WO1996020974A1 - Procede de stabilisation de polymeres d'ethylene au cours d'operations de traitement de matiere en fusion a haute temperature - Google Patents

Procede de stabilisation de polymeres d'ethylene au cours d'operations de traitement de matiere en fusion a haute temperature Download PDF

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Publication number
WO1996020974A1
WO1996020974A1 PCT/US1995/013826 US9513826W WO9620974A1 WO 1996020974 A1 WO1996020974 A1 WO 1996020974A1 US 9513826 W US9513826 W US 9513826W WO 9620974 A1 WO9620974 A1 WO 9620974A1
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polymer
viscosity
transition metal
copper
antioxidant
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PCT/US1995/013826
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English (en)
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Thoi H. Ho
Robert T. Johnston
Evelyn J. Morrison
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The Dow Chemical Company
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Priority to AU42787/96A priority Critical patent/AU4278796A/en
Publication of WO1996020974A1 publication Critical patent/WO1996020974A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0091—Complexes with metal-heteroatom-bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
    • C08K5/098—Metal salts of carboxylic acids

Definitions

  • This invention relates to ethylene polymers.
  • the invention relates to ethylene homopolymers while in another aspect, the invention relates to ethylene interpolymers.
  • this invention relates to stabilizing ethylene polymers against changes in viscosity due to crosslinking under high temperature (i.e. in excess of 175 C) melt processing conditions by adding to the polymer a viscosity-stabilizing amount of a transition metal, optionally in combination with one or both of a control led-metal deactivator and an antioxidant.
  • Ethylene homopolymers and interpolymers are known classes of thermoplastic polymers, each having many members. They are prepared by homopolymerizing ethylene or interpolymerizing (e.g. copolymerizing) ethylene with one or more vinyl- or diene-based comonomers, e.g. ⁇ -olefins of 3 to about 20 carbon atoms, vinyl esters, vinyl acids, styrene-based monomers, monomers containing two or more sites of ethylenic unsaturation, etc., using known copolymerization reactions and conditions.
  • ethylene or interpolymerizing e.g. copolymerizing
  • vinyl- or diene-based comonomers e.g. ⁇ -olefins of 3 to about 20 carbon atoms
  • vinyl esters e.g. ⁇ -olefins of 3 to about 20 carbon atoms
  • vinyl esters e.g. ⁇ -olefins of 3 to
  • the viscosity of these homopolymers and interpolymers tends to change during high temperature melt process operations such as extrusion molding and the like.
  • Such thermally-induced changes in viscosity have been attributed to the changes in molecular weight and/or linearity of the homopolymers or interpolymers caused by crosslinking.
  • antioxidants have been developed to reduce the changes (e.g. crosslinking) that can occur during melt processing or under conditions of use.
  • Many of the stabilizers are organic compounds which are classified in the plastics industry as antioxidants.
  • Many antioxidants tend to function as free radical scavengers, and they interact with free radicals that are formed during polymerization or in the presence of air or other oxidizing medium.
  • Antioxidants are a known class of stabilizers which includes, for example, hindered phenols, triaryl phosphites, arylamines, hydroxylamines, and the like.
  • Viscosity changes in polyolefins are directly related to the crosslinking that results from combination of alkyl radicals or the addition of alkyl radicals to double bonds.
  • polyolefins may scission due to ⁇ -cleavage of alkyl or alkoxy radicals.
  • the ratio of alkyl radical chemistry to alkoxy/peroxy radical chemistry depends on oxygen concentration.
  • conditions that favor high rates of carbonyl formation do not necessarily favor high rates of crosslinking.
  • hydroperoxide decomposition leads to carbonyl formation, it does not necessarily lead to increased crosslinking (it may lead to increased scission).
  • Antioxidants have been added as stabilizers to polyethylenes and ethylene interpolymers with mixed success. Typically, such antioxidants have protected articles made from these materials against oxidative degradation at ambient conditions but have not been particularly effective at protecting the polymer against thermally-induced changes in viscosity during melt processing.
  • polypropylene and polymers that change properties due to crosslinking
  • LDPE low density polyethylene
  • processing stabilizer systems commonly used in polypropylene i.e. phosphites and a long-term heat stabilizer in overall concentrations up to 0.1 wt % could be used as process stabilizers for linear low density polyethylene (LLDPE).
  • LLDPE linear low density polyethylene
  • Hydroperoxides undergo thermally-induced (120 C and higher) homolytic decomposition to free radicals, which in turn initiate new oxidation chains which attack the polymer and cause degradation.
  • This homolytic decomposition reaction is said to be catalyzed in a redox reaction by the presence of catalytic amounts of certain metal ions, particularly transition metal ions, such as iron, cobalt, manganese, copper and vanadium.
  • transition metal ions such as iron, cobalt, manganese, copper and vanadium.
  • the polyolefin resin and stabilizer are homogenized (i.e. thoroughly blended) in a suitable lab scale kneader (e.g. Brabender plastograph), or by first milling the resin and then adding 1 wt % fine copper power or 0.1 wt % copper stearate, making a compression molded plaque, and then oven aging the plaque to determine polymer changes over time.
  • a suitable lab scale kneader e.g. Brabender plastograph
  • Chiquet in USP 4,931 ,488 included starch in a thermoplastic polymer (e.g. polyethylene) to make a thermoplastic composition which allegedly degrades under the action of heat, ultraviolet light, sunlight and/or composting conditions.
  • Chiquet used iron and another transition metal compound (e.g. copper stearate) to catalyze the degradation of the starch.
  • polyolefins have had problems, because they undergo more severe processing histories than virgin polyolefins leading to degradation, discoloration, etc., and because they are generally not free of contamination by labels, dirt, glue, and other polymers leading to melt processing problems such as gelling.
  • ethylene polymers are stabilized against changes in viscosity due to crosslinking under high temperature melt processing conditions by adding to the polymer a viscosity-stabilizing amount of a transition metal other than nickel, optionally in combination with one or both of a controlled-metal deactivator and an antioxidant.
  • ethylene interpolymers having pendent polar functionality or ethylene/diene interpolymers are stabilized against changes in viscosity due to crosslinking under high temperature melt processing conditions by adding to the polymers a viscosity-stabilizing amount of a transition metal other than nickel, optionally in combination with one or both of a controlled metal deactivator and an antioxidant.
  • ethylene homopolymers or ethylene interpolymers made by the interpolymerization of ethylene and at least one ⁇ -olefin and/or at least one diene are stabilized against changes in viscosity due to crosslinking under high temperature melt processing conditions by adding to the polymers a viscosity-stabilizing amount of a mixture or complex of a transition metal other than nickel and a controlled-metal deactivator, optionally in combination with an antioxidant.
  • Another aspect of this invention is a process for recycling polyolefin materials by adding to a recycled polyolefin composition a viscosity-stabilizing amount of a transition metal other than nickel, optionally in combination with one or both of a controlled-metal deactivator and an antioxidant and melt processing the recycled polyolefin composition.
  • This aspect includes melt viscosity stabilized compositions obtained by adding a viscosity-stabilizing amount of transition metal other than nickel, with or without a controlled metal deactivator and an antioxidant, to a polymer composition comprising recycled polyolefin, stabilizer concentrates for making the melt viscosity stabilized compositions, and recycled products made by melt processing the melt viscosity stabilized compositions.
  • Another aspect of this invention is a process for stabilizing aluminum compound-containing polyolefins against changes in viscosity due to crosslinking under melt processing conditions by adding to the polyolefin a viscosity-stabilizing amount of chromium, manganese, ruthenium, cobalt, rhodium, iridium, rhenium, and/or osmium, optionally in combination with one or both of a controlled-metal deactivator and an antioxidant and melt processing the polyolefin.
