Title of Invention	ELECTRICALLY CONDUCTIVE POLYMER COMPOSITE COMPOSITIONS METHOD FOR MAKING , AND METHOD FOR ELECTRICAL CONDUCTIVITY ENHANCEMENT.
Abstract	INCLUSION OF RELATIVELY SMALL AMOUNTS OF ORGANIC IONIC SPECIES, SUCH AS CALCIUM STEARATE, IN THE PREPARATION OF AN ELECTRICALLY CONDUCTIVE POLYMER COMPOSITE COMPOSITION PROVIDES A COMPOSITION HAVING ENHANCED ELECTRICAL PROPERTIES RELATIVE TO THE COMPOSITE COMPOSITION LACKING THE ADDED ORGANIC IONIC SPECIES. AS A RESULT OF THIS ENHANCEMENT, NORMALLY INSULATING MATERIALS WHICH RELY UPON A CONDUCTIVE FILLER TO RENDER THEM ELECTRICALLY CONDUCTIVE, CAN BE MADE TO ACHIEVE A GIVEN LEVEL OF CONDUCTIVITY USING LESS OF THE CONDUCTIVE FILLER THAN WOULD OTHERWISE BE REQUIRED. AS A RELULT, THE ADVERSE EFFECTS OF THE CONDUCTIVE FILLER ON THE POLYMER'S PHYSICAL PROPERTIES CAN BE MINIMIZED WHILE MAINTAINING A HIGH LEVEL OF ELECSTRICAL CONDUCTIVITY.

Title of Invention

ELECTRICALLY CONDUCTIVE POLYMER COMPOSITE COMPOSITIONS METHOD FOR MAKING , AND METHOD FOR ELECTRICAL CONDUCTIVITY ENHANCEMENT.

Abstract

INCLUSION OF RELATIVELY SMALL AMOUNTS OF ORGANIC IONIC SPECIES, SUCH AS CALCIUM STEARATE, IN THE PREPARATION OF AN ELECTRICALLY CONDUCTIVE POLYMER COMPOSITE COMPOSITION PROVIDES A COMPOSITION HAVING ENHANCED ELECTRICAL PROPERTIES RELATIVE TO THE COMPOSITE COMPOSITION LACKING THE ADDED ORGANIC IONIC SPECIES. AS A RESULT OF THIS ENHANCEMENT, NORMALLY INSULATING MATERIALS WHICH RELY UPON A CONDUCTIVE FILLER TO RENDER THEM ELECTRICALLY CONDUCTIVE, CAN BE MADE TO ACHIEVE A GIVEN LEVEL OF CONDUCTIVITY USING LESS OF THE CONDUCTIVE FILLER THAN WOULD OTHERWISE BE REQUIRED. AS A RELULT, THE ADVERSE EFFECTS OF THE CONDUCTIVE FILLER ON THE POLYMER'S PHYSICAL PROPERTIES CAN BE MINIMIZED WHILE MAINTAINING A HIGH LEVEL OF ELECSTRICAL CONDUCTIVITY.

