Highly conductive molding compounds for use as fuel cell plates and the resulting products

Abstract

A conductive polymer is disclosed which is suitable for use in applications which require corrosion resistance including resistance to corrosion when subjected to acidic flow at temperature ranging from −40 to 140 degrees Fahrenheit and which can be molded such as by compression and/or injection molding techniques, into highly intricate and thin specimens without significant post machining. and which exhibit consistent conductivity, sufficient strength and flexibility, and appropriate surface characteristics. In particular the invention involves molding resin composition, which have high loadings of conductive fillers. Further the compositions may include rheological modifiers such as Group II oxides and hydroxides; carbodiamides; aziridines; polyisocyanates; polytetrafluorethylene (PTFE); perfluoropolyether (PFPE), and polyethylene. In an additional embodiment of the invention, an anti-shrink additive is added to improve the characteristics of the molded fuel cell plate.

Description

[0001] THIS PATENT APPLICATION IS A CONTINUATION-IN-PART APPLICATION OF U.S. PROVISIONAL PATENT APPLICATION Ser. No. 601211,582, FILED Jun. 15, 2000 WHICH IS A CONTINUATION-IN-PART APPLICATION OF U.S. patent application Ser. No. 09/526,641,FILED Mar. 16,2000, BASED UPON U.S. PROVISIONAL APPLICATION Ser. No. 60/125,138, FILED Mar. 3, 1999.

FIELD OF INVENTION

[0002] The field of invention is highly conductive compositions that are particularly useful for molding processes such as those using thermosetting bulk molding compositions. Further, in an additional embodiment, these compositions are useful for novel injection, and injection/compression molding processes.

[0003] These molding compositions can be formed into high definition complex configurations, including configurations, which are particularly suitable for injections molding techniques. For example, they can be molded into thin plate-like specimens (e.g. 60 to 200 thousandths of an inch) having an intricately patterned network of very narrow, relatively smooth, flow passages. Moreover in accordance with the present invention, these labyrinthine plates can be made substantially exclusively by molding, meaning that the need for complex and expensive machining processes is virtually eliminated. Such specimens are used as electrochemical cell bipolar plates. These plates desirably have a bulk conductivity of at least 40, 50, 60, 70, 80, 90 or even 96 S/cm. They also have desirable surface characteristics; heat, temperature, chemical and shrink resistance; strength; and cost.

BACKGROUND OF THE INVENTION

[0004] Conductive polymers have applications in providing alternatives to traditional conductive materials, which often involve greater labor expenses to manufacture into complex parts. In particular, in instances where the demand justifies significant volumes of a product, polymer-molding expenses may prove far more cost effective than comparable machining expenses for other materials. However in the past, it has proved difficult to achieve both a high level of conductivity and desirable molding characteristics. Generally, high-level weight percentages of an appropriate filler in a polymeric matrix are necessary to achieve satisfactory levels of conductivity. However, these high load levels lead to problems with the strength, durability, and moldability of the resulting composition.

[0005] One area in particular where it would be beneficial to solve the previously mentioned strength, durability, and molding issues is for application in fuel cells. Electrochemical fuel cells have great appeal as a potentially limitless energy source that is clean and environmentally friendly. These fuel cells can, in addition, be constructed at an appropriate scale for small-scale energy consumption, such as household use, or for industrial scale use, and even for commercial power generation. They have portable applications to power small appliances (such as computers or camping equipment), or automobiles and other forms of transportation. Although these different applications involve differences in size, the fundamental construction remains the same for generation of power varying from less than one to a few thousand kilowatts.

[0006] Basically, a fuel cell is a galvanic cell in which the chemical energy of a fuel is converted directly into electrical energy by means of an electrochemical process. The fundamental components of the fuel cell are an electrode comprising an anode and a cathode, eletrocatalysts, and an electrolyte. Work has been done in perfecting both liquid and solid electrolyte fuel cells and the present invention may find use in both types of fuel cells.

[0007] Solid electrolytes include polymeric membranes, which act as proton exchange membranes typically fueled by hydrogen. These membranes usually comprise a perfluorinated sulphonic acid polymer membrane sandwiched between two catalyzed electrodes that may utilize platinum supported on carbon as an electrocatalyst. Hydrogen fuel cells form a reaction chamber, which consumes hydrogen at the anode. At the cathode, oxygen reacts with protons and electrons at the electrocatalytic sites yielding water as the reaction product. A three-phase interface is formed in the region of the electrode and a delicate balance must be maintained between the electrode, the electrolyte, and the gaseous phases.

[0008] Systems involving the use of other electrolytes have been also been studied. These would include alkaline fuel cells, phosphoric acid fuel cell, molten carbonate fuel cells, and solid oxide fuel cells. However, the principles are similar, as are some of the issues in perfecting these products.

[0009] A fuel cell reactor may comprise a single-cell or a multi-cell stack. In any case, the cell includes at least two highly conductive flow field plates that serve multiple functions. These plates may function as current collectors that provide electrical continuity between the fuel cell voltage terminals and electrodes. They also provide mechanical support (for example for the membrane/electrode assembly). In addition, these plates act to transport reactants to the electrodes and are essential to establishing the previously mentioned delicate phase balance.

[0010] Typically, the fuel cell plates are thin relatively flat plate members that include a highly complex network of interconnecting channels that form the flow field area of the plate. The configuration of these channels is highly developed in order to maintain the proper flow of reactants and to avoid channeling or the formation of stagnant areas, which results in poor fuel cell performance. It is critical that the flow of the reactants is properly managed, and that the electrocatalysts are continuously supplied with precisely the appropriate balance of reactants. Thus, it is essential for the plates to define and maintain clear passages within the highly engineered flow labyrinth. Moreover, in order to assure a satisfactory life, the plates must be able to resist surface corrosion under a variety of conditions. For example, fuel cells may be placed outside and subject to ambient weather. Thus, the cells must be resistant to stress cracking and corrosion at temperature ranging from −40 to 200 degrees Fahrenheit. Further, since the conditions within the cell are corrosive, the cells must also be resistant to chemical attack at these temperatures from various corrosive substances. For example, the plates may be subjected to de-ionized water, methanol, formic acid, formaldehyde, heavy naptha, hydrofluoric acid, tertafluoroethylene, and hexafluoropropylene depending on the fuel cell type. Moreover, the conditions within the fuel cell may lead to elevated temperatures, i.e. from 150 to 200 degrees Fahrenheit, as well as elevated pressures, i.e. from ambient to 30 p.s.i. Corrosive decomposition needs to be avoided since it almost certainly would cause a system failure by changing the flow patterns within the fuel cell.

[0011] Past attempts at solving the various requirements for fuel cell plates have included the use of metal and machined graphite plates. The use of metal plates result in higher weight per cell, higher machining costs and possibly corrosion problems. Machined graphite plates solve the weight and corrosion problems but involve high machining cost and result in fragile products, especially when prepared as very thin plates. Some use of graphite/poly(vinylidene fluoride) plates has been made but these have been characterized as being expensive and brittle and having long cycle times.

[0012] U.S. Pat. No. 4,197,178 is incorporated herein for its teaching of the working and compositions of electrochemical cells. U.S. Pat. No. 4,301,222 is incorporated herein for its teachings on graphite-based separators for electrochemical cells.

SUMMARY OF THE INVENTION

[0013] In the past, known conventional bulk molding compounds have been modified to be conductive by the addition of large amounts of conductive filler, such as graphite. During molding it was observed that the liquid resin phase separated from the filler and was exuded from the molding. Further, it was observed that this occurrence tended to cause cracking in molded specimens that were thin. Moreover, bulk conductivity measurements at different locations within the specimen were inconsistent. In accordance with the present invention, it was discovered that compositions could be formulated which solved the foregoing issues. In particular, the formulations involve the use of a resin matrix with high loadings of a conductive filler; various additional additives, such as initiators, mold-release agents, and carbon black; and optionally one or more rheological agents selected from the group comprising group II oxides, alkaline earth oxides, carbodiamides, polyisocynates, polyethylene and polytetraethylene fluoethylene. One possible explanation for the mechanism by which the molding agents work, is that they act to build the apparent molecular weight of the prepolymer (e.g. vinyl ester resin or unsaturated polyester resin). Alternatively, these agents may promote flow such as by reducing shear during molding. The use of these rheological agents eliminates phase separation, as well as cracking and inconsistent conductivity measurements. It is anticipated that these problems are a result of the complex configuration of the specimens being molded along with the very high concentrations of conductive filler.

[0014] In addition to solving molding and cracking problems it is anticipated that other properties such as the coefficient of thermal expansion, electrical and thermal conductivity, shrink resistance and mechanical properties may be more uniform and/or otherwise improved as a result of the use of the present invention. In addition to the foregoing improvements it was found that a resin composition of the invention demonstrated a higher glass transition temperature and resulted in an improvement in the hot strength of the molded part. Further improvements are also possible by optimizing both gel time and cure time for the prepolymer by controlling initiator type and amount and inhibitor type and amount. Additionally, in a yet further embodiment of the invention, a low shrink additive is added to the composition which acts to help perfect the surface characteristics of the molded plate made in accordance with the invention. These additives are generally used in the range of 10 to 50 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers. For the purpose of this invention, the term “low shrink additive” is used but may encompass additives which are also termed “low profile additives” and help to reduce the roughness of the surface. Resins may have a tendency to shrink during cure which results in surface defects such as sink marks and microscopic irregularities. Other problems include internal voids and cracks, as well as warpage and inability to mold to close tolerances. For molded fuel cell plates, these imperfections inhibit the ability of the resultant product to contact the proton exchange membrane. The “low profile additives” of the present invention help to compensate for shrinkage and improve the surface smoothness. Further, eliminating the shrink problems results in better stacking of the plates and a better overall fuel cell.

[0015] The foregoing improvements in specimens molded from these compositions enable the low cost mass production of bipolar plates as an additional embodiment of the invention. These could be used for portable fuel cells, as well as stationary power units.