  • melt viscosity stabilized compositions for use in this process, which optionally can include adding the aluminum compound together with the viscosity-stabilizing amount of transition metal selected from the foregoing, with or without a controlled metal deactivator and an antioxidant, to a polyolefin, stabilizer concentrates for making the aluminum compound-containing melt viscosity stabilized compositions, and polymer materials made by melt processing the melt viscosity stabilized compositions of this invention.
  • Another aspect of this invention is the gel-free, or substantially gel-free, polyolefin polymer, preferably comprising an ethylene polymer, obtainable by melt processing a polyolefin polymer containing a viscosity-stabilizing amount of a transition metal other than nickel and, optionally, a controlled metal deactivator, antioxidant and/or an aluminum compound.
  • metals are due to their catalytic decomposition of hydroperoxide.
  • the metal(s) can then have a positive effect on polymer stability under conditions in which alkyl radical chemistry (e.g. crosslinking) is important.
  • alkyl radical chemistry e.g. crosslinking
  • the metals used in this invention are believed to act as alkyl radical traps which prevent or retard alkyl radical chemistry.
  • the resulting ethylene polymer compositions are new, melt-stabilized, crosslink-resistant, substantially gel-free polymer compositions having many uses and which are capable of being recycled through several iterations with little or no degradation, discoloration, etc.
  • Figure 1 shows torque curves for maleic acid anhydride grafted high density polyethylene alone, with IrganoxTM 1010 and with IrganoxTM 1010 combined with copper stearate during melt processing at 250 C.
  • Figure 2 shows torque curves at 250 C for maleic acid anhydride grafted high density polyethylene blends with ASPUN fiber grade linear low density polyethylene alone, with IrganoxTM 1010, with copper acetate (abbreviated CuAc) and with a combination of copper acetate and IrganoxTM 1010.
  • CuAc copper acetate
  • Figure 3 shows torque curves at 250 C for ethylene acrylic acid copolymer resins alone, and with cobalt stearate, with the combination of copper stearate and distearylamine, with cobalt phthalocyanine and with a combination of cobalt stearate and IrganoxTM 1010.
  • Figure 4 shows torque curves at 250 C for a 20/80 blend of ethylene acrylic acid copolymer resin and linear low density polyethylene alone and with IrganoxTM
  • Figure 5 shows torque curves at 250 C for linear low density polyethylene alone and with 1% Ox-PE wax, with copper stearate, with a combination of copper stearate and 1 % Ox-PE wax, and with a combination of copper stearate
  • Figure 6 shows torque curves at 250 C for linear low density polyethylene alone and with IrganoxTM 1010, with copper stearate, and with a combination of copper stearate and IrganoxTM 1010.
  • Figure 7 shows torque curves at 250 C for low molecular weight ethylene acetic acid wax alone and with 1 % Allied EAA 5120 and with a combination of 1%
  • Figure 8 shows torque curves at 250 C for a sodium ethylene acetic acid ionomer alone and with IrganoxTM 1010, with a combination of IrganoxTM 1010 and copper acetate, with cobalt stearate, and with cobalt phthalocyanine.
  • Figure 9 shows torque curves at 250 C for ethylene carbon monoxide copolymer containing 500 ppm IrganoxTM 1010 alone and with 20 ppm copper stearate, with 20 ppm copper stearate and an additional 500 ppm IrganoxTM 1010, and with 50 ppm copper stearate.
  • Figure 10 shows torque curves at 250 C for ethylene carbon monoxide copolymer containing 500 ppm IrganoxTM 1010 alone and with copper/Irganox MD1024 complex, with Irganox MD1024, with copper sulfate pentahydrate, with copper acetate, with copper phthalocyanine, with 10 ppm cobalt phthalocyanine, and with 1000 ppm cobalt phthalocyanine.
  • Figure 11 shows torque curves at 250 C for 12% vinyl acetate copolymer
  • Elvax 3135X alone and with IrganoxTM 1010, with copper stearate, and with a combination of copper stearate and IrganoxTM 1010.
  • Figure 12 shows torque curves at 250 C for Elvax 3135X alone and with two combinations of copper stearate and IrganoxTM 1010, one trial at 20 ppm copper stearate and another trial at 50 ppm copper stearate.
  • Figure 13A shows torque curves at 250 C for additional combinations of Elvax 3135X with copper stearate and IrganoxTM 1010 compared with Elvax 3135X alone.
  • Figure 13B shows the torque curve at 250 C for Elvax 3135X with a complex of copper sulfate pentahydrate and Irganox MD1024.
  • Figure 13C shows a torque curve at 250 C for Elvax 3135X with VERSENE AGTM.
  • Figure 14 shows torque curves at 250 C for ElvaxTM 3120 alone and with IrganoxTM 1010, with 10 ppm copper stearate, with a combination of 10 ppm copper stearate and 1000 ppm IrganoxTM 1010, and with a combination of 20 ppm copper stearate and 2000 ppm IrganoxTM 1010.
  • Figure 15 shows torque curves at 250 C for the same combinations of stabilizer/ antioxidant as in Figure 14, except ElvaxTM 3120 is replaced by ElvaxTM 3175.
  • Figure 16 shows torque curves at 250 C for ethylene/ethylene acetate (18%) copolymer alone and with IrganoxTM 1010, with a combination of copper acetate and IrganoxTM 1010, with copper acetate and with a combination of copper acetate and IrganoxTM 1010.
  • Figures 17A and 17B show torque curves at 250 C for various combinations of antioxidant and transition metal stabilizer with linear low density polyethylene produced by constrained geometry catalysis (CGC LLDPE).
  • CGC LLDPE constrained geometry catalysis
  • Figure ,17C shows torque curves at 250 C for Dowlex 2045 polyethylene resin combined with various amounts of molybdenum Ten-CemTM (molybdenum neodecanoate from Mooney Chemicals).
  • Figure 18 shows torque curves at 250 C for Dowlex 2045 polyethylene resin alone and with para-t-butyl phenol (PTBP) and a combination of copper stearate and PTBP.
  • PTBP para-t-butyl phenol
  • Figures 19A through 191 show torque curves at 250 C of Dowlex 2045 polyethylene resin containing melt viscosity stabilizers and antioxidants according to the present invention with and without the presence of various aluminum compounds.
  • FIGS 20A through 20E show torque curves at 250 C for recycled polyethylene alone and in combination with antioxidant and melt viscosity stabilizers according to the present invention. These figures are described in more detail in the examples below.
  • ethylene polymers that can be melt stabilized by the practice of this invention are well known, and include both ethylene homopolymers and
  • interpolymers of ethylene and one or more other vinyl or diene-based monomers are interpolymers of ethylene and one or more other vinyl or diene-based monomers.
  • the ethylene homopolymers include both high and low density polyethylene (i.e. HDPE and LDPE).
  • the ethylene interpolymers i.e. copolymers are those that contain ethylene and minor amounts of one or more vinyl- or diene-based monomers, polyenes, etc.
  • ⁇ -olefins ethylene acrylic acid (EAA), ethylene acetate (EVA), 1 ,4-hexadiene, 1 ,4,7-octatriene, ethylidene norbornene, the naphthenics (e.g., cyclopentene, such as cyclopentadiene, cyclohexene, and cyclooctene, etc.) in interpolymerized form.
  • ethylene interpolymers that can be used in the practice of this invention are: copolymers of ethylene and C 3 -C 20 ⁇ -olefins (e.g.