Full Text	ELECRICALLY CONDUCTIVE POLYMER COMPOSITE COMPOSITIONS, METHOD FOR MAKING, AND METHOD FOR ELECTRICAL CONDUCTIVITY ENHANCEMENT BACKGROUND OF THE INVENTION This invention relates to electrically conductive polymer composite materials, and more particularly to methods for improving the electrical conductivity of such materials. Normally electrically insulating polymers can be made electrically conductive via the addition of electrically conductive fillers, such as carbon fibers, carbon blacks, or metal fibers. In each case, sufficient amount of filler must be added to overcome the percolation threshold, the critical concentration of filler at which the polymer will i conduct an electrical current. Beyond this1 threshold conductivity increases markedly as additional electrically conductive filler is added. It is believed that at the percolation threshold, uninterrupted chains of conducting particles first appear in the system. The addition of still greater amounts of electrically conductive filler produces a correspondingly higher number of uninterrupted chains and this results in still higher levels of conductivity. Electrically conductive polymer systems are prized as materials for electromagnetic shielding in electronics applications and as materials used in the fabrication of structures to which paiat may be applied using electrostatic painting techniques. A variety of electrically conductive fillers, such as carbon fibers, carbon fibrils and carbon black have bees employed to impart electrical conductivity to otherwise insulating polymeric materials. The use of such fillers may however degrade other important physical characteristics of the material such as its impact strength. In addition, certain fillers such as carbon fibris are high cost materials. Some electrically conductive fillers have a more pronounced negative effect on a material"s physical properties than others but nearly all polymer systems incorporating them suffer a degradation of impact strength, or other physical property not related to conductivity, relative to the unfilled polymer systems. In many instances, the desired level of electrical conductivity cannot be obtained without sacrificing at least some part of the material"s inherent impact strength. Therefore, it would be desirable to maximizing the electrical conductivity enhancing effect of the conductive filler while minimizing the resultant loss in impact properties. US Patent No. 4,451,536 discloses a heat distortion-resistant thermoplastic semi- conductive composition which includes ethylene-vinyl acetate and/or an ethylene acrylate ester copolymer, and an admixture of high density polyethylene and linear low density polyethylene in addition to the electrically conductive component and other additives normally forming part of such compositions. US Patent No. 5,382,622 discloses a method of making a semiconductor polymeric compound includes an "A" phase consisting of preparing a mixture of a polymeric matrix consisting essentially of about 60% by weight low density polyethylene and about 8.5% by weight ethylene vinyl acetate based on a total amount of the polymeric compound to be prepared with about 20% by weight of a conductive lampblack with a porous structure and about 4.0% by weight of a spreading agent consisting of calcium stearate, about 3 by weight of an antioxidant, and about 0.5% of a coupling agent consisting of calcium titanate; and a "B" phase including incorporating the conductive component in the polymeric matrix by the steps of spreading the mixture using "bamburg" type intermittent mixers under process conditions to obtain a high rate of lampblack shearing and homogenizing of a sheared lampblack and spreading and coupling agent portion. A semiconductor body according to the invention is made by extruding and calendaring the semiconductor polymeric compound with lampblack aggregations having a high degree of shearing and low degree of orientation. EP0582919 discloses a process for the preparation of a plastics material which is based on a doped polyaniline. The process is characterized in that when using as a plastics material a polyaniline which has been doped with a protonic acid, the difficulty how to combine the melt-processability and neutrality of the material. A well processable, with a protonic acid doped polyaniline has herefore always been so acidic that it has disturbed both the processing apparatus, and the environment as a finished product. It has now, anyhow, been invented a process for the preparation of a plastics material which is based on a doped polyaniline, during or after bringing in contact a polyaniline or a derivative thereof and a protonic acid also a metal compound is admixed. The metal compound is preferably first reacted with a first acid, whereupon the obtained produ is brought together with a blend or reaction product formed by a polyaniline or a derivative thereof and a second protonic acid. In the mentioned process as the metal compound e.g. zinc oxide is used, as the first acid preferably the same acid as for the second protonic acid, i.e. dodecylbenzenesulphonic acid, is used. The plastics mixture thus prepared is preferably brought together with a thermoplastic polymer such as a polyolefin, wherein a neutral, plastic, stabile plastics material having a low percolation threshold is obtained. The instant invention is based upon the discovery that certain organic compounds function as conductivity enhancing agents in organic conductive composite compositions, and that the inclusion of one or more of these conductivity enhancing agents reduces the amount of conductive filler required in order to achieve a given level of electrical conductivity composite polymer systems in that high levels of electrical conductivity can be achieved at reduced concentrations of electrically conductivity relative to that require in the absence of the conductivity enhancing agent. The instant invention overcomes the limitation of earlier conductive composite polymer system in that high levels of electrical conductivity can be achieved at reduced concentration of electrically conductive filler relative to compositions lacking the conductivity enhancing agents. In this way, the present invention reduces the amount of electrically conductive filler required, thereby reducing the cost of the polymer system. BRIEF SUMMARY OF THE INVENTION The present invention is directed to organic conductive materials comprising a conductivity enhancing agent, said organic conductive materials having improved conductivity relative to materials lacking said conductivity enhancing agent. One aspect of the invention, therefore, is an electrically conductive polymer composite composition comprising: (A) an organic polymer matrix; (b) an electrically conductive filler; and (c) a conductivity enhancing agent selected from the group consisting of salts of carboxylic acids, salts of thiocarboxylic acids, salts of dithiocarboxylic acids, salts of sulfonic acids, salts of sulfinic acids, salts of phosphonic acids, salts of phosphonic acids, and mixtures thereof. The invention further relates to methods of preparing electrically conductive polymer composite materials, to methods of enhancing the conductivity of electrically conductive polymer composite materials and articles prepared from these materials. DETAILED DESCRIPTION OF THE INVENTION The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included herein. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings. As used herein the term "electrically conductive polymer composite composition" is used interchangeably with the term "electrically conductive polymer composite material" and refers to a composition having a measurable level of electrical conductivity, comprising an organic polymer matrix and an electrically conductive filler and optionally a conductivity enhancing agent. As used herein the term "organic polymer matrix" refers to an organic polymer or mixture of one or more organic polymers. As used herein the term "electrically conductive filler" refers to a material, such as carbon fibrils or carbon fibers, which when added to a nonconductive organic polymer matrix produces an electrically conductive composite material. As usei besets the term "conductivity enhancing agent" refers to an-additive which when combined ia a composition comprising an organic polymer matrix and. an electrically connductive filler, improves the electrical conductivity of the composition, as measured by its conductivity or resistivity, relative to an otherwise identical composition lacking the conductivity enhancing agent. The term "structural units" made in reference to polymers is used to designate the structure of repeat units within the polymer. In the case of poiyphenylene ethers, structural units are understood to be derived from the monomer, or in the alternative the mixture of monomers, used in the preparation of the poiyphenylene ether. For example the polyphenylene Uther, poly (2,6-dimethyl-1,4-phenylene-co-2,3,6- trimethyl-l,4-phenylene ether)(CAS Number 58295-79-7)) contains structural units derived from 2,6-dimethylphenol and 3 2,3,5-trmethylphenol. As defined herein the term "thermoplastics" includes materials commonly referred to as "thermoplastic elastomers". As defined herein the term "carbon fibril" includes materials commonly referred to as "carbon nanotubes". In addition the term "carbon fibril" includes derivatized carbon fibrils such as metal coated carbon fibrils. As defined herein the terms "carbon fiber" includes derivatized carbon fibers such as metal coated carbon fibers . As used herein the term "weight percent"" refers to the weight of a constituent of a composition relative to the entire weight of the composition unless otherwise indicated. As used herein the term "aromatic radical" refers to a radical having a valency of at least one comprising at least one aromatic group. Examples of aromatic radicals include, but are not limited to phenyl, pyridyl, furanyl, thienyl, naphthyl, phenylene, biphenyl. The term includes groups containing both aromatic and aliphatic components; for example a benzyl group or the diarylmethytene group (i). As used herein the term "aliphatic radical" refers to a radical having a valency of at least one comprising a linear or branched array of atoms which is not cyclic. The array may include heteroatoms such as nitrogen, sulfur and oxygen or may be composed exclusively of carbon and hydrogen. Examples of aliphatic radicals include, but are not limited to methyl, methylene, ethyl, ethylene, hexyl, hexamethylene, an array of carbon atoms (ii) with valencies at positions 2, 5, and 8 and the like. As used herein the term "cycloaliphatic radical" refers to a radical having a valency of at least one comprising an array of atoms which is cyclic but which is not aromatic. The array may include heteroatoms such as nitrogen, sulfur and oxygen or may be composed: exclusively of carbon and hydrogen. Examples of cycloaliphatic radicals include, but are not limited to cyclcopropyl, cyclopentyl cyclohexyl, tetrahydrofuranyl, an array of carbon atoms (iii) with valencies indicated at positions a and b, and the like. As used herein the term "C1-C40 dialkylammonium" refers to an organic ammonium group bearing two alkyl groups each of which may be comprised of from 1 to 40 carbon atoms. Like terms such as C1-C40 trialkylammonium, C1-C40 tetraalkylammonium, C4-C40 tetraarylphosphonium, C1-C40 trialkylsulfonium, C4-C40 triarylsulfonium have analogous meanings. Thus a C1-C40 trialkylsulfonium ion might contain as few as three and as many as 120 carbon atoms. Component (A) of the electrically conductive composite composition of the present invention comprises at least one thermoplastic or thermosetting polymeric material in which the electrically conductive filler, Component (B), and conductivity enhancing agent, Component (C), may be dispersed. Component (A) may include organic linear and branched thermoplastics and thermosetting materials. Where component (A) is a mixture of two or two or more polymeric components, said mixture may have the characteristics of a blend in which the components form discrete phases or a miscible blend or polymer alloy in which the polymeric components have substantial solubility in oae another and tend to form a single phase composition. Alternatively, a mixture of polymeric components comprising component (A) may have characteristics mitermediate; between a phase separated blend aad a substantially single phase material. Polymeric materials comprising component (A) are commonly known materials , which are either commercially available or prepared according to known synthetic methodology such as those methods found in Organic Polymer Chemistry, by K. J. Saunders, 1973, Chapman and Hall Ltd.. Examples of classes of thermoplastic polymeric materials suitable for use as component (A), either singly or in combination with another material include polyphenylene ethers, polyamides, polysiloxanes, polyesters, polyimides, polyetherimides, polysulfides, polysulfones, polyethersulfones, olefin polymers, polyurethanes and polycarbonates. Component (A) may comprise thermosetting materials as well. Examples of classes of thermosetting materials which may be used as component (A) include polyepoxides, phenolic resins, polybismaleimides, natural rubber, synthetic rubber, silicone gums, thermosetting polyurethanes and the like. Examples of thermoplastic and thermosetting materials which may comprise component (A) include materials illustrated in (1) through (10) below. (1) Polyphenylene ethers comprising structural units I wherem R1-R4 are independentfy hydrogen, halogen, C1-C10 alkyl, C4-C20 aryl or C4- C20 cycloalyl. Polyphenylene ethers incorporating structure waits I include poly(2,6- dimethyl-1,4-phenylene ether), poly(2,3,6-trimgthyl-1,4-phenylene ether), poly(3- benzyl-yl-2,6-dimethyl-1,4-phenylene ether), poly (2,6-dtethyl-1,4-phenyl ether), poly (2-methyl-6-ethyl-1,4-phenyiene ether), poly(2-methyl-6-isobutyl-1,4-phenylene ether), poly(2,6-diisopropyl-1,4-phenylene ether), poly(3-bromo-2,6-dimethyl-1,4- phenylene ether), poly(2-methyl-6-phenyl-1,4-phenyIene ether), poly(2,6-diphenyl- 1,4-phenylene ether) and copolyphenylene ethers such as poly(2,6-dimethyl-1,4- phenylene-co-2,3,6-trimethyl-1,4-phenylene ether) incorporating two or more of the structural units found in the homopolyphenylene ethers listed above; (2) Polyamides comprising structural units II wherein R5 and R6 are independently C1-C20 alkylene, C4-C20 arylene or C5-C20 cycloalkylene; R7and R8are independentlyl hydrogen, C1-C20 alkyl, C6-C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl; and III wherein R9 is C1-C20 alkylene, C4-C20 arylene or C5-20 cycloalkylene; and R10 is C1-C20 alkyl, C6-C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl. Polyamides incorporating structural units II include polyamides and copolyamides obtained by polycondensation of a diamine selected from the group consisting of 1,3- diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine and mixtures thereof; with a diacid selected from the group consisting of succinic acid, adipic acid, nonanedioic acid, sebacic acid, dodecandioic acid, terephthalic acid, isophthalic acid and mixtures thereof. Polyamides incorporating structural units III include those polyamides derived from polymerization of a-pyrrolidone, a- piperidone, caprolactam, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminonanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid or mixtures thereof. Polyamides falling within the scope of the present invention which may serve as component (A) include nylon 4/6, nylon 6, nylon 6/6, nylon 6/9, nylon 6/10 and nylon 6/12. (3) Polysiloxanes comprising structural units IV wherein Rn and R12 are independently C1-C20 alkyl, C2-C20 alkenyl, C6-C20 aryl, C7- C21 aralkyl or C5-C20 cycloalkyl Polysiloxanes incorporating structural units IV include branched and linear harnopotymers such as polydimethylsiloxane polymethylphenylsiloxane, polydiphenylsiloxane, polymethylvinylsiloxane, and copolymers thereof incorporating two or more of the structural units of said homopolysiloxanes. (4) Polyesters comprising structural units V wherein Rl3and R14 are independently C1-C20 alkylene, C4-C20 arylene or C5-C20 cycloalkylene; and VI