[0016] In a further embodiment of the invention, the following compositions can be used in a new molding process to accomplish injection molding. In particular, the process of the present invention involves using a double auger to convey the highly loaded molding compositions of the present invention to the feed throat of an injection molding apparatus. This process contrasts to the traditional process using a hydraulic ram to port the molding composition to the feed throat. However, the traditional molding methods and equipment would fail with potentially catastrophic results when the composition would pack out during the molding process. It is more preferred that a double auger system with a first and larger horizontally oriented screw, which feeds the smaller vertical type auger feeding into the feed throat. Further, the process involves some zoned temperature gradients with a first and second zone in the first screw barrel having a temperature of from about 90 to about 150 degrees F, and more particularly about 110 to about 140 degrees F. A third zone is located at the mold. This zone is maintained at about 275 to about 325 (i.e. 300 F) which is the temperature at which cure is initiated for most of the compositions in accordance with the invention. It is preferable to avoid temperature variations at the mold level. At normal cure rates, the mold time is typically around 10 to 600 seconds, or more usually 30 to 300 seconds or around one or two minutes. The process can be practiced for single or double gate cavity tools, or even for injection/compression processes in which the mold is slightly opened during fill and the mold is shut to compress the shot.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is an illustration of a fuel cell assembly utilizing a bipolar cell plate;

[0018] FIG. 2 is an illustration of a bipolar fuel cell plate that can be made in accordance with the present invention;

[0019] FIG. 3 is an illustration of a process failure for composition in accordance with the present invention molded using the convention hydraulic ram injection molding process;

[0020] FIG. 4 is an illustration of the mold plug shown in FIG. 3; and

[0021] FIG. 5 is a schematic illustration of the molding equipment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The invention relates to improvements in conductive molding compositions. In particular, the compositions can be used in compression molding processes and in injection molding processes. Further these compositions enable the production of thin and intricate specimens that have high concentrations of conductive filler.

[0023] Sheet molding and bulk molding compositions are described in U.S. Pat. Nos. 5,998,510; 5,342,554; 5,854,317; 5,744,816; and 5,268,400; all of which are hereby incorporated by reference for their teachings on the various modifications to molding compositions that are known to the art.

[0024] One component of a molding resin composition is a crosslinkable prepolymer such as an unsaturated polyester resin or vinyl ester resin. Desirably the prepolymer has a relatively low molecular weight such as from about 200 to about 5000 (weight average). They are described in detail with examples in the above patents incorporated by reference. The polyester resins are the condensation product derived from the condensation of unsaturated polybasic acids and/or anhydrides with polyols such as dihydroxy or trihydroxy compounds. Desirably, these polyester resins are the esterification reaction product of diacids, or anhydrides of diacids, generally having from about 3 to about 12, or more preferably from about 4 to about 8 carbon atoms, with a polyol or a cyclic ether having from about 2 to about 12, or more preferably from about 2 to about 6 carbon atoms.

[0025] In general, the vinyl ester resins that can be used are the reaction products of epoxy resins and a monofunctional ethlenically unsaturated carboxylic acid. More specifically, these vinyl ester resins are the reaction product of an epoxy terminated oligomer, for example, an epoxy functionalized bisphenol A with an acrylic acid, or methacrylic acid forming acrylic terminal groups on the oligomer. The vinyl esters have predominantly terminal unsaturation while the unsaturated polyesters have predominantly internal unsaturation.

[0026] Another component of the molding composition is one or more unsaturated monomers that are copolymerizable with the resin. Desirably, this component is cabable of dissolving the resin component at room temperature. Thus, in one embodiment the resin is dissolved in the monomeric component prior to being combined with the remaining components. Examples of suitable monomers are styrene, alpha-methyl styrene, chloro-styrene, vinyl toluene, divinyl benzene, diallylphthalate, methyl methacrylate, and mixture of these, with preferred monomers being styrene and methyl methacrylate. The ratio of monomer(s) to resin is desirably from about 40:60 to about 75:25 and preferably from about 40:60 to about 65:35 by weight.

[0027] Another component to the molding composition is fillers. In accordance with the invention the predominant filler is a conductive filler in order to impart electrical conductivity of the final molded product. A preferred filler is graphite particles, in particular, a synthetic crystalline graphite particle, such as currently supplied by Asbury Graphite in Asbury, N.J. under the designation Asbury 4012. This graphite is characterized as having less than 10% particles greater than 150 microns and less than 10% smaller than 44 microns in diameter. Other graphite fillers include: Ashbury A99, Ashbury 3243, Ashbury modified 4012, Ashbury 3285, Ashbury 230U; TimrexR KS 75 and 150, and TimrexR KC 44, all sold by TIMCAL of Westlake, Ohio; and Calgraph Sold by SGL Technic Inc of Valencia, Calif. This filler is used at a loading of at least 50% by weight. Other conductive fillers such as other forms of graphite (including graphite pitch-based fibers), metal particles, or metal coat particles may be used in conjunction with the graphite filler, or even alone. Desirably conductive fillers are at least about 50,about 60, or about 65 weight percent of the molding composition. More desirably the filler is more than about 70 or 75 percent to about 80 weight percent of the molding composition. Alternatively this amount can be expressed as at least about 250 phr, more preferably at least about 275, or even 300 phr. Alternatively stated the conductive fillers are present in an effective amount to result in a bulk conductivity of at least about 40, about 50, about 60, about 70, about 80, about 85, about 90 or about 96 S/cm when measured in accordance with ASTM Test Standard No. F1529-97 for a molded article having a thickness from about 0.060 to about 0.200 inches. Current technology in fuel cell plates uses a bulk conductivity of at least about 55, and preferably at least about 70.

[0028] An initiator is another component of the molding composition. The initiator initiates the copolymerization of the resin and the monomer(s). Initiators include any free radical initiator capable of forming radicals in the correct concentration under the molding conditions. They may include peroxides, hydroperoxides, redox systems, diazo compounds, persulfates, perbenzoates etc. The initiators are typically used in amounts of about 0.05 to about 5 weight percent, and more preferably about 0.1 to about 2 weight percent. Alternatively, these amount can be expressed in parts per hundred parts by weight of resin, i.e. from about 0.5 to about 4.0 phr, preferably from about 0.7 to about 3.0 phr, and most preferably from about 0.8 to about 2.25 phr. Alternatively high temperature initiators such as Di-cup, e.g. dicumyl peroxide can be used for molding applications where higher iniation temperatures are desirable. The inclusion of 0.5 to 10phr, preferably about 1 to 8 phr, of a mold release agent, such as calcium stearate, zinc stearate, or the like may also be of advantage to achieving without machining the highly complex molded part of the present invention.

[0029] Another optional component to the improved molding composition is a rheological modifier, which may act to increase the molecular weight such as by chain extension of the resin prepolymer. Suitable modifiers include Group II oxides and hydroxides, such as calcium or magnesium oxide; carbodiamides; aziridines; and polyisocyanates. It is believed that the foregoing modifiers act chemically by co-reacting into the polymer backbone at carboxy or hydroxy sites. Other suitable modifiers include polytetrafluorethylene (PTFE); perfluoropolyether (PFPE), and polyethylene. These modifiers may act to reduce shear and thus promote flow in the composition during molding. Fumed silica is an example of a substance, which may act mechanically to increase molding viscosity and therefore be a suitable rheological modifier for this invention. Combinations of two or more Theological modifiers may be desirable for optimum properties. In this application they are used to modify the resin structure to prevent phase separation of the resin from the conductive filler (in particular in view of the high loadings of the conductive filler, i.e. over 50% or even 65% by weight or more of graphite) The modifiers are further used in general to enable the achievement of a high definition conductive polymeric fuel cell plate.

[0030] Desirably the Theological modifiers are used in an effective amount to prevent phase separation during molding. For the purpose of this application molding will desirably be at pressures from about 400 to about 5000 psi, and preferably from about 2000 to about 3500 psi, and most preferably from about 2500 to about 3000 psi. Desirable amounts of group II oxides (including group II hydroxides and mixtures of these compounds) is from about 0.1 to about 1 or about 2 weight percent, more desirably from about 0.2 or about 0.3 to about 0.7 or about 0.8 weight percent. This can also be expressed as from about 0.5 to about 4.0 phr, preferably from about 1.0 to about 3.0 phr, and most preferably from about 1.5 to about 2.5 phr. Specific preferred compounds include magnesium oxide, or magnesium hydroxide or calcium oxide. Examples of a suitable magnesium oxide additives is 99% pure magnesium oxide sold under the tradename “Elastomag” from Morton Thiokol, Inc. in Danvers, Mass. Other examples include a magnesium oxide dispersion sold under the tradename “pg-9033” by plasticolors, and a magnesium hydroxide dispersion also sold by plasticolors under the tradename “pg-91146”. Another suitable magnesium hydroxide is Barcroft, which is a powdered version. Examples of aziridine compounds include polyfunctional aziridines supplied by EIT, Inc. under the trade designation XAMA, including XAMA-2, which is identified as trimethylol propane-tris (beta-(N-aziridinyl) proprionate), and, in particular, XAMA-7, which is identified as pentaerythritol-tris-(beta-(aziridinyl) propioanate); a product of Sybron Chemicals, under the tradename lonac including PFAZ-322, identified as a trifuncional aziridine; and including CX-100, a product of Zeneca Resins, identified as a polufunctional aziridine. Desirable amounts of aziridine and/or polyisocyanate modifiers is from about 1 to about 10 or about 15 weight percent, and more desirably from about 2 or about 3 to about 8 or about 9 weight percent. This can also be expressed as from about 0.5 to about 20 phr, preferably from about 1 to about 17 phr, and most preferably from about 2 to about 15 phr. Polyisocyanates in general are described in more detail in U.S. Pat. No. 5,268,400 column 6 lines 59 through column 7 line 17. A specific diisocynate, which can be used is diphenylmethane diisocynate such as that sold by ICI Americas of Wst Depiford, N.J., under the tradename “Rubinate R MF-1780. Additionally, a suitable diisocynate is Lupranate MP102, solvent free urethane-modified diphenylmethane diisocynate from BASF. Desirable amounts of polytetrafluorethylene (PTFE) (and/or perfluoropolyether (PFPE)) is from about 0.5 to about 1 or about 2 weight percent, more desirably from about 0.6 or about 0.7 to about 1.8 or about 1.3 weight percent. This can also be expressed as from about 0.5 to about 20 phr, preferably from about 3 to about 15 phr, and most preferably from about 5 to about 12 phr. A suitable fine particle PTFE powder (having an average particle size by Coulter Counter of less than microns) is sold under the tradename “Marzon #5 by Marshall Products Company of West Chester Pa. It is preferable to use a linear low density polyethylene such as sold by Equistar of Houston Tex. under the tradename FN 510 It is preferable to use it in amounts of from about 3 to about 20 phr, more preferably from about 4 to about 17, and most preferably from about 5 to about 15 phr/Fumed silica could be used at from about 0.5 to about 20 phr, preferably from about 1 to 10 phr.

