acids useful in the instant elastomeric modifier as functional groups include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, glycidyl methacrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, and the like.

[0041] Examples of hydrolyzable unsaturated silane compounds useful as functional groups in the instant elastomeric modifier include compounds comprising a radical polymerizable unsaturated group and a Ci-C₂Q alkoxysilyl group, or a silyl group, such that the compound has a hydrolyzable silyl group bonded to a vinyl group and/or a hydrolyzable silyl group bonded to the vinyl group via an alkyl group, and/or a compound having a hydrolyzable silyl group bonded to an ester or an amide of acrylic acid, methacrylic acid, or the like. Examples thereof include vinyltrichlorosilane, vinyl tris(beta- methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, gamma- methacryloxypropyltrimethoxysilane, monovinylsilane, and monoallylsilane. [0042] Examples of unsaturated halogenated hydrocarbons useful as functional groups include vinyl chloride and vinylidene chloride. [0043] In a preferred embodiment, the polymer to be functionalized comprises ethylene and one or more C4-C30 olefins. The olefins may be linear, cyclic, or a combination thereof. Preferably, the olefins are alpha-olefins. The polymer is also preferably grafted with maleic anhydride (MA), to produce the functionalized polymer. Preferably, the alpha-olefϊn is butene, pentene, hexene, heptene, and/or octene. In a preferred embodiment, the functionalized polymer is an ethylene- octene polymer grafted with maleic anhydride (i.e., EO-g-MA), wherein the maleic anhydride is covalently bonded to the backbone polymer chain of the polymer. The anhydride functionality grafted onto the polymer may remain as an anhydride, may be oxidized into acid functional groups, and/or may be further reacted by processes known in the art to induce other functional groups such as amides, amines, nitriles, alcohols, esters, acid chlorides, and the like. [0044] The unfunctionalized polymer, the functionalized polymer, or both, may have a density less than 0.87, more preferably less than or equal to about 0.865, with a density of less than or equal to about 0.863 being still more preferred.

[0045] The elastomeric modifier preferably comprises from 5 to 95 wt% of the unfunctionalized polymer with the remainder being the functionalized polymer (i.e., 5 to 95 wt% functionalized polymer), based on the total weight of the unfunctionalized polymer and the functionalized polymer present in the elastomeric modifier. Preferably, the elastomeric modifier comprises at least 20 wt%, preferably at least 30 wt%, preferably at least 40 wt%, preferably at least 50 wt%, preferably at least 60 wt%, preferably at least 70 wt%, preferably at least 80 wt%, preferably at least 90 wt% of the unfunctionalized polymer, with the remainder of the polymer present being the fϊinctionalized polymer, based on the total weight of the unfunctionalized polymer and the functionalized polymer present in the elastomeric modifier.

[0046] The functionalized polymer may comprise from about 0.01 wt% to about 10 wt% of a functional group, based on the total weight of the functionalized polymer. Preferably, the functionalized polymer comprises greater than or equal to about 0.1 wt%, preferably at least 0.2 wt%, preferably at least 0.3 wt%, preferably at least 0.4 wt%, preferably at least 0.5 wt%, preferably at least 0.6 wt%, preferably at least 0.7 wt%, preferably at least 0.8 wt%, preferably at least 0.9 wt%, preferably at least 1.0 wt% of one or more functional groups. Also preferably, the functionalized polymer comprises less than or equal to about 5 wt%, preferably less than 4 wt%, preferably less than 3 wt%, preferably less than 2 wt% of one or more functional groups, based on the total weight of the functionalized polymer.

[0047] The elastomeric modifier can be made by melt mixing or by dry blending the functionalized polymer with the unfunctionalized polymer. Melt mixing may be achieved in any suitable mixing equipment such as an internal mixer like a Banbury, a mixing extruder like single or twin screw extruders, a co- kneader and the like. The elastomeric modifier can also be produced in one step by first performing the grafting of the polymer in one part of a grafting extruder, and adding the unfunctionalized polymer in a subsequent zone of the mixing extruder after the grafting has been completed.