wherein R15 is C1-C20 alkylene, C4-C20 arylene or C5-20 cycloalkylene. Polyesters incorporating structural tmrts V and VI include poly(ethylene terephthalate), poly(butylene terephthalate), polyethylene 2,6-naphthalenedicarboxylate), poly(butylene 2,6-naphthalenedicarboxylate), polybulyrolactone and polyvalerolactone. (5) Polyepoxides comprising structural units VII wherein R16 and R17 are independently at each occurrence halogen, C1-C20 alkyl, C6-. C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl; R18 and R19 are independently hydrogen, C1-C20 alkyl, C6-C20 aryl, C7-C21 aralkyl or C5- C20 cydoalkyl, and further R18 and R19 may together form a C4-C20 cycloahphatic ring which may be substituted by one or more! C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl or C5-C20 cycloalkyl groups, or a combination thereof; and n is an integer from 0 to 4. Polyepoxides incorporating structural units VII include epoxy resins prepared from the mono- and diglycidy ethers of bisphenol A. (6) Polyetherimides comprising structural units VIII wherein R20 and R22 are independently ajt each occurrence halogen, C1-C20 alkyl, C6- C20 aryl, C7.C21 aralkyl or C5-C20 cycloalkyl; R21 is C2-C20 alkylene, C4-C20 arylene or C5-C20 cycloalkylene; each A1 and A2 is a is a monocyclic divalent aryl radical and Y1 is a bridging radical in which one or two carbon atoms separate A1 and A2; and m is an integer from 0 to 3. Examples of polyether imides are Ultem ® polyether imides available from the General Electric Company. (7) Polyethersufones comprising structural units DC wherein R23 and R24 are independently at.each occurrence halogen, C1-C20 alkyl, C6- C20 aryl, C5.C21 aralkyl or C5-C20 cycloalkyl; each A3 and A4 is a is a monocyclic divalent aryl radical and Y2 is a bridging radical in which one or two carbon atoms separate A3 and A4; and p is an integer from 0 to 3. Examples of polyethersulfones include those prepared from 4,4"- dichlorodiphenylsulfone and bisphenols such as bisphenol A, bisphenol Z and bisphenol M. (8) Olefin polymers comprising structural units X wherein R25, R26, R27 and R28 are indepenikntly at each occurrence halogen, cyano, carboxyl, C2-C20 aHcoxycarbonyl, C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl, C5-C20 cycloalkylor groups, wherein R29 and R30 are C1-C20 alkyl, C6-C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl groups; or R29 and R30 together form a C5-C20 cycloaltphatic group. Olefin polymer containing structural units X include polystyrene, polyacrylonitrile, polymaleic acid, copolymers of styrene and maleic acid, poly(acrylonitrile-co- butadiene-co-styrene), poly(acrylic acid) and poly(methyl methacrylate). (9) Polyurethanes comprising structural XI wherein R31 and R32 are independently C2-C20 alkylene, C4-C20 arylene, C4-C20 diarylene, C4-C20 diaralkylene or C5-C20 cycloalkylene. Polyurethanes incorporating structural units XI include poly(1,4-butandiol)-tolylene-2,4-diisocyante and poly[(4,4"methylenebis(phenylisocyanate)-alt-1,4-butanediol/polytetrahydrofuran] available from Aldrich Chemical Company. wherein R33 and R36 are independently at each occurrence halogen, C1-C20 alkyl, C6- C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl; R34 and R35 are independently hydrogen, C1-C20 alkyl, C6-C20 aryl, C7.C21 aralkyl or C5- C20 cycloalkyl, and further R34 and R35 may together form a C4-C20 cycloaliphatic ring which may be substituted by one or more C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl, C5-C20 cycloalkyl groups or a combination thereof; and q is an integer from 0 to 4. Polycarbonates incorporating structural units XII include bisphenol A polycarbonate, bisphenol Z polycarbonate, bisphenol M polycarbonate, copolycarbonates incorporating bisphenol A and bisphenol Z, and polyester carbonates such as Lexan SP® available from the General Electric company. Where component (A) comprises a polyphenylene ether and a polyamide in combination it may be desirable to include an impact modifying polymer, as part of the polymer matrix, to improve the impact resistance of articles prepared from the compositions of the present invention. Suitable impact modifying agents for the purposes of the present invention include, but are not limited to, commercially available impact modifying agents, such as Kraton rubber impact modifiers available from Shell Chemicals. Additionally, polymeric materials prepared from styrene, ethylene, and maleic acid or maleic anhydride; polymeric materials prepared from ethylene and unsaturated carhoxylic acids and their metal salts; polymeric materials prepared from olefins containing acid groups; block copolymers prepared from vinylaromatic monomers, such as styrene and alpha-methyl styrene, conjugated dienes, such as butadiene and cyctopentadiene, and unsaturated carboxylic acids and anhydrides; block copolymers prepared from vinylaromatic monomers, such as stytene and alpha-methyl styrene, olefins such as propylene, conjugated dienes, such as butadiene and cyclopentadiene, and unsaturated carboxylic acids and anhydrides may be employed. Examples of other suitable impact modifying agents are styrene- butadiene random and block copolymers, styrene-ethylene-propylene terpolymers, styrene-propylene-styrene block copolymers, styrene-butadiene-styrene block copolymers, partially hydrogenated styrene-butadiene-styrene block copolymers, fully . hydrogenated styrene-butadiene-styrene block copolymers and the like. Other additives which may be included in component (A) include compatibilizing agents such as dicarboxylic acids, tricarboxylic acids and cyclic carboxylic acid anhydrides wherein said dicarboxylic acids, tricarboxylic acids and cyclic carboxylic acid anhydrides contain at least one carbon-carbon double bond, carbon-carbon triple bond or a latent carbon-carbon double bond. Examples of dicarboxylic acids and their anhydride derivatives which may be used include maleic acid, fumaric acid, itaconic acid, 2-hydroxysuccinic acid, citric acid, 2-butynedioic acid, maleic anhydride, 2- hydroxysuccinic anhydride and citraconic anhydride. Among the forgoing examples the five membered ring .cyclic anhydrides and citric acid are preferred when component (A) comprises a blend of a polyphenylene ether and a polyamide. Maleic anhydride and citric acid are particularly preferred. Other suitable compatibilizing agents include multifunctional epoxides, ortho esters, oxazolidines and isocyanates. The electrically conductive composite compositions of the present invention may optionally include other commonly available conventional additives which enhance their utility in various applications such as the preparation of molded articles for use in computer and automotive applications. Said conventional additives include but are not limited to flame retardants, UV.absorbers, antioxidants, heat stabilizers, antistatic agents and mold release agents, slip agents, antiblocking agents, lubricants, anticlouding agents, coloring agents, natural oils, synthetic oils, waxes, inorganic fillers and mixtures thereof. Component (B) of the electrically conductive polymer composite materials of the present invention comprises at least one electrically conductive filler which when dispersed in an organic polymer matrix affords an electrically conductive material. Suitable electrically conductive fillers include carbon black , carbon fibers, carbon fibrils, carbon nanotubes, metal coated carbon fibers, metal coated graphite, metal coated glass fibers, conductive polymer filaments, metallic particles, stainless steel fibers, metallic flakes, metallic powders and the like. Electrically conductive fillers comprising component (B) are commonly known materials such as carbon balck and carbon fibrils which are either commercially available or prepared according to known synthetic methodology such as those methods found in U.S. Patent No.s 5,591,382 and 4,663,230. Carbon black is available from the Cabot Corporation. Vapor grown carbon fibers are commercially available from Applied Sciences Corporation. Carbon and graphite fibers are available from the Hexcel, Zoltek and Akzo Nobel corporations. Singlewall nanotubes which may likewise serve as the conductive filler are available from the Tubes@Rice and Carbolex companies. Multiwall nanotubes are available from the MER and Carbon Solutions companies among others. Metal coated fibers are available from the Composite Materials Corporation, LLC and Ostolski Laboratories. Metallic powders are available from the Bekaert Corporation. Component (C) of the electrically conductive polymer composite materials of the present invention comprises at least one conductivity enhancing agent which when combined with components (A) and (B) affords a composition possessing a greater level of conductivity than an otherwise: identical composition comprising only components (A) and (B). In one embodiment, the present invention provides conductivity enhancing agents which may be added to improve the conductivity of an already electrically conductive polymer composite material, without sacrificing other important physical properties of the material such as glass transition temperature or impact resistance. Suitable conductivity enhancing agents include the salts of carboxylic acids, salts of thio- and dithiocarboxylic acids, sate of organic sulfonic and organic sulfinic acids, and salts of organic phosphorous and organic phosphoric acids represented by structure XIII. wherein R37 is a C1-C40 aliphatic radical, a C3-C40 cylcoaliphatic radical, or a C4-C40 aromatic radical, said radicals being optionally substituted by one or more substituents, said substituents being independently at each occurrence halogen, amino, ammonium, C1-C40 alkylamino, C1-C40 dialkylamino, C1-C40 trialkylammonium, C4.C40 arylamino, C4-C40 diarylamino, C1-C40 alkyl, C1-C40 alkoxy, C1-C40 alkylthio, C1-C40 alkylsulfinyl, C1-C40 alkylsulfonyl, C3-C40 cycloalkyl, C4-C40 aryl, C4-C40 aryloxy, C4-C40 arylthio, C4-C40 arylsulfinyl, C4-C40 arylsulfonyl, hydroxysulfonyl, hydroxy, mercapto, cyano, oxo, imino, aminoimino, hydroxyimino, alkoxyimino, nitro, nitroso, formyl, carboxyl, carboxylate, thiocarboxyl, dithocarboxyl, C1-C40 alkoxycarbonyl, C1-C40 alkoxythiocarbonyl, C1-C40 alkylthiocarbonyl, or phosphonyl groups; r is an integer having a value of from 0 to about 10; Q1 is independently at each occurrence structure (a), (b), (c), (d), (e), (f), (g) or (h) wherein M is selected from the group consisting of monovalent metal cations, divalent metal cations , trivaleni metal cations, ammonium ions, C1-C40 alkylammonium ions, C1-C40 dialkylaramonium ions, C1-C49 trialkytammonium ions, C1-C40 tetraalkylaromonimn ions, C4-C40 tetraarylplhosphaonium ions, C1-C40 trialkylsulfonium ions, C4-C40 triarjisulfonium ions or C4-C40 aryl C1-C40 dialkylsulfonium ions; and s is an integer or a fraction of an integer having a value of 1, 1/2 or 1/3. Groups (a)-(h) of structure XIII comprise metal cations, ammonium ions, organic ammonium ions, organic sulfonium ions and organic phosphonium ions. Conductivity enhancing agents comprising metal cations include carboxylic, thiocarboxylic, dithiocarboxylic, sulfonic, sulfinic, phosphoric and phosphorus acid salts comprising cations of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, copper, silver, zinc, cadmium and tin. Fully ionized and partially ionized calcium salts of mono- and polycarboxylic acids having structure XIV may serve as component (C), R38-(CO2-)t(Ca++)u(H+)v ^^* XIV wherein R38 is a C1C40 aliphatic radical; C3-C40 cylcoaliphatic radical, or a C4-C40 aromatic radical; t is an integer having a value of from 1 to 10; u is an integer or half integer having a value of from 1/2 to 5; and v is an integer having a value of t-2u. Calcium salts of mono- and polycarboxylic acids having structure XIV are illustrated by, but are not limited to, the calcium salts of formic, acetic, propionic, butyric, valeric, octanoic, dodecandioic, tetradecanedioc, stearic, oleic, oxalic, malonic, succinic, sebacic, dodecandioic, terephthailic, 2,6-naphthalenedioic, Kemp"s triacid, and 9-carboxydodecanedioic acid or mixtures thereof. In addition, one or more salts of polymeric materials bearing one or more of the groups (a)-(h) may be ased as component (C), Salts of polymeric acids such ia which some or all of the carboxyl group hydrogen atoms have been exchanged with one or more suitable metal, ammonium, phosphonium or sulfonkim cations are illustrated by the calcium salts of polyacrylic and polymaleic acids and the like. Where component (C) comprises organic ammonium ions, said organic ammonium ions are illustrated by, but not limited to, tetramethylammonium decylmethylammonium, methylundecylammonium, dodecylmethylammonium, methyltridecylammonium, methyltetradecylammonium, methylpentadecylammonium, hexadecylmethylammonium, heptadecylmethylammonium, methyloctadecylammonium, decyldimethylammonium, dimethylundecylammonium, dimethyldodecylammonium, dimethyltridecylammonium, dimethyltetradecylammonium, dimethylpentadecylammonium, dimethylhexadecylammonium, dimethylheptadecylammonium, dimethyloctadecylammonium, decyltrimethylammonium, trimethylundecylammonium, dodecyltrimethylammonium, tridecyltrimethylammonium, tetradecyltrimethylammonium, pentadecyltrimethylammonium, hexadecyltrimethylammonium, heptadecyltrimethylammoniura and octadecyltrimethylammonium cations. Component (C) may comprise phosphonium and sulfonium ions which are illustrated by, but not limited to, tetraphenylphosphonium, triphenylundecylphosphonium, triphenyl sulfonium and trimethylsulfonium ions. The instant invention provides electrically conductive polymer composite materials wherein component (A), comprises from about 50 to about 99.9 weight percent of the composition, component (B) comprises from about 0.1 to about 20 weight percent of the composition, and component (C) comprises from about 0.001 to about 10 weight percent of the composition. In a preferred embodiment, the instant, invention provides electrically conductive polymer composite materials wherein component (A), comprises from about 80 to about 99 j0 weight percent of the composition, component (B) comprises from about 0.1 to about 10.0 weight percent of the composition, and component (C) comprises from about 0.01 to about 5 weight percent of the composition. In a still more preferred embodiment, the instant invention provides electrically conductive polymer composite materials wherein component (A), comprises from about 90 to about 99.0 weight percent of the composition, component (B) comprises from about 03 to about 2.0 weight percent of the composition, and component (C) comprises from about 0.1 to about 1 weight percent of the composition. In an even more preferred embodiment, the instant invention provides electrically conductive polymer composite materials wherein component (A), comprises a polyphenylene ether, a polyamide and an impact modifier wherein the polyphenylene ether is present in amount in a range between about 35 and about 65 weight percent, the polyamide is present in an amount in a range between about 65 and about 35 weight percent and the impact modifier is present in a range between about 0.1 and about 20 weight percent of the total weight of the composition. The composite compositions of the present invention may prepared using melt processing techniques. Typically, melt processing involves subjecting component (A), (B) and (C) of the electrically conductive polymer composite composition to intimate mixing at a temperature in a range between about 400 degrees Fahrenheit (°F) and about 600°F. Melt processing in an extruder is preferred. In one embodiment the present invention provides an electrically conductive polymer composite composition by extruding a mixture comprising components (A), (B) and (C) together with any additives such as flame retardants, UV stabilizers, mold release agents and the like at temperatures ranging from about 400°F to about 600°F to provide an extrudate. Coextrusion of components (A), (B) and (C) may be carried out as follows: A dry blend comprising components (A), (B) and (C) is charged to the feed inlet of an extruder and mixed and heated at temperatures ranging from about 400°F to about 600°F to produce an extrudate which may be pelletized for further processing into molded articles. Any vested