[0031] Other optional components to a molding composition include urethane based or urethane containing oligomers or polymers, low shrinkage additives like polyvinyl acetate or polyethylene; fibrous reinforcing agents such as cotton glass microfibers or graphite microfibers; flexibilizing agents; mold release agents; polymerization inhibitors to inhibit premature polymerization during storage or the initial stages of molding; viscosity modifiers like fumed silica; and mold lubricant like stearates of calcium, zinc or magnesium. Carbon black may be added to influence the surface conductivity and to change the appearance of the molded product. Suitable carbon blacks include an electrically conductive low residue carbon black having a nitrogen surface area m2/g of 270, a STSA surface Area m2/g of 145 a sieve residue at 35 mesh of 0 ppm and at 325 mesh of 20 ppm as sold under the tradename Conductex 975 by Columbia Chemicals of Jamesburg, N.J. Also, suitable conductive carbon black is supplied by Akzo Nobel Chemicals of Chicago, Illinois under the tradename Ketjenblack EC-300 J and EC-600JD. Cabot Corporation of Boston Mass. also supplies a conductive carbon black. Wherever possible given enough other information take out the product designation. It is noted that polyethylene and fumed silica can function as the rheological modifier in addition to the foregoing functions.

[0032] As a further embodiment of the invention, low shrink additives can advantageously be added to improve the surface characteristics and the dimensional stability of the resulting products. As previously mentioned “low profile additives” are also encompassed within this aspect of the invention. These additives generally include thermoplastics or elastomerics such as homopolymers of ethylene, styrene, vinyl toluene, alkyl methacrylates, polyethylene ether, polyphenylene oxide and alkyl acrylates. Additional examples include copolymers using the foregoing and in addition, vinyl chloride, vinyl acetate, acrylonitrile, and butadiene. In particular these co-polymers would advantageously include copolymers of vinyl chloride and vinyl acetate; styrene and acrylonitrile; methyl methacrylate and alkyl esters of acrylic acid; methyl methacrylate and styrene; methyl methacrylate and acrylamide; and SBS block copolymers. These additives are generally used in the range of 10 to 50 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers. More preferably this range would be 20 to 45 weight percent, with a particularly preferred range of about 30 to 40 weight percent. These additives are usually added with the resin blending. As necessary the cure system may be adjusted to compensate for the presence of the additive.

[0033] The molding compositions may be formulated and mixed using a variety of mixing conditions including either continuous or batch and using a variety of known mixing equipment. Specific examples are set forth in the example section. The compositions may be advantageously stored for reasonable times before molding. The compositions can be molded by a variety of methods including compression molding and injection molding. The compositions can be molded under typical conditions for these types of molding including at pressures from about 400 to about 5000 psi, and preferably from about 2000 to about 3500 psi, and most preferably from about 2500 to about 3000 psi and temperatures at from about 225 to about 400 degrees Fahrenheit. Dwell times are from about 50 seconds to about four minutes. The compositions are useful for molding complex configurations including thin or intricate conductive articles such as those having a thickness from about 0.050 to about 0.200 inches, and more preferably from about 0.060 to about 0.150 inches. The compositions are useful for articles having bulk conductivity of at least 40, 50, 60, 70, 80, 85, 90 or even 96 S/cm at a thickness given above. The articles from the composition desirably have tensile strength from about 2000 to about 6000 psi as measured in accordance with ASTM test No.D638 and flexural modulus from about 3000 to about 10,000 psi when tested in accordance with ASTM test no. D790.

[0034] Molded products made from the compositions of the present invention are useful for a variety of applications demanding complex configurations, conductivity, as well as strength, and corrosion resistance. One particularly advantageous product, which can be made by compression molding, is a bipolar plate for use in fuel cells. An example of such a plate is shown in FIG. 1. The drawing of this plate is intended to illustrate the molding capabilities of the conductive compound of the present invention. It is not necessarily intended to provide optimal, or even operative, field flow design. It should not limit the invention in any way. The plate 10 includes a fluid flow face with one or more generally parallel and or serpentine flow channels 12. The flow channels receive and transmit fluids through ports 14 and 16, which are in fluid communication with corresponding entry and exit fluid manifolds 18 and 19. The plate has a dimension, which will vary from 1 to 20 inches in length and width, and having a thickness of 0.02 to 0.3 inch, with a cross-sectional depth of the flow channel in the range of about 0.005 to 0.080 inch. The cross-sectional width of a land separating adjacent flow channel sections is in the range of 0.01 to 0.1 inch. The plate may include a number of peripheral through holes that act as a manifold for fuel transportation. The plate made using the compositions of the present invention can be made substantially exclusively by molding operations. The intricate pattern can be established without the need for expensive, post plate production machining operations, such as drilling, or reaming or the like.

[0035] FIG. 2 illustrates the unassembled components of a fuel cell. This fuel cell has a base unit 12, which includes debossed means to accept a reformer 14 and a fuel cell stack 16, which is comprised of a plurality of bipolar plates 20 which are sandwiched between a stack cap 22 and a stack base 24. The fuel cell further includes a heat exchanger 26. An enclosure provides a leak-proof housing for the unit.

EXAMPLES

[0036] The following examples use the components set forth below.

[0037] Resin A is Hetron 922 available from Ashland Chemical Co in Columbus Ohio. It is a low viscosity epoxy vinyl ester resin. It is about 55 wt. % solids and about 45 wt. % reactive monomer.

[0038] Resin B is Atlac 382ES from Reichhold Chemicals, Inc. in Research Triangle Park, N.C. It is characterized as a bisphenol fumarate resin. It was diluted to about 55 wt. % solids with styrene.

[0039] Resin C is Dion 6694 diluted to 55 wt. % solids in styrene. It is available from Reichhold Chemicals, Inc. It is characterized as a modified bisphenol fumarate polyester.

[0040] Resin D is 42-2641 from Cook Composites and Polymers in Kansas City, Mo. It was diluted to 55 wt. % solids with styrene. It is characterized as an unsaturated polyester resin.

[0041] Resin E is ATLAC 3581-61 from Reichhold Chemicals, Inc. It is characterized as a vinyl ester resin at 19wt %, polyester at 27 wt % and urethane polymer at 4 wt % combined with 50wt % styrene. Thus, it was diluted to 50 wt % solids with styrene.

[0042] Resin F is 580-05 from Reichhold Chemicals, Inc. It is characterized as a urethane-modified vinyl ester resin. It was diluted to 54 wt % solids with styrene.

[0043] Resin G is 9100 from Reichhold Chemicals, Inc. It is characterized as a bisphenol-epoxy vinyl ester. It was diluted to 54-58 wt % solids with styrene.

[0044] Resin H is Dow Derakane R8084 from Dow Chemicals, Inc. It is characterized as an elastomer-modified vinyl ester resin. It was diluted to 50-60 wt % solids with styrene.

[0045] Resin I is 9480-00 from Reichhold Chemicals, Inc. It is characterized as an epoxy novolac vinyl ester. It was diluted to 53.5 wt % solids with styrene.

[0046] Resin J is Atlac 31-632 from Reichhold Chemicals, Inc. It is an unsaturated isocyanurate vinyl ester resin.

[0047] Resin K is Dow Derakane 797 from Dow Chemicals, Inc. It is characterized as a one pack resin which is an epoxy vinyl ester resin containing 7-13 weight percent of divinyl benzene, 5-15 weight percent of styrene butadiene rubber co-polymer, 2-6 weight percent of styrene homopolymer, and 0.5 to 1.5 weight percent of styrene-ethylene oxide block copolymer, as a low profile additive. It was diluted to 60-65 wt % solids with styrene.

[0048] Resin L is Dow Derakane 790 from Dow Chemicals, Inc. It is also characterized as a one pack resin which is an epoxy vinyl ester resin containing 5-15 weight percent of styrene butadiene rubber co-polymer, 2-6 weight percent of styrene homopolymer, and 0.5 to 1.5 weight percent of styrene-ethylene oxide block copolymer, as a low profile additive. It was diluted to 50-60 wt % solids with styrene.

[0049] Resin M is 31633-00 from Reichhold Chemicals, Inc. It is characterized as a isocyanurate vinyl ester resin with 4wt % polyether polyol It was diluted to 60 wt % solids with styrene.

[0050] Resin N is Dow Derakane 780 from Dow Chemicals, Inc. It is also characterized as a vinyl ester resin. It was diluted to 60-70 wt % solids with styrene.

[0051] Monomer A is styrene.

[0052] Monomer B is Divinylbenzene HP from the Dow Chemical Company and characterized as 80wt % divinyl benzene, 18 wt % ethylvinylbenzene, less than 0.12wt % p-tert butylcatechol, less than 0.5wt % diethylbenzene and less than 1 wt % of Napthalene.

[0053] Rheological Modifier A is Elastomag from Morton Thiokol. Inc. in Danvers, Mass. It is characterized as 99% pure magnesium oxide.

[0054] Rheological Modifier B is a polyisocyanate. The material used in these experiments is 40-7263 from Cook Composites and Polymers. It is characterized by a NCO content of 17.7 to 20.9, a viscosity of 110-170, a flash point of 87° F., and a crystallization point of 40° F.

[0055] Rheological Modifier C is RCI RD THL55 (also known as RD-1070) from Reichhold, Inc. It is specifically a polyurethane resin.

[0056] Rheological Modifier D is Rubinate 1780 available from ICI. It is characterized as a polymeric methylene diphenyl diisocyanate.

[0057] Rheological Modifier E is Marzon #5 from Marshall Products Company of West Chester, Pa. It is characterized as a finely divided powder polytetrafluorethylene.

[0058] Rheological Modifier F is FN-510, a linear low-density polyethylene from Equistar Chemicals, L.P. of Houston, Tex.

[0059] Initiator A is Vazo (2,2-azo bisisobutyronitrile) available from Dupont, I & B Industrial and Biochemical Dept, Wilmington Del.

[0060] Initiator B is tert-butyl peroxy isopropyl carbonate (Triginox BPIC) available from Durr Marketing in Pittsburgh, Pa.

[0061] Initiator C is t-butylperbenzoate (TBPB) available from Durr Marketing.

[0062] Initiator D is 1,3 di-t-butyl peroxy-3,5,5 trimethylcyclohexane catalyst (Trig 29B75) available from Durr Marketing.

[0063] Mold release agent A is calcium stearate.

[0064] Mold release agent B is zinc stearate sold as COAD 27 by the Norac Company, Incorporated of Azusa, Calif.

[0065] Graphite A is graphite 4012 available from Asbury Graphite in Asbury, N.J. It is characterized by having less than 10% greater than 150 microns and less than 10% smaller than 44 microns in diameter.

[0066] Graphite B is SGL Ash02 characterized as a natural graphite flake product sold by SGL Corporation.

[0067] Graphite C is XC-72.SGLV Fine characterized as a natural graphite flake product sold by SGL Corporation.

[0068] Graphite D is available from Asbury Graphite in Asbury, N.J. It is a modified version of the 4012 product.

[0069] Graphite E is a conductive flake graphite available from Asbury Graphite in Asbury, N.J. under the trade designation 3243. It is characterized by having less than 18% greater than 75 microns and less than 65% smaller than 44 microns in diameter.

[0070] Graphite F is a conductive flake graphite available from Asbury Graphite in Asbury, N.J. under the trade designation 230U. It is characterized by having 100% smaller than 44 microns in diameter.

[0071] Graphite G is a synthetic graphite available from Asbury Graphite in Asbury, N.J. under the trade designation A99. It is characterized by having less than 3% greater than 44 microns and less than 99% smaller than 44 microns in diameter.

[0072] Graphite H is a synthetic graphite available under the designation KS 75, from Timrex America, Inc. It is characterized by having less than 95% greater than 96 microns and less than 95% smaller than 75 microns in diameter.

[0073] Graphite I is a synthetic graphite available under the designation KS 150, from Timrex America, Inc. It is characterized by having at least 95% less than 180 microns in diameter.

[0074] Graphite J is a synthetic graphite available under the designation KC44, from Timrex America, Inc. It is characterized by having at least 90% less than 48 microns in diameter.

[0075] Carbon Black B is characterized as an electrically conductive low residue carbon black having a nitrogen surface area m2/g of 270, a STSA surface Area m2/g of 145 a sieve residue at 35 mesh of 0 ppm and at 325 mesh of 20 ppm as sold under the tradename Conductex 975 by Columbia Chemicals of Jamesburg, N.J.

[0076] Carbon Black C is conductive carbon black supplied by Cabot Corporation of Boston, Mass. under the tradename, Black Pearls, while Graphite D is supplied by this company under the designation XC-72.

[0077] Carbon Black E is conductive carbon black supplied by Akzo Nobel Chemicals of Chicago, Ill. under the tradename Ketjenblack EC-300 J and EC-600JD. EC-300 J has an iodine absorption of 740-840 mg/g; a pore volume of 310-345 cm3/100 g and an apparent bulk density of 125-145 kg/m3. EC-600 JD has an iodine absorption of 1000-1150 mg/g; a pore volume of 480-510 cm3/100 g and an apparent bulk density of 100-120 kg/m3.

[0078] The Glass fibers were from Owens-Corning Fiberglass and are characterized as continuous glass filaments hammermilled into a specific length used as a reinforcing and filler medium.

[0079] The inhibitor was 2,6-di-tertbutyl-p-cresol (25% in vinyl toluene).

[0080] Low profile additive A is FN-510, a linear low-density polyethylene from Equistar Chemicals, L.P. of Houston, Tex.

[0081] Low profile additive B is SGP-70C from Esprit Chemical of Sarasota, Fla. It is characterized as a styrene divinyl benzene copolymer with 0.4wt % styrene monomer and 0.1 wt % divinyl benzene.

[0082] Low profile additive C is R-134 from Premix, Inc of North Kingsville, Ohio. It is characterized as a styrene and thermoplastic solution with 70-80wt % resin and styrene monomer and 20-30wt % styrene butadiene styrene and styrene ethylene propylene copolymer.

[0083] Low profile additive D is Resin RP-700 from Owens-Corning Fiberglas. It is characterized as a styrene solution of polymethyl methacrylate with 30-35wt % resin, and styrene.

[0084] Low profile additive E is Neulon polyester modifier T-plus from Union Carbide. It is characterized as a polyvinyl acetate/ester epoxide with less than 4 wt % acetate, greater than 5wt % ester, epoxide, greater than 20wt % polyvinyl acetate copolymer, and less than 60 wt % styrene.

[0085] Low profile additive F is Microthene F from Equistar Chemicals, L.P. of Houston, Tex. It is characterized as a microfine polypropylene powder having an average particle size of 20 microns.

[0086] Low profile additive G is Levapren 450 from Bayer Corporation. It is characterized as an ethylene-vinyl acetate copolymer in styrene.

[0087] Low profile additive H is XLP-1889 from Union Carbide. It is characterized as an acetic acid ethenyl ester, homopolymer in styrene with 0.5 wt % ketone, 0.5 wt % vinyl acetate, greater than 10 wt % ether ester, less than 34 wt % polyvinyl acetate and greater than 55 wt % styrene.

[0088] Low profile additive I is Neulon conductive E from Union Carbide. It is characterized as a carbon black/vinyl resin compound with greater than 70 wt % of carboxyl modified vinyl resin, less than 30 wt % of carbon black, less than 2 wt % vinyl acetate, and less than 1.5 wt % ketone.

[0089] Low profile additive J is RCI 31703, (Polylite R) from Reichhold, Inc. It is characterized as a urethane pre-polymer having 75 wt % polymer solids and 25 wt % styrene monomer.

[0090] Low profile additive K is PPO MX5587 from GE Plastics Canada, Ltd. It is characterized as a capped PPO resin which is a modified polyphenylene ether resin.

[0091] Low profile additive L is PPO SA120 from GE Plastics Canada, Ltd. It is characterized as a PPO resin which is a polyphenylene ether resin.

[0092] The molding compositions are generally prepared by adding the resin, monomer initiator, inhibitor, mold release agent, and rheological modifier (if present) to a high shear cowels disperser and blending for 2 minutes. The conductive filler is added to the mix in a Baker Perkin Mixer and mixed 15 minutes. When mixing is complete the composition is put in a suitable barrier bag and allowed to mature for approximately one day before molding.

[0093] The molding parameters for the molding compositions are as follows: Molding temperature for plaques was 295° F. with a molding time of 3 minutes and a charge weight of 173 g. The molding temperature for prototype bipolar plates was 290° F. with a molding time of 3 minutes and a charge weight of 300 g. These plates were highly detailed including an elaborate flow maze having about a 10 to 40 thousandth depth and corresponding width as typified in FIG. 1.

[0094] It was observed that the use of specific thermosetting resins with a conductive filler in combination with various rheological additives (thickeners) improved the bipolar plate composition in regards to having a product which can be used in mass production of electrochemical, e.g. fuel, cell bipolar plates.

[0095] The results of the formulation changes include non-cracking molding compound, better hot strength out of the mold, lower production costs, shorter cycle times, better overall electrical conductivity, increased mechanical properties, and better rheological characteristics.

[0096] In Table IA the Control L-23012 provided a compression molded plate, having an intricate flow field design formed therein, useful as a fuel cell plate. However, the plate suffered from cracking during molding and had non-uniform conductivity and resistivity along the surface of the plate due to phase separation of the conductive filler and resin during molding compared with a preferred embodiment described herein in which the molded composition contains a rheological modifier. Samples L-23185, L-23120, L-23119 and L-23126 had desirable properties.

[0097] In Table IB Samples L-23125, L-23186, L-23039 had desirable properties. Samples L-23184 and L-23022 had lower than optimal bulk conductivity and higher than optimal resistivity.

[0098] In Table IC Samples L-23023, L-23063, L-23024, L-323027, and L-23026 had lower than optimal bulk conductivity and higher than optimal resistivity.

[0099] In Table ID Samples L-23209 and L-23215 had good properties. Samples L-23028, L-23210, and L-23211 had lower than optimal bulk conductivity and higher than optimal resistively. 1 TABLE IA Control Component L-23012 L-23185 L-23120 L-23119 L-23126 Resin A 30.1 g Resin B Resin C 19.95 g Resin D 17.13 15.63 23.33 Initiator 0.6 g (A) 0.4 (B) 0.4 (B) 0.4 (B) 0.4 (B) Inhibitor 0.1 0.1 0.1 0.1 0.1 Mold 1.2 1.2 1.2 1.2 1.2 Release Graphite A 68 g 75 78 78 Graphite B 68 Graphite C Thickener A — 0.35 g Thickener B — 6.17 4.67 6.97 Glass fibers Bulk 85 85 90 90 70 Conductivity S/cm Areal 300 260 260 260 220 Conductivity S/cm2 Tensile psi 3500 3700 3600 3100 3500 Flexural psi 4100 5500 4300 3500 4200 Resistivity 70.9 87.51 71.2 37.7 OHMS/M2

[0100] 2 TABLE IB Component L-23125 L-23186 L-23039 L-23184 L-23022 Resin A Resin B 19.95 29.95 Resin C 22.65 27.65 Resin D 23.33 g Initiator 04 (B) 0.4 (C) 0.4 (B) 0.4 (C) 0.4 (B) Inhibitor 0.1 0.1 0.1 0.1 0.1 Mold 1.2 1.3 1.2 1.3 1.2 Release Graphite A 34 70 68 70 68 Graphite B 34 Graphite C Thickener A 0.55 0.35 0.55 0.35 Thickener B 6.97 Glass fibers 5 10 Bulk 70 70 65 45 40 Conductivity S/cm Areal 210 210 200 140 140 Conductivity S/cm2 Tensile psi 3400 3000 2800 3000 4100 Flexural psi 4200 3700 3800 4000 5000 Resistivity 58.13 123.8 117.6 155.6 222.1 OHMS/M2