Thermoplastic Polymer Composition

[0048] The elastomeric modifier is preferably dispersed within a thermoplastic polymer to produce a thermoplastic polymer composition. The thermoplastic polymer is preferably a reactive thermoplastic polymer, which is capable of reacting with the functionalized polymer, preferably under melt conditions, to produce the thermoplastic composition. [0049] Preferred reactive thermoplastic polymers include polyamides (nylons), polyesters, polyacetals, polycarbonates, and the like, which may be referred to in the art as engineering thermoplastics.

[0050] Polyamides useful herein include polymers comprising monomers derived from diamines and dicarboxylic acids, or the functional equivalents of dicarboxylic acids. Examples of suitable monomers include dicarboxylic acid chlorides, diamides, amino acids, lactams, and /or combinations thereof. [0051] Representative polyamides which can be used herein include polyhexamethylene adipamide (6,6 nylon), poly-ε-caprolactam (6 nylon), polyhexamethylene sebacamide (610 nylon), polyhexamethylene dodecanoamide (612 nylon) and polytetramethylene adipamide (4,6 nylon). In general, useful polyamides have a number average molecular weight of at least about 5,000. [0052] The polyamides can be either crystalline or amorphous, or blends thereof. Similarly, blends of two or more chemically different polyamides can also be used. For example, blends of nylon 6 and nylon 6,6 exhibit excellent performance characteristics when combined with elastomeric modifiers in accordance with the instant disclosure, as do copolymers of the same polyamides. Nylon 4,6 may be preferred because of its excellent high temperature properties, and nylon 612 is particularly good for the preparation of polyamides, since it is less moisture sensitive than many other polyamides.

[0053] The elastomeric modifier of the instant disclosure is preferably dispersed within the reactive thermoplastic polymer in a shell and core arrangement. In an embodiment, the functionalized polymer acts as a shell, and the unfunctionalized polymer acts as a core, which unexpectedly provides an improvement to the impact strength of the thermoplastic polymer composition, as compared to a thermoplastic polymer composition comprising 100% grafted modifier (100% functionalized polymer) having a higher density, or to core-shell blends containing modifiers of higher density. In some instances, these core-shell structures have impact strength comparable to thermoplastic polymer compositions comprising elastomeric modifiers comprised of 100% grafted low- density modifiers (i.e., those ^having a density below 0.865) and thus the instant elastomeric modifiers provide an evident economic advantage. [0054] The thermoplastic polymer composition preferably comprises greater than- or equal to about 5 wt%, and less than or equal to about 95 wt% of the instant elastomeric modifier. Within this range, the thermoplastic polymer composition preferably comprises greater than or equal to about 5 wt%, preferably greater than or equal to about 10 wt%, of the elastomeric modifier.

[0055] In a preferred embodiment, the elastomeric modifier comprises maleic anhydride grafted ethylene-octene copolymer having a density below 0.865 g/ml, in a blend with an ungrafted ethylene, alpha-olefin copolymer having a density of about 0.88 g/ml or below, preferably a density of about 0.87 g/ml or below. [0056] In blends with reactive thermoplastics like polyamide, the softer nature of the shell is believed to ensure optimum energy absorption upon impact. Alternate combinations consist of a Ma-grafted ethylene-octene copolymer shell having a density preferably of about or below 0.88, with an ungrafted ethylene- octene copolymer core of density below 0.865 for better impact resistance. [0057] Thermoplastic polymer compositions comprising the instant elastomeric modifier have unexpectedly been found to comprise improved low temperature impact properties. The advantage of these compositions over 100 % EPDM based compositions is that the ethylene-octene copolymers are in general, less expensive, and can be grafted at higher grafting yields compared to EP or EPDM's. This approach offers thus more flexibility in compounding since the ratio of shell to core in the formulations can be easily varied as well as the type of ungrafted polymer in function of the properties desired.

[0058] The thermoplastic polymer compositions are prepared by physically admixing the components, so as to disperse the elastomeric modifier within the thermoplastic polymer, wherein the average particle size of the elastomeric modifier is from about 0.01 to 3 microns, and preferably at least about 0.1 micron. Conventional polymer processing equipment can be used, such as multi-screw extruders, or other conventional plasticating devices such as co-kneaders, so long as the components can be melted and the applied shear is sufficient to provide the required small particle size without significant degradation of the blend components. In the alternative, the polymer blends can be made by coprecipitation from solution, blending, or by dry mixing the components together followed by melt fabrication of the mixture.

