WO2007008633A2

WO2007008633A2 - Electrically conductive long fiber thermoplastic concentrate and method for its preparation

Info

Publication number: WO2007008633A2
Application number: PCT/US2006/026435
Authority: WO
Inventors: Richard T. Fox; Vijay Wani; Ludo M. Aerts; Robert W. Ranger
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2005-07-07
Filing date: 2006-06-30
Publication date: 2007-01-18
Anticipated expiration: 2008-01-07
Also published as: WO2007008633A3

Abstract

Disclosed is a process to make an electrically conductive long fiber thermoplastic concentrate wherein an electrically conductive continuous fiber strand is coated with an aqueous melt-kneaded thermoplastic dispersion, dried, and chopped.

Description

ELECTRICALLY CONDUCTIVE LONG FIBER THERMOPLASTIC CONCENTRATE AND

METHOD FOR ITS PREPARATION

FIELD OF THE INVENTION

This invention relates to an electrically conductive long fiber thermoplastic concentrate in the form of pellets having electrically conductive long fibers with substantially the same length and in parallel in the same direction in a matrix of a thermoplastic resin and a method to make such pellets.

BACKGROUND OF THE INVENTION

With the increased usage of electronic equipment such as computers and other digital devices there is a heightened concern for the hazards associated with electromagnetic radiation, in particular radar waves, microwaves and electromagnetic radiation produced by electronic circuits. As the electronic industry continues to grow at a rapid pace, there exists a need to create improved electromagnetic wave shielding materials, which can be incorporated into electronic products. Over the years, a number of electrically conductive materials have been developed to fabricate composite articles, such as plastic articles, for electromagnetic shielding, electrostatic dissipation, and other electrically enhanced characteristics. Plastic articles formed from electrically conductive materials are particularly convenient as compared to traditional metal materials because they are lightweight, easily produced using injection molding techniques, and low cost. Typically these electrically conductive materials are composites of plastics and conductive powders and cut fibers.

Various techniques have been employed when incorporating electrically conductive powders and chopped fibers into a composite article. For example, a traditional thermoplastic extrusion compounding technique (generally called compounding) has been commonly employed. In this method, a thermoplastic resin is fed into a compounder. The resin is heated to a molten temperature and then fibers or powders are fed into the compounder. The mixture is kneaded to mix in the conductive powders or chopped fibers. The resin and broken fiber and/or powder mixture is extruded, cooled in a water bath, then chopped by a strand cutter into pellets. Unfortunately, when kneading conductive fibers with a molten thermoplastic, the fibers are often broken due to the cutting action by the kneading screw and by the shearing of the resin.

These fibers are broken into smaller and smaller segments such that the resulting composite article contains only shorter length broken fibers. Such shortened fibers impart reduced electromagnetic shielding properties to the composite due to their reduced ability to form a conductive fiber network and conduct electricity through the composite article. Alternatively, when mixing conductive powders with the molten thermoplastic it is typically necessary to employ a very large amount of the conductive powder. Such large amounts of powder can result in a poor dispersion of the powder or reduced mechanical strength of the final product. Accordingly, composite articles formed with broken fibers and powders require higher loadings of filler concentrations leading to embrittlement of the composite article formed and higher material costs. In an alternate approach, chopped conductive fibers are mixed with the thermoplastic resin directly at the injection molding operation. However, this can result in poor fiber dispersion and inconsistent electrical performance from part to part. Furthermore, operators working directly with the chopped fibers and powders can experience skin irritation when handling the materials.

To avoid the problems with directly mixing in cut fibers and powders, attempts have been made to provide an electrically conductive long fiber thermoplastic concentrate by coating an electrically conductive fiber with a synthetic resin and then cutting the coated fiber into pellet form. Typically, such a process involves the use of continuous lengths of filaments, which are passed through a bath containing a molten thermoplastic resin whereby bundles or groups of such filaments become impregnated with the thermoplastic resin. Once the filaments are impregnated they are continuously withdrawn from the bath, commingled either before or after passage through a heat source and cooled to solidify the molten thermoplastic resin around the fibers. These impregnated fibers are then cut to form pellets, which are then combined with the same or different non- conductive thermoplastic resin to form an electrically conductive article. Unfortunately, this direct impregnation process is very slow, and the impregnated fibers may fray when cut into pellets and can become separated from the thermoplastic resin.

Another method employed in the formation of an electrically conductive long fiber thermoplastic concentrate is the optional coating of electrically conductive fibers with a coupling agent and coating the (coated) fibers with a thermoplastic resin layer (generally referred to as pultrusion), for example, see USP 4,530,779. Similarly, other attempts at forming an electrically conductive long fiber thermoplastic concentrate have passed electrically conductive fibers through a bath of a molten thermoplastic resin to first impregnate the fibers. These impregnated fibers are then sheathed with a second thermoplastic material. As generally described in USP 4,664,971 and 5,397,608, when forming a composite article, an electrically conductive fiber may be impregnated and sheathed to provide a more even distribution of the conductive fibers, under minimal shear force and without substantial fiber breakage. Yet, as generally described by USP 4,960,642, another method of forming impregnated and sheathed fibers involves the extrusion of an impregnating thermoplastic resin onto the fiber and then extruding a second thermoplastic resin onto the impregnated fiber.

Previous methods of impregnating and sheathing conductive fibers have not been entirely satisfactory for uniformly impregnating conductive fibers from a bath of molten thermoplastic or pultrusion to form an impregnated tow having a high level of conductive fibers and a low level of thermoplastic resin.

Additionally, as described in WO 98/06551, a chemical treatment may be applied to fibers, such as reinforcing fibers suitable for making a composite article, so as to size and/or impregnate the fibers. Composite strands of WO 98/06551 may be used to form fiber-reinforced thermoplastic conductive articles. It would be desirable to provide a practical and economical process to make an electrically conductive long fiber thermoplastic concentrate for use in making electromagnetic wave shielded articles for use in electronic devices.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process to prepare such an electrically conductive long fiber thermoplastic concentrate. Preferably, a process to prepare an electrically conductive long fiber thermoplastic concentrate which can be mixed at an extruder and/or injection molding machine hopper with a non-conductive thermoplastic for use in making articles used in electronic devices. Preferably, said concentrate provides a high and consistent electrically conductive long fiber content combined with a thermoplastic sheathing resin (sometimes referred to as the carrier resin) which is compatible with the non-conductive thermoplastic with which it is combined. Further, it is desirable to have economics competitive with direct mixing of bare conductive fibers and thermoplastic resin. Preferably, the electrically conductive long fiber thermoplastic concentrate is provided as a pellet.

