JP2003100313A - Separator for fuel cell and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a fuel cell and its manufacturing method by which characteristics of filler available in a melting process can be displayed in a highly efficient manner. SOLUTION: The separator is manufactured by forming a filler high filling resin composition which comprises one or more kinds of thermoplastic resin of 1 to 40 volume % selected from a liquid crystalline polyester resin and/or a polyphenylene sulfide resin, and the filler of 99 to 60 volume %.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell separator capable of being melt-processed and capable of exhibiting highly efficiently the characteristics of the filler used in the obtained molded article, and a method for producing the same. It is a thing.

[0002]

2. Description of the Related Art In recent years, the degree of freedom in the shape of molded articles has been required due to the diversification of designs. But,
Conventionally, the metal used has a limit in the degree of freedom of the molded product. Therefore, a filler-reinforced thermoplastic resin is being studied as a metal substitute. For example, the properties required for each application, such as thermal conductivity, electromagnetic wave shielding properties, and dimensional accuracy at high temperatures, are not satisfied by conventional filler-reinforced thermoplastic resins, and properties that are as close as possible to filler alone are required. It started to come. In particular, there has been a growing demand for resins used for resinizing separators for fuel cells, which require high conductivity and the like.

[0003]

However, in order to meet the above-mentioned needs, a filler alone can provide a brittle material without joining fillers, or a thermosetting resin can be used for molding processability and production. Is not good,
Also, in the filler-reinforced thermoplastic resin, there is a limit to the high filling of the filler by the usual melt-kneading method, and it is difficult to obtain a sufficiently high-filling material to meet the required characteristics, and the mechanical strength and heat dissipation (heat conduction ) Property or conductivity, a material obtained by cutting carbon was used.

Further, as a method for obtaining a composition with a highly filled filler, which is different from the conventional method, a production method characterized by kneading and extruding with the head portion of the extruder open has been proposed (JP-A-8- 1663).

However, since the die is removed during kneading in the above method, the pressure in the extruder barrel does not rise during kneading, so that the thermoplastic resin and the filler are not sufficiently mixed, and in the resulting composition There is a possibility that composition variations will occur, which will lead to large variations in characteristics.

Therefore, an object of the present invention is, in order to solve the above-mentioned problems, a fuel cell separator capable of being melt-processed and capable of exhibiting highly efficiently the characteristics of the filler to be used, and a method for producing the same. To provide.

[0007]

In order to solve the above-mentioned problems, the fuel cell separator according to the present invention comprises at least one thermoplastic resin 1-40 selected from liquid crystalline polyester resin and / or polyphenylene sulfide resin. It is characterized by being formed by molding a filler-filled resin composition comprising volume% and filler 99 to 60 volume%.

In the resin composition with a high filler content, it is preferable that the thermoplastic resin comprises 3% by volume or more and less than 15% by volume and 97% by volume or less of the filler and more than 85% by volume.

The specific gravity of the filler is preferably 3.5 or less. As the filler, for example, a fibrous, plate-shaped, or scaly form can be used.

The thermoplastic resin for the fuel cell separator as described above is preferably a liquid crystal polymer. As the liquid crystal polymer, for example, a liquid crystal polyester having the following structural units (I), (II), (III) and (IV) can be used.

[0011]

[Chemical 4] However, in the formula, R1 represents one or more groups selected from the following formula 5, and R2 represents one or more groups selected from the following formula 6. However, in the formula, X represents a hydrogen atom or a chlorine atom.

[0012]

[Chemical 5]

[0013]

[Chemical 6]

In order to produce the fuel cell separator as described above, the method for producing the fuel cell separator according to the present invention comprises at least one thermoplastic resin selected from liquid crystalline polyester resin and / or polyphenylene sulfide resin. 1-40% by volume and filler 99-60% by volume
When melt-kneading and, a resin composition is produced by using a die head in which a flow path leading to a discharge port is formed in a tapered shape with few retention parts, and the resin composition is molded. Become.

In this manufacturing method, the taper-shaped flow passage having a small amount of staying portion is branched midway in the flow direction, and each flow passage portion up to the discharge port after branching also corresponds to it. It is preferably formed in a tapered shape toward the discharge port. It is preferable that the branch portion is formed in a substantially sharp shape toward the upstream side in the flow direction.