[00591 I" ^an embodiment, the thermoplastic polymer composition can be prepared by conducting reactive extrusion in a first zone wherein a base polymer is contacted with the functional group to produce a functionalized polymer, followed by introduction of an unfunctionalized polymer in a second zone, and optionally one or more additives to produce the elastomeric modifier, followed by introduction of the reactive thermoplastic polymer into a third zone, to produce the thermoplastic polymer composition.

[0060] The elastomeric modifier, the thermoplastic polymer composition, or both, may also include one or more additives including a stabilizer, an inhibitor of oxidative, thermal, and/or ultraviolet light degradation; lubricants, mold release agents, colorants including dyes and pigments, fibrous and particulate fillers and reinforcements, nucleating agents, plasticizers, and the like, each used in quantities typical in thermoplastic polymer compositions (e.g., toughened polyamide compositions), as known to those skilled in the art. [0061] As shown in the Examples and Comparative Examples, the unfunctionalized polymer, which is more readily prepared than the functionalized polymer, improves the low temperature toughness of the thermoplastic polymer composition, rather than depreciate properties thereof, as would normally be expected when replacing quantities of functionalized polymer with unfunctionalized polymer.

[0062] The toughness of the thermoplastic polymer composition depends on the properties of the thermoplastic polymer in which the elastomeric modifier is dispersed. In an embodiment, wherein the reactive thermoplastic polymer comprises polyamide 6, the Izod Notch strength of the thermoplastic polymer composition, determined according to ISO 180/4A, is greater than or equal to about 70 kJ/m² at 0 ⁰C, preferably greater than or equal to about 75, with greater than or equal to about 80 kJ/m² at 0 ⁰C being more preferred. [0063] In an embodiment wherein the reactive thermoplastic polymer comprises polyamide 6,6, the Izod Notch strength of the thermoplastic polymer composition, determined according to ISO 180/4A is greater than or equal to about 19 kJ/m² at 0 ⁰C, preferably greater than or equal to about 22, with greater than or equal to about 40 kJ/m² at 0 ⁰C being more preferred. [0064] The excellent low temperature properties of the present thermoplastic polymer compositions make them especially useful in a wide variety of applications in which the final molded component is exposed to extended periods of low temperatures, including sporting goods such as ski bindings, backpack components, and ice skate blade supports; automotive components such as luggage racks and door handles; and cases for outdoor radio and communication equipment; as well as other applications which will be readily apparent to those skilled in the art of designing and fabricating thermoplastic articles.

Test Methods

[0065] Polymer purification was performed by dilution in toluene and reprecipitation in acetone and drying in vacuo. Maleic anhydride was measured on purified functional polymers via acid-base titration of a toluene solution. MFR was measured according to ASTM D 1238. Flexural modulus was measured according to ISO 178. Tensile properties were measured according to ISO 527. Izod impact strength was measured according to ISO 180/4A.

Examples

[0066] The polymers used in the Examples and in the Comparative Examples are listed in Table 1. The functionalized polymers were prepared as dry blends and/or as melt blends using reactive extrusion, wherein the base polymer was contacted with maleic anhydride under melt conditions to produce the functionalized polymers

[0067] Grafting with maleic anhydride was performed in a Welding Engineer twin screw extruder at 180⁰C, in the presence of Luperox 130 (supplied by

Arkema) as peroxide used as 10 wt% solution in a white oil (Marcol 52 supplied by ExxonMobil).

[0068] The modifiers were prepared by melt blending the functionalized and unfunctionalized polymers in a Leistritz extruder at 180⁰C, or by pellet dry blending. [0069] The reactive thermoplastic polymers utilized to produce the thermoplastic polymer compositions were commercially prepared polymers, namely Ultramid® B3, a polyamide 6, produced by BASF, and Zytel® 101, a polyamide 6,6 produced by DuPont. ^~. ., .-, «,_* -*

[00701 The blends of polyamide with the modifiers were prepared in a Leistritz extruder at 230/210⁰C for the polyamide 6 blends and 260/230⁰C for the polyamide 6,6 blends.