[0101] 3 TABLE IC Component L-23023 L-23063 L-23024 L-23027 L-23026 Resin A Resin B 29.95 29.95 29.95 Resin C 29.95 29.950 Resin D Initiator 0.4 (C) 0.4 (B) 0.4 (D) 0.4 (C) 0.4 (B) Inhibitor 0.1 0.1 0.1 0.1 0.1 Mold 1.2 1.2 1.2 1.2 1.2 Release Graphite A 68 68 68 68 68 Graphite B Graphite C Thickener A 0.35 0.35 0.35 0.35 0.35 Thickener B Glass fibers Bulk 40 40 35 30 30 Conductivity S/cm Areal 140 120 130 90 90 Conductivity S/cm2 Tensile psi 4200 3500 3100 4700 4300 Flexural psi 4900 4200 3400 6000 5300 Resistivity 205.9 — 181.7 320.9 246.8 OHMS/M2

[0102] 4 TABLE 1D Component L-23028 L-23209 L-23210 L-23211 L-23215 Resin A Resin B Resin C 29.95 28.65 22.65 Resin D 21.49 21.49 Initiator 0.4 (D) 0.4 (B) 0.4 (B) 0.4 (B) 0.4 (B) Inhibitor 0.1 0.1 0.1 0.1 0.1 Mold 1.2 1.2 1.2 1.3 1.3 Release Graphite A 68 42 42 43 70 Graphite B 26 Graphite C 0.35 26 26 Thickener A 0.35 0.55 0.55 Thickener B 8.81 8.81 Glass fibers Bulk 30 77 25 45 79 Conductivity S/cm Areal 100 227 74 132 233 Conductivity S/cm2 Tensile psi 3800 2700 3900 3000 2600 Flexural psi 5100 3900 5500 4500 4300 Resistivity 220.9 62.02 377.8 186.46 102.74 OHMS/M2

[0103] 5 TABLE 2A Component 23012 23039 23022 23023 23063 Resin A 100 Resin B 100 100 100 100 Initiator A 1.99 Initiator B 2.01 1.34 1.34 Inhibitor 1.34 Release 3.99 6.02 4.01 4.01 4.01 Agent Graphite A 225.91 227.05 340.85 227.05 227.05 Modifier A 1.17 1.17 1.17 Fiber A 50.13 Bulk 85 65 40 40 40 Conductivity S/cm Areal 300 200 140 140 120 Conductivity S/cm2 Tensile psi 3500 2800 4100 4200 3500 Flexural psi 4100 3800 5000 4900 4200

[0104] 6 TABLE 2B Component 23024 23119 23186 23184 23027 Resin B 100 Resin C 100 100 100 100 Initiator B 2.01 Initiator C 1.77 1.45 1.34 Initiator D 1.34 Inhibitor 0.33 0.50 0.44 0.36 0.33 Release 4.01 6.02 5.74 4.70 4.01 Agent Graphite A 227.05 390.98 309.05 253.16 227.05 Modifier A 1.17 1.75 2.43 1.99 1.17 Fibers A Bulk 22.08 Conductivity S/cm Areal 35 90 70 45 30 Conductivity S/cm2 Tensile psi 135 260 210 140 90 Flexural psi 3100 3100 3000 3000 4700

[0105] 7 TABLE 2C Component 23026 23028 23211 23215 23185 Resin C 100 100 100 100 Resin D 100 Initiator B 1.34 1.40 1.77 2.34 Initiator D 1.34 Inhibitor 0.33 0.33 0.35 0.44 0.58 Release 4.01 4.01 4.54 5.74 7.01 Agent Graphite A 227.05 227.05 150.09 309.05 437.83 Graphite C 90.75 Modifier A 1.17 1.17 1.92 2.43 Modifier B 36.02 Fiber B 22.08 Bulk 30 30 45 79 85 Conductivity S/cm Areal 90 100 132 233 260 Conductivity S/cm2 Tensile psi 4300 3800 3000 2600 3700 Flexural psi 5300 5100 4500 4300 5500

[0106] 8 TABLE 2D Component 23120 23126 23125 23209 23210 Resin D 100 100 100 100 100 Initiator A 2.56 1.71 1.71 1.86 1.86 Inhibitor 0.64 0.43 0.43 0.43 0.47 Release 7.68 5.14 5.14 5.58 5.58 Agent Graphite A 499.04 145.74 195.44 195.44 Graphite B 291.47 145.74 20.99 Graphite C 120.99 Modifier B 29.88 29.88 29.88 41.00 41.00 Bulk 90 70 70 77 25 Conductivity S/cm Areal 260 220 210 227 74 Conductivity S/cm2 Tensile psi 3600 3500 3400 2700 3900 Flexural psi 4300 4200 4200 3900 5500

[0107] 9 TABLE 3A Component 23227 23236 23274 23275 23293 Resin D 100 100 100 100 100 Initiator B 1.56 1.44 1.51 2.34 2.34 Inhibitor 0.52 0.48 0.50 0.58 0.58 Release 6.24 5.77 6.06 7.01 7.01 Agent Graphite A 390.02 350.96 68.50 420.32 420.32 Carbon A 17.51 Modifier B 21.68 22.12 28.22 36.02 36.02 Fiber C 11.68 Bulk 90 Conductivity S/cm Tensile psi 2672 Flexural psi 6543

[0108] 10 TABLE 3B Component 23292 23293 23343 23344 23345 Resin D 100 100 100 100 100 Initiator B 1.48 1.56 1.44 1.29 1.20 Inhibitor 0.49 0.52 0.48 0.43 0.40 Release 5.93 6.24 5.75 5.14 4.80 Agent Graphite A 370.74 395.22 349.78 299.91 72.22 Modifier B 15.67 16.48 21.71 21.68 21.70 Bulk 72.5 58 Conductivity S/cm Tensile psi 2170 2547 2448 2679 Flexural psi 4616 6503 5423 5897

[0109] 11 TABLE 3C Component 23346 23347 23348 23349 23350 Resin D 100 100 100 100 100 Initiator B 1.09 1.02 0.95 0.90 0.84 Inhibitor 0.36 0.34 0.32 0.30 0.28 Release 4.37 4.23 3.80 3.61 3.36 Agent Graphite A 236.79 216.57 90.11 174.70 154.19 Modifier B 21.68 21.69 21.67 21.69 21.67 Tensile psi 3083 3053 2923 3107 3470 Flexural psi 5715 5766 5666 5398 5378

[0110] 12 TABLE 3D Component 23335 23352 23360 23361 23362 Resin D 100 100 100 100 100 Initiator B 0.80 0.75 2.27 2.21 2.14 Inhibitor 0.27 0.25 0.57 0.55 0.54 Release 3.22 3.02 6.81 6.62 6.43 Agent Graphite A 142.05 125.75 425.41 413.45 02.14 Modifier B 21.68 21.73 32.16 28.45 24.93 Bulk 85.5 Conductivity S/cm Tensile psi 2787 2629 2155 Flexural psi 6167 5998 6017

[0111] 13 TABLE 4A Component 23364 23365 23366 23367 23368 Resin D 100 100 100 100 100 Monomer A 9.72 8.18 7.05 6.20 5.53 Initiator B 1.46 1.23 1.06 0.93 0.83 Inhibitor 0.49 0.41 0.35 0.31 0.28 Release 5.83 4.91 4.23 3.72 3.32 Agent Graphite A 340.30 265.85 211.57 170.54 138.31 Modifier B 28.43 28.34 28.35 28.37 28.35 Bulk 55.99 36.57 32.86 18.37 13.59 Conductivity S/cm Tensile psi 2647 2697 2701 2880 2992 Flexural psi 6044 6131 6149 7002 7338 Density 1.75 1.74 1.71 1.72 1.71 g/cm3 Shrink mils/in −2.5 −2.83 −3.17 −3.33 −3.83

[0112] 14 TABLE 4B Component 23369 23370 23371 23372 23373 Resin D 100 100 100 100 100 Initiator B 1.36 1.15 1.00 0.89 0.79 Release 5.42 4.61 4.01 3.55 3.18 Agent Graphite A 316.17 249.52 200.33 162.48 132.45 Modifier B 28.27 28.21 28.21 28.21 28.21 Bulk 49.49 27.74 25.05 14.01 8.12 Conductivity S/cm Tensile psi 2974 3358 3014 2952 3154 Flexural psi 6394 6099 6520 6312 6071 Density 1.72 1.76 1.69 1.73 1.72 g/cm3 Shrink mils/in −3.5 −2.5 −2.83 −3.17 −3.53

[0113] 15 TABLE 4C Component 23443 23444 23445 23466 23467 Resin D 100 100 100 100 100 Initiator B 1.84 1.72 1.56 1.81 1.54 Inhibitor 0.46 0.43 0.39 0.45 0.39 Release 5.52 5.15 4.69 5.44 4.62 Agent Graphite A 32.14 291.85 253.91 317.17 250.29 Modifier B 30.23 30.04 30.08 28.23 28.23 Bulk 36 21.2 15 39 21 Conductivity S/cm Tensile psi 2312 2765 Flexural psi 6154 5994 Density 1.76 1.76 1.75 1.75 1.73 g/cm3 Shrink mils/in −2 −2 −2.33 −1.67 −1.83

[0114] 16 TABLE 4D Component 23468 23469 23470 23471 23472 Resin D 100 100 100 100 100 Initiator B 1.69 1.75 1.95 2.11 1.46 Inhibitor 0.42 0.44 0.49 0.53 0.37 Release 5.52 5.15 4.69 5.44 4.62 Agent Graphite A 287.77 284.46 331.55 369.39 241.01 Modifier B 28.23 28.23 28.23 28.23 23.47 Fiber D 17.51 19.50 21.11 Bulk 34 45 60 61 Conductivity S/cm Tensile psi 2466 2804 1797 2010 2821 Flexural psi 5272 7390 6682 4726 4898 Density 1.71 1.6 1.62 1.58 1.75 g/cm3 Shrink mils/in −2.33 −2 −1.42 −1.67 −2.5

[0115] 17 TABLE 5A Component 23506 23507 23508 23509 23510 Resin D 100 100 100 100 100 Initiator B 1.63 1.75 1.45 1.59 1.70 Inhibitor 0.41 0.44 0.36 0.40 0.43 Release 4.89 5.24 4.34 4.77 5.11 Agent Graphite A 277.10 305.41 235.17 270.38 298.00 Modifier B 23.47 23.47 20.48 20.48 20.48 Bulk 55 45 52 60 65 Conductivity S/cm Tensile psi 2680 2645 2483 Flexural psi 4556.7 5264.4 4773.67 Density 1.74 1.74 1.79 1.78 1.76 g/cm3 Shrink mils/in −2.5 −2.33 −2.33 −2.42 −1.75

[0116] 18 TABLE 5B Component 23566 23567 23568 23581 23582 Resin D 100 100 100 100 100 Initiator B 1.85 1.79 1.75 1.77 1.83 Inhibitor 0.46 0.45 0.44 0.44 0.46 Release 5.54 5.38 5.26 5.30 5.50 Agent Graphite A 346.42 336.32 328.95 313.33 329.820 Modifier B 20.48 20.48 Modifier D 7.62 4.48 2.19 Bulk 92 94 Conductivity S/cm Density 1.77 1.78 1.75 1.79 1.76 g/cm3 Shrink mils/in −1.67 −1.25 −1.25 −1.67 −1.58

[0117] 19 TABLE 5C Component 23583 23584 23585 23592 23593 Resin D 100 100 100 100 100 Initiator B 1.90 1.98 2.07 1.88 1.97 Inhibitor 0.48 0.50 0.52 0.47 0.49 Release 5.71 5.95 6.20 5.63 5.91 Agent Graphite A 347.62 366.88 387.80 352.11 369.46 Modifier B 20.48 20.48 20.48 Modifier D 9.39 14.78 Bulk 88 59 Conductivity S/cm Density 1.78 1.75 1.71 1.71 1.71 g/cm3 Shrink mils/in −1.5 −1.25 −1.25 −1.67 −1.67

[0118] 20 TABLE 5D Component 23594 23721 23722 23723 23724 Resin D 100 100 100 100 100 Initiator B 2.07 2.19 2.24 1.94 2.00 Inhibitor 0.52 0.55 0.56 0.48 0.50 Release 6.22 6.57 6.71 5.82 6.00 Agent Graphite A 347.62 366.88 387.80 352.11 369.46 Modifier B 27.53 30.24 22.70 26.56 Modifier D 20.73 Bulk 86 93 68 65 Conductivity S/cm Density 1.71 1.74 1.77 1.77 1.78 g/cm3 Shrink mils/in −1.25 −1.42 −1.08 −1.5 −1.25

[0119] 21 TABLE 6A Component 23725 23726 23727 23728 23729 Resin D 100 100 100 100 100 Initiator B 2.14 1.90 2.14 1.90 2.14 Inhibitor 0.54 0.48 0.54 0.48 0.54 Release 6.43 5.71 6.43 5.71 6.43 Agent Graphite D 402.14 347.62 Graphite E 402.14 347.62 Graphite F 402.14 Modifier B 24.93 20.48 24.93 20.48 24.93 Bulk 96 75 81 62 Conductivity S/cm Density 1.77 1.78 1.77 1.81 1.8 g/cm3 Shrink mils/in −1.67 −2.33 −0.83 −1.5 −1.

[0120] 22 TABLE 6B Component 23730 23731 23732 23733 23734 Resin D 100 100 100 100 100 Initiator B 1.90 2.14 1.90 2.14 2.14 Inhibitor 0.48 0.54 0.48 0.54 0.54 Release 5.71 6.43 5.71 6.43 6.43 Agent Graphite A 249.33 249.33 Graphite E 152.82 Graphite F 347.62 152.82 Graphite G 402.14 347.62 Modifier B 20.48 24.93 20.48 24.93 24.93 Bulk 32 30 48 25 Conductivity S/cm Density 1.81 1.81 g/cm3 Shrink mils/in −1.33 −1.83

[0121] 23 TABLE 6C Component 23735 23736 23737 23738 23739 Resin D 100 100 100 100 100 Initiator B 2.14 2.14 1.90 1.90 1.90 Inhibitor 054 0.54 0.48 0.48 0.48 Release 6.43 6.43 5.71 5.71 5.71 Agent Graphite A 249.33 249.33 215.52 215.52 215.52 Graphite D 152.82 Graphite E 132.10 Graphite F 347.62 132.10 Graphite G 152.82 132.10 Modifier B 24.93 24.93 20.48 20.48 20.48 Bulk 38 90 50 26 31 Conductivity S/cm Density 1.79 1.67 1.79 1.8 1.8 g/cm3 Shrink mils/in −2.08 −1.58 −1.83 −2.33 −2.67

[0122] 24 TABLE 6D Component 23740 23755 23756 23757 23758 Resin D 100 100 100 100 100 Initiator B 1.90 2.17 2.20 1.93 1.95 Inhibitor 0.48 0.54 0.55 0.48 0.49 Release 5.71 6.52 6.61 5.78 5.85 Agent Graphite A 215.52 407.61 413.22 341.81 356.10 Graphite D 132.10 Modifier B 20.48 23.91 22.87 19.52 18.54 Modifier D 2.72 5.51 2.41 4.88 Bulk 68 70 97 92 89 Conductivity S/cm Density 1.75 1.67 1.79 1.8 1.8 g/cm3 Shrink mils/in −2.08 −1.58 −1.83 −2.33 −2.67

[0123] 25 TABLE 7A Component 23803 23804 23805 23806 23830 Resin D 100 100 100 100 100 Initiator B 2.06 2.09 2.18 2.19 2.16 Inhibitor 0.52 0.52 0.54 0.55 0.54 Release 6.19 6.27 6.49 6.58 6.49 Agent Graphite A 376.29 381.20 394.59 405.48 394.59 Modifier B 25.26 25.59 25.59 26.30 30.00 Modifier E 5.15 6.53 10.81 6.85 6.76 Bulk 62 83 83 90 Conductivity S/cm

[0124] 26 TABLE 7B Component 23831 23832 23833 23834 23835 Resin D 100 100 100 100 100 Initiator B 2.11 2.16 2.23 2.09 2.09 Inhibitor 0.53 0.54 0.56 0.52 0.52 Release 6.33 6.54 6.69 6.27 6.27 Agent Graphite A 385.22 397.82 406.69 Graphite H 381.20 Graphite I 381.20 Modifier B 25.59 25.61 25.63 25.59 25.59 Modifier E 6.81 6.96 6.53 6.53

[0125] 27 TABLE 7C Component 23836 23837 23838 23839 23840 Resin D 100 100 100 100 100 Initiator B 2.09 2.24 2.24 2.24 2.24 Inhibitor 0.52 0.56 0.56 0.56 0.56 Release 6.27 6.71 6.71 6.71 6.71 Agent Graphite A 408.28 408.28 408.28 408.28 Graphite J 381.20 Carbon B 0.56 381.20 Carbon C 0.56 Carbon D 0.56 Carbon E 0.56 Modifier B 25.59 25.56 25.56 25.56 25.56 Modifier E 6.53 6.99 6.99 6.99 6.99 Modifier F 8.39 8.39 8.39 8.39

[0126] 28 TABLE 7D Component 23878 23879 23880 23881 23896 Resin D 100 100 100 100 100 Initiator B 2.26 2.37 2.28 2.39 1.48 Inhibitor 0.57 0.59 0.57 0.60 0.49 Release 6.79 7.11 6.83 7.16 5.93 Agent Graphite A 418.55 444.31 421.41 447.49 370.74 Modifier B 25.57 25.59 25.57 25.60 5.68 Modifier C 9.99 Modifier E 7.12 7.46 Modifier F 11.88 12.44 5.69 5.97

[0127] 29 TABLE 8A Component 23297 23301 23302 23363 23422 Resin E 100 100 100 100 100 Initiator B 1.56 1.38 1.33 1.06 1.75 Inhibitor 0.52 0.46 0.44 0.35 0.58 Release 6.24 5.50 5.31 4.24 7.00 Agent Graphite A 395.22 343.88 331.86 240.03 466.74 Modifier B 5.98 2.66 1.28 2.65 2.68 Modifier C 10.50 4.63 2.26 4.66 4.67 Bulk 72.5 35 Conductivity S/cm Density 1.62 1.53 1.6 g/cm3 Shrink mils/in −2.33 −1.33 −0.92

[0128] 30 TABLE 8B Component 23423 23452 23453 23454 23455 Resin D 50.03 60.00 70.03 80.00 Resin E 100 Resin F 49.97 40.00 29.97 20.00 Initiator B 2.40 2.14 2.14 2.14 2.14 Inhibitor 0.80 0.54 0.54 0.54 0.54 Release 9.61 6.43 6.43 6.43 6.43 Agent Graphite A 680.54 402.14 402.14 402.14 402.14 Modifier B 2.64 24.93 24.93 24.93 24.93 Modifier C 4.64 Bulk 63 70.5 70 83.5 Conductivity S/cm Tensile psi 2441 2497 2404 2561 Flexural psi 5030 5126 4284 5391 Density 1.47 1.71 1.74 1.75 1.66 g/cm3 Shrink mils/in −0.25 −1.17 −1.58 −1.67 −1.42

[0129] 31 TABLE 8C Component 23530 23531 23646 23647 23648 Resin F 100 100 Resin G 100 100 100 Initiator B 1.85 1.79 1.81 1.91 2.02 Inhibitor 0.46 0.45 0.45 0.48 0.50 Release 5.54 5.38 5.42 5.72 6.06 Agent Graphite A 346.42 336.32 338.75 357.65 378.60 Modifier B 5.24 11.11 17.62 Modifier D 7.62 4.48 Bulk 86 58 46 Conductivity S/cm Tensile psi 2305.56 2155.56 Flexural psi 4548.8 4421.3 Density g/cm3 1.69 1.75 1.71 1.72 1.65 Shrink mils/in −0.42 −1.67 −1.58 −1.42 −1.33