zones in the extruder may be maintained at atmospheric pressure or adapted for a vacuum venting. In yet another embodiment, the present invention provides an electrically conductive polymer composite composition by extruding a mixture comprising components (A), (B) and (€} as follows: A portion of component (A) together with any additives which may be desirable, such as compatibilizing agents, impact modifying agents, flame retardants, mold retease agents and the like, is charged to the feed inlet of an extruder and mixed and heated at temperatures ranging from about 400°F to about 600°F. Component (B), dispersed in component (A) itself or in at least one component of component (A), and component (C), likewise dispersed in component (A) itself or in at least one component of component (A), are introduced at a feed inlet of the extruder closer to the the than the feed inlet used to introduce components (A). Control of the rates of introduction of the dispersions of components (B) and (C) provides a means to vary the amounts of each of the components present in the electrically conductive polymer composite composition. Articles made from the compositions of the present invention may be obtained by forming the electrically conductive polymer composite composition by such means as injection molding, compression molding and extrusion methods. Injection molding is the more preferred method of forming the article. Among the molded articles which may be prepared from the compositions of the present invention are automotive articles such as automotive body panels, fenders and the like; and computer housings and the like. Examples The following examples are put forth so as to provide those of ordinary skill in the art with a detailed disclosure and description of how the methods claimed herein are evaluated, and are not intended to limit the scope of what the inventors regard as their invention. Unless indicated otherwise, parts are by weight, temperature is in degrees centigrade. The materials and testing procedures used for the results shown herein are as follows: The organic conductive composite materials exemplifying me present invention were prepared from commercially available nylon 6,6 and polyphenylene ether (PPE available from General Electric) and graphite fibrils as the electrically conductive filler. Carbon fibril-nylon 6,6 mixtures are available torn Hyperion Catalysis International. Resistivity measurements employed standard injection molded tensile bars as follows. An injection molded tensile bar was first lightly scored and then frozen in liquid nitrogen before fracturing the tab ends off (on the score marks) to obtain the narrow section having dimensions of approximately 2.5 x 0.5 x 0.125 inches. The sample was allowed to warm to room temperature and the fractured ends were painted with conductive silver paint (sold by Ernest F. Fullam, item # 14811) to provide a uniform contact area across the entire cross section. Resistance was measured on a Wavetek RMS225 phm-meter for samples having resistance values less than 40 MO or on a Keithley 617 electrometer for samples having resistance values between 40 MO and 200 GO. The specific volume resistivity (SVR or bulk resistivity) of the sample was calculated by multiplying the measured resistance times the cross sectional area of the bar divided by the length of the bar. Notched IZOD impact test values were obtained at room temperature and are reported in foot-pounds per inch (ft.lb/in). Example 1 A dry blend of 40.72 parts PPE, poly(2,6-dimethyl-1,4-phenylene)ether, having an intrinsic viscosity of about 0.4 deciliters per gram (dl/g) as measured in chloroform at 30°C, 7.43 parts Kraton G1651 and 3.71 parts Kraton G1701 impact modifier, 0.1 parts potassium iodide, and 0.01 parts copper iodide was fed at a rate of 20.74 pounds per hour (phr) to the throat of a twin screw extruder operated at 290°C at 400 rpm. Simultaneously, a blend of 38.03 parts nylon 6,6 powder, 5.90 parts nylon 6,6-carbon fibril mixture containing 20.0 percent by weight carbon fibrils, and 4.20 parts of a dispersion of calcium stearate powder in ground nylon 6,6 containing 5.0 percent by weight calcium stearate, was fed at a rate of 1925 phr through a downstream inlet of the extruder. The extruded composite composition contained 1.20 percent by weight carbon fibrils based on the total weight of the composition and 0.45 percent by weight calcium stearate based upon the weight of nylon 6,6. Comparative Example 1 The control sample was produced as in Example 1 with the exception that nylon 6,6 was substituted for the nylon 6,6-calcium stearate mixture. The resultant organic conductive material had a fibril concentration of 12% by weight based on the total weight of the composition, and the same relative amounts of nylon 6,6 and PPE as in the composition of Example 1 and a bulk resistivity of 14.54 K ohm-cm Examples 2-5, in which the weight fraction of carbon fibrils was maintained at 1.2 percent based on the total weight of the composition while varying the amount of calcium stearate, were prepared in a manner analogous to Example 1 using the same relative amounts of nylon 6,6 and PPE. Examples 6-8, in which the weight fraction of calcium stearate was maintained at 0.9 percent based on the total weight of nylon 6,6 while varying the amount of carbon fibrils, were prepared in a manner analogous to Example 1 using the same relative amounts of nylon 6,6 and PPE. Examples 9-14 were prepared in a manner analogous to that employed in Example 1 using the same relative amounts of nylon 6,6 and PPE, wherein a conductivity enhancing agent other than calcium stearate was added as a 5% dispersion in nylon 6,6 powder. The compositions of Exampleis 9-15 comprise 1.2 weight percent carbon fibrils. The materials of Examles 9-14 contained 0.9 weight percent calcium stearate based upon the weight of nylon 6,6. : Table I illustrates the effect of calcium stearate on electrical and impact properties of polyphenylene ether-nylon 6,6-carbon fibril composite compositions comprising about 40.72 parts polyphenylene ether, about 46.74 parts nylon 6,6, about 11.14 parts impact modifiers, about 1.2 parts carbon fibrils and calcium stearate in a range between about 0 and about 2.5 weight percent based upon the weight of nylon 6,6 present in the composition. It can be seen that the SVR decreases steadily as the amount of calcium stearate in the composition is increased. As a result of calcium stearate addition, less of the conductive filler is required to achieve the desired level of electrical conductivity and there is little effect on impact strength. This is demonstrated in Table 2 wherein the level of calcium stearate is maintained at 0.9 weight percent with respect to the weight of nylon 6,6 while the amount of carbon fibrils is varied. As illustrated in Example 7, the presence of the 0.9% calcium stearate together with 0.8 % carbon fibrils affords composite composition having conductivity superior to a control sample containing 30 percent more carbon fibrils, Comparative Example 1. TABLE 2. EFFECT OF CARBON FIBRIL LOADING ON RESISTIVITVAT IMPACT PROPERTIES AT CONSTANT CALCIUM STEARATE LOADING Table 3 illustrates the relative effectiveness of a variety of carboxylic acid salts at reducing the resistivity ( i.e. enhancing the conductivity) of conductive polymer blends. a All samples contained 1.2 weight percent carbon fibril and 0.9 weight percent calcium stearate based upon the weight of nylon 6,6. Specific volume resistivity in kO-cm.c Contains no calcium stearate. d Calcium salt of montanic acid CAS# 68308- 22-5. The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. We Claim 1. An electrically conductive polymer composite composition comprising: (A) an organic polymer matrix; (B) an electrically conductive filler; and (C) a conductivity enhancing agent comprising calcium stearate, said organic polymer matrix (A) comprising polyphenylene ether structural units corresponding to structure I wherein R1-R4 are independently hydrogen, halogen, C1-C10 alkyl, C4-C20 aryl, or C4-C20 cycloalkyl; and polyamide structural units corresponding to structure II or III wherein R5 and R6 are independently C1-C20 alkylene, C4-C2O arylene, or C5-C20 cycloalkylene, R7 and R8 are independently hydrogen, C1-C20 alkyl, C1-C20 aryl, C7 -C21 aralkyl, or C5 -C20 cycloalkyl, R9 is C1- C20 alkylene, C4-C20 arylene, or C5-C20 cycloalkylene, and R10 is C1- C20 alkyl, C6 -C20 aryl, C7 -C21, aralkyl, or C5 -C20 cycloalkyl; said component (A) being present in an amount between about 50 and about 99.9 percent, said component (B) being present in an amount between about 0.1 and about 20 percent and said component (C) being present in an amount between about 0.001 and about 10 percent, based on the total weight of the composition. 2. A composition as claimed in claim 1, comprising at least one impact modifying agent, said impact modifying agent being present in an amount between about 0.1 and about 20 weight percent based upon the total weight of the composition. 3. A composition as claimed in claim 2, wherein component (A) comprises poly (2,6-dimethyl-1,4 -phenylene ether) and nylon 6,6. 4. A method of making an electrically conductive polymer composite composition comprising: (A) an organic polymer matrix; (B) an electrically conductive filler; and (C) a conductivity enhancing agent comprising calcium stearate; said method comprising mixing components (A), (B) and (C) under melt processing conditions, said organic polymer matrix (A) comprising polyphenylene ether structural units corresponding to structure I wherein R1 -R4 are independently hydrogen, halogen, C1 -C10 alkyl, C4 - C20 aryl, or C4 -C20 cycloalkyl; and polyamide structural units corresponding to structure II or III wherein R5 and R6 are independently C1-C20 alkylene, C4-C20 arylene, or C5 -C20 cycloalkylene, and R7 and R8 are independently hydrogen, C1-C20 alkyl, C6-C20 aryl, C7 -C21, aralkyl, or C5 -C20 cycloalkyl, R9 is C1-C20 alkylene, C1 -C20 arylene, or C5 -C20 cydoalkylene, and R10 is C1-C20 alkyl, C6 -C20 aryl, C7 -C21 aralkyl, or C5 -C20 cycloalkyl; said electrically conductive filler (B) comprising carbon fibrils, said component (A) being present in an amount between about 50 and about 99.9 percent, said component (B) being present in an amount between about 0.1 and about 20 percent and said component (C) being present in an amount between about 0.001 and about 10 percent, based on the total weight of the composition. 5. A method as claimed in claim 4, comprising at least one impact modifying agent, said impact modifying agent being present in an amount between about 0.1 and about 20 weight percent based upon the total weight of the composition. 6. A method as claimed in claim 5, wherein component (A) comprises poly (2,6-dimethyl-1,4-phenylene ether) and nylon 6,6. 7. A method of enhancing the electrical conductivity of an electrically conductive polymer composite composition comprising: (A) an organic polymer matrix; and (B) an electrically conductive filler; said method comprising combining components (A) and (B) under melt processing conditions with a conductivity enhancing agent (C) comprising calcium stearate, said organic polymer matrix (A) comprising polyphenylene ether structural units corresponding to structure I wherein R1 -R4 are independently hydrogen, halogen, C1-C10 alkyl, C4 -C20 aryl, or C4 -C20 cycloalkyl; and polyamide structural units corresponding to structure II or III wherein R5 and R6 are independently C1 -C20 alkylene, C4 -C20 arylene, or C5 -C20 cycloalkylene, R7 and R8 are independently hydrogen, C1- C20 alkyl, C6-C20 aryl, C7 -C21 aralkyl, or C5 -C20 cycloalkyl, R9 is C1 - C20 alkylene, C4-C20 arylene, or C5 -C20 cycloalkylene, and R10 is C1-C20 alkyl, C6 -C20 aryl, C7 -C21, aralkyl, or C5 -C20 cycloalkyl; said electrically conductive filler (B) comprising carbon fibrils, said component (A) being present in an amount between about 50 and about 99.9 percent, said component (B) being present in an amount between about 0.1 and about 20 percent and said component (C) being present in an amount between about 0.001 and about 10 percent, based on the total weight of the composition. 8. A method as claimed in claim 7, comprising at least one impact modifying agent, said impact modifying agent being present in an amount between about 0.1 and about 20 weight percent based upon the total weight of the composition. 9. A method as claimed in claim 8, wherein component (A) comprises poly (2,6-dimethyl-1,4-phenylene ether) and nylon 6,6. 10. An electrically conductive polymer composite composition comprising: (A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4- phenylene ether) in an amount equivalent to about 35 to about 65 weight percent, nylon 6,6 in an amount equivalent to about 65 to about 35 weight percent, and an impact modifier in an amount equivalent to about 5 to about 15 weight percent; (B) an electrically conductive filler comprising carbon fibrils in an amount equivalent to from about 0.1 to about 2.0 weight percent; and (C) a conductivity enhancing agent comprising calcium stearate in an amount equivalent to about 0.1 and about 2.0 weight percent; wherein weight percent refers to the weight percent of the component relative to the total weight of the composition. 11. A molded article prepared from the composition as claimed in claim 10. 12. A method of preparing an electrically conductive polymer composite composition comprising: (A) an organic polymer matrix comprising poly (2,6-dimethyl-1,4- phenylene ether) in an amount equivalent to about 35 to about 65 weight percents nylon 6,6 in an amount equivalent to about 65 to about 35 weight percent, an impact modifier in an amount equivalent to about 5 to about 15 weight percent; (B) an electrically conductive filler comprising carbon fibrils in an amount equivalent to about 0.1 to about 2.0 weight percent; and (C) a conductivity enhancing agent comprising calcium stearate in an amount equivalent to about 0.1 and about 2.0 weight percent; wherein weight percent refers to the weight percent of constituent relative to the total weight of the composition; said method comprising combining components (A), (B) and (C) under melt processing conditions. 13.A method as claimed in claim 12 wherein the poly(2,6-dimethyl-1,4- phenylene)ether and impact modifier are first melt mixed under melt processing conditions at a temperature in a range between about 270 and 320°C, and thereafter nylon 6,6 carbon fibrils and calcium stearate are added to the mixture of poly(2,6-dimethyl-1,4-phenylene)ether and impact modifier, and the whole is subjected to further melt processing. 14. A method of enhancing the electrical conductivity of an electrically conductive polymer composite composition comprising: (A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4- phenylene ether) in an amount equivalent to about 35 to about 65 weight percent, nylon 6,6 in an amount equivalent to about 6 5 to about 3 5 weight percent, an impact modifier in an amount equivalent to about 5 to about 15 weight percent; and (B) an electrically conductive filler comprising carbon fibrils in an amount equivalent to from about 0.1 to about 2.0 weight percent; wherein weight percent refers to the weight percent of constituent relative to the total weight of the composition; said method comprising combining components (A) and (B) with a conductivity enhancing agent comprising calcium stearate in an amount equivalent to about 0.1 to about 2.0 weight percent calcium stearate based upon the total weight of the composition. Inclusion of relatively small amounts of organic ionic species, such as calcium stearate, in the preparation of an electrically conductive polymer composite . composition provides a composition having enhanced electrical properties relative to the composite composition lacking the added organic ionic species. As a result of this enhancement, normally insulating materials which rely upon a conductive filler to render them electrically conductive, can be made to achieve a given level of conductivity using less of the conductive filler than would otherwise be required. As a result, the adverse effects of the conductive filler on the polymer"s physical properties can be minimized while maintaining a high level of electrical conductivity.