  • HDPE-g-MAH high density polyethylene grafted with maleic anhydride
  • oxidized polyethylene wax copolymers of ethylene interpolymerized with two or more C 3 -C 20 ⁇ -olefins; and copolymers of ethylene interpolymerized with one or more dienes (e.g. ethylene/propylene/diene monomer (EPDM), ethylene/octene/diene monomer (EODM), ethylene-propylene rubber (EPR), and the like).
  • EPDM ethylene/propylene/diene monomer
  • EODM ethylene/octene/diene monomer
  • EPR ethylene-propylene rubber
  • copolymer includes polymers made from two or more monomers
  • die includes aliphatic and cycloaliphatic monomers containing two or more sites of ethylenic unsaturation.
  • the ethylene polymers are prepared by known polymerization processes, including: high pressure, free radical initiated polymerizations to make LDPE and HDPE resins; the "Phillips" process which uses a chromium catalyst to make HDPE resins; gas phase polymerizations and solution phase polymerizations in which ethylene is homopolymerized, or copolymerized with an alkene of 3 to 20 carbon atoms (e.g. butene-1 , hexene-1, octene-1. etc.) over a suitable transition metal catalyst to make linear low density polyethylene (LLDPE); the slurry process for making HDPE; and other known techniques.
  • the polymerization techniques are broadly classified as solution, gas phase or slurry polymerization reactions.
  • the ethylene polymers and their methods of preparation are described in many sources. See, for example, the Kirk-Othmer Encyclopedia of Chemical
  • the structure of the ethylene polymers can be branched or linear in molecular configuration, and the physical properties (e.g. melt index, density) can be varied by the reaction conditions, catalysts and olefin monomers used in the polymerization.
  • the ethylene polymers that can be stabilized by the process of this invention specifically include the elastic, substantially linear ethylene polymers comprising at least one ⁇ -olefin comonomer and made through the action of a constrained geometry catalyst. These polymers and their method of preparation are fully described in USP 5,272,236 and 5,278,272, each of which is incorporated herein in its entirety by reference.
  • ethylene interpolymers having pendent polar functionality include homopolymers of ethylene that have pendent polar functionality, e.g. HDPE-g-MAH and the like.
  • the unsaturated organic compound typically contains a double bond conjugated with the double bond of an acyl group, e.g. the acids and anhydrides of maleic, fumaric, acrylic, methacrylic, itaconic, crotonic, ⁇ -methyl crotonic, cinnamic and the like.
  • the ethylene polymers of this invention do not include ethylene vinyl alcohol (EVOH). All the ethylene
  • interpolymers having pendent polar functionality that can be used in the practice of this invention are prepared by known copolymerization, grafting and/or oxidation processes.
  • recycled polyolefin materials may be used to make melt viscosity stabilized polyolefin compositions according to this invention.
  • the inventors have surprisingly found that such melt viscosity stabilized compositions can be processed under conventional melt processing conditions without excessive and deleterious changes in polymer molecular weight or viscosity. The absence of such changes is unexpected, because recycled polyolefins undergo more severe processing histories than virgin polyolefins, particularly when they are post-consumer.
  • composition comprising recycled polyolefins, with or without a controlled metal deactivator and/or an antioxidant.
  • an antioxidant e.g., a hindered or unhindered phenol
  • a controlled metal deactivator is present, with or without a hindered or unhindered phenol functionality
  • the transition metal is molybdenum.
  • the recycled polyolefin and/or stabilized composition therefrom may be blended with one or more virgin polymers such as polyethylene, polypropylene, EVA copolymer, etc., in any amount. The amount may be from about 1 wt% or less to about 95 wt% or more, but is more typically in the range from about 5 wt% to about 30 wt%.
  • the term "virgin polymer” refers to polymer which has not yet been fabricated for the first time (i.e., it has not yet been recycled).
  • transition metal used in the present invention are transition metals of Groups 5 through 11 , rows 4 through 6 of the CAS Version of the Periodic Chart, Handbook of Chemistry and Physics. 69th Edition, edited by Robert C. Weast, CRC Press (1989-1990).
  • transition metal include the metals in both their metallic state, e.g. as finely-divided particulate solids, and in their ionic states, e.g. as metal salts. In either state, the metals are used in a form such that they are dispersible in the ethylene polymers.
  • the metals are preferably used as dispersible metal carboxylate salts, and most preferably as metal carboxylate salts of fatty acids. Vanadium, chromium, manganese, cobalt, copper, molybdenum, ruthenium, palladium, platinum, rhodium and iridium, and the dispersible carboxylate salts of such metals are preferred, with metallic copper, cobalt and molybdenum, and their carboxylate salts, most preferred. Copper and molybdenum and their respective salts are particularily preferred. In addition to high temperature melt processing stability, molybdenum salts also provide desirable long-term heat stability to the
  • polyethylenes in which they are dispersed.
  • ethylene polymers that do not contain polar functionality e.g. HDPE, LLDPE, LDPE, ultra low density polyethylene (ULDPE), etc.
  • iron and nickel (and their carboxylate salts) are operable in the present invention, but they are less effective in providing viscosity stabilization than comparable amounts of manganese, molybdenum, cobalt and copper, elements which are near or adjacent to iron and/or nickel in the Periodic Chart.
  • silver (and its carboxylate salts) do not perform as well as comparable amounts of copper, a metal which is adjacent to silver in the Periodic Chart.
  • Suitable metals include, for example, the finely divided metals and the formate, acetate, acetylacetonate, octanoate, neodecanoate, and stearate salts of chromium, manganese, cobalt, copper, molybdenum and the various mixtures of one or more of these materials.
  • the melt processing temperature of the polyethylene is maintained at a temperature in excess of 175 C, preferably in excess of 200 C, and more preferably in excess of 225 C.
  • thermal decomposition of hydroperoxide is so fast that the presence of a catalyst has little, if any, influence on the overall decomposition rate of hydroperoxide.
  • the maximum hydroperoxide concentration in the melt is very low because other mechanisms (e.g. bimolecular decomposition, catalytic effects of oxidation products, etc.) cause the hydroperoxide to
  • these compounds contain at least two carbonyl groups and at least two nitrogen atoms, e.g. derivatives of oxamides and hydrazines (e.g., oxamide, oxamido, hydrazine and hydrazide compounds). More preferably, these include compounds having one or more
  • inertly substituted is meant that the substituents are essentially nonreactive with the ethylene polymer under high temperature melt processing conditions other than in its capacity as an antioxidant.
  • R and R' do not contain aryl amine or hindered phenol functionality, but may contain one or more unhindered phenol functionalities derived from the unhindered phenol antioxidants described below.
  • one or both of R and R' preferably contains aryl amine or hindered or unhindered phenol functionality (i.e., functionality derived from the antioxidants described below), especially 2,6-di-t-butylphenol functionality.
  • Examples include 2,2'-oxamido bis[ethyl-3-(3,5-di-t- butyl-4-hydroxyphenyl)propionate] and N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl] hydrazide; 1 ,2-diacetylhydrazine; 1-acetyl-2-phenylacetylhydrazine; oxalic bis(benzylidenehydrazide); 1 ,2-dibenzoylhydrazine; N,N-bis-(2-hydroxyethyl)oxamide; 3-aminophthalhydrazide; N,N'- dihexadecyloxamide; 1 ,2-dicarbethoxyhydrazine; diethyl-1,2-dimethyl-1,2- hydrazine-dicarboxylate; and 1,2-diethylhydrazine dihydrochloride.