[0130] 32 TABLE 8D Component 23649 23650 23651 23688 Resin I 100 100 100 Resin J 100 Initiator B 1.75 1.77 1.79 1.91 Initiator D 2.08 Inhibitor 0.44 0.44 0.45 0.52 Release Agent 5.26 5.31 5.38 6.25 Graphite A 328.95 331.86 336.32 385.42 Modifier B 15.63 Modifier D 2.19 3.10 4.48 Bulk Conductivity 93 79 64 S/cm Density g/cm3 1.77 1.74 1.73 Shrink mils/in −1.5 −1.08 −1.5

[0131] 33 TABLE 9A Component 24004 24005 24006 24007 24008 Resin D 100 85.12 80.15 50.02 50.02 Resin K 49.98 Resin L 49.98 Initiator B 1.11 1 0.99 0.99 0.98 Inhibitor 0.56 0.5 0.49 0.49 0.49 Release Agent A 6.69 5.97 5.93 5.93 5.93 Graphite A 412.26 368.16 365.43 365.43 365.43 Modifier B 18.38 15.67 14.81 14.81 14.81 Low Profile A 6.96 6.21 6.17 6.17 6.17 Low Profile B 11.14 Low Profile C 14.86 Low Profile D 19.85 Shrink mils/in −1 −0.65 −0.45 −1.1 −1.03

[0132] 34 TABLE 9B Component 24009 24010 24011 24012 24052 Resin D 84.99 89.98 Resin K 100 Resin L 100 100 Initiator B 0.92 0.92 0.99 0.99 0.91 Inhibitor 0.46 0.46 0.49 0.49 0.46 Release Agent A 5.53 5.53 5.93 5.48 Graphite A 345.62 345.62 365.43 365.43 342.47 Modifier A 2.53 2.53 1.6 Modifier B 14.81 14.81 Low Profile A 5.76 5.76 6.17 6.17 5.71 Low Profile C 14.86 Low Profile D 15.01 10.02 Shrink mils/in 0.34 −0.21 −1.3 −0.89 0.02

[0133] 35 TABLE 9C Component 24053 24054 24055 24056 Resin K 100 100 Resin L 100 100 Initiator B 0.91 0.9 0.91 0.91 Inhibitor 0.45 0.45 0.46 0.45 Release Agent A 5.45 5.43 5.48 5.45 Graphite A 340.91 339.37 342.46 340.91 Modifier B 1.14 0.68 1.6 1.14 Low Profile A 5.68 5.66 5.71 5.68 Shrink mils/in −0.02 0.21 −0.24 −0.21

[0134] 36 TABLE 10A Component 24141 24142 24149 24159 24160 Resin K 100 100 100 Resin Q 80 70 Initiator B 0.92 0.93 0.93 0.93 Initiator D 0.55 Inhibitor 0.46 0.46 0.47 0.47 0.47 Release Agent A 2.97 2.96 3.96 3.96 3.96 Release Agent B 2.97 2.96 3.96 3.96 3.96 Graphite A 343.25 342 349.65 349.65 349.65 Modifier A 1.37 1.37 1.4 1.4 0.93 Low Profile A 5.72 5.7 5.83 5.82 5.82 Low Profile E 20 29.98 Shrink mils/in −0.89 −1.58 −0.72 −0.26 0.03

[0135] 37 TABLE 10B Component 24161 24194 24195 24196 24197 Resin D 100 100 Resin K Resin Q 60 70 70.29 Initiator B 0.93 1.03 0.93 0.93 0.93 Inhibitor 0.47 0.47 0.47 0.47 3.14 Release Agent A 3.96 7.3 3.96 3.96 3.98 Release Agent B 3.96 3.96 3.96 3.98 Graphite A 349.65 450.4 349.65 349.65 350.96 Modifier A 1.4 18.87 1.4 1.4 1.78 Low Profile A 5.83 5.85 Low Profile E 40 30.43 29.98 29.71 Low Profile F 3.96 7.3 5.83 5.83 Shrink mils/in −0.41 −0.38 0.18 −0.45 0.07

[0136] 38 TABLE 10 C Component 24249 24250 24261 24262 24287 Resin D 70 68.83 61.53 Resin K 88.3 Resin Q 64.44 Monomer B 11.7 11.7 12.5 12.99 12.79 Initiator B 0.93 0.94 1 1.04 1.02 Inhibitor 0.47 0.47 0.5 0.52 0.51 Release Agent A 3.98 6 6.23 6.3 Release Agent B 3.98 Graphite A 350.96 350.96 370 384.42 378.52 Modifier B 1.78 16.25 20.78 Low Profile A 5.84 5.85 6.26 6.49 6.39 Low Profile E 23.86 17.5 18.18 25.68 Shrink mils/in −0.86 −0.55 −0.93 −0.83 −0.79

[0137] 39 TABLE 10 D Component 24288 24317 24318 24319 24320 Resin D 53.84 60.53 52.47 59.04 100 Monomer B 12.54 14.66 14.37 17.18 32.72 Initiator B 1 1.17 1.15 1.37 2.62 Inhibitor 0.5 0.59 0.57 0.69 1.31 Release Agent A 6.02 7.04 6.9 8.25 15.71 Graphite A 371.3 451.61 442.53 549.83 1047.12 Modifier B 16.66 18.77 16.38 18.56 30.76 Low Profile A 6.27 7.33 7.18 8.59 16.36 Low Profile E 33.62 24.81 33.16 23.78 62.3 Shrink mils/in −0.73 −0.34 0 0.14 −0.52

[0138] 40 TABLE 11A Component 24364 24365 24495 24496 24497 Resin D 60.53 52.47 Resin N 60.93 52.19 60.93 Monomer B 14.66 14.37 13.01 13 13 Initiator B 1.17 1.15 Initiator D 0.57 0.57 0.57 Inhibitor 0.59 0.57 0.52 0.52 0.52 Release Agent A 7.04 6.9 6.24 6.24 6.24 Graphite A 451.61 442.53 400.62 400.62 400.62 Modifier B 18.77 16.38 5.83 Modifier D 5.83 5.83 Low Profile A 7.33 7.18 6.5 6.5 6.5 Low Profile E 26.06 34.81 Low Profile G 24.81 33.16 26.07 Shrink mils/in −0.52 0.17 0 0.14 0.14

[0139] 41 TABLE 11B Component 24498 24499 24500 24523 24524 Resin D 60.53 59.09 58.33 Resin N 52.19 60.93 Monomer B 13 13 14.66 15.2 15.48 Initiator B 1.17 1.22 1.24 Initiator D 0.57 0.57 Inhibitor 0.52 0.52 0.59 0.61 0.62 Release 6.24 6.24 7.04 7.29 7.43 Agent A Graphite A 400.62 400.62 451 .61 468.09 476.78 Modifier B 18.77 23.1 25.39 Modifier D 5.83 5.83 Low Profile A 6.5 6.5 7.33 7.6 7.74 Low Profile E 25.71 26.19 Low Profile H 34.81 Low Profile I 26.07 24.81 Shrink mils/in 0.23 −0.33 −0.29 −0.45 −0.66

[0140] 42 TABLE 11C Component 24525 24526 24527 24631 24632 Resin D 60.53 79.98 69.99 Resin N 65.64 52.19 Monomer B 14.66 14.01 13 Initiator B 1.17 1.02 1.02 Initiator D 0.62 0.57 Inhibitor 0.59 0.5 0.52 0.51 0.51 Release 7.04 6.72 6.24 6.11 6.11 Agent A Graphite A 451.61 431.61 400.62 376.97 376.97 Modifier B 18.77 18.44 18.44 Modifier D 6.28 5.83 Low Profile A 7.33 7.01 6.5 6.37 6.37 Low Profile J 24.81 28.08 34.81 Low Profile K 20.02 30.01 Shrink mils/in −1.79 −2.65 −3.02

[0141] 43 TABLE 12 Component 24633 24634 24635 24636 Resin D 60.01 79.98 69.99 60.01 Initiator B 1.02 1.02 1.02 1.02 Inhibitor 0.51 0.51 0.51 0.51 Release 6.11 6.11 6.11 6.11 Agent A Graphite A 376.97 376.97 376.96 376.97 Modifier B 18.44 18.44 18.44 18.44 Low Profile A 6.37 6.37 6.37 6.37 Low Profile K 39.99 Low Profile L 20.02 30.01 39.99

[0142] The examples of Tables 9 through 12 illustrate that acceptable shrink characteristics can be achieved using a low profile additive. In general, these samples had a shrink measurement of less absolute than two mils/in as measured by ASTM D792. Further the samples had improved surface characteristics including a smoother surface with the avoidance of roughness such as orange peel and ripple.

[0143] In accordance with a further embodiment of the invention, the following compositions can be used in a new molding process to accomplish injection molding. In particular, as is illustrated in FIG. 5, the process of the present invention involves using a phenolic style screw 105, in a auger 106, to convey the highly loaded molding compositions of the present invention to the feed throat 108 of an injection molding apparatus 110. This process contrasts to the traditional process using a hydraulic ram to port the molding composition to the feed throat. However, the traditional molding methods and equipment would fail with potentially catastrophic results when the composition would pack out during the molding process. For example, FIGS. 3 and 4 are photographs of packing out at the feed throat, which occurred using a highly loaded composition such as Sample 23808 in the previously described apparatus. The composition was fed into a traditional injection molding machine, which uses an hydraulic ram to feed the composition from a screw barrel to the feed throat (i.e. a restricted orifice at the mold gate.) The composition packed out in the mold orifice.

[0144] In contrast to this situation, when the same composition was processed using a phenolic screw auger, it could be molded into complex shapes compared to that of FIG. 1 using otherwise conventional injection molding techniques. It is more preferred that a double auger system with a first and larger horizontally oriented screw 120 which feeds the smaller phenolic resin type screw 105 feeding into the feed throat 108 which ports directly into a single or double gate cavity mold 109. Further, the process involves some zoned temperature gradients with a first and second zone 122, 124 in the first screw barrel 126 having a temperature of from about 90 to about 150 degrees F, and more particularly about 110 to about 140 degrees F. A third zone 128 is located at the mold. This zone is maintained at about 275 to about 325, (i.e. 300 F) which is the temperature at which cure is initiated for most of the compositions in accordance with the invention. It is preferable to avoid temperature variations at the mold level. At normal cure rates, the mold time is typically around 10 to 600 seconds, or more usually 30 to 300 seconds or around one or two minutes. The process can be practiced for single or double gate cavity tools, or even for injection/compression processes in which the mold is slightly opened during fill and the mold is shut to compress the shot.