It is a further object of the present invention to provide an electrically conductive long fiber thermoplastic concentrate with a thermoplastic carrier resin of the same type as and/or chosen to be compatible with the non-conductive thermoplastic resin which it is ultimately intended to be mixed with in the extruder and/or injection molding machine. Preferably, the thermoplastic carrier resin has a molecular weight compatible to the non-conductive thermoplastic resin it is being mixed with.

It is a further objective of the present invention to provide an electrically conductive thermoplastic concentrate wherein the electrically conductive long fiber content is in a substantially parallel direction for substantially the entire length of the pellet. It is a further object of the present invention to provide a method for preparing high electrically conductive long fiber content pellets of the electrically conductive long fiber thermoplastic concentrate of the present invention, preferably having fiber levels greater than about 50 weight percent, preferably greater than about 90 weight percent.

The foregoing objects of the present invention are provided by a method to produce an electrically conductive long fiber concentrate comprising electrically conductive long fibers and a thermoplastic resin comprising the steps of i) coating continuous electrically conductive fibers with an aqueous thermoplastic dispersion to form thermoplastic coated continuous electrically conductive fiber strands, ii) drying and/or fusing the thermoplastic coated continuous electrically conductive fiber strands, iii) chopping the dried thermoplastic coated continuous electrically conductive fiber strands forming dried electrically conductive long fiber concentrate pellets, and iv) isolating dried electrically conductive long fiber concentrate pellets. Preferably, the aqueous thermoplastic dispersion is a melt-kneaded aqueous thermoplastic dispersion.

Alternatively, the foregoing objects of the present invention are provided by a method to produce an electrically conductive long fiber concentrate comprising electrically conductive long fibers and a thermoplastic resin comprising the steps of i) coating continuous electrically conductive fibers with an aqueous thermoplastic dispersion to form thermoplastic coated continuous electrically conductive fiber strands, ii) chopping the thermoplastic coated continuous electrically conductive fiber strands forming electrically conductive long fiber concentrate pellets, iii) drying and/or fusing the electrically conductive long fiber concentrate pellets, and iv) isolating dried electrically conductive long fiber concentrate pellets. Preferably, the aqueous thermoplastic dispersion is a melt-kneaded aqueous thermoplastic dispersion.

Alternatively, the foregoing objects of the present invention are provided by a method to produce an electrically conductive long fiber concentrate comprising electrically conductive long fibers and a thermoplastic resin comprising the steps of i) coating chopped electrically conductive long fibers with an aqueous thermoplastic dispersion to form thermoplastic coated chopped electrically conductive long fiber pellets, ii) drying and/or fusing the coated chopped electrically conductive long fiber concentrate pellets, and iii) isolating dried electrically conductive long fiber concentrate pellets. Preferably, the aqueous thermoplastic dispersion is a melt-kneaded aqueous thermoplastic dispersion. In one embodiment of the method of the present invention, the aqueous thermoplastic dispersion is a melt-kneaded aqueous thermoplastic dispersion comprising a thermoplastic resin, a dispersing agent, and water, preferably comprising from about 0.5 to about 30 parts per weight dispersing agent and from about 1 to about 35 parts per weight water, parts by weight are based on 100 parts by weight of the thermoplastic resin. In another embodiment, the aqueous thermoplastic dispersion as produced can be further diluted so that it contains from about 10 to about 70 weight percent thermoplastic resin, preferably from about 15 to about 55, and more preferably from about 20 to about 45 weight percent thermoplastic resin.

The thermoplastic resin used in the dispersion of the method of the present invention is polyethylene, polypropylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, a styrene and acrylonitrile copolymer, an acrylonitrile, styrene, and butadiene terpolymer, polyphenylene oxide, polyacetal, polyetherimide, polycarbonate, or blends thereof; preferably the polyethylene resin is an ethylene and alpha-olefin copolymer and the polypropylene resin is a propylene-rich alpha-olefin copolymer; and more preferably, the ethylene copolymer is a substantially linear ethylene polymer or a linear ethylene polymer and the propylene-rich copolymer comprises at least about 60 weight percent of units derived from propylene and at least about 0.1 weight percent of units derived from ethylene made using a nonmetallocene metal-centered, heteroaryl ligand catalyst characterized as having ¹³C NMR peaks corresponding to a region-error at about 14.6 and about 15.7 parts per million wherein these peaks are about equal in intensity. The dispersing agent used in the dispersion of the method of the present invention is a carboxylic acid, a salt of a carboxylic acid, a carboxylic acid ester, a salt of an acid ester, an ethylene carboxylic acid polymer, a salt of an ethylene carboxylic acid polymer, an alkyl ether carboxylate, a petroleum sulfonate, a sulfonated polyoxyethylenated alcohol, a sulfated polyoxyethylenated alcohol, a phosphated polyoxyethylenated alcohol, a polymeric ethylene oxide/propyleneoxide/ethylene oxide dispersing agent, a primary alcohol ethoxylate, a secondary alcohol ethoxylate, an alkyl glycoside, an alkyl glyceride, or combinations thereof; preferably montanic acid, an alkali metal salt of montanic acid, an ethylene acrylic acid copolymer, an ethylene methacrylic acid copolymer, or combinations thereof.

The dispersion used in the method of the present invention preferably has a volume average particle size of less than about 5 micrometers, a pH of less than 12, or a volume average particle size of less than about 5 micrometers, a pH of less than about 12, and the dispersing agent comprises less than about 4 percent by weight based on the weight of the thermoplastic resin.

The fiber suitable for use in the electrically conductive long fiber concentrate and method of the present invention preferably is a continuous electrically conductive metal fiber, for example copper, aluminum, silver, zinc, gold, nickel, stainless steel and alloys thereof. Alternatively, the electrically conductive long fiber of the present invention is a metal coated fiber such as carbon, graphite, and glass fibers that are coated with a conductive metal. Generally, the metal coatings are formed from copper alloys, silver, gold, tin, nickel, aluminum, zinc and alloys thereof. The fiber suitable for use in the electrically conductive long fiber concentrate and method of the present invention may be one or more continuous metal fiber, one or more continuous metal coated fiber, or mixtures thereof. Preferred electrically conductive fibers of the invention are metal coated carbon and glass fibers. Alternatively, the electrically conductive long fiber of the present invention is an inherently conductive organic fiber such as polyacetylene, polythiophene and these or other fibers with doping agents. Another embodiment of the present invention is an electrically conductive thermoplastic composition comprising a thermoplastic resin and the electrically conductive long fiber thermoplastic concentrate of the present invention.