  • EDTA ethylenediaminetetraacetic acid
  • transition metal and controlled metal deactivator can be used to stabilize a polyethylene resin during melt processing.
  • the controlled metal deactivator contains nitrogen atoms, and the metal and deactivator are present in a mole ratio of at least about 2:1, more preferably of at least about 4:1, based on the ratio of nitrogen atoms in the deactivator to metal.
  • Nonlimiting examples of controlled metal deactivator/metal systems include copper stearate, cobalt stearate, ruthenium acetylacetonate, or copper sulfate solution blended with any of the controlled metal deactivators described above, and the copper diammonium complexes of EDTA in aqueous solution (manufactured and sold by The Dow Chemical Company under the trademark VERSENE).
  • the transition metal is used in combination with an antioxidant, particularly a hindered phenol or aryl amine antioxidant.
  • an antioxidant particularly a hindered phenol or aryl amine antioxidant.
  • antioxidants are well known in the art, and the preferred hindered phenol and hindered amine antioxidants are more fully described in USP 3,979,180 which is herein incorporated in its entirety by reference.
  • Representative antioxidants include octadecyl 3-(3,5-di-t-butyl-4-hydroxy-phenyl)-propionate; tetrakis-(2,4-di-t-butyl-phenyl)4,4'-biphenylphosphonite; di(stearyl)pentaerythritol diphosphite (+l% triisopropanolamine).
  • IrganoxTM 1010 tetrakis[methylene(3,5-di- t-butyl-4-hydroxyhydrocinnamate)] methane
  • the inventors have found that when non- hindered phenols are added to polyolefin compositions together with the transition metals in accordance with this invention, the polyolefin compositions have melt stabilization characteristics at least as good as that obtained with hindered phenols and transition metals while reducing or preventing the discoloration caused by the highly colored oxidation products formed by oxidation of the hindered phenol antioxidants. While not being bound to a particular theory, the ability of the nonhindered phenols to achieve stabilization against oxidation while resisting discoloration may be due to the oxidation resulting in coupling at the phenoxy functionality rather than formation of quinone compounds having intense color.
  • any nonhindered phenol may be used as the antioxidant or antioxidant functionality of this invention.
  • These include phenol, mono-substituted phenols, and polysubstituted phenols not having more than one bulky group in the ortho position.
  • Bulky groups include bulky hydrocarbyl groups such as the t-butyl group and hydrocarbyl having more than four carbon atoms.
  • a specific example of an unhindered phenol is para-t-butyl phenol.
  • the transition metals are added to the ethylene polymers in small but viscosity-stabilizing amounts prior to or during melt processing operations.
  • viscosity-stabilizing is meant an amount sufficient to reduce the absolute value of the slope of a torque curve (see Figure 1). The goal is to approach a flat line with a slope of zero, but any reduction in the absolute value of the slope relative to the ethylene polymer alone is an unexpected improvement and the amount of metal added is a viscosity-stabilizing amount.
  • a controlled metal deactivator In those embodiments in which a controlled metal deactivator is used, it is generally used in an amount of about 5 to about 20,000 ppm, preferably about 50 to about 5000 ppm, which is about 0.0005 to about 2, preferably about 0.005 to about 0.5 wt % based on the weight of the deactivator relative to the weight of the ethylene polymer.
  • the most preferred amount of deactivator will vary with the nature of the deactivator, the ethylene polymer, the transition metal and its physical state, the melt processing conditions, and the like.
  • an antioxidant in those embodiments in which an antioxidant is used, it is generally used in an amount of about 100 to about 5000 ppm, preferably about 200 to about 1000 ppm, which is about 0.001 to about 0.5 wt %% preferably about 0.002 to about 0.1 wt %, based on the weight of the antioxidant relative to the weight of the ethylene polymer.
  • the most preferred amount of antioxidant will vary with the nature of the antioxidant, the ethylene polymer, the metal and its physical state, the nature of the controlled metal deactivator, the melt processing conditions, and similar variables.
  • an unhindered phenol is used as the antioxidant the amount thereof is preferably in the range from about 0.01 to about 3.0 weight percent, more preferably in the range from about 0.05 to about 0.3 weight percent range.
  • the transition metal can be added to the ethylene polymer in any convenient manner which results in the metal being substantially dispersed throughout the resin.
  • the sequence of adding the antioxidant and the metal deactivator/metal compound system will vary with the polymer and processing conditions.
  • the controlled metal deactivator/metal compound system can be made in situ or blended with one another prior to addition to the polymer melt.
  • Aluminum-containing acid neutralizers such as hydrotalcite (e.g., DHT-4A from Kyowa Co.); aluminum-containing fire retardants (e.g., aluminum trihydrate), aluminum-containing catalyst residues and aluminum-contamination from processing equipment, etc.
  • aluminum-containing fire retardants e.g., aluminum trihydrate
  • aluminum-containing catalyst residues and aluminum-contamination from processing equipment etc.
  • the range of what may be present as aluminum in this aspect of this invention can include inorganic aluminum salts, organic aluminum salts, and finely dispersed aluminum as metal. It may be present in any amount, but is typically present in the range from about 10 ppm to about 10 wt.% based on the weight of aluminum.
  • the inventors have found that there is an antagonistic effect between aluminum and the viscosity stabilizing effect of the otherwise preferred transition metals in polymeric compositions, reducing the effectiveness of those transition metal stabilizers.
  • transition metal stabilizers having transition metals selected from the group consisting of chromium, manganese, ruthenium, cobalt, rhodium, iridium, rhenium, and osmium, preferably manganese, cobalt and iridium, and most preferably cobalt.
  • the transition metal stabilizer is preferably a transition metal compound, such as one comprising an inorganic anion, a carboxylate (e.g., a stearate), or other organic molecule such as acetylacetonate.
  • transition metals and transition metal compounds are preferably present in the range from about 0.1 ppm to about 1 wt%, preferably from about 0.5 ppm to about 0.1 wt %, based on the weight of the transition metal.
  • Preferred polymeric compositions in this aspect of the present invention are those comprising polyolefin, more preferably an ethylene polymer, and a preferred aluminum compound is hydrotalcite.
  • Hydrotalcite is known as a metal deactivator so that from the prior art one would have expected less, not more, transition metal stabilization.
  • One method of adding these materials to the polymer is by blending them in a polymer masterbatch under conditions where the components may be intimately mixed, e.g. in the mixing section of an extruder.
  • Other methods include dissolving or dispersing the components in a solvent and spraying the resulting mixture onto pellets or powders of the polymer prior to melt processing, or dry-blending the components with pellets or powders of the polymer prior to melt processing.
  • Other methods will be apparent to those skilled in the art.
  • a stabilizer concentrate is prepared which comprises a polymer, sometimes referred to herein as a "stabilizer base polymer", and the metal, with or without a controlled metal deactivator and/or antioxidant, the latter dispersed throughout the former (i.e. the stabilizer base polymer).
  • This stabilizer concentrate (generally molten) is then added to the molten ethylene or other polyolefin polymer as it passes through an extruder or other processing equipment.
  • the stabilizer base polymer is preferably the same type of polymer as the molten polymer passing through the processing equipment, and may be the same as the molten polymer.
  • concentrate is a convenient form of storage and handling for the metal, with or without controlled metal deactivator and/or antioxidant, and it can be easily metered into the extruder in reasonably precise quantities.
  • MAH-g-HDPE Maleic Anhydride-graft-High Density Polyethylene
  • EAA Ethylene Acrylic Acid Copolymer
  • the ionomer was a Dow product.
  • EVA Ethylene Vinyl Acetate Copolymer
  • ElvaxTM 3135x was a nominal 12% vinyl acetate copolymer having a 0.4 Ml.