As the thermoplastic resin, 1000 μ
It is preferable to use one having a size that can pass through a sieve corresponding to m.

By such a manufacturing method, a fuel cell separator obtained by molding pellets cut after being discharged from the die head can be obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In the present invention, "weight" means "mass".

The fuel cell separator of the present invention is formed from a filler-filled resin composition in which a filler such as a conductive agent is added to one or more thermoplastic resins selected from liquid crystalline polyester resins and / or polyphenylene sulfide resins. It is a thing.

The liquid crystalline polyester resin used in the present invention is a polyester resin capable of forming an anisotropic molten phase. For example, a liquid crystalline polyester comprising a structural unit selected from an aromatic oxycarbonyl unit, an aromatic dioxy unit, an aromatic and / or aliphatic dicarbonyl unit, an alkylenedioxy unit and the like and forming an anisotropic melt phase is More specifically, a liquid crystalline polyester comprising a structural unit produced from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, a structural unit produced from p-hydroxybenzoic acid, 6-hydroxy-
Liquid crystalline polyester comprising a structural unit produced from 2-naphthoic acid, an aromatic dihydroxy compound and / or a structural unit produced from an aliphatic dicarboxylic acid, a structural unit produced from p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl , A liquid crystalline polyester comprising a structural unit formed from an aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid and / or an aliphatic dicarboxylic acid such as adipic acid and sebacic acid, p
-A liquid crystalline polyester comprising a structural unit produced from hydroxybenzoic acid, a structural unit produced from ethylene glycol, a structural unit produced from terephthalic acid, a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from ethylene glycol, Liquid crystalline polyester consisting of structural units produced from terephthalic acid and isophthalic acid, structural units produced from p-hydroxybenzoic acid, structural units produced from ethylene glycol, structural units produced from 4,4′-dihydroxybiphenyl, terephthalic acid And / or a liquid crystalline polyester comprising a structural unit produced from an aliphatic dicarboxylic acid such as adipic acid or sebacic acid, a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from ethylene glycol, an aromatic dihydroxy compound Examples thereof include liquid crystalline polyesters such as liquid crystalline polyesters composed of structural units formed from an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid.

Among the above liquid crystalline polyesters, specific examples of preferable structures include (I) and (I
Examples thereof include liquid crystalline polyesters composed of structural units I), (III) and (IV), and liquid crystalline polyesters composed of structural units (I), (III) and (IV). Particularly preferred is a liquid crystalline polyester comprising structural units (I), (II), (III) and (IV).

[0022]

[Chemical 7] However, in the formula, R1 represents one or more groups selected from the following chemical formula 8, and R2 represents one or more groups selected from the following chemical formula 9. However, in the formula, X represents a hydrogen atom or a chlorine atom.

[0023]

[Chemical 8]

[0024]

[Chemical 9]

The structural unit (I) is a structural unit formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,
4'-dihydroxybiphenyl, 3,3 ', 5,5'-
Tetramethyl-4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, methylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene,
The structural unit formed from one or more aromatic dihydroxy compounds selected from 2,2-bis (4-hydroxyphenyl) propane and 4,4′-dihydroxydiphenyl ether, and the structural unit (III) is a structure formed from ethylene glycol. The structural unit (IV) is terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,
6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid and 4,4'- Each of the structural units formed from one or more aromatic dicarboxylic acids selected from diphenyl ether dicarboxylic acids is shown. Of these, R1 is
And those in which R2 is the following formula 11 are particularly preferable.

[0026]

[Chemical 10]

[0027]

[Chemical 11]

The liquid crystalline polyester which can be preferably used in the present invention is, as described above, structural units (I), (III) and (IV).
And a structural unit (I), (II), (II
It is one or more selected from the copolymers consisting of I) and (IV), and the copolymerization amount of the structural units (I), (II), (III) and (IV) is arbitrary. However, in order to exert the characteristics of the present invention, the following copolymerization amount is preferable.