A further embodiment of the present invention is a molded or extruded thermoplastic article made from an electrically conductive thermoplastic composition comprising a thermoplastic resin and the electrically conductive long fiber thermoplastic concentrate of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block flow diagram showing an apparatus suitable for practicing the process of the present invention.

FIG. 2 is a block flow diagram showing an alternative apparatus suitable for practicing the process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the method as practiced in FIG. 1, a continuous electrically conductive fiber strand, or roving, 1 is fed from a supply reel 2 through a bath 4 containing an aqueous thermoplastic dispersion 5 forming a coated strand. The coated strand is air dried or optionally passed through a heat source such as an oven 6 in which the water of the dispersion is driven off, i.e., the strand is dried, and/or the thermoplastic resin is fused. The coated strand after solidification of the thermoplastic resin may optionally pass near one or more heaters 7 where the strand is further dried and/or the temperature of the strand is raised, when required to an appropriate temperature wherein it will be ready for pelletizing in unit 9 to form pellets of the electrically conductive long fiber thermoplastic concentrate of the invention. The strand- may be drawn through the apparatus by the pelletizing unit 9 or optionally, a draw-off device 8. Optionally, the coated strand may be passed through a shaping device 13 at any point between the bath 4 and the pelletizing unit 9.

Alternatively, in the method as practiced in FIG. 2, a continuous electrically conductive fiber strand, or roving, 1 is fed from a supply reel 2 through a bath 4 containing an aqueous thermoplastic dispersion 5. The coated strand is next passed through a pelletizer 9, or other chopping device, comminuting the coated strand into pre-dried pellets 11 which fall onto a conveyer belt 12 which allows for the pre-dried pellets to air dry or optionally passes the pre-dried pellets 11 through a heat source such as an oven 6 in which the water of the dispersion is driven off, i.e., the pre-dried pellets 11 are dried and/or the thermoplastic resin is fused providing pellets 10 of the electrically conductive long fiber thermoplastic concentrate of the invention. If necessary, the dried pellets scraped from the conveyer belt by a scraper 14. The strand may be drawn through the apparatus by the pelletizing unit 9 or optionally, a draw-off device 8. Optionally, the coated strand may be passed through a shaping device 13 at any point between the bath 4 and the pelletizing unit 9. Any method to transport the predried pellets 11 to the oven 6 is acceptable, for example in alternative to a conveyer belt, transporting them with a stream such as a stream of air. As a process for producing the electrically conductive long fiber thermoplastic concentrate of the present invention, a process other than the ones described hereinabove, may be employed. For example, the fiber bundle may be cut into a prescribed length to obtain long chopped strands, then a thermoplastic resin dispersion may be coated on the long chopped strands by a method such as spraying, followed by heating to obtain dried and/or fused pellets. The preferred method of applying the thermoplastic resin to the electrically conductive fiber is a continuous method, wherein the roving strands are passed through a bath of an aqueous thermoplastic dispersion. If desired, the strands may be opened by any suitable means prior to introduction into the bath of aqueous thermoplastic dispersion or while immersed in the resin bath, and the amount of resin picked up by the strand is controlled by one or more of the following: a. speed of strand through the dispersion, b. concentration of the thermoplastic in the dispersion, c. viscosity of the thermoplastic dispersion, d. the degree to which the excess resin is wiped off by a suitable mechanism such as passing the strand through a shaping device, for example a restricting orifice. After passage of the strand through the melt-kneaded thermoplastic dispersion, it can then be passed through an oven maintained above the softening temperature, e.g., glass transition temperature or melting point, of the thermoplastic, typically 5O⁰C to 25O⁰C to remove water and/or other volatiles and to fuse the resin. The specific temperatures employed in the oven will depend upon the resins employed. As mentioned hereinabove, the strand may be passed through the oven before or after it has been chopped into long fiber pellets. If desired, the strand may be further heated prior to pelletizing in order to bring the strand to proper pelletizing temperature.

The pellets are three dimensional and may be described by their length, width, and height "h". The longest dimension is its length "I". "Long" fiber means fibers equal to or greater than 0.125 inch in length, whereas "short" fibers refer to fibers less than 0.125 inch in length. The electrically conductive long fiber thermoplastic concentrate pellet of the present invention has a length equal to or greater than about 0.125 inch, preferably equal to or greater than about 0.188 inch, and most preferably equal to or greater than about 0.25 inch. The electrically conductive long fiber thermoplastic concentrate pellet of the present invention has a length equal to or less than about 5 inches, preferably equal to or less than about 2.5 inches, even more preferably equal to or less than about 1 inch, even more preferably equal to or less than 0.5 inch, and most preferably equal to or less than about 0.313 inch.

The cross sectional shape of the pellet is not critical and is largely dependent on the intended application the electrically conductive long fiber concentrate is used for and/or the design of the shaper 13. For example, the strand prior to pelletizing can be shaped like a ribbon, a rectangle, a square, a triangle, an oval, circular, a circle, or other possible geometric shapes, preferably circular or oval like. If the shape is not circular, it can be described by its width; "w" which is the second longest dimension after the length and the height "h" which is the smallest dimension. If the strand or resulting pellet is circular its width and height are about the same and its cross sectional shape may be described by its diameter "d". Preferably, the smallest dimension of the pellet (i.e., h or d if circular) is equal to or greater than about 0.0156 inch, preferably equal to or greater than about 0.0313 inch, more preferably equal to or greater than about 0.0469 inch and most preferably about 0.0625 inch. Preferably, the smallest dimension of the pellet (i.e., h or d if circular) is equal to or less than about 0.25 inch, preferably equal to or less than about 0.188 inch, more preferably equal to or less than about 0.125 inch.