[00711 In the examples, the functionalized polymer is referred as to the shell, while the unfunctionalized polymer is referred as to the core. [00721 Table 2 and Table 3 disclose the properties of polyamide 6 blends (Table 2) and polyamide 6,6 blends (Table 3) with 20 wt % elastomeric modifier, where the shell consisted of a 0.882 g/ml density ethylene-octene copolymer and the core consists of ethylene-octene or ethylene-propylene copolymers having densities in the range of 0.882 g/ml to less than or equal to 0.865 g/ml. The grafted and ungrafted polymers are dry blended before being mixed and reacted with polyamide under melt conditions in a twin screw extruder. [0073J Examples 1-3 and 5-7 used a low-density core (ethylene-octene copolymers of 0.857 density) and showed better impact property than similar blends based on higher density cores (i.e., ethylene-octene copolymer of 0.882 and 0.87 density, see Comparative Examples C1-C4). In some instances, the core- shell modifiers had impact properties comparable to a 100 % grafted EP elastomer modifier (Exxelor VA 1801, see Comparative Examples C5 and C9). Comparative Examples C5a and C5b indicate that core-shell blends with a low-density ethylene-octene copolymer as the core have similar impact properties and better flow than core-shell blends where the core is an EPM.

[0074] Several of these experiments exemplify the usefulness of the core-shell approach which maximizes formulation flexibility by simply dry blending the MA-grafted shell component (the functionalized polymer) with the core component (the unfunctionalized polymer) prior to feeding the dry blend into a mixing extruder together with the polyamide (the reactive thermoplastic polymer) for the production of the thermoplastic polymer compositions. [0075] Table 4 and Table 5 disclose the properties of polyamide 6 blends (Table 4) and polyamide 6,6 blends (Table 5) with 20 wt % modifier, where the density of the shell is varied. The functionalized polymer (shell) comprised ethylene-octene copolymers of density ranging from 0.882 g/ml to 0.86 g/ml and the core component comprises an ethylene-octene copolymer of 0.87 g/ml density. [0076] Examples 8-13 and 14-19 show that the combination of a 0.86 g/ml density MA-grafted functionalized polymer as the shell, with a 0.87 g/ml density unfunctionalized polymer as the core, generates better impact properties than 100% grafted modifiers based on ethylene-octene copolymers of 0.882 and 0.87 g/ml density (see Comparative Examples ClO-CI l and C 14-Cl 5). In some instances, impact properties almost comparable to a 100% grafted modifier based on an ethylene-octene copolymer of 0.86 g/ml density can be obtained by blending a 0.86 g/ml density shell with a 0.87 g/ml density core (compare Examples 8-9, 14-15 with Comparative Examples C12 and C 16). Although the present invention deals with unfunctionalized polymers of ethylene and a C4-C30 alpha-olefin as core, it is also expected, based on the good impact strength of modifiers having a 0.882 g/ml density shell with EPM as core that improved impact strength will also be achieved if an EPM or an EPDM is used as unfunctionalized polymer core in combination with a functionalized polymer shell of density equal or lower than 0.865.

[0077] As the examples show, the presence of a functionalized polymer of density less than or equal to about 0.865 g/ml enables the use of less functionalized polymer as the polymer shell, compared to functionalized polymers of higher density (see Example 8 and C13 using polyamide 6, and Example 14 and C 17 using polyamide 6,6.)

[0078] In the above examples, it is clear that the properties of the modifier, and thus the properties of the thermoplastic polymer composition can be tailored by adjusting the ratio of the functionalized polymer (the shell) to the unfunctionalized polymer (the core) in the elastomeric modifier, and/or by adjusting the level of functional groups present in the functionalized polymer, and/or by adjusting the density of the functionalized polymer, and/or the density of the unfunctionalized polymer, and/or by adjusting the amount of the elastomeric modifier present in the thermoplastic polymer composition.

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[0079] All documents described herein are incorporated by reference ^"herein, including any priority documents and/or testing procedures. As is apparent from the foregoing general description and the specific embodiments, while forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited thereby.

Claims

ClaimsWe Claim:

1. An elastomeric modifier comprising: a) about 5 to about 95 wt% of a functionalized polymer comprising ethylene, a C₄-C₃₀ alpha-olefϊn, and a functional group; and b) about 5 to about 95 wt% of an unfunctionalized polymer comprising ethylene and a C₄-C₃₀ alpha-olefin, wherein the functionalized polymer, the unfunctionalized polymer, or both, have a density less than or equal to about 0.865 g/ml.