That is, the above structural units (I), (II) and (II
In the case of a copolymer consisting of (I) and (IV), the above structural unit (I)
The total of (II) and (II) is preferably 30 to 95 mol%, more preferably 40 to 85 mol% with respect to the total of structural units (I), (II) and (III). Further, the structural unit (III) is a structural unit
70-5 mol% is preferable with respect to the total of (I), (II) and (III), and 60-15 mol% is more preferable. The molar ratio [(I) / (II)] of the structural unit (I) to (II) is preferably 75/25 to 95/5, and more preferably 78.
/ 22 to 93/7. Further, the structural unit (IV) is preferably substantially equimolar to the total of the structural units (II) and (III).

On the other hand, when the structural unit (II) is not contained, the structural unit (I) is the structural unit (I) and (I
It is preferably 40 to 90 mol%, particularly preferably 60 to 88 mol%, based on the total of II), and the structural unit (IV) is substantially equimolar to the structural unit (III). Is preferred.

The term "substantially equimolar" means that the units constituting the polymer main chain excluding the terminals are equimolar, but the units constituting the terminals are not necessarily equimolar.

The liquid crystalline polyester which can be preferably used is 3,3'-diphenyldicarboxylic acid, 2,2'-, in addition to the components constituting the structural units (I) to (IV).
Aromatic dicarboxylic acids such as diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone,
Aromatic diols such as 3,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxybenzophenone and 3,4′-dihydroxybiphenyl, propylene glycol, Aliphatic and alicyclic diols such as 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, and m-hydroxybenzoic acid, 2, Aromatic hydroxycarboxylic acids such as 6-hydroxynaphthoic acid and p-aminobenzoic acid can be further copolymerized to the extent that liquid crystallinity is not impaired.

The method for producing the above-mentioned liquid crystalline polyester used in the present invention is not particularly limited, and can be produced according to a known polyester polycondensation method. For example, in the production of the above liquid crystalline polyester, the following production method is preferably exemplified.

(1) p-acetoxybenzoic acid and 4,
Diacylated aromatic dihydroxy compounds such as 4′-diacetoxybiphenyl and diacetoxybenzene, and 2,
A method for producing a liquid crystalline polyester from an aromatic dicarboxylic acid such as 6-naphthalenedicarboxylic acid, terephthalic acid or isophthalic acid by a deacetic acid condensation polymerization reaction.

(2) p-hydroxybenzoic acid and 4,
Aromatic dihydroxy compounds such as 4′-dihydroxybiphenyl and hydroquinone and aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, terephthalic acid and isophthalic acid are reacted with acetic anhydride to acylate the phenolic hydroxyl group, A method for producing a liquid crystalline polyester by a deacetic acid polycondensation reaction.

(3) Phenyl ester of p-hydroxybenzoic acid and aromatic dihydroxy compound such as 4,4'-dihydroxybiphenyl and hydroquinone, and 2,6
A method for producing a liquid crystalline polyester from a diphenyl ester of an aromatic dicarboxylic acid such as naphthalenedicarboxylic acid, terephthalic acid or isophthalic acid by a dephenol polycondensation reaction.

(4) p-hydroxybenzoic acid and 2,
Aromatic dicarboxylic acids such as 6-naphthalenedicarboxylic acid, terephthalic acid and isophthalic acid are reacted with a predetermined amount of diphenyl carbonate to form diphenyl esters, and then aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl and hydroquinone. And a liquid crystalline polyester by a dephenol polycondensation reaction.

(5) Polyester polymers such as polyethylene terephthalate, oligomers or bis (β-
A method for producing a liquid crystalline polyester by the method (1) or (2) in the presence of a bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid such as hydroxyethyl) terephthalate.

The liquid crystalline polyester used in the present invention is
The melt viscosity is preferably 0.5 to 80 Pa · s, and particularly 1 to 50 Pa · s in order to suppress the deterioration of fluidity due to high filling of the filler.
Is more preferable. Further, in order to obtain a composition having more excellent fluidity, the melt viscosity is preferably 40 Pa · s or less.

The melt viscosity is the melting point (Tm) +10.
It is a value measured by a Koka type flow tester under conditions of a shear rate of 1,000 (1 / sec) under conditions of ° C. Here, the melting point (Tm) is Tm1 +20 after the observation of the endothermic peak temperature (Tm1) observed when measuring the temperature of the polymer that has completed polymerization at a temperature rise rate of 20 ° C./min in the differential calorimetry. Hold at 5 ℃ for 5 minutes, then 20 ℃
After cooling once to room temperature under the temperature lowering condition of 1 / min, the temperature is 20 ℃ again.
The endothermic peak temperature (Tm2) observed when measured under a temperature rising condition of 1 / min.