Various types of electrically conductive fibers may be employed in the present invention. Generally, the electrically conductive fibers employed in the invention are metal fibers and/or metal coated fibers. Suitable metal fibers include, but are not limited to, copper, aluminum, silver, zinc, gold, nickel, stainless steel and alloys thereof. The metal fiber is preferably stainless steel. Suitable metal coated fibers include carbon, such as graphite, and glass fibers that are coated with a conductive metal. Generally, the metal coatings are formed from copper alloys, copper, silver, gold, tin, nickel, aluminum, zinc and alloys thereof. The electrically conductive fibers of the present invention may be one or more continuous metal fiber, one or more continuous metal coated fiber, or mixtures thereof. The preferred electrically conductive fibers of the invention are stainless steel, nickel coated carbon, silver coated glass fibers, or mixtures thereof.

It is preferred that the conductive fibers of the invention, when forming composite materials, are capable of being dispersed under sufficiently low shear forces without substantial breakage. Accordingly, preferred conductive fibers of the invention have a diameter ranging from about 2 to about 20 microns, more preferably about 3 to about 15, most preferably about 5 to about 10 microns. The fibers of the invention may be provided from a variety of sources including a bushing of molten reinforcing material, e.g., glass, or one or more spools or other packages of preformed fibers which are conductive or may be rendered conductive. For example, an in-line process may be employed in which glass fibers are continuously formed from a molten glass material. These glass fibers may then be coated with a metal via known processes, such as electroplating or chemical vapor deposition, such that conductive, metallized glass fibers are formed. Preferably, however, the electrically conductive fibers are fed off-line from a package or spool.

Additionally, it is possible to feed a mixture of conductive fibers and/or a mixture of conductive and nonconductive fibers to the impregnating bath to form an impregnated tow. For example, it is possible to feed a side by side configuration of conductive fibers and non-conductive fibers to the impregnating bath to form an impregnated tow. Examples of suitable lower conductive and/or non-conductive fibers are inorganic fibers such as glass fibers, carbon fibers, or organic fibers such as ones made from polypropylene; polyamide, e.g., NYLON™; polytetrafluoroethylene, e.g., TEFLON™; polyester, for example polybutylene terephthalate and polyethylene terephthalate; aromatic polyamide, e.g., ARAMID™; ultra high molecular weight polyethylene, polybisbenzoxazole (PBO), natural fibers such as cotton, hemp, flax, jute, and the like.

In the present invention the reinforcing material is present in the long fiber-reinforced thermoplastic concentrate in an amount of equal to or greater than about 30 weight percent, preferably equal to or greater than about 50 weight percent, more preferably equal to or greater than about 70 weight percent, even more preferably equal to or greater than about 85 weight percent, and most preferably equal to or greater than about 90 weight percent, wherein weight percent is based on the weight of the long fiber-reinforced thermoplastic concentrate. In the present invention the reinforcing material is present in the long fiber-reinforced thermoplastic concentrate in an amount of equal to or less than about 99 weight percent, preferably equal to or less than about 98 weight percent, more preferably equal to or less than about 97 weight percent, and most preferably equal to or less than about 95 weight percent, wherein weight percent is based on the weight of the long fiber-reinforced thermoplastic concentrate.

In addition to the fiber-reinforcing material the long fiber-reinforced concentrate of the present invention comprises a thermoplastic coating, sometimes referred to as the matrix or carrier resin. The thermoplastic coating is applied to the fiber as an aqueous thermoplastic melt-kneaded dispersion. The thermoplastic resin used in the aqueous thermoplastic melt-kneaded dispersion is not particularly limited, and it is possible to employ, for example, polyethylene (PE), polypropylene (PP), thermoplastic polyurethane (TPU), polyamide (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), a styrene and acrylonitrile copolymer (SAN), an acrylonitrile, styrene, and butadiene terpolymer (ABS), polyphenylene oxide (PPO) or sometimes referred to as polyphenylene ether (PPE), polyacetal, polyetherimide, polycarbonate (PC), blends thereof, e.g., PC/ABS, PPO/PS, and the like.

In the present invention, the thermoplastic resin has a weight average molecular weight (Mw) of from about 5,000 to about 5,000,000, from about 20,000 to about 1,000,000, from about 100,000 to about 500,000, or from about 150,000 to about 300,000 and a weight average molecular weight/number average molecular weight (Mw/Mn, sometimes referred to as a "polydispersity index" (PDI)) ranging from a lower limit of 1.01, 1.5, or 1.8 to an upper limit of 20, 10₁ 5, or 3.

Preferably, when the thermoplastic resin matrix of the long fiber-reinforced thermoplastic concentrate of the present invention is added to the same type of non-reinforced thermoplastic resin, the matrix resin has a Mw compatible with the non-reinforced thermoplastic resin it is being combined with. As used herein, "compatible Mw" means a Mw of the long fiber-reinforced thermoplastic matrix resin that is within ± 75 percent of the Mw value for the non-reinforced resin, preferably ± 50 percent, more preferably ± 35 percent, even more preferably about ± 25 percent, and most preferably ± 10 percent of the Mw value for the non-reinforced resin. Preferably, when the thermoplastic resin matrix of the long fiber-reinforced thermoplastic concentrate of the present invention is added to a different type of non-reinforced thermoplastic, the matrix resin has a viscosity compatible with the non-reinforced thermoplastic resin it is being combined with. As used herein, "compatible viscosity" means a viscosity of the long fiber-reinforced thermoplastic matrix resin that is within ± 75 percent of the viscosity value for the non-reinforced resin, preferably ± 50 percent, more preferably ± 35 percent, even more preferably about ± 25 percent, and most preferably + 10 percent of the viscosity value for the non-reinforced resin. Viscosity values can be determined by any standard test method applicable to a specific thermoplastic.

Alternatively, "compatible" means that the addition of the matrix resin from the long fiber- reinforced thermoplastic concentrate of the present invention to the non-reinforced thermoplastic resin, whether it is the same type of thermoplastic resin or different, does not cause deleterious effects to the non-reinforced resin, for example, delamination, loss of physical properties, loss of thermal properties, loss of mechanical properties, loss of heat and/or color stability, or combinations thereof. A preferred thermoplastic matrix resin is a copolymer, sometimes referred to as an interpolymer, of ethylene with a C₃ to C₂₀ alpha-olefin. A preferred ethylene and alpha-olefin copolymer is a polyolefin elastomer having a glass transition temperature less than 25°C, preferably less than 0⁰C. Examples of suitable polyolefin elastomers include ethylene and a copolymer with an alpha-olefin such as propylene (EPM), 1-butene, 1-hexene, and 1-octene, propylene and a diene copolymer such as hexadiene or ethylidene norbornene (EPDM). A particularly preferred polyolefin elastomer is a substantially linear ethylene polymer or linear ethylene polymer (S/LEP), both are well known. Substantially linear ethylene polymers and their method of preparation are fully disclosed in USP 5,272,236 and 5,278,272 and linear ethylene polymers and their method of manufacture are fully disclosed in USP 3,645,992; 4,937,299; 4,701 ,432; 4,937,301 ; 4,935,397; and 5,055,438 the disclosures of which are incorporated herein by reference.