Full Text

ELECRICALLY CONDUCTIVE POLYMER COMPOSITE COMPOSITIONS,
METHOD FOR MAKING, AND METHOD FOR ELECTRICAL CONDUCTIVITY
ENHANCEMENT
BACKGROUND OF THE INVENTION
This invention relates to electrically conductive polymer composite materials, and
more particularly to methods for improving the electrical conductivity of such
materials.
Normally electrically insulating polymers can be made electrically conductive via the
addition of electrically conductive fillers, such as carbon fibers, carbon blacks, or
metal fibers. In each case, sufficient amount of filler must be added to overcome the
percolation threshold, the critical concentration of filler at which the polymer will
i
conduct an electrical current. Beyond this1 threshold conductivity increases markedly
as additional electrically conductive filler is added. It is believed that at the
percolation threshold, uninterrupted chains of conducting particles first appear in the
system. The addition of still greater amounts of electrically conductive filler produces
a correspondingly higher number of uninterrupted chains and this results in still
higher levels of conductivity.
Electrically conductive polymer systems are prized as materials for electromagnetic
shielding in electronics applications and as materials used in the fabrication of
structures to which paiat may be applied using electrostatic painting techniques. A
variety of electrically conductive fillers, such as carbon fibers, carbon fibrils and
carbon black have bees employed to impart electrical conductivity to otherwise
insulating polymeric materials. The use of such fillers may however degrade other
important physical characteristics of the material such as its impact strength. In
addition, certain fillers such as carbon fibris are high cost materials. Some electrically
conductive fillers have a more pronounced negative effect on a material"s physical
properties than others but nearly all polymer systems incorporating them suffer a
degradation of impact strength, or other physical property not related to conductivity,
relative to the unfilled polymer systems. In many instances, the desired level of
electrical conductivity cannot be obtained without sacrificing at least some part of the
material"s inherent impact strength. Therefore, it would be desirable to maximizing the
electrical conductivity enhancing effect of the conductive filler while minimizing the
resultant loss in impact properties.
US Patent No. 4,451,536 discloses a heat distortion-resistant thermoplastic semi-
conductive composition which includes ethylene-vinyl acetate and/or an ethylene
acrylate ester copolymer, and an admixture of high density polyethylene and linear low
density polyethylene in addition to the electrically conductive component and other
additives normally forming part of such compositions.
US Patent No. 5,382,622 discloses a method of making a semiconductor polymeric
compound includes an "A" phase consisting of preparing a mixture of a polymeric matrix
consisting essentially of about 60% by weight low density polyethylene and about 8.5%
by weight ethylene vinyl acetate based on a total amount of the polymeric compound to
be prepared with about 20% by weight of a conductive lampblack with a porous structure
and about 4.0% by weight of a spreading agent consisting of calcium stearate, about 3 by
weight of an antioxidant, and about 0.5% of a coupling agent consisting of calcium
titanate; and a "B" phase including incorporating the conductive component in the
polymeric matrix by the steps of spreading the mixture using "bamburg" type intermittent
mixers under process conditions to obtain a high rate of lampblack shearing and
homogenizing of a sheared lampblack and spreading and coupling agent portion. A
semiconductor body according to the invention is made by extruding and calendaring the
semiconductor polymeric compound with lampblack aggregations having a high degree
of shearing and low degree of orientation.
EP0582919 discloses a process for the preparation of a plastics material which is based
on a doped polyaniline. The process is characterized in that when using as a plastics
material a polyaniline which has been doped with a protonic acid, the difficulty how to
combine the melt-processability and neutrality of the material. A well processable, with a
protonic acid doped polyaniline has herefore always been so acidic that it has disturbed
both the processing apparatus, and the environment as a finished product. It has now,
anyhow, been invented a process for the preparation of a plastics material which is based
on a doped polyaniline, during or after bringing in contact a polyaniline or a derivative
thereof and a protonic acid also a metal compound is admixed. The metal compound is
preferably first reacted with a first acid, whereupon the obtained produ is brought
together with a blend or reaction product formed by a polyaniline or a derivative thereof
and a second protonic acid. In the mentioned process as the metal compound e.g. zinc
oxide is used, as the first acid preferably the same acid as for the second protonic acid,
i.e. dodecylbenzenesulphonic acid, is used. The plastics mixture thus prepared is
preferably brought together with a thermoplastic polymer such as a polyolefin, wherein a
neutral, plastic, stabile plastics material having a low percolation threshold is obtained.
The instant invention is based upon the discovery that certain organic compounds
function as conductivity enhancing agents in organic conductive composite compositions,
and that the inclusion of one or more of these conductivity enhancing agents reduces the
amount of conductive filler required in order to achieve a given level of electrical
conductivity composite polymer systems in that high levels of electrical conductivity can
be achieved at reduced concentrations of electrically conductivity relative to that require
in the absence of the conductivity enhancing agent. The instant invention overcomes the
limitation of earlier conductive composite polymer system in that high levels of electrical
conductivity can be achieved at reduced concentration of electrically conductive filler
relative to compositions lacking the conductivity enhancing agents. In this way, the
present invention reduces the amount of electrically conductive filler required, thereby
reducing the cost of the polymer system.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to organic conductive materials comprising a
conductivity enhancing agent, said organic conductive materials having improved
conductivity relative to materials lacking said conductivity enhancing agent. One aspect
of the invention, therefore, is an electrically conductive polymer composite composition
comprising:
(A) an organic polymer matrix;
(b) an electrically conductive filler; and
(c) a conductivity enhancing agent selected from the group consisting of salts
of carboxylic acids, salts of thiocarboxylic acids, salts of dithiocarboxylic acids, salts of
sulfonic acids, salts of sulfinic acids, salts of phosphonic acids, salts of phosphonic acids,
and mixtures thereof.
The invention further relates to methods of preparing electrically conductive polymer
composite materials, to methods of enhancing the conductivity of electrically
conductive polymer composite materials and articles prepared from these materials.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily by reference to the following
detailed description of preferred embodiments of the invention and the examples
included herein. In this specification and in the claims which follow, reference will be
made to a number of terms which shall be defined to have the following meanings.
As used herein the term "electrically conductive polymer composite composition" is
used interchangeably with the term "electrically conductive polymer composite
material" and refers to a composition having a measurable level of electrical
conductivity, comprising an organic polymer matrix and an electrically conductive
filler and optionally a conductivity enhancing agent.
As used herein the term "organic polymer matrix" refers to an organic polymer or
mixture of one or more organic polymers.
As used herein the term "electrically conductive filler" refers to a material, such as
carbon fibrils or carbon fibers, which when added to a nonconductive organic
polymer matrix produces an electrically conductive composite material.
As usei besets the term "conductivity enhancing agent" refers to an-additive which
when combined ia a composition comprising an organic polymer matrix and. an
electrically connductive filler, improves the electrical conductivity of the composition,
as measured by its conductivity or resistivity, relative to an otherwise identical
composition lacking the conductivity enhancing agent.
The term "structural units" made in reference to polymers is used to designate the
structure of repeat units within the polymer. In the case of poiyphenylene ethers,
structural units are understood to be derived from the monomer, or in the alternative
the mixture of monomers, used in the preparation of the poiyphenylene ether. For
example the polyphenylene Uther, poly (2,6-dimethyl-1,4-phenylene-co-2,3,6-
trimethyl-l,4-phenylene ether)(CAS Number 58295-79-7)) contains structural units
derived from 2,6-dimethylphenol and 3 2,3,5-trmethylphenol.
As defined herein the term "thermoplastics" includes materials commonly referred to
as "thermoplastic elastomers".
As defined herein the term "carbon fibril" includes materials commonly referred to as
"carbon nanotubes". In addition the term "carbon fibril" includes derivatized carbon
fibrils such as metal coated carbon fibrils.
As defined herein the terms "carbon fiber" includes derivatized carbon fibers such as
metal coated carbon fibers .
As used herein the term "weight percent"" refers to the weight of a constituent of a
composition relative to the entire weight of the composition unless otherwise
indicated.
As used herein the term "aromatic radical" refers to a radical having a valency of at
least one comprising at least one aromatic group. Examples of aromatic radicals
include, but are not limited to phenyl, pyridyl, furanyl, thienyl, naphthyl, phenylene,
biphenyl. The term includes groups containing both aromatic and aliphatic

components; for example a benzyl group or the diarylmethytene group (i).
As used herein the term "aliphatic radical" refers to a radical having a valency of at
least one comprising a linear or branched array of atoms which is not cyclic. The
array may include heteroatoms such as nitrogen, sulfur and oxygen or may be
composed exclusively of carbon and hydrogen. Examples of aliphatic radicals
include, but are not limited to methyl, methylene, ethyl, ethylene, hexyl,
hexamethylene, an array of carbon atoms (ii) with valencies at positions 2, 5, and 8
and the like.
As used herein the term "cycloaliphatic radical" refers to a radical having a valency of
at least one comprising an array of atoms which is cyclic but which is not aromatic.