  • ElvaxTM 3175 was a nominal 28% vinyl acetate (VA), 3.0 Ml resin.
  • ElvaxTM 3120 was a nominal 7.5% VA, 1.2 Ml resin. All ElvaxTM copolymers were products of the E.I. DuPont de Nemours, Co.
  • EAA Ethylene Ethyl Acrylate Copolymer
  • the CGC LLDPE used in these examples are ethylene-1-octene
  • LLDPE Linear Low Density Polyethylene
  • Dowlex 2047A (a trademark and product of Dow) has a nominal density of 0.92 and Ml of 2.3 and contains 500 ppm DHT-4A hydrotalcite acid neutralizer, 500 ppm IrganoxTM 1076 and 800 ppm PEPQ.
  • IrganoxTM 1010 is tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, an antioxidant from Ciba-Geigy.
  • IrganoxTM 1076 is n - octadecyl-beta-(3,5 - dibutyl - 4 - hydroxy phenyl)-propionate, an antioxidant from Ciba Geigy.
  • Cu-lrganoxTM MD 1024 complex (Irganox MD1024 is N,N" -bis[3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionyl]hydrazide, from Ciba-Geigy).
  • the complex was prepared by placing 0.0120 g copper sulfate pentahydrate (CSP) and 1.2010 g IrganoxTM MD1024 in a 150 ml beaker containing Isopar E hydrocarbon solvent (obtained from Exxon). The mixture was heated and stirred until the temperature reached 85 C. Water (15 ml) was then added with vigorous stirring. The copper compound changed color from blue to green, and then was observed to transfer from the aqueous phase to the hydrocarbon phase. The mixture was placed in a glass dish and the solvent/water were evaporated.
  • Copper sulfate pentahydrate (CSP) - IrganoxTM MD1024 complex prepared by placing 6.7737 g CSP in 300 ml of deionized water, and heating the mixture until a clear, light blue solution was obtained.
  • IrganoxTM MD 1024 (30.00 g) was heated with stirring to 50 C in 1500 ml acetone. The aqueous CSP was stirred into the acetone/MD 1024 solution, and immediately an olive-green precipitate was formed. The mixture was cooled to 45 C, and then it was poured into a glass dish from which the solvent/water was evaporated at room temperature. The resulting product had a melting point of 197 C, and it was a light green, fine powder.
  • VERSENE AG (a trademark of Dow Chemical Co., referring to a copper diammonium complex of EDTA in aqueous solution, containing 7.5% copper).
  • PTBP para-t-butyl phenol, a nonhindered phenol available from
  • PEPQ refers to Sandostab PEPQTM, an antioxidant which was available from Sandoz and is now available from Clariant Corp., tetrakis-(2,4-di-t-butyl-phenyl-Y,Y'-biphenyl phosphonite).
  • a Rheocord System 40TM torque rheometer from HaakeBuchler Instruments was used to test the melt processing stability of the various formulations.
  • the mixer was a Rheomix 600TM model equipped with roller style blades.
  • the mixer was modified, with -glass-filled TEFLONTM or stainless steel bushings replacing the original bronze brushings.
  • the torque rheometer was operated isothermally at temperatures between 150-275 C depending on the particular polymer.
  • the ram was kept up, allowing exposure to air.
  • Mixing speed was 10 rpm.
  • a 60 second adiabatic initial mixing period at 60 rpm was used at the start of each experiment.
  • the additive was incorporated accurately by weighing it into a capsule molded from the base interpolymer, then adding the additive package and polymer into the mixer via a loading chute and ram and then, unless stated otherwise below, processing for 1000, 1500 or 3000 seconds.
  • Sample size was typically 40 g but in interpolymers with higher melt densities, larger amounts were used in order to fill approximately the same mixer volume each time.
  • Mixing conditions were not selected based on typical fabrication processing conditions for the given interpolymer, but were based on conditions believed most likely to reflect a reasonable rate of thermo-oxidative degradation and opportunity to observe the possible stabilizing action of metal compounds.
  • Figure 1 shows that MAH-g-HDPE by itself crosslinked so severely that by approximately 2500 seconds it began to grind to a powder and climb out of the mixer bowl, resulting in a rapid torque decrease due to the reduced polymer volume in the mixer and the cessation of viscoelastic flow as a mechanism of deformation. 1000 ppm Irganox 1010 reduced the rate of torque increase
  • crosslinking A combination of 10 ppm copper stearate and 1000 ppm Irganox 1010 provided an even greater reduction in crosslinking rate.
  • MAH-g-HDPE is in a blend with ASPUN fiber grade LLDPE (a trademark and ethylene/1-octene copolymer of The Dow Chemical Company with an Ml of 18 and a density of 0.930 g/cc) to produce fibers.
  • LLDPE a trademark and ethylene/1-octene copolymer of The Dow Chemical Company with an Ml of 18 and a density of 0.930 g/cc
  • Figure 2 shows the stabilization of this blend with copper acetate. 10 ppm copper acetate had a torque reducing effect when used alone, and a combination of copper
  • acetate/lrganox 1010 produced a lower torque curve than Irganox 1010 alone.
  • Table I shows the results of melt index analyses on samples removed at the end of each 1500 second experiment. These data clearly show the viscosity stabilizing effect of copper acetate formulations.
  • Figure 5 shows that copper stearate produced a lower torque in LLDPE when used with 1 % Ox-PE wax than when used by itself.
  • a slightly lower torque was obtained in the combination of 1 % Ox-PE wax with copper stearate/lrganox 1010 than with copper stearate/lrganox 1010 alone (Figure 6), but the torque trended upwards after 1000 seconds.
  • Copper stearate was also active when used with Allied EAA 5120 wax ( Figure 7).
  • EAA acid groups do not inhibit the activity of copper stearate unless they are present at very high concentrations (e.g., pure EAA). Alternatively, these groups may not deactivate copper at all. EAA and polyethylene may simply degrade via different mechanisms such that the degradation of EAA is inhibited by Co but not by Cu, and the degradation by polyethylene is inhibited by both.
  • Figure 8 shows that a sodium EAA ionomer had slightly improved stability when 1000 ppm Irganox 1010 was added. However, the additional incorporation of 10 ppm copper acetate had no further stabilizing effect. Cobalt stearate or cobalt phthalocyanine produced higher rates of torque increase in sodium EAA ionomer, in contrast to their effects in EAA.
  • Figures 9 and 10 show that the torque stability of an ethylene carbon monoxide copolymer was not substantially affected by up to 50 ppm copper stearate, copper sulfate, copper acetate or copper phthalocyanine.
  • 10 ppm cobalt phthalocyanine caused a significant reduction in the rate of torque increase.
  • the "protected form" of copper (Cu/lrganox MD1024) complex) also significantly reduced torques and had a larger effect than Irganox MD1024 alone. When 1000 ppm cobalt phthalocyanine was used, no torque increase was observed.
  • Figure 11 shows the effect of copper stearate and copper stearate/lrganox 1010 blends on the torque stability of Elvax 3135X, a 12% vinyl acetate
  • ElvaxTM 3120 was a lower acetate content resin (7.5% VA). Copper stearate caused more torque reduction in this resin (Figure 14) that in the 12% VA resin. In a 28% VA resin (ElvaxTM 3175), the effect of copper stearate may have been less ( Figure 15).
  • this possible correlation of copper effectiveness and VA content must be considered speculative since the resins varied widely in molecular weight and possibly other characteristics such as VA distribution or additive content. Nonetheless, these data clearly show that copper
  • stearate/lrganox 1010 together provide improved torque stability over either component alone in a range of EVA copolymers.
  • An additive-free ethylene/ethyl acrylate (18%) copolymer (Figure 16) had significantly better torque stability when copper acetate and Irganox 1010 were used together than when either component was used alone.
  • FIG 17A shows that a copper/lrganox MD1024 complex produces a favorable torque response relative to the base resin (the torque curve of which is reported in Figure 17B), and relative to the base resin in combination with Irganox
  • Figure 17B also reports that arylamine (Ageright WhiteTM from R.T. Vanderbilt, sym. dibetanaphthyl-p-phenylenediamine) are effective in reducing the torque curves of these polymers.
  • the CSP/lrganox MD1024 complex I was prepared by heating a mixture of 0.0120 g CSP and 1.210 g Irganox MD 1024 in Isopar E with stirring to about 85 C. Since the CSP did not enter the solution, 15 ml of water was added with vigorous stirring. The aqueous phase was at first blue, and then turned green. Eventually the color transferred to the hydrocarbon phase. The solution was transferred to a glass dish from which the solvent/water was evaporated at room temperature.
  • the CSP/lrganox MD1024 complex II was prepared by placing 6.6738 g Irganox MD1024 into a 1000 ml beaker with 500 ml of Isopar E hydrocarbon solvent. CSP (0.31479 g) was added in solid form. The mixture was heated with stirring to about 85 C, and then 100 ml of water was added with vigorous stirring. The solution changed color from aqua blue to olive green, and then dispersed into the hydrocarbon phase. The solution was then transferred to a glass dish, and the solvent/water evaporated at room temperature.
  • hydroperoxide concentration increases significantly with time, both in static and dynamic oxidation environments, i.e. static oxidation of polymer films and melt processing, respectively.
  • the hydroperoxide concentration eventually reaches a maximum, and it then begins to decrease due to bimolecular hydroperoxide decomposition mechanisms as described by W.L. Hawkins in "The Thermal Oxidation of Polyolefins-Mechanisms of Degradation and Stabilization", Degradation and Stablization of Polymers.
  • hydroperoxide concentrations where homolytic cleavage of hydroperoxides predominantly occurs In addition to this change in the predominant
  • hydroperoxide concentration achieved in the polymer melt is likely to be very low. This behavior is further demonstrated by the data reported in Tables 11 A, IIB, and IIC.
  • concentrations of high redox potential transition metals like cobalt cause increased rates of carbonyl formation even at 250 C, but low (e.g. 100 or less ppm) concentrations of these metals, or either low or high concentrations of copper, do not sharply increase carbonyl formation rates at this high temperature. Moreover, even at a high concentration of these metals, a sharp difference in temperature sensitivity is observed.
  • Table IIIA for example, 1000 ppm of cobalt and copper stearate cause 2.6 and 1.4 carbonyls/1000 C, respectively, after 3000 seconds at 250 C as compared to 1.15 for the control resin or in other words, an increase of 116 percent and 16 percent, respectively, in the rate of carbonyl formation. At lower concentrations (e.g. 1 - 53 ppm) but at the same temperature (250 C), the increase in carbonyls is much less (see Table IIIB).
  • transition metals as melt processing stabilizers in polyethylene are their tendency to destabilize the polymer during long-term use at relatively low temperatures (e.g. less than 175 C). By catalyzing hydroperoxide decomposition, they accelerate the rate of oxidation and can potentially reduce the shelf life of the polymer by a significant amount. This can be particularly troublesome in applications in which the polyethylene is in contact with a metal, such as the copper conductor in wire and cable applications. To offset this tendency, the transition metal is often formulated with a metal deactivator to maintain the properties of the polyethylene during long term use.
  • transition metal stabilizers of this invention do not catastrophically reduce the long-term heat stability of ethylene polymers.
  • 500 ppm copper stearate reduced the long-term heat stability of DOWLEX LLDPE by only 20 percent in a 90 C oven-aging test.
  • antioxidants impart outstanding long-term stability to ethylene polymers. For example, when 10 ppm copper stearate was used in combination with 1000 ppm Irganox 1010 antioxidant, the LLDPE samples lasted the length of the test (614 days) without embrittlement, as compared to 44-81 days for existing LLDPE based stabilization systems (200 ppm Irganox 1010). This clearly suggests that the melt stabilizer systems of this invention, particularly those of copper stearate and hindered phenol, impart good resistence to physical deterioration. However, some discoloration of the polymer can occur.
  • transition metal/controlled metal deactivator systems such as copper/lrganox MD1024, especially when combined with antioxidants.
  • ethylene polymers stabilized with a molybdenum compound e.g. molybdenum neodecanoate such as Mo TEN-CEM from Mooney Chemical, even at 500 ppm and even in the absence of antioxidant, provides stability against embrittlement over the duration of a 614 day 90 C oven-aging test.
  • the inventors have dound thta molybdenum by itself in an additive free base resin (DowlexTM 2045 Polyethylene base resin provides outstanding melt viscosity stability as shown in Figure 17C. Controlled Metal Deactivators
  • controlled metal deactivators are those compounds that coordinate with the transition metal such that it (the metal) is inactive towards hydroperoxides at low to moderate temperatures (e.g. less than about 175 C) yet it remains active as a viscosity stabilizer at high temperatures (e.g. in excess of 175
  • the efficacy of any particular compound to act as a controlled metal deactivator in a given polymer requires the juxtaposing of two measurements.
  • the first measurement is the extent to which the deactivator passivates the transition metal toward the catalysis of hydroperoxide decomposition, and the other measurement is the extent to which the transition metal (while complexed with the deactivator) is available to viscosity stabilize the polymer at high temperature.
  • the juxtaposing of these measurements is demonstrated in Table IV.
  • Additive-free LLDPE-hydroperoxide was prepared from a 1 M.I. LLDPE resin in a Banbury mixer for 75 minutes at 145-151 C.
  • This product i.e. DowlexTM 2045 Polyethylene
  • 0.19 carbonyls/1000 C and 0.39 hydroperoxide/1000 C accordinging to the 3550 cm -1 peak method described previously.
  • This was the sample material used to generate the data reported in Table IV.
  • the catalytic effect of transition metal compounds on polyethylene hydroperoxide decomposition was determined.
  • transition metal/metal deactivator compounds used in Table IV were prepared by dissolving the respective transition metal and deactivator in an appropriate solvent, and then either precipitating the compound or evaporating the solvent.
  • the systems were prepared as a solution followed by drying or precipitation of the transition metal/controlled metal deactivator complex. These complexes were either added to the polymer neat or in the form of a polymer concentrate.
  • the respective components of the systems were weighed into the same capsule and then added to the melt to form the system in situ.
  • Systems containing a controlled metal deactivator in combination with a transition metal should perform no worse than the transition metal at comparable transition metal concentrations relative to hydroperoxide decomposition.
  • the base resin Preferably it should perform the same as the base resin, and more preferably it should perform better than the base resin, (i.e. have a lower hydroperoxide decomposition rate). At the same time, it should impart melt viscosity stability greater than the stability of the base resin itself (i.e. it should flatten the torque curve) and preferably, it should perform as good as a transition metal, and more preferably better than a transition metal, at comparable transition metal concentrations.
  • carboxylate and similar metal salts are useful aids in the dispersion of the metal throughout the polymer melt, these organic radicals are effective at controlling the metal relative to its reactivity towards hydroperoxides.
  • metal carboxylates and the like are not controlled metal deactivators.
  • Table IV identifies various controlled metal deactivators within the scope of this invention.
  • the base resin (Control A which is an average of five separate runs and did not contain a transition metal) reported a 20 percent decrease in the hydroperoxide concentration over the period of 400 to 3000 seconds at 150 C.
  • copper stearate (Control B) was added after 400 seconds at 150 C, the hydroperoxide concentration decreased 63 percent between the period of 400 seconds to 3000 seconds.
  • the controlled metal deactivators of this invention for this particular polymer under these particular conditions should cause a reduction in hydroperoxide concentration no greater than 63%, and preferably 20% or less.
  • Sample A reports that IrganoxTM 1010 is a poor controlled metal deactivator (it does not pacify the copper stearate with respect to catalyzing hydroperoxide decomposition) and consistent with this failure to pacify, the copper is available to stabilize the viscosity at high temperatures (as reported by the 340 m-g peak torque value).
  • EDTA demonstrates some effect as a pacifier for copper stearate, but it complexes with the copper so tightly that the copper is only marginally effective as a viscosity stabilizer (a peak torque value of 1050 m-g versus 1200 m-g for the base resin).
  • Versene AGTM a 46 percent diammonium copper complex of EDTA in aqueous solution (54 percent water, and containing 7.5 percent copper) is a very effective controlled metal deactivator (Sample N).
  • Samples C and D identify a good controlled metal deactivator. While the peak torque was not measured for Sample E, it was measured for a similar sample at 1000 ppm and this sample demonstrated both good stabilization and good control. Since NaugardTM XL-1 did not completely deactivate the copper as a viscosity stabilizer at 1000 ppm, then it clearly would not do so at 593 ppm.
  • Samples G, H and I report good to marginal deactivators that demonstrate good viscosity control, while Samples K, M and N report controlled metal deactivators that combine excellent metal passivity relative to hydroperoxide decomposition catalysts and excellent metal availability with respect to viscosity stabilization.
  • the metal/controlled metal deactivator system retains its resistance to reaction with hydroperoxide after heat treatment (such as extrusion).
  • Other types of transition metals can be classified as "copper-like” (e.g. ruthenium, chromium) or "cobalt-like” (e.g.
  • Unhindered Phenol The same test procedure was used to test the melt viscosity stabilizing effect and reduction of discoloration effect of substituting unhindered phenols for hindered phenols as the antioxidant, except that the samples were removed after 300, 600, and 1000 seconds for coiorimetric analysis and torque was measured during the first 1000 seconds of melt processing to obtain data for melt viscosity stabilization over a processing time period corresponding to the coiorimetric data.
  • Stabilizer concentrates were prepared in DOWLEX 2047A (an ethylene-octene copolymer containing 500 ppm DHT-4A hydrotalcite acid neutralizer, 500 ppm Irganox 1076 antioxidant and 800 ppm PEPQ).
  • DOWLEX 2047A an ethylene-octene copolymer containing 500 ppm DHT-4A hydrotalcite acid neutralizer, 500 ppm Irganox 1076 antioxidant and 800 ppm PEPQ.
  • the concentrates were prepared by melt blending in a Haake torque rheometer mixer with Rheomix 3000 mixing bowl, roller style blades, and glass-filled TEFLON bushings. Resin was added gradually to the mixer at 20 r.p.m. and mixed until it was melted, then additive was added and the ram was lowered and rotor speed increased to 60 r.p.m. for 60 seconds. The speed was then reduced to 20 r.p.m.
  • Stabilizer Concentrate A 180.10 g of Stabilizer Concentrate A was tumble blended with DowlexTM 2045 LLDPE pellets from Dow Chemical Co. to prepare a total of 3.5 lbs. of extrudable mixture.
  • the stabilizer mixture was placed in the hopper of a 1 inch diameter, 20:1 L/D laboratory scale MPM single screw extruder running at 156 r.p.m. and having a temperature profile of 350, 482 and 500oF for the two extrude zones and die, respectively.
  • the polymer composition was extruded through a nozzle die, then the extrudate was quenched in a water bath, passed through a compressed air strand drier, and pulled through a chopper for granulation.
  • the granulated pellets were compression molded (150oC) into 125 mil plaques for color determinations. Color was measured using a Hunter ColorQuest
  • a torque rheometer was used to evaluate the change in torque (e.g., viscosity) occurring in an ethylene-octene copolymer during melt processing at 250oC, both in the presence and absence of hydrotalcite, aluminum hydroxide, aluminum acetylacetonate, and/or transition metal salts using the same equipment and procedures used above to test polyolefin compositions containing controlled metal deactivator and/or antioxidant.
  • Irganox 1010 hindered phenolic antioxidant was optionally added as a co-stabilizer.
  • Torque versus time data were collected and plotted using a computer graphics program. Those data plots are shown in Figs. 19 A to 19H.
  • Figure 19A shows the torque increase (viscosity increase) due to thermooxidative crosslinking in additive-free LLDPE in the absence of any stabilizer. It also shows the torque reducing effects of copper stearate and how DHT-4A hydrotalcite has an antagonistic effect such that the torque is increased as compared to the copper-stabilized formulation free of DHT-4A.
  • Figure 19B shows the excellent stabilization obtained with a combination of 10 ppm copper stearate and 1000 ppm Irganox 1010 antioxidant. as previously disclosed. It also shows how 500 ppm DHT-4A reduces the effectiveness of the stabilizer system.
  • Figure 19C shows that other aluminum containing compounds have similar effects, though not all.
  • a hydrated alumina from AluChem did not have an antagonistic effect.
  • Hydrated alumina (e.g., aluminum hydroxide) from Aldrich did.
  • Figure 19D shows that aluminum acetylacetonate also had an antagonistic effect on copper stearate.
  • Figures 19E and 19F show that the antagonistic effect is not limited to copper, but also applies to other transition metal salts such as zinc stearate or molydenum neodecanoate compositions.
  • Figure 19G shows that ruthenium acetylacetonate is only slightly reduced in its activity when DHT-4A is present.
  • Figure 19H shows that manganic acetylacetonate is not affected at all by
  • DHT-4A and Figure 191 shows that cobalt stearate had improved performance when used in the presence of DHT-4A.
  • Recycle Stream #1 (“Natural Flake”): This consisted mostly of clear flakes, with only an occasional pigmented one. These natural bottle flakes were mostly from HDPE milk bottles, believed to consist mostly of Phillips HDPE resin. The natural flakes had a composite average melt index of approximately 0.7 g/10 minutes, and a 0.960 g/cc density.
  • Recycle Stream #2 (“Pigmented Flake”): This was predominantly natural flakes but with many pigmented flakes of a wide variety of colors also present. Based on a 7.68 g random sample, 27% of the flakes were pigmented and 73% were clear. The dominant colors were white, blue and red or orange. A smaller number of black, yellow, green, and off-white were present. The pigmented flakes were derived from a wide assortment of household bottles. This recycle stream had a melt index of approximately 0.5 g/10 min. and 0.955 g/cc density. The melt processing stability of recycled polyethylene formulations was tested using the equipment and procedure used to test polyolefin compositions containing controlled metal deactivator and/or antioxidant.
  • Additives were incorporated by weighing them into a small film envelope made from compression molded flakes of the relevant recycle stream, then adding this envelope right after the base resin flakes were loaded into the mixer (e.g., approximately 20-30 seconds into the run). Samples totaling 40.00 g in weight were processed for either 1000 or 3000 seconds. Torque versus time data were collected and plotted by a computer graphics program.
  • Figure 20A shows the torque curves for the natural flakes processed at 250 C for 1000 seconds.
  • the torque increase with time is due to thermo-oxidative crosslinking.
  • Addition of 1600 ppm Irganox 1076 reduced the rate of torque increase significantly, but did not completely eliminate it.
  • the additional incorporation of 10 ppm copper acetate resulted in an approximately 30 m-g lower torque after 1000 seconds.
  • Copper stearate was also tested. Although the copper metal content was significantly lower in the polymer composition containing copper stearate than in the polymer composition containing copper acetate, the torque curves were similar. Copper stearate is preferred because of its improved dispersibility.
  • GPC data are summarized in Table VIII.
  • the molecular weight of the starting material is not known; no GPC data were obtained on the unprocessed flakes because they were not homogeneous. Thus, comparisons must be made to the other processed samples.
  • the GPC data show that the copper containing formulations reduced crosslinking (lower Mw) without significant evidence of accelerated scission (lower Mn). This confirms the crosslinking inhibition mechanism of these stabilizers, and that the torque-lowering effect of copper is n simply due to increased rates of competitive scission.
  • Figure 20B shows the torque curves for 3000 second experiments. While 3000 seconds is severe compared to the conditions experienced by the bulk of polyethylene passing through typical extrusion processes, small amounts of polyethylene in stagnant zones of extruders (where gels are typically formed) might experience thermo-oxidative conditions this severe.
  • the 3000 second experiments more clearly differentiated the performance of Irganox 1076 alone a compared to its combinations with copper carboxylates. There was not a significant difference in performance of copper stearate as compared to copper acetate.
  • Figure 20C shows 1000 second torque curves for the pigmented flakes.
  • the rate of torque increase was somewhat lower for this resin than in the natural flakes ( Figure 20A).
  • the effects of copper acetate and copper stearate were similar in pigmented flakes as in natural flakes.
  • Figure 20C shows the subtle differences in torque shown in Figure 20C.
  • Figure 20D shows the results of 3000 second experiments. Copper stearate performed slightly better than copper acetate over the course of 3000 seconds, but otherwise the results were not much different than those for natural flakes.
  • Certain metal deactivators such as Irganox MD 1024 may be used to increase the long-term stability of polyolefins by inhibiting the catalytic decomposition of hydroperoxides caused by the catalyzing effects of certain metals such as copper. Adding metal deactivators to polyolefin compositions containing a melt viscosity stabilizer that causes such catalyzing effects, such as copper carboxylate, may thus increase long term stability of the polymer product.
  • Figure 20E shows the effect of 1000 ppm Irganox MD1024 alone and as a complex with copper. The latter formulation was based on 47.3 ppm copper sulfate pentahydrate, or approximately 12 ppm copper.
  • Irganox MD1024 Because of its hindered phenolic functionality, Irganox MD1024 alone provided stability not unlike Irganox 1076 (see Figure 20D). However, the complex with copper was much higher in effectiveness and, due to the relatively high copper content or protection of the copper by the controlled metal deactivator from antagonistic materials postulated to be in the pigmented flakes, the torque curve was flat. This effect was surprising given the known metal-deactivating effects of IrganoxTM MD1024. The copper was not deactivated with respect to its ability to stabilize polyolefins at elevated melt processing temperatures because IrganoxTM MD1024 is a controlled metal deactivator.

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Abstract

On stabilise les polymères d'éthylène, par exemple le polyéthylène basse densité linéaire, avec ou sans fonctionnalité polaire pendante, vis-à-vis des variations de viscosité dues à la réticulation au cours des opérations de traitement de matière en fusion à haute température (par exemple température supérieure à 175 °C), en ajoutant au polymère, avant ou pendant l'opération, une quantité stabilisatrice de viscosité d'un métal de transition, par exemple du cuivre métallique ou un sel de cuivre tel que le stéarate de cuivre, éventuellement en association avec un désactivateur de métaux contrôlés, par exemple un oxamide ou une hydrazine, et/ou avec un antioxydant tel qu'un phénol encombré ou une amine arylée. On préfère, à titre d'agents stabilisant la viscosité en fusion, certains métaux de transition autres que le cuivre lorsque sont présents des composés d'aluminium tels qu'un agent de neutralisation d'acides à base d'hydrotalcite. On peut également stabiliser les polymères d'éthylène en ajoutant des phénols non encombrés, notamment lorsque le jaunissement pose un problème. On peut améliorer le recyclage des polyoléfines en ajoutant au flux de polyoléfine recyclée une quantité stabilisatrice de viscosité d'un métal de transition, éventuellement en association avec un désactivateur de métaux contrôlé et/ou avec un antioxydant, et ce avant ou pendant le traitement de la matière en fusion.
PCT/US1995/013826 1994-10-26 1995-10-26 Procede de stabilisation de polymeres d'ethylene au cours d'operations de traitement de matiere en fusion a haute temperature WO1996020974A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009017930A1 (fr) * 2007-07-31 2009-02-05 Dow Global Technologies Inc. Compositions polymères ayant un indice de blancheur amélioré, procédé pour la produire et articles faits avec celles-ci

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB751751A (en) * 1952-12-05 1956-07-04 Du Pont Melt-extrusion of polyethylene
GB1078738A (en) * 1963-11-05 1967-08-09 Basf Ag Processing polyolefines having molecular weights of more than 120,000
US3634238A (en) * 1969-03-12 1972-01-11 Mobil Oil Corp Organic compositions containing amines and metals or salts thereof
US3935141A (en) * 1971-09-27 1976-01-27 Union Carbide Corporation Environmentally degradable ethylene polymeric compositions
US4122033A (en) * 1976-11-26 1978-10-24 Black James F Oxidation inhibitor and compositions containing the same
US4931488A (en) * 1987-02-27 1990-06-05 Amrotex Ag. Degradable plastic compositions

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB751751A (en) * 1952-12-05 1956-07-04 Du Pont Melt-extrusion of polyethylene
GB1078738A (en) * 1963-11-05 1967-08-09 Basf Ag Processing polyolefines having molecular weights of more than 120,000
US3634238A (en) * 1969-03-12 1972-01-11 Mobil Oil Corp Organic compositions containing amines and metals or salts thereof
US3935141A (en) * 1971-09-27 1976-01-27 Union Carbide Corporation Environmentally degradable ethylene polymeric compositions
US4122033A (en) * 1976-11-26 1978-10-24 Black James F Oxidation inhibitor and compositions containing the same
US4931488A (en) * 1987-02-27 1990-06-05 Amrotex Ag. Degradable plastic compositions

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
GAECHTER, "Metal Deactivators", in, "Plastics Additives Handbook", Published 1984, by HANSER PUBLISHERS (N.Y.), pages 75-95. *
J. OF APPLIED POLYMER SCIENCE, Vol. 23, issued 1979, OSAWA et al., "The Effect of Transition Metal Stearates on the Photodegradation of Polyethylene", pages 3583-3590. *
ORGANIC COATING AND APPLIED POLYMER SCIENCE PROCEEDINGS, Vol. 46, issued 1981, GUGUMUS, "Advances in U.V. Stabilization of Polyethylene", pages 449-456. *
POLYMER DEGRADATION AND STABILITY, 11, issued 1985, OSAWA et al., "Mechanism of Inhibition by Copper Stearate of the Photodegradation of Polyolefins", pages 63-73. *
STEPEK et al., "Additives for Plastics", Published 1983, by SPRINGER-VERLAG (N.Y.), pages 182-183. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009017930A1 (fr) * 2007-07-31 2009-02-05 Dow Global Technologies Inc. Compositions polymères ayant un indice de blancheur amélioré, procédé pour la produire et articles faits avec celles-ci

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