Another preferred thermoplastic resin is polypropylene. The propylene polymer suitable for the present invention is syndiotactic, atactic or preferably isotactic. It can be a homopolymer or a copolymer with an alpha-olefin, preferably a C₂, or C₄ to C₂₀ alpha-olefin, for example, a random or block copolymer or preferably an impact propylene copolymer. The propylene polymer may also comprise a polyolefin elastomer such as those described hereinabove, preferably a substantially linear ethylene polymer or a linear ethylene polymer.

A preferred propylene polymer is a propylene-rich alpha-olefin copolymer or interpolymer comprising 5 to 25 weight percent ethylene-derived units and 95 to 75 weight percent of propylene- derived units. In some embodiments, propylene-rich alpha-olefin copolymers having (a)- a melting point of less than 9O⁰C; a relationship of elasticity to 500 percent tensile modulus such that the elasticity is less than or equal to 0.935M+12, where elasticity is in percent and M is the 500 percent tensile modulus in mega Pascal (MPa); and a relationship of flexural modulus to 500 percent tensile modulus such that flexural modulus is less than or equal to 4.2e^α27M + 50, where flexural modulus is in MPa and M is the 500 percent tensile modulus in MPa are preferred. In some embodiments the propylene-rich alpha-olefin copolymer comprise 6 to 20 weight percent of ethylene-derived units and 94 to 80 weight percent of propylene-derived units with 92 to 80 weight percent of propylene-derived units preferred. In still other embodiments, polymers comprising 10 to 20 weight percent of ethylene-derived units and 90 to 80 weight percent of propylene-derived units. In another embodiment, a propylene-rich alpha-olefin copolymer that comprises a copolymer of propylene and at least one comonomer selected from the group consisting of C₂ and C₄ to C_2O alpha-olefins, wherein the copolymer has a propylene content of greater then 65 mole percent, a Mw of from about 15, 000 to about 200,000, a Mw/Mn of from about 1.5 to about 4 is preferred. In an other embodiment, a preferred propylene-rich alpha-olefin copolymer has a heat of fusion of less than about 80 Joule per gram (J/g), preferably from about 8 to about 80, or more preferably from about 8 to about 30 J/g as determined by differential scanning calorimeter (DSC).

A preferred thermoplastic resin is a propylene-based copolymer comprising a propylene and ethylene copolymer made using a nonmetallocene metal-centered, heteroaryl ligand catalyst as described in US Patent Application Publication No. 2003-0204017, which is incorporated by reference herein in its entirety.

Preferably, the propylene-rich copolymer comprises at least about 60 weight percent of units derived from propylene and at least about 0.1 weight percent of units derived from ethylene. The propylene and ethylene copolymers made with such nonmetallocene, metal-centered, heteroaryl ligand catalyst exhibit a unique region-error. The copolymer is characterized as having ¹³C NMR peaks corresponding to a region-error at about 14.6 and about 15.7 parts per million (ppm), which are believed to be the result of stereoselective 2,1-insertion errors of propylene units into the growing polymer chain. In this particularly preferred aspect, these peaks are about equal in intensity, and they typically represent about 0.02 to about 7 mole percent of the propylene insertions into the homopolymer or copolymer chain.

These propylene-rich polymers can be made by a number of processes, such as by single stage, steady state, polymerization conducted in a well-mixed continuous feed polymerization reactor. In addition to solution polymerization, other polymerization procedures such as gas phase or slurry polymerization may be used. Suitable processes for preparing such polymers are described in USP 6,525,157, which is incorporated herein by reference in its entirety. Further, to the thermoplastic resin, known additives such as a colorant, a flow modifier, an antistatic additive, a mold release, an impact modifier, a stabilizer, i.e., heat, light, UV, and the like, a compatibilizer, a filler (other than the fiber-reinforcing material), and the like may suitably be incorporated depending on the particular application or molding/extrusion conditions, and such additives may be used by mixing them with the resin in accordance with a conventional method.

The thermoplastic resin is applied to the electrically conductive fiber as an aqueous thermoplastic dispersion. A particularly useful aqueous thermoplastic dispersion is one of a thermoplastic resin produced by a process wherein a polymerizable monomer which is the resin raw material is polymerized by emulsion polymerization in an aqueous medium in the presence of an emulsifying agent. Advantageously, emulsion polymerized may produce high molecular weight thermoplastic resins. Examples of such aqueous thermoplastic dispersions are latexes such as grafted rubbers; acrylonitrile, butadiene, and styrene terpolymer (ABS); styrene and butadiene copolymers; styrene homopolymers, acrylates, polyurethanes, etc.

Alternatively, the aqueous thermoplastic dispersion is an aqueous melt-kneaded thermoplastic dispersion. Aqueous melt-kneaded thermoplastic dispersions are known, for example as disclosed in US Patent Application Serial Nos. 10/925693 and 11/068573; and in US Patent Nos. 6,448,321 ; 5,798,410; 5,688,842; 5,574,091; and 5,539,021; each of which is incorporated herein by reference in its entirety. The aqueous dispersion comprises, in addition to (A) at least one thermoplastic resin as disclosed hereinabove, (B) at least one dispersing agent, and (C) water. In one embodiment of the aqueous dispersion used in the present invention, it comprises (A) at least one thermoplastic resin; (B) a salt of a higher fatty acid, such as an alkali metal salt of montanic acid; and (C) water. In another embodiment the aqueous dispersion comprises (A) at least one thermoplastic resin; (B) at least one dispersing agent; and (C) water wherein the dispersion has a volume average particle size of less than about 5 micrometers. In another embodiment of the aqueous dispersion used in the present invention, it comprises (A) at least one thermoplastic resin; (B) at least one dispersing agent; and (C) water wherein the dispersion has a pH of less than about 12. In some dispersions according to any embodiment, the dispersing agent comprises less than about 4 percent by weight based on the weight of the thermoplastic resin. In some dispersions having a pH of 12 or less, the dispersion also has a volume average particle size of less than about 5 micrometers. Some dispersions that have a particle size of less than about 5 micrometers also have a pH of less than 12. In still other embodiments, the dispersion has a pH of less than 12, and an average particle size of less than about 5 micrometers, and wherein the dispersing agent comprises less than about 4 percent by weight based on the weight of the thermoplastic resin. Any suitable dispersing agent can be used. However, in particular embodiments, the dispersing agent comprises at least one carboxylic acid, a salt of at least one carboxylic acid, or carboxylic acid ester or salt of the carboxylic acid ester. One example of a carboxylic acid useful as a dispersant is a fatty acid such as montanic acid, a preferred salt of montanic acid is the alkali metal salt of montanic acid. In some preferred embodiments, the carboxylic acid, the salt of the carboxylic acid, or at least one carboxylic acid fragment of the carboxylic acid ester or at least one carboxylic acid fragment of the salt of the carboxylic acid ester has fewer than 25 carbon atoms. In other embodiments, the carboxylic acid, the salt of the carboxylic acid, or at least one carboxylic acid fragment of the carboxylic acid ester or at least one carboxylic acid fragment of the salt of the carboxylic acid ester has 12 to 25 carbon atoms. In some embodiments, carboxylic acids, salts of the carboxylic acid, at least one carboxylic acid fragment of the carboxylic acid ester or its salt has 15 to 25 carbon atoms are preferred. In other embodiments, the number of carbon atoms is 25 to 60. Some preferred salts comprise a cation selected from the group consisting of an alkali metal cation, alkaline earth metal cation, or ammonium or alkyl ammonium cation.

In still other embodiments, the dispersing agent is selected from the group consisting of ethylene carboxylic acid polymers, and their salts, such as ethylene acrylic acid copolymers or ethylene methacrylic acid copolymers.

In other embodiments, the dispersing agent is selected from alkyl ether carboxylates, petroleum sulfonates, sulfonated polyoxyethylenated alcohol, sulfated or phosphated polyoxyethylenated alcohols, polymeric ethylene oxide/propylene oxide/ethylene oxide dispersing agents, primary and secondary alcohol ethoxylates, alkyl glycosides and alkyl glycerides. Combinations any of the above-enumerated dispersing agents can also be used to prepare some aqueous dispersions.

Some dispersions described herein have an advantageous particle size distribution. In particular embodiments, the dispersion has a particle size distribution defined as volume average particle diameter (Dv) divided by number average particle diameter (Dn) of less than or equal to about 2.0. In other embodiments, the dispersion has a particle size distribution of less than or equal to about less than 1.5.

The term "dispersion" as used herein is intended to include within its scope both emulsions of essentially liquid materials, prepared by employing the thermoplastic resin and the dispersing agent, and dispersions of solid particles. Such solid dispersions can be obtained, for example, by preparing an emulsion and then causing the emulsion particle to solidify by various means. Thus, when the components are combined, some embodiments provide an aqueous dispersion wherein content of the dispersing agent is present in the range of from 0.5 to 30 parts by weight, and content of (C) water is in the range of 1 to 35 percent by weight per 100 parts by weight of the thermoplastic polymer; and total content of (A) and (B) is in the range of from 65 to 99 percent by weight. In particular embodiments, the dispersing agent ranges from 2 to 20 parts by weight based on 100 parts by weight of the polymer. In some embodiments, the amount of dispersing agent is less than about 4 percent by weight, based on the weight of the thermoplastic polymer. In some embodiments, the dispersing agent comprises from about 0.5 percent by weight to about 3 percent by weight, based on the amount of the thermoplastic polymer used. In other embodiments, about 1.0 to about 3.0 weight percent of the dispersing agent are used. Embodiments having less than about 4 weight percent dispersing agent are preferred where the dispersing agent is a carboxylic acid.

One feature of some embodiments of the invention is that the dispersions have a small particle size. Typically the average particle size is less than about 5 micrometer. Some preferred dispersions have an average particle size of less than about 1.5 micrometer. In some embodiments, the upper limit on the average particle size is about 4.5 micrometer, 4.0 micrometer, 3.5 micrometer, 3.75 micrometer, 3.5 micrometer, 3.0 micrometer, 2.5 micrometer, 2.0 micrometer, 1.5 micrometer, 1.0 micrometer, 0.5 micrometer, or 0.1 micrometer. Some embodiments have a lower limit on the average particle size of about 0.05, 0.7 micrometer, 0-.1 micrometer, 0.5 micrometer, 1.0- micrometer, 1.5 micrometer, 2.0 micrometer, or 2.5 micrometer. Thus, some particular embodiments have, for example, an average particle size of from about 0.05 micrometer to about 1.5 micrometer. While in other embodiments, the particles in the dispersion have an average particle size of from about 0.5 micrometer to about 1.5 micrometer. For particles that are not spherical the diameter of the particle is the average of the long and short axes of the particle. Particle sizes can be measured on a Coulter LS230 light-scattering particle size analyzer or other suitable device.

While any method may be used, one convenient way to prepare the dispersions described herein is by melt-kneading. Any melt-kneading means known in the art may be used. In some embodiments a kneader, a Banbury mixer, single-screw extruder, or a multi-screw extruder is used. The melt-kneading may be conducted under the conditions which are typically used for melt- kneading the thermoplastic resin (A). A process for producing the dispersions in accordance with the present invention is not particularly limited. One preferred process, for example, is a process comprises melt-kneading the above-mentioned components according to USP 5,756,659. A preferred melt-kneading machine is, for example, a multi screw extruder having two or more screws, to which a kneading block can be added at any position of the screws. If desired, it is allowable that the extruder is provided with a first material-supplying inlet and a second material-supplying inlet, and further third and forth material-supplying inlets in this order from the upper stream to the down stream along the flow direction of a material to be kneaded. Further, if desired, a vacuum vent may be added at an optional position of the extruder. In some embodiments, the dispersion is first diluted to contain about 1 to about 3 percent by weight of water and then subsequently further diluted to comprise greater than 25 percent by weight of water. In some embodiments, the further dilution provides a dispersion with at least about 30 percent by weight of water. The aqueous dispersion obtained by the melt kneading may be further supplemented with an aqueous dispersion of an ethylene-vinyl compound copolymer, or a dispersing agent. The aqueous thermoplastic dispersions described hereinabove may be used as prepared or diluted further with water to provide a thermoplastic resin level equal to or less than about 70 weight percent, preferably equal to or less than about 55, and more preferably equal to or less than about 45 weight percent. The aqueous thermoplastic dispersions described hereinabove may be used as prepared or diluted further with water to provide a thermoplastic resin level equal to or greater than about 10 weight percent, preferably equal to or greater than about 15, and more preferably equal to or greater than about 20 weight percent.

The aqueous dispersion may be coated onto a substrate by various procedures, and for example, by spray coating, curtain flow coating, coating with a roll coater or a gravure coater, brush coating, preferably dipping or drawing through a bath. The coating is preferably dried and/or fused by heating the coated substrate to 50⁰C to 150°C for 1 to 300 seconds although the drying and/or fusing may be accomplished by any suitable means including air drying at ambient temperature.

To illustrate the practice of this invention, examples of preferred embodiments are set forth below. However, these examples do not in any manner restrict the scope of this invention.

EXAMPLES

Example 1

316 Stainless steel (SS) fiber (with about 4,500 strands per tow, available from M2 Fiber,

Korea), and Nickel-Carbon (NiC) fiber (with about 12,000 strands per tow, 12K50, available from lnco Special Products, Inc) are drawn according to the process described in FIG. 1 independently through a bath of Latex (available from The Dow Chemical Company as DL 460NA S/B Latex) and Dl water at an overall thermoplastic resin content of about 10.5 percent. The fiber strands are pressed and air dried overnight, total fiber weight fraction within the strands is about 0.911 for both the NiC and the SS. Following drying, the fiber tows are chopped into about 4 to 6 mm lengths. Chopped fiber tows are dry blended with polycarbonate (available from The Dow Chemical Company as CALIBRE™ 401-18 Polycarbonate Resin) such that the volume (Vf) contents of SS and NiC materials are about 0.0064 and 0.03, respectively. This mixture is molded into plaques 1.8 mm thick on a Krauss-Maffei KM110-390/390CL molding machine (3.5 cm (1.38") screw diameter, 23 L/D ratio). Barrel temperatures are (from nozzle to throat): 296/296/291/291/282°C (565/565/555/555/540⁰F) and the mold temperature is 66°C (150°F).

Example 2

316 SS fiber (with about 4,500 strands per tow, from M2 Fiber, Korea), and NiC fiber (with about 12,000 strands per tow, 12K50, from lnco Special Products, Inc.) are independently drawn according to the process described in FIG. 1 through a bath of thermoplastic polymer dispersion (an ethylene-octene substantially linear ethylene copolymer (S/LEP-1) having a 500 melt index (Ml) and a density of 0.87 grams per cubic centimeter (g/cc), the dispersion having an overall thermoplastic resin content of about 50 percent. The fiber strands are pressed and air dried overnight, the total fiber weight fraction within the strands is about 0.77 for the stainless steel, and about 0.71 for the NiC. Following drying, the fiber tows are chopped into about 4 to 6 mm lengths. Chopped fiber tows are dry blended with polycarbonate (CALIBRE 401-18 Polycarbonate Resin) such that the volume contents of SS and NiC materials are about 0.0064 and 0.03, respectively. This mixture is molded into plaques 1.8 mm thick on a Krauss-Maffei KM110-390/390CL molding machine (3.5 cm (1.38") screw diameter, 23 L/D ratio). Barrel temperatures are (from nozzle to throat): 296/296/291/291/282°C (565/565/555/555/54O⁰F) and the mold temperature is 66°C (150°F). Comparative Examples 1 and 2

Comparative Examples 1 and 2 are prepared at identical loadings as Examples 1 and 2, respectively, using pellets manufactured via standard thermoplastic extrusion/pultrusion methods. PC-impregnated stainless steel fiber tows are purchased from Bekaert Fibers (GR75/C20 product designation, with about 12,000 strands per tow), and PC-impregnated NiC fiber is purchased from lnco Special Products (Inco PC with about 12,000 strand per tow). The total fiber weight fraction within the stainless steel and NiC tows is about 0.75 and about 0.60, respectively. The fiber tows are about 4-6 mm lengths. The fiber tows are dry blended with polycarbonate (CALIBRE 401-18 Polycarbonate Resin) such that the volume contents of SS and NiC materials are about 0.0064 and 0.03, respectively. This mixture is molded into plaques 1.8 mm thick on a Krauss-Maffei KM110- 390/390CL molding machine (3.5 cm (1.38") screw diameter, 23 L/D ratio). Barrel temperatures were (from nozzle to throat): 296/296/291/291/282°C (565/565/555/555/540⁰F) and a mold temperature of 66°C (150⁰F). Example 3

316 SS fiber (with about 4,500 strands per tow, from M2 Fiber, Korea), and NiC fiber (with about 12,000 strands per tow, 12K50, from lnco Special Products, Inc) is drawn according to the process described in FIG. 1 through an aqueous melt-kneaded thermoplastic polymer dispersion (Dow, ENGAGE™ 8407, ethylene-octene substantially linear ethylene copolymer (S/LEP-2) having a 30 Ml and a density of 0.87 g/cc, with an overall thermoplastic resin content of about 50 percent. The fiber strands are dried with the aid of a heat gun and the total fiber weight fraction within the strands is about 0.65 for the stainless steel and about 0.51 for the NiC. Following drying, the fiber tows are chopped into about 4 to 6 mm lengths. Chopped fiber tows are dry blended with polycarbonate (CALIBRE 401-18 Polycarbonate Resin) such that the volume contents of SS and NiC materials are about 0.015 and 0.03, respectively. This mixture is molded into plaques 1.8 mm thick on-a Krauss-Maffei KM110-390/390CL molding machine (3.5 cm (1.38") screw diameter, 23 L/D ratio). Barrel temperatures are (from nozzle to throat): 296/296/291/291/282°C (565/565/555/555/540°F) and a mold temperature of 66°C (150⁰F). The shielding results for Examples 1 to 3 and Comparative Examples A and B are summarized in Table 1. The method used to measure Shielding Effectiveness (SE) is ASTM D 4935. SE values are reported in decibels (dB) and are averaged responses over 30 megahertz (MHz) to 2 gigahertz (GHz). Table 1

Claims

CLAIMS:

1. A method to make an electrically conductive long fiber concentrate comprising electrically conductive fibers and a thermoplastic resin comprising the steps of: i coating continuous electrically conductive fibers with an aqueous thermoplastic dispersion to form thermoplastic coated continuous electrically conductive fiber strands, ii drying and/or fusing the thermoplastic coated continuous electrically conductive fiber strands, iii chopping the dried thermoplastic coated continuous electrically conductive fiber strands forming dried electrically conductive long fiber concentrate pellets, and iv isolating dried electrically conductive long fiber concentrate pellets.

2. A method to make an electrically conductive long fiber concentrate comprising electrically conductive fibers and a thermoplastic resin comprising the steps of: i coating continuous electrically conductive fibers with an aqueous thermoplastic dispersion to form thermoplastic coated continuous electrically conductive fiber strands, ii chopping the thermoplastic coated continuous electrically conductive fiber strands forming electrically conductive long fiber concentrate pellets, iii drying and/or fusing the electrically conductive long fiber concentrate pellets, and iv isolating dried electrically conductive long fiber concentrate pellets.

3. A method to make an electrically conductive long fiber concentrate comprising electrically conductive long fibers and a thermoplastic resin comprising the steps of: i coating chopped electrically conductive long fibers with an aqueous melt-kneaded thermoplastic dispersion to form thermoplastic coated chopped electrically conductive long fiber pellets, ii drying and/or fusing the coated chopped electrically conductive long fiber concentrate pellets, and iii isolating dried electrically conductive long fiber concentrate pellets.

4. The method of Claim 1, 2, or 3 wherein the aqueous dispersion is an aqueous melt-kneaded thermoplastic dispersion or an emulsion polymerized aqueous thermoplastic dispersion.

5. The method of Claim 4 wherein the aqueous melt-kneaded thermoplastic dispersion comprises a thermoplastic resin, a dispersing agent, and water.

6. The method of Claims 1 , 2, or 3 wherein the thermoplastic resin is polyethylene, polypropylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, a styrene and acrylonitrile copolymer, an acrylonitrile, styrene, and butadiene terpolymer, polyphenylene oxide, polyacetal, polyetherimide, polycarbonate, or blends thereof.

7. The method of Claim 6 wherein the thermoplastic polyethylene resin is an ethylene and alpha-olefin copolymer.

8. The method of Claim 7 wherein the thermoplastic polyethylene resin is a substantially linear ethylene polymer or a linear ethylene polymer.

9. The method of Claim 6 wherein the thermoplastic polypropylene resin is a propylene-rich and alpha-olefin copolymer.

10. The method of Claim 9 wherein the thermoplastic polypropylene-rich resin is a propylene and ethylene copolymer comprising at least about 60 weight percent of units derived from propylene and at least about 0.1 weight percent of units derived from ethylene made using a nonmetallocene metal-centered, heteroaryl ligand catalyst characterized as having ¹³C NMR peaks corresponding to a region-error at about 14.6 and about 15.7 parts per million wherein these peaks are about equal in intensity.

11. The method of Claim 5 wherein the aqueous melt-kneaded thermoplastic dispersion comprises from about 10 to about 70 weight percent thermoplastic resin.

12. The method of Claim 5 wherein the dispersing agent is a carboxylic acid, a salt of a carboxylic acid, a carboxylic acid ester, a salt of an acid ester, an ethylene carboxylic acid polymer, a salt of an ethylene carboxylic acid polymer, an alkyl ether carboxylate, a petroleum sulfonate, a sulfonated polyoxyethylenated alcohol, a sulfated polyoxyethylenated alcohol, a phosphated polyoxyethylenated alcohol, a polymeric ethylene oxide/propyleneoxide/ethylene oxide dispersing agent, a primary alcohol ethoxylate , a secondary alcohol ethoxylate, an alkyl glycoside, an alkyl glyceride, or combinations thereof.

13. The method of Claim 5 wherein the dispersing agent is montanic acid, an alkali metal salt of montanic acid, an ethylene acrylic acid copolymer, an ethylene methacrylic acid copolymer, or combinations thereof.

14. The method of Claim 5 wherein the dispersion has a volume average particle size of less than about 5 micrometers.

15. The method of Claim 5 wherein the dispersion has a pH of less than 12.

16. The method of Claim 5 wherein the dispersion has a volume average particle size of less than about 5 micrometers, a pH of less than about 12, and the dispersing agent comprises less than about 4 percent by weight based on the weight of the thermoplastic resin.

17. The method of Claim 1, 2 or 3 wherein the electrically conductive fiber is copper, aluminum, silver, zinc, gold, nickel, stainless steel, or alloys thereof.

18. The method of Claim 1 , 2 or 3 wherein the electrically conductive fiber is a metal coated fiber of carbon or glass fibers coated with a copper alloy, copper, silver, gold, tin, nickel, aluminum, zinc or alloys thereof.

19. The method of Claim 1, 2 or 3 wherein the electrically conductive fiber is one or more inherently conductive organic fiber.

20. The method of Claim 1, 2 or 3 wherein the electrically conductive fiber is one or more metal fiber, one or more metal coated fiber, one or more inherently conductive organic fiber, or mixtures thereof.

21. The method of Claim 20 wherein the electrically conductive fiber is stainless steel, metal- coated carbon fibers, or combinations thereof.

22. The method of Claim 1 , 2 or 3 wherein step i further comprises coating a non-conductive fiber.

23. An electrically conductive long fiber thermoplastic concentrate of Claim 1 , 2, or 3 comprising a conductive fiber level of between 85 to 99 weight percent based on the weight of the electrically conductive long fiber thermoplastic concentrate.

24. An electrically conductive long fiber thermoplastic composition comprising a thermoplastic resin and the electrically conductive long fiber thermoplastic concentrate of Claims 1 , 2, or 3.

25. A method for producing an electrically conductive long fiber thermoplastic article comprising the steps of: i dry blending the electrically conductive long fiber thermoplastic concentrate of Claims 1, 2, or 3 with a non-conductive thermoplastic resin and ii injection molding or extruding said blend to form an injection molded or extruded electrically conductive long fiber thermoplastic article.

26. A molded or extruded thermoplastic article comprising the electrically conductive long fiber thermoplastic concentrate of Claims 1, 2, or 3.