The array may include heteroatoms such as nitrogen, sulfur and oxygen or may be
composed: exclusively of carbon and hydrogen. Examples of cycloaliphatic radicals
include, but are not limited to cyclcopropyl, cyclopentyl cyclohexyl,
tetrahydrofuranyl, an array of carbon atoms (iii) with valencies indicated at positions
a and b, and the like.
As used herein the term "C1-C40 dialkylammonium" refers to an organic ammonium
group bearing two alkyl groups each of which may be comprised of from 1 to 40
carbon atoms. Like terms such as C1-C40 trialkylammonium, C1-C40
tetraalkylammonium, C4-C40 tetraarylphosphonium, C1-C40 trialkylsulfonium, C4-C40
triarylsulfonium have analogous meanings. Thus a C1-C40 trialkylsulfonium ion might
contain as few as three and as many as 120 carbon atoms.
Component (A) of the electrically conductive composite composition of the present
invention comprises at least one thermoplastic or thermosetting polymeric material in
which the electrically conductive filler, Component (B), and conductivity enhancing
agent, Component (C), may be dispersed. Component (A) may include organic linear
and branched thermoplastics and thermosetting materials. Where component (A) is a
mixture of two or two or more polymeric components, said mixture may have the
characteristics of a blend in which the components form discrete phases or a miscible
blend or polymer alloy in which the polymeric components have substantial solubility
in oae another and tend to form a single phase composition. Alternatively, a mixture
of polymeric components comprising component (A) may have characteristics
mitermediate; between a phase separated blend aad a substantially single phase
material.
Polymeric materials comprising component (A) are commonly known materials ,
which are either commercially available or prepared according to known synthetic
methodology such as those methods found in Organic Polymer Chemistry, by K. J.
Saunders, 1973, Chapman and Hall Ltd.. Examples of classes of thermoplastic
polymeric materials suitable for use as component (A), either singly or in combination
with another material include polyphenylene ethers, polyamides, polysiloxanes,
polyesters, polyimides, polyetherimides, polysulfides, polysulfones,
polyethersulfones, olefin polymers, polyurethanes and polycarbonates. Component
(A) may comprise thermosetting materials as well. Examples of classes of
thermosetting materials which may be used as component (A) include polyepoxides,
phenolic resins, polybismaleimides, natural rubber, synthetic rubber, silicone gums,
thermosetting polyurethanes and the like.
Examples of thermoplastic and thermosetting materials which may comprise
component (A) include materials illustrated in (1) through (10) below.
(1) Polyphenylene ethers comprising structural units I
wherem R1-R4 are independentfy hydrogen, halogen, C1-C10 alkyl, C4-C20 aryl or C4-
C20 cycloalyl. Polyphenylene ethers incorporating structure waits I include poly(2,6-
dimethyl-1,4-phenylene ether), poly(2,3,6-trimgthyl-1,4-phenylene ether), poly(3-
benzyl-yl-2,6-dimethyl-1,4-phenylene ether), poly (2,6-dtethyl-1,4-phenyl ether),
poly (2-methyl-6-ethyl-1,4-phenyiene ether), poly(2-methyl-6-isobutyl-1,4-phenylene
ether), poly(2,6-diisopropyl-1,4-phenylene ether), poly(3-bromo-2,6-dimethyl-1,4-
phenylene ether), poly(2-methyl-6-phenyl-1,4-phenyIene ether), poly(2,6-diphenyl-
1,4-phenylene ether) and copolyphenylene ethers such as poly(2,6-dimethyl-1,4-
phenylene-co-2,3,6-trimethyl-1,4-phenylene ether) incorporating two or more of the
structural units found in the homopolyphenylene ethers listed above;
(2) Polyamides comprising structural units II
wherein R5 and R6 are independently C1-C20 alkylene, C4-C20 arylene or C5-C20
cycloalkylene; R7and R8are independentlyl hydrogen, C1-C20 alkyl, C6-C20 aryl, C7-C21
aralkyl or C5-C20 cycloalkyl; and III wherein R9 is C1-C20 alkylene, C4-C20 arylene or C5-20 cycloalkylene; and R10 is C1-C20
alkyl, C6-C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl. Polyamides incorporating
structural units II include polyamides and copolyamides obtained by
polycondensation of a diamine selected from the group consisting of 1,3-
diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, hexamethylenediamine,
nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine and
mixtures thereof; with a diacid selected from the group consisting of succinic acid,
adipic acid, nonanedioic acid, sebacic acid, dodecandioic acid, terephthalic acid,
isophthalic acid and mixtures thereof. Polyamides incorporating structural units III
include those polyamides derived from polymerization of a-pyrrolidone, a-
piperidone, caprolactam, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminonanoic
acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid
or mixtures thereof. Polyamides falling within the scope of the present invention
which may serve as component (A) include nylon 4/6, nylon 6, nylon 6/6, nylon 6/9,
nylon 6/10 and nylon 6/12.
(3) Polysiloxanes comprising structural units IV
wherein Rn and R12 are independently C1-C20 alkyl, C2-C20 alkenyl, C6-C20 aryl, C7-
C21 aralkyl or C5-C20 cycloalkyl Polysiloxanes incorporating structural units IV
include branched and linear harnopotymers such as polydimethylsiloxane
polymethylphenylsiloxane, polydiphenylsiloxane, polymethylvinylsiloxane, and
copolymers thereof incorporating two or more of the structural units of said
homopolysiloxanes.
(4) Polyesters comprising structural units V
wherein Rl3and R14 are independently C1-C20 alkylene, C4-C20 arylene or C5-C20
cycloalkylene; and VI
wherein R15 is C1-C20 alkylene, C4-C20 arylene or C5-20 cycloalkylene. Polyesters
incorporating structural tmrts V and VI include poly(ethylene terephthalate),
poly(butylene terephthalate), polyethylene 2,6-naphthalenedicarboxylate),
poly(butylene 2,6-naphthalenedicarboxylate), polybulyrolactone and
polyvalerolactone.
(5) Polyepoxides comprising structural units VII
wherein R16 and R17 are independently at each occurrence halogen, C1-C20 alkyl, C6-.
C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl;
R18 and R19 are independently hydrogen, C1-C20 alkyl, C6-C20 aryl, C7-C21 aralkyl or C5-
C20 cydoalkyl, and further R18 and R19 may together form a C4-C20 cycloahphatic ring
which may be substituted by one or more! C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl or
C5-C20 cycloalkyl groups, or a combination thereof; and n is an integer from 0 to 4.
Polyepoxides incorporating structural units VII include epoxy resins prepared from
the mono- and diglycidy ethers of bisphenol A.
(6) Polyetherimides comprising structural units VIII
wherein R20 and R22 are independently ajt each occurrence halogen, C1-C20 alkyl, C6-
C20 aryl, C7.C21 aralkyl or C5-C20 cycloalkyl;
R21 is C2-C20 alkylene, C4-C20 arylene or C5-C20 cycloalkylene;
each A1 and A2 is a is a monocyclic divalent aryl radical and Y1 is a bridging radical
in which one or two carbon atoms separate A1 and A2; and m is an integer from 0 to 3.
Examples of polyether imides are Ultem ® polyether imides available from the

General Electric Company.
(7) Polyethersufones comprising structural units DC
wherein R23 and R24 are independently at.each occurrence halogen, C1-C20 alkyl, C6-
C20 aryl, C5.C21 aralkyl or C5-C20 cycloalkyl;
each A3 and A4 is a is a monocyclic divalent aryl radical and Y2 is a bridging radical
in which one or two carbon atoms separate A3 and A4; and p is an integer from 0 to 3.
Examples of polyethersulfones include those prepared from 4,4"-
dichlorodiphenylsulfone and bisphenols such as bisphenol A, bisphenol Z and
bisphenol M.
(8) Olefin polymers comprising structural units X
wherein R25, R26, R27 and R28 are indepenikntly at each occurrence halogen, cyano,
carboxyl, C2-C20 aHcoxycarbonyl, C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl, C5-C20
cycloalkylor
groups, wherein R29 and R30 are C1-C20 alkyl, C6-C20 aryl, C7-C21 aralkyl or C5-C20
cycloalkyl groups; or R29 and R30 together form a C5-C20 cycloaltphatic group. Olefin
polymer containing structural units X include polystyrene, polyacrylonitrile,
polymaleic acid, copolymers of styrene and maleic acid, poly(acrylonitrile-co-
butadiene-co-styrene), poly(acrylic acid) and poly(methyl methacrylate).
(9) Polyurethanes comprising structural XI
wherein R31 and R32 are independently C2-C20 alkylene, C4-C20 arylene, C4-C20
diarylene, C4-C20 diaralkylene or C5-C20 cycloalkylene. Polyurethanes incorporating
structural units XI include poly(1,4-butandiol)-tolylene-2,4-diisocyante and
poly[(4,4"methylenebis(phenylisocyanate)-alt-1,4-butanediol/polytetrahydrofuran]
available from Aldrich Chemical Company.
wherein R33 and R36 are independently at each occurrence halogen, C1-C20 alkyl, C6-
C20 aryl, C7-C21 aralkyl or C5-C20 cycloalkyl;
R34 and R35 are independently hydrogen, C1-C20 alkyl, C6-C20 aryl, C7.C21 aralkyl or C5-
C20 cycloalkyl, and further
R34 and R35 may together form a C4-C20 cycloaliphatic ring which may be substituted
by one or more C1-C20 alkyl, C6-C20 aryl, C5-C21 aralkyl, C5-C20 cycloalkyl groups or a
combination thereof; and q is an integer from 0 to 4. Polycarbonates incorporating
structural units XII include bisphenol A polycarbonate, bisphenol Z polycarbonate,
bisphenol M polycarbonate, copolycarbonates incorporating bisphenol A and
bisphenol Z, and polyester carbonates such as Lexan SP® available from the General
Electric company.
Where component (A) comprises a polyphenylene ether and a polyamide in
combination it may be desirable to include an impact modifying polymer, as part of
the polymer matrix, to improve the impact resistance of articles prepared from the
compositions of the present invention. Suitable impact modifying agents for the
purposes of the present invention include, but are not limited to, commercially
available impact modifying agents, such as Kraton rubber impact modifiers available
from Shell Chemicals. Additionally, polymeric materials prepared from styrene,
ethylene, and maleic acid or maleic anhydride; polymeric materials prepared from
ethylene and unsaturated carhoxylic acids and their metal salts; polymeric materials
prepared from olefins containing acid groups; block copolymers prepared from
vinylaromatic monomers, such as styrene and alpha-methyl styrene, conjugated
dienes, such as butadiene and cyctopentadiene, and unsaturated carboxylic acids and
anhydrides; block copolymers prepared from vinylaromatic monomers, such as
stytene and alpha-methyl styrene, olefins such as propylene, conjugated dienes, such
as butadiene and cyclopentadiene, and unsaturated carboxylic acids and anhydrides
may be employed. Examples of other suitable impact modifying agents are styrene-
butadiene random and block copolymers, styrene-ethylene-propylene terpolymers,
styrene-propylene-styrene block copolymers, styrene-butadiene-styrene block
copolymers, partially hydrogenated styrene-butadiene-styrene block copolymers, fully
. hydrogenated styrene-butadiene-styrene block copolymers and the like.
Other additives which may be included in component (A) include compatibilizing
agents such as dicarboxylic acids, tricarboxylic acids and cyclic carboxylic acid
anhydrides wherein said dicarboxylic acids, tricarboxylic acids and cyclic carboxylic
acid anhydrides contain at least one carbon-carbon double bond, carbon-carbon triple
bond or a latent carbon-carbon double bond. Examples of dicarboxylic acids and their
anhydride derivatives which may be used include maleic acid, fumaric acid, itaconic
acid, 2-hydroxysuccinic acid, citric acid, 2-butynedioic acid, maleic anhydride, 2-
hydroxysuccinic anhydride and citraconic anhydride. Among the forgoing examples
the five membered ring .cyclic anhydrides and citric acid are preferred when
component (A) comprises a blend of a polyphenylene ether and a polyamide. Maleic
anhydride and citric acid are particularly preferred. Other suitable compatibilizing
agents include multifunctional epoxides, ortho esters, oxazolidines and isocyanates.
The electrically conductive composite compositions of the present invention may
optionally include other commonly available conventional additives which enhance
their utility in various applications such as the preparation of molded articles for use
in computer and automotive applications. Said conventional additives include but are
not limited to flame retardants, UV.absorbers, antioxidants, heat stabilizers, antistatic
agents and mold release agents, slip agents, antiblocking agents, lubricants,
anticlouding agents, coloring agents, natural oils, synthetic oils, waxes, inorganic
fillers and mixtures thereof.
Component (B) of the electrically conductive polymer composite materials of the
present invention comprises at least one electrically conductive filler which when
dispersed in an organic polymer matrix affords an electrically conductive material.
Suitable electrically conductive fillers include carbon black , carbon fibers, carbon
fibrils, carbon nanotubes, metal coated carbon fibers, metal coated graphite, metal
coated glass fibers, conductive polymer filaments, metallic particles, stainless steel
fibers, metallic flakes, metallic powders and the like. Electrically conductive fillers
comprising component (B) are commonly known materials such as carbon balck and
carbon fibrils which are either commercially available or prepared according to
known synthetic methodology such as those methods found in U.S. Patent No.s
5,591,382 and 4,663,230. Carbon black is available from the Cabot Corporation.
Vapor grown carbon fibers are commercially available from Applied Sciences
Corporation. Carbon and graphite fibers are available from the Hexcel, Zoltek and
Akzo Nobel corporations. Singlewall nanotubes which may likewise serve as the
conductive filler are available from the Tubes@Rice and Carbolex companies.
Multiwall nanotubes are available from the MER and Carbon Solutions companies
among others. Metal coated fibers are available from the Composite Materials
Corporation, LLC and Ostolski Laboratories. Metallic powders are available from the
Bekaert Corporation.
Component (C) of the electrically conductive polymer composite materials of the
present invention comprises at least one conductivity enhancing agent which when
combined with components (A) and (B) affords a composition possessing a greater
level of conductivity than an otherwise: identical composition comprising only
components (A) and (B). In one embodiment, the present invention provides
conductivity enhancing agents which may be added to improve the conductivity of an
already electrically conductive polymer composite material, without sacrificing other
important physical properties of the material such as glass transition temperature or
impact resistance. Suitable conductivity enhancing agents include the salts of
carboxylic acids, salts of thio- and dithiocarboxylic acids, sate of organic sulfonic
and organic sulfinic acids, and salts of organic phosphorous and organic phosphoric
acids represented by structure XIII.
wherein R37 is a C1-C40 aliphatic radical, a C3-C40 cylcoaliphatic radical, or a C4-C40
aromatic radical, said radicals being optionally substituted by one or more
substituents, said substituents being independently at each occurrence halogen,
amino, ammonium, C1-C40 alkylamino, C1-C40 dialkylamino, C1-C40
trialkylammonium, C4.C40 arylamino, C4-C40 diarylamino, C1-C40 alkyl, C1-C40 alkoxy,
C1-C40 alkylthio, C1-C40 alkylsulfinyl, C1-C40 alkylsulfonyl, C3-C40 cycloalkyl, C4-C40
aryl, C4-C40 aryloxy, C4-C40 arylthio, C4-C40 arylsulfinyl, C4-C40 arylsulfonyl,
hydroxysulfonyl, hydroxy, mercapto, cyano, oxo, imino, aminoimino, hydroxyimino,
alkoxyimino, nitro, nitroso, formyl, carboxyl, carboxylate, thiocarboxyl,
dithocarboxyl, C1-C40 alkoxycarbonyl, C1-C40 alkoxythiocarbonyl, C1-C40
alkylthiocarbonyl, or phosphonyl groups;
r is an integer having a value of from 0 to about 10;
Q1 is independently at each occurrence structure (a), (b), (c), (d), (e), (f), (g) or (h)
wherein M is selected from the group consisting of monovalent metal cations,
divalent metal cations , trivaleni metal cations, ammonium ions, C1-C40
alkylammonium ions, C1-C40 dialkylaramonium ions, C1-C49 trialkytammonium ions,
C1-C40 tetraalkylaromonimn ions, C4-C40 tetraarylplhosphaonium ions, C1-C40
trialkylsulfonium ions, C4-C40 triarjisulfonium ions or C4-C40 aryl C1-C40
dialkylsulfonium ions; and
s is an integer or a fraction of an integer having a value of 1, 1/2 or 1/3.
Groups (a)-(h) of structure XIII comprise metal cations, ammonium ions, organic
ammonium ions, organic sulfonium ions and organic phosphonium ions. Conductivity
enhancing agents comprising metal cations include carboxylic, thiocarboxylic,
dithiocarboxylic, sulfonic, sulfinic, phosphoric and phosphorus acid salts comprising
cations of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium,
calcium, copper, silver, zinc, cadmium and tin. Fully ionized and partially ionized
calcium salts of mono- and polycarboxylic acids having structure XIV may serve as
component (C),
R38-(CO2-)t(Ca++)u(H+)v ^^*
XIV
wherein R38 is a C1C40 aliphatic radical; C3-C40 cylcoaliphatic radical, or a C4-C40
aromatic radical; t is an integer having a value of from 1 to 10; u is an integer or half
integer having a value of from 1/2 to 5; and v is an integer having a value of t-2u.
Calcium salts of mono- and polycarboxylic acids having structure XIV are illustrated
by, but are not limited to, the calcium salts of formic, acetic, propionic, butyric,
valeric, octanoic, dodecandioic, tetradecanedioc, stearic, oleic, oxalic, malonic,
succinic, sebacic, dodecandioic, terephthailic, 2,6-naphthalenedioic, Kemp"s triacid,
and 9-carboxydodecanedioic acid or mixtures thereof.
In addition, one or more salts of polymeric materials bearing one or more of the
groups (a)-(h) may be ased as component (C), Salts of polymeric acids such ia which
some or all of the carboxyl group hydrogen atoms have been exchanged with one or
more suitable metal, ammonium, phosphonium or sulfonkim cations are illustrated by
the calcium salts of polyacrylic and polymaleic acids and the like.
Where component (C) comprises organic ammonium ions, said organic ammonium
ions are illustrated by, but not limited to, tetramethylammonium
decylmethylammonium, methylundecylammonium, dodecylmethylammonium,
methyltridecylammonium, methyltetradecylammonium, methylpentadecylammonium,
hexadecylmethylammonium, heptadecylmethylammonium,
methyloctadecylammonium, decyldimethylammonium, dimethylundecylammonium,
dimethyldodecylammonium, dimethyltridecylammonium,
dimethyltetradecylammonium, dimethylpentadecylammonium,
dimethylhexadecylammonium, dimethylheptadecylammonium,
dimethyloctadecylammonium, decyltrimethylammonium,
trimethylundecylammonium, dodecyltrimethylammonium,
tridecyltrimethylammonium, tetradecyltrimethylammonium,
pentadecyltrimethylammonium, hexadecyltrimethylammonium,
heptadecyltrimethylammoniura and octadecyltrimethylammonium cations.
Component (C) may comprise phosphonium and sulfonium ions which are illustrated
by, but not limited to, tetraphenylphosphonium, triphenylundecylphosphonium,
triphenyl sulfonium and trimethylsulfonium ions.
The instant invention provides electrically conductive polymer composite materials
wherein component (A), comprises from about 50 to about 99.9 weight percent of the
composition, component (B) comprises from about 0.1 to about 20 weight percent of
the composition, and component (C) comprises from about 0.001 to about 10 weight
percent of the composition.
In a preferred embodiment, the instant, invention provides electrically conductive
polymer composite materials wherein component (A), comprises from about 80 to
about 99 j0 weight percent of the composition, component (B) comprises from about
0.1 to about 10.0 weight percent of the composition, and component (C) comprises
from about 0.01 to about 5 weight percent of the composition.
In a still more preferred embodiment, the instant invention provides electrically
conductive polymer composite materials wherein component (A), comprises from
about 90 to about 99.0 weight percent of the composition, component (B) comprises
from about 03 to about 2.0 weight percent of the composition, and component (C)
comprises from about 0.1 to about 1 weight percent of the composition.
In an even more preferred embodiment, the instant invention provides electrically
conductive polymer composite materials wherein component (A), comprises a
polyphenylene ether, a polyamide and an impact modifier wherein the polyphenylene
ether is present in amount in a range between about 35 and about 65 weight percent,
the polyamide is present in an amount in a range between about 65 and about 35
weight percent and the impact modifier is present in a range between about 0.1 and
about 20 weight percent of the total weight of the composition.
The composite compositions of the present invention may prepared using melt
processing techniques. Typically, melt processing involves subjecting component (A),
(B) and (C) of the electrically conductive polymer composite composition to intimate
mixing at a temperature in a range between about 400 degrees Fahrenheit (°F) and
about 600°F. Melt processing in an extruder is preferred.
In one embodiment the present invention provides an electrically conductive polymer
composite composition by extruding a mixture comprising components (A), (B) and
(C) together with any additives such as flame retardants, UV stabilizers, mold release
agents and the like at temperatures ranging from about 400°F to about 600°F to
provide an extrudate. Coextrusion of components (A), (B) and (C) may be carried out
as follows: A dry blend comprising components (A), (B) and (C) is charged to the
feed inlet of an extruder and mixed and heated at temperatures ranging from about
400°F to about 600°F to produce an extrudate which may be pelletized for further
processing into molded articles. Any vested zones in the extruder may be maintained
at atmospheric pressure or adapted for a vacuum venting.
In yet another embodiment, the present invention provides an electrically conductive
polymer composite composition by extruding a mixture comprising components (A),
(B) and (€} as follows: A portion of component (A) together with any additives which
may be desirable, such as compatibilizing agents, impact modifying agents, flame
retardants, mold retease agents and the like, is charged to the feed inlet of an extruder
and mixed and heated at temperatures ranging from about 400°F to about 600°F.
Component (B), dispersed in component (A) itself or in at least one component of
component (A), and component (C), likewise dispersed in component (A) itself or in
at least one component of component (A), are introduced at a feed inlet of the
extruder closer to the the than the feed inlet used to introduce components (A).
Control of the rates of introduction of the dispersions of components (B) and (C)
provides a means to vary the amounts of each of the components present in the
electrically conductive polymer composite composition.
Articles made from the compositions of the present invention may be obtained by
forming the electrically conductive polymer composite composition by such means as
injection molding, compression molding and extrusion methods. Injection molding is
the more preferred method of forming the article. Among the molded articles which
may be prepared from the compositions of the present invention are automotive
articles such as automotive body panels, fenders and the like; and computer housings
and the like.
Examples
The following examples are put forth so as to provide those of ordinary skill in the art
with a detailed disclosure and description of how the methods claimed herein are
evaluated, and are not intended to limit the scope of what the inventors regard as their
invention. Unless indicated otherwise, parts are by weight, temperature is in degrees
centigrade. The materials and testing procedures used for the results shown herein are
as follows:
The organic conductive composite materials exemplifying me present invention were
prepared from commercially available nylon 6,6 and polyphenylene ether (PPE
available from General Electric) and graphite fibrils as the electrically conductive
filler. Carbon fibril-nylon 6,6 mixtures are available torn Hyperion Catalysis
International.
Resistivity measurements employed standard injection molded tensile bars as follows.
An injection molded tensile bar was first lightly scored and then frozen in liquid
nitrogen before fracturing the tab ends off (on the score marks) to obtain the narrow
section having dimensions of approximately 2.5 x 0.5 x 0.125 inches. The sample was
allowed to warm to room temperature and the fractured ends were painted with
conductive silver paint (sold by Ernest F. Fullam, item # 14811) to provide a uniform
contact area across the entire cross section. Resistance was measured on a Wavetek
RMS225 phm-meter for samples having resistance values less than 40 MO or on a
Keithley 617 electrometer for samples having resistance values between 40 MO and
200 GO. The specific volume resistivity (SVR or bulk resistivity) of the sample was
calculated by multiplying the measured resistance times the cross sectional area of the
bar divided by the length of the bar.
Notched IZOD impact test values were obtained at room temperature and are reported
in foot-pounds per inch (ft.lb/in).
Example 1
A dry blend of 40.72 parts PPE, poly(2,6-dimethyl-1,4-phenylene)ether, having an
intrinsic viscosity of about 0.4 deciliters per gram (dl/g) as measured in chloroform at
30°C, 7.43 parts Kraton G1651 and 3.71 parts Kraton G1701 impact modifier, 0.1
parts potassium iodide, and 0.01 parts copper iodide was fed at a rate of 20.74 pounds
per hour (phr) to the throat of a twin screw extruder operated at 290°C at 400 rpm.
Simultaneously, a blend of 38.03 parts nylon 6,6 powder, 5.90 parts nylon 6,6-carbon
fibril mixture containing 20.0 percent by weight carbon fibrils, and 4.20 parts of a
dispersion of calcium stearate powder in ground nylon 6,6 containing 5.0 percent by
weight calcium stearate, was fed at a rate of 1925 phr through a downstream inlet of
the extruder. The extruded composite composition contained 1.20 percent by weight
carbon fibrils based on the total weight of the composition and 0.45 percent by weight
calcium stearate based upon the weight of nylon 6,6.
Comparative Example 1
The control sample was produced as in Example 1 with the exception that nylon 6,6
was substituted for the nylon 6,6-calcium stearate mixture. The resultant organic
conductive material had a fibril concentration of 12% by weight based on the total
weight of the composition, and the same relative amounts of nylon 6,6 and PPE as in
the composition of Example 1 and a bulk resistivity of 14.54 K ohm-cm
Examples 2-5, in which the weight fraction of carbon fibrils was maintained at 1.2
percent based on the total weight of the composition while varying the amount of
calcium stearate, were prepared in a manner analogous to Example 1 using the same
relative amounts of nylon 6,6 and PPE.
Examples 6-8, in which the weight fraction of calcium stearate was maintained at 0.9
percent based on the total weight of nylon 6,6 while varying the amount of carbon
fibrils, were prepared in a manner analogous to Example 1 using the same relative
amounts of nylon 6,6 and PPE.
Examples 9-14 were prepared in a manner analogous to that employed in Example 1
using the same relative amounts of nylon 6,6 and PPE, wherein a conductivity
enhancing agent other than calcium stearate was added as a 5% dispersion in nylon
6,6 powder. The compositions of Exampleis 9-15 comprise 1.2 weight percent carbon
fibrils. The materials of Examles 9-14 contained 0.9 weight percent calcium stearate
based upon the weight of nylon 6,6. :
Table I illustrates the effect of calcium stearate on electrical and impact properties of
polyphenylene ether-nylon 6,6-carbon fibril composite compositions comprising
about 40.72 parts polyphenylene ether, about 46.74 parts nylon 6,6, about 11.14 parts
impact modifiers, about 1.2 parts carbon fibrils and calcium stearate in a range
between about 0 and about 2.5 weight percent based upon the weight of nylon 6,6
present in the composition. It can be seen that the SVR decreases steadily as the
amount of calcium stearate in the composition is increased.
As a result of calcium stearate addition, less of the conductive filler is required to
achieve the desired level of electrical conductivity and there is little effect on impact
strength. This is demonstrated in Table 2 wherein the level of calcium stearate is
maintained at 0.9 weight percent with respect to the weight of nylon 6,6 while the
amount of carbon fibrils is varied. As illustrated in Example 7, the presence of the
0.9% calcium stearate together with 0.8 % carbon fibrils affords composite
composition having conductivity superior to a control sample containing 30 percent
more carbon fibrils, Comparative Example 1.
TABLE 2. EFFECT OF CARBON FIBRIL LOADING ON RESISTIVITVAT
IMPACT PROPERTIES AT CONSTANT CALCIUM STEARATE LOADING
Table 3 illustrates the relative effectiveness of a variety of carboxylic acid salts at
reducing the resistivity ( i.e. enhancing the conductivity) of conductive polymer
blends.
a All samples contained 1.2 weight percent carbon fibril and 0.9 weight percent
calcium stearate based upon the weight of nylon 6,6. Specific volume resistivity in
kO-cm.c Contains no calcium stearate. d Calcium salt of montanic acid CAS# 68308-
22-5.
The invention has been described in detail with particular reference to preferred
embodiments thereof, but it will be understood that variations and modifications can
be effected within the spirit and scope of the invention.
We Claim
1. An electrically conductive polymer composite composition comprising:
(A) an organic polymer matrix;
(B) an electrically conductive filler; and
(C) a conductivity enhancing agent comprising calcium stearate, said
organic polymer matrix (A) comprising polyphenylene ether
structural units corresponding to structure I
wherein R1-R4 are independently hydrogen, halogen, C1-C10 alkyl, C4-C20
aryl, or C4-C20 cycloalkyl; and
polyamide structural units corresponding to structure II or III
wherein R5 and R6 are independently C1-C20 alkylene, C4-C2O arylene,
or C5-C20 cycloalkylene, R7 and R8 are independently hydrogen, C1-C20
alkyl, C1-C20 aryl, C7 -C21 aralkyl, or C5 -C20 cycloalkyl, R9 is C1-
C20 alkylene, C4-C20 arylene, or C5-C20 cycloalkylene, and R10 is C1-
C20 alkyl, C6 -C20 aryl, C7 -C21, aralkyl, or C5 -C20 cycloalkyl;
said component (A) being present in an amount between about 50 and
about 99.9 percent, said component (B) being present in an amount
between about 0.1 and about 20 percent and said component (C)
being present in an amount between about 0.001 and about 10
percent, based on the total weight of the composition.
2. A composition as claimed in claim 1, comprising at least one impact
modifying agent, said impact modifying agent being present in an amount
between about 0.1 and about 20 weight percent based upon the total
weight of the composition.
3. A composition as claimed in claim 2, wherein component (A) comprises
poly (2,6-dimethyl-1,4 -phenylene ether) and nylon 6,6.
4. A method of making an electrically conductive polymer composite
composition comprising:
(A) an organic polymer matrix;
(B) an electrically conductive filler; and
(C) a conductivity enhancing agent comprising calcium stearate;
said method comprising mixing components (A), (B) and (C) under melt
processing conditions,
said organic polymer matrix (A) comprising polyphenylene ether structural
units corresponding to structure I
wherein R1 -R4 are independently hydrogen, halogen, C1 -C10 alkyl, C4 -
C20 aryl, or C4 -C20 cycloalkyl; and
polyamide structural units corresponding to structure II or III
wherein R5 and R6 are independently C1-C20 alkylene, C4-C20 arylene, or
C5 -C20 cycloalkylene, and R7 and R8 are independently hydrogen, C1-C20
alkyl, C6-C20 aryl, C7 -C21, aralkyl, or C5 -C20 cycloalkyl, R9 is C1-C20
alkylene, C1 -C20 arylene, or C5 -C20 cydoalkylene, and R10 is C1-C20 alkyl,
C6 -C20 aryl, C7 -C21 aralkyl, or C5 -C20 cycloalkyl;
said electrically conductive filler (B) comprising carbon fibrils,
said component (A) being present in an amount between about 50 and
about 99.9 percent, said component (B) being present in an amount
between about 0.1 and about 20 percent and said component (C) being
present in an amount between about 0.001 and about 10 percent, based
on the total weight of the composition.
5. A method as claimed in claim 4, comprising at least one impact modifying
agent, said impact modifying agent being present in an amount between
about 0.1 and about 20 weight percent based upon the total weight of the
composition.
6. A method as claimed in claim 5, wherein component (A) comprises poly
(2,6-dimethyl-1,4-phenylene ether) and nylon 6,6.
7. A method of enhancing the electrical conductivity of an electrically
conductive polymer composite composition comprising:
(A) an organic polymer matrix; and
(B) an electrically conductive filler;
said method comprising combining components (A) and (B) under melt
processing conditions with a conductivity enhancing agent (C) comprising
calcium stearate,
said organic polymer matrix (A) comprising polyphenylene ether structural
units corresponding to structure I
wherein R1 -R4 are independently hydrogen, halogen, C1-C10 alkyl,
C4 -C20 aryl, or C4 -C20 cycloalkyl; and
polyamide structural units corresponding to structure II or III
wherein R5 and R6 are independently C1 -C20 alkylene, C4 -C20 arylene,
or C5 -C20 cycloalkylene, R7 and R8 are independently hydrogen, C1-
C20 alkyl, C6-C20 aryl, C7 -C21 aralkyl, or C5 -C20 cycloalkyl, R9 is C1 -
C20 alkylene, C4-C20 arylene, or C5 -C20 cycloalkylene, and R10 is C1-C20
alkyl, C6 -C20 aryl, C7 -C21, aralkyl, or C5 -C20 cycloalkyl;
said electrically conductive filler (B) comprising carbon fibrils,
said component (A) being present in an amount between about 50
and about 99.9 percent, said component (B) being present in an
amount between about 0.1 and about 20 percent and said
component (C) being present in an amount between about 0.001
and about 10 percent, based on the total weight of the
composition.
8. A method as claimed in claim 7, comprising at least one impact modifying
agent, said impact modifying agent being present in an amount between
about 0.1 and about 20 weight percent based upon the total weight of the
composition.
9. A method as claimed in claim 8, wherein component (A) comprises poly
(2,6-dimethyl-1,4-phenylene ether) and nylon 6,6.
10. An electrically conductive polymer composite composition comprising:
(A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4-
phenylene ether) in an amount equivalent to about 35 to about 65
weight percent, nylon 6,6 in an amount equivalent to about 65 to
about 35 weight percent, and an impact modifier in an amount
equivalent to about 5 to about 15 weight percent;
(B) an electrically conductive filler comprising carbon fibrils in an
amount equivalent to from about 0.1 to about 2.0 weight percent;
and
(C) a conductivity enhancing agent comprising calcium stearate in an
amount equivalent to about 0.1 and about 2.0 weight percent;
wherein weight percent refers to the weight percent of the
component relative to the total weight of the composition.
11. A molded article prepared from the composition as claimed in claim 10.
12. A method of preparing an electrically conductive polymer composite
composition comprising:
(A) an organic polymer matrix comprising poly (2,6-dimethyl-1,4-
phenylene ether) in an amount equivalent to about 35 to about 65
weight percents nylon 6,6 in an amount equivalent to about 65 to
about 35 weight percent, an impact modifier in an amount
equivalent to about 5 to about 15 weight percent;
(B) an electrically conductive filler comprising carbon fibrils in an
amount equivalent to about 0.1 to about 2.0 weight percent; and
(C) a conductivity enhancing agent comprising calcium stearate in an
amount equivalent to about 0.1 and about 2.0 weight percent;
wherein weight percent refers to the weight percent of constituent
relative to the total weight of the composition;
said method comprising combining components (A), (B) and (C)
under melt processing conditions.
13.A method as claimed in claim 12 wherein the poly(2,6-dimethyl-1,4-
phenylene)ether and impact modifier are first melt mixed under melt
processing conditions at a temperature in a range between about 270 and
320°C, and thereafter nylon 6,6 carbon fibrils and calcium stearate are
added to the mixture of poly(2,6-dimethyl-1,4-phenylene)ether and
impact modifier, and the whole is subjected to further melt processing.
14. A method of enhancing the electrical conductivity of an electrically
conductive polymer composite composition comprising:
(A) an organic polymer matrix comprising poly(2,6-dimethyl-1,4-
phenylene ether) in an amount equivalent to about 35 to about 65
weight percent, nylon 6,6 in an amount equivalent to about 6 5 to
about 3 5 weight percent, an impact modifier in an amount
equivalent to about 5 to about 15 weight percent; and
(B) an electrically conductive filler comprising carbon fibrils in an
amount equivalent to from about 0.1 to about 2.0 weight percent;
wherein weight percent refers to the weight percent of constituent
relative to the total weight of the composition;
said method comprising combining components (A) and (B) with a
conductivity enhancing agent comprising calcium stearate in an
amount equivalent to about 0.1 to about 2.0 weight percent
calcium stearate based upon the total weight of the composition.
Inclusion of relatively small amounts of organic ionic species, such as calcium
stearate, in the preparation of an electrically conductive polymer composite .
composition provides a composition having enhanced electrical properties relative to
the composite composition lacking the added organic ionic species. As a result of this
enhancement, normally insulating materials which rely upon a conductive filler to
render them electrically conductive, can be made to achieve a given level of
conductivity using less of the conductive filler than would otherwise be required. As a
result, the adverse effects of the conductive filler on the polymer"s physical properties
can be minimized while maintaining a high level of electrical conductivity.