Among the above-mentioned resins, p-hydroxybenzoic acid and 6 are used in view of mechanical properties and moldability.
-A liquid crystalline polyester consisting of a structural unit formed from hydroxy-2-naphthoic acid, a structural unit formed from p-hydroxybenzoic acid, a structural unit formed from ethylene glycol, a structural unit formed from 4,4'-dihydroxybiphenyl, From liquid crystalline polyester consisting of structural units formed from aliphatic dicarboxylic acids such as terephthalic acid and / or adipic acid and sebacic acid, structural units formed from p-hydroxybenzoic acid, structural units formed from ethylene glycol, and aromatic dihydroxy compounds Generated structural unit, terephthalic acid, isophthalic acid, 2,6-
A liquid crystalline polyester composed of a structural unit formed from an aromatic dicarboxylic acid such as naphthalene dicarboxylic acid, and one or a mixture of two or more selected from a polyphenylene sulfide resin can be preferably used.

Among them, polyphenylene sulfide, p
Liquid crystalline polyester consisting of structural units formed from -hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, structural units formed from p-hydroxybenzoic acid, structural units formed from ethylene glycol, and aromatic dihydroxy compounds A liquid crystalline polyester having a structural unit, a structural unit produced from terephthalic acid, a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from ethylene glycol, or a structural unit produced from terephthalic acid is particularly preferably used. You can Further, from the viewpoint of fluidity and processability at the time of high filling, a structural unit produced from p-hydroxybenzoic acid,
A liquid crystalline polyester having a structural unit formed from an aromatic dihydroxy compound and / or ethylene glycol or a structural unit formed from terephthalic acid is preferably used. Examples of commercially available products having these structures include "Ciberas" manufactured by Toray Industries, Inc. and "Sumika Super" manufactured by Sumitomo Chemical Co., Ltd.

Examples of the filler used in the present invention include fibrous or non-fibrous fillers such as plate-like, scale-like, granular, irregular and crushed products. Specific examples thereof include glass fiber and PAN-based fillers. Pitch carbon fiber, stainless fiber, metal fiber such as aluminum fiber and brass fiber, organic fiber such as aromatic polyamide fiber, gypsum fiber, ceramic fiber, asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber , Silicon carbide fiber, rock wool, potassium titanate whiskers, barium titanate whiskers, aluminum borate whiskers, silicon nitride whiskers, mica, talc, kaolin, silica, calcium carbonate, glass beads, glass flakes,
Glass micro-balloon, clay, molybdenum disulfide,
Examples include wollastonite, titanium oxide, zinc oxide, calcium polyphosphate, graphite, metal powder, metal flakes, metal ribbons, metal oxides, carbon powder, graphite, carbon flakes, scaly carbon, and carbon nanotubes. Specific examples of the metal species of the metal powder, the metal flakes and the metal ribbon include silver, nickel, copper, zinc, aluminum, stainless steel, iron, brass, chromium and tin. The type of glass fiber or carbon fiber is not particularly limited as long as it is generally used for reinforcing a resin, and for example, long fiber type or short fiber type chopped strand, milled fiber, etc. can be selected and used.
In the present invention, among the above-mentioned fillers, fibrous, plate-like, scale-like shapes and crushed products are preferably used from the viewpoint of the obtainability of the resin composition, and further, such as the strength of the fuel cell separator as a molded product. From the viewpoint, fibrous, plate-like, and scale-like shapes are preferable. In the present invention, the fibrous shape is usually called a fibrous shape, and includes a whisker shape, for example, average fiber length or average major axis / average fiber diameter or average minor axis (aspect ratio, etc.) 3 to
One having a shape of about 10,000 is mentioned. Plate-like and scale-like are usually called plate-like and scale-like, and also include those called scale-like and have a shape having a thickness with respect to the major axis, for example, an average major axis / average thickness of 3 to 50.
Some of them are around 00. The granules have a shape relatively close to a sphere, for example, the average major axis /
The average minor axis is about 1 or more and less than 3. An irregular shape is one in which the shape of a crushed product or the like is not fixed. The shape of these fillers (average fiber length / average fiber diameter,
The average major axis / average thickness and the average major axis / average minor axis are calculated by measuring 100 fiber lengths, fiber diameters, major axes, minor axes or thicknesses with a scanning electron microscope (SEM) and calculating the number average thereof. be able to.