[0145] It was also found that the composition could be molded by injection molding using a single auger Krauss-Maffei AZ50 stuffer with porting directly into the feed throat of the injection molding machine. This machine has a angled rotating conical hopper with a rotating auger screw.

[0146] While in accordance with the Patent Statutes, the best mode and preferred embodiment have been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims.

Claims

1. A process for making a fuel cell plate having an intricate flow pattern molded therein comprising the steps of mixing a composition comprising;

a) an unsaturated prepolymer resin which comprises one or more of unsaturated polyester and vinyl ester resin;

b) an unsaturated material copolymerizable with said resin and including a terminal ethylene group;

c) an inorganic conductive filler in an amount sufficient to provide a bulk conductivity of at least 40 S/cm to the resulting fuel cell plate; and

d) an initiator to initiate said copolymerization; and

molding the composition to form said fuel cell plate having the pattern therein substantially without machining the pattern.

2. A process as set forth in

claim 1 wherein the conductive filler is a particulate filler and the amount of said conductive filler is at least 60 weight percent.

3. A process as set forth in

claim 2 wherein the filler is a graphite filler and the amount of said conductive filler is at least 65 weight percent.

4. A process as set forth in

claim 1 wherein the molding step is an injection or compression molding step or a combination thereof.

5. An electrochemical cell flow field plate comprising

a molded thermosetting resin composition having an intricate fuel flow pattern molded therein and having a thickness from about 0.050 to about 0.200 inches and a bulk conductivity of at least 55 S/cm, said molded thermosetting resin composition being the reaction product of at least:

a) an unsaturated prepolymer resin which comprises one or more of unsaturated polyester and vinyl ester resin;

b) an unsaturated material copolymerizable with said resin and including a terminal ethylene group;

c) a conductive filler in an amount sufficient to provide a bulk conductivity of at least 40 S/cm to the resulting fuel cell plate; and

d) an initiator to initiate said copolymerization.

6. An electrochemical cell flow field plate as set forth in

claim 5 further comprising an effective amount of a Theological modifier to prevent phase separation between said resin and said conductive filler during molding, said rheological modifier being one or more compositions selected from the group consisting of Group II oxides and hydroxides, carbodiamides, aziridines, polyisocyanates, polytetrafluorethylene, perfluoropolyether, polyethylene and fumed silica.

7. An electrochemical cell flow field plate as set forth in

claim 6 wherein the effective amount of said Theological modifier is from about 0.5% to about 15% by total weight of the system.

8. An electrochemical cell flow field plate as set forth in

claim 5 wherein said conductive filler is an inorganic particulate filler and the amount of said conductive filler is at least 50 weight percent.

9. An electrochemical cell flow field plate as set forth in

claim 8 wherein the filler is a graphite filler and the amount of said conductive filler is at least 65 weight percent.

10. An electrochemical cell flow field plate as set forth in

claim 6, wherein said rheological modifier comprises one or more of magnesium oxide, calcium oxide, magnesium hydroxide, and calcium hydroxide; and said effective amount is from about 0.1 to about 2 weight percent based on the weight of said composition.

11. An electrochemical cell flow field plate as set forth in

claim 6, wherein said rheological modifier is one or more of aziridine, carbodiamides, and an isocyanate and said effective amount is from about 1 to about 10 weight percent based on the weight of said composition.

12. An electrochemical cell flow field plate as set forth in

claim 6, wherein said effective amount of rheological modifier is an effective amount to prevent cracking of a part molded at a pressure from about 100 to about 5000 psi and to a thickness of from about 0.050 to about 0.200 inches.

13. An electrochemical cell flow field plate as set forth in

claim 6, wherein said rheological modifier comprises one or more of polytetrafluorethylene, and perfluoropolyether and said effective amount is from about 0.1 to about 5 weight percent based on the weight of said molding composition.

14. An electrochemical cell flow field plate as set forth in

claim 6, wherein said rheological modifier is an isocyanate and said effective amount is from about 2 to about 8 weight percent based on the weight of said molding composition.

15. An electrochemical cell flow field plate as set forth in

claim 5 wherein said conductive filler is one or more of a synthetic crystalline graphite particle and a crystalline graphite particle, and said unsaturated prepolymer resin is one or more resins selected from the group consisting of epoxy vinyl resin, bisphenol fumarate resin, modified bisphenol fumarate polyester resin, unsaturated polyester resin, urethane modified vinyl ester resin, bisphenol-epoxy vinylester resin, elastomer-modified vinyl ester resin, epoxy novolac vinyl ester resin and unsaturated isocyanurate vinyl ester resin.

16. An electrochemical cell flow field plate as set forth in

claim 15 wherein said copolymerizable material is one or more monomers selected from the group consisting of styrene, alpha-methyl styrene, chloro-styrene, vinyl toluene, divinyl benzene, diallylphthalate, and methyl methacrylate, and mixture thereof.

17. An electrochemical cell flow field plate as set forth in

claim 16 wherein said copolymerizable material is one or more monomers selected from the group consisting of styrene and methyl methacrylate.

18. An electrochemical cell flow field plate as set forth in

claim 5 wherein said initiator is a free radical initiator.

19. An electrochemical cell flow field plate as set forth in

claim 18 wherein said initiator is selected from the group consisting of peroxides, hydroperoxides, redox systems, diazo compounds, persulfates, and perbenzoates, and is used in amounts of about 0.05 to about 5 weight percent based on the total weight of the system.

20. An electrochemical cell flow field plate as set forth in

claim 19 further comprising carbon black.

21. An electrochemical cell flow field plate as set forth in

claim 20 further comprising reinforcing fillers.

22. A process for making a fuel cell plate having an intricate flow pattern molded therein comprising the steps of mixing a composition comprising;

a) an unsaturated prepolymer resin which comprises one or more of unsaturated polyester and vinyl ester resin;

b) an unsaturated material copolymerizable with said resin and including a terminal ethylene group;

c) an inorganic conductive filler in an amount sufficient to provide a bulk conductivity of at least 40 S/cm to the resulting fuel cell plate;

d) an initiator to initiate said copolymerization of said composition; and

e) a low profile additive; and

molding the composition to form said fuel cell plate having the pattern therein substantially without machining the pattern.

23. A process as set forth in

claim 22 wherein said low profile additive is selected from the group selected from homopolymers of ethylene, styrene, vinyl toluene, alkyl methacrylates, polythylene ether, polyphenylene oxide and alkyl acrylates. vinyl chloride, vinyl acetate, acrylonitrile, and butadiene

24. A process as set forth in

claim 22 wherein said low profile additive is selected from the group selected from copolymers of vinyl chloride and vinyl acetate; styrene and acrylonitrile; methyl methacrylate and alkyl esters of acrylic acid; methyl methacrylate and styrene; methyl methacrylate and acrylamide; and SBS block copolymers.

25. A process as set forth in

claim 22 wherein said low profile additive is present in the amount of 10 to 50 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers.

26. A process as set forth in

claim 22 wherein said low profile additive is present in the amount of 20 to 45 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers.

27. A process as set forth in

claim 22 wherein said low profile additive is present in the amount of 30 to 40 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers.

28. A process for making a fuel cell plate having an intricate flow pattern molded therein comprising the steps of mixing a composition comprising;

a) an unsaturated prepolymer resin which comprises one or more of unsaturated polyester and vinyl ester resin;

b) an unsaturated material copolymerizable with said resin and including a terminal ethylene group;

c) an inorganic conductive filler in an amount sufficient to provide a bulk conductivity of at least 40 S/cm to the resulting fuel cell plate;

d) a Theological modifier to prevent phase separation between said resin and said conductive filler during molding, said rheological modifier being one or more compositions selected from the group consisting of Group II oxides and hydroxides, carbodiamides, aziridines, polyisocyanates, polytetrafluorethylene, perfluoropolyether, polyethylene and fumed silica.

e) an initiator to initiate said copolymerization of said composition;

f) a low profile additive; and molding the composition to form said fuel cell plate having the pattern therein substantially without machining the pattern.

29. A process as set forth in

claim 28 wherein said low profile additive is selected from the group selected from homopolymers of ethylene, styrene, vinyl toluene, alkyl methacrylates, polythylene ether, polyphenylene oxide and alkyl acrylates. vinyl chloride, vinyl acetate, acrylonitrile, and butadiene

30. A process as set forth in

claim 28 wherein said low profile additive is selected from the group selected from copolymers of vinyl chloride and vinyl acetate; styrene and acrylonitrile; methyl methacrylate and alkyl esters of acrylic acid; methyl methacrylate and styrene; methyl methacrylate and acrylamide; and SBS block copolymers.

31. A process as set forth in

claim 22 wherein said low profile additive is present in the amount of 10 to 50 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers.

32. A process as set forth in

claim 28 wherein said low profile additive is present in the amount of 20 to 45 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers.

33. A process as set forth in

claim 31 wherein said low profile additive is present in the amount of 30 to 40 weight percent based on the total weight of the additive and the resin system, i.e. the resin and any monomers.

34. A process for making a fuel cell plate having an intricate flow pattern molded therein comprising the steps of mixing a composition comprising;

a) an unsaturated prepolymer resin which comprises one or more of unsaturated polyester and vinyl ester resin;

b) an unsaturated material copolymerizable with said resin and including a terminal ethylene group;

c) an inorganic conductive filler in an amount sufficient to provide a bulk conductivity of at least 40 S/cm to the resulting fuel cell plate; and

d) a mold release agent; and molding the composition to form said fuel cell plate having the pattern therein substantially without machining the pattern.

35. A process as set forth in

claim 33 wherein said mold release agent comprises one or more of calcium stearate and zinc stearatey.