Documents:

345-kolnp-2003-granted-abstract.pdf

345-kolnp-2003-granted-assignment.pdf

345-kolnp-2003-granted-claims.pdf

345-kolnp-2003-granted-correspondence.pdf

345-kolnp-2003-granted-description (complete).pdf

345-kolnp-2003-granted-form 1.pdf

345-kolnp-2003-granted-form 18.pdf

345-kolnp-2003-granted-form 2.pdf

345-kolnp-2003-granted-form 3.pdf

345-kolnp-2003-granted-form 5.pdf

345-kolnp-2003-granted-gpa.pdf

345-kolnp-2003-granted-letter patent.pdf

345-kolnp-2003-granted-reply to examination report.pdf

345-kolnp-2003-granted-specification.pdf

345-kolnp-2003-granted-translated copy of priority document.pdf

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Patent Number

218558

Indian Patent Application Number

345/KOLNP/2003

PG Journal Number

14/2008

Publication Date

04-Apr-2008

Grant Date

02-Apr-2008

Date of Filing

24-Mar-2003

Name of Patentee

GENERAL ELECTRIC COMPANY

Applicant Address

1 RIVER ROAD, SCHENECTADY, NEW YORK 12345

Inventors:

#	Inventor's Name	Inventor's Address
1	RODRIGUES, DAVID ERNEST	4 SCOTCH MIST WAY, MALTA, NEW YORK 12020
2	TING, SAI-PEI	18 BITTERSWEET LANE, SLINGERLANDS, NEW YORK 12159
3	TODT, MICHAEL, LESLIE	1801 AVENUE A SCHENECTADY, NEW YORK 12308

PCT International Classification Number

H01B 1/22

PCT International Application Number

PCT/US01/22468

PCT International Filing date

2001-07-17

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	09/705,265	2000-11-03	U.S.A.