Further, the above-mentioned fillers may be used in combination of two or more kinds in order to obtain a balance between mechanical strength and warpage of a molded article. For example, glass fiber and mica or kaolin, glass fiber and glass beads, Examples thereof include carbon fiber and mica or kaolin, carbon fiber and graphite, glass fiber or carbon fiber and carbon nanotube, graphite and carbon black and / or carbon nanotube.

The surface of the above-mentioned filler used in the present invention is treated with a known coupling agent (for example, a silane coupling agent, a titanate coupling agent, etc.) or another surface treatment agent before use. You can also Also,
The above-mentioned filler can be used after being coated with a conductive substance.

Further, the glass fiber may be coated or bundled with a thermoplastic resin such as ethylene / vinyl acetate copolymer or the like, or a thermosetting resin such as an epoxy resin or the like.

Further, among the above-mentioned fillers, a conductive filler is particularly used to impart conductivity to the resin composition. The conductive filler is not particularly limited as long as it is a conductive filler usually used for making a resin conductive,
Specific examples thereof include metal powder, metal flakes, metal ribbons, metal fibers, metal oxides, carbon powder, graphite, PA.
Examples thereof include N-based or pitch-based carbon fibers, carbon flakes, scaly carbon, carbon nanotubes, and inorganic fillers coated with a conductive substance.

Here, specific examples of the metal species of the above metal powder, metal flakes and metal ribbons include silver, nickel,
Examples thereof include copper, zinc, aluminum, stainless steel, iron, brass, chromium and tin.

Specific examples of the metal species of the metal fibers include iron, copper, stainless steel, aluminum and brass.

The metal powder, metal flakes, metal ribbons and metal fibers may all be surface-treated with a surface-treating agent such as titanate, aluminum or silane.

Specific examples of the above metal oxide include SnO.
₂ (antimony-doped), In ₂ O ₃ (antimony-doped), ZnO (aluminum-doped) and the like can be exemplified, and these are surface-treated with a surface-treating agent such as titanate-based, aluminum-based or silane-based. May be.

Specific examples of the conductive material in the inorganic filler coated with the conductive material include aluminum,
Examples thereof include nickel, silver, carbon, SnO ₂ (antimony-doped), In ₂ O ₃ (antimony-doped), and the like. Further, as the inorganic filler to be coated, mica, glass beads, glass fibers, carbon fibers, potassium titanate whiskers, barium sulfate, zinc oxide,
Examples thereof include titanium oxide, aluminum borate whiskers, zinc oxide type whiskers, titanic acid type whiskers, and silicon carbide whiskers. Examples of the coating method include a vacuum vapor deposition method, a sputtering method, an electroless plating method and a baking method. The inorganic filler coated with these conductive substances may also be surface-treated with a surface treatment agent such as titanate-based, aluminum-based or silane-based.

The above carbon powder is classified into acetylene black, gas black, oil black, naphthalene black, thermal black, furnace black, lamp black, channel black, roll black, disk black and the like according to the raw materials and the manufacturing method thereof. Carbon powder that can be used in the present invention,
The raw material and manufacturing method are not particularly limited,
Of these, acetylene black and furnace black are particularly preferably used. As the carbon powder, various carbon powders having different characteristics such as particle size, surface area, DBP (dibutyl phthalate) oil absorption and ash content are manufactured and commercially available. The carbon powder that can be used in the present invention is not particularly limited in these characteristics, but from the viewpoint of the balance of strength and electrical conductivity, the average particle size of the primary particle size is 500 nm or less, particularly 5 to 1
It is preferably in the range of 00 nm, more preferably 10 to 70 nm. The surface area (BET method) is preferably 10 m ² / g or more, and more preferably 30 m ² / g or more. Further, it is preferable that the DBP oil supply amount is in the range of 50 ml / 100 g or more, particularly 100 ml / 100 g or more. Furthermore, the ash content is 0.5% or less, particularly, 0.
It is preferably in the range of 3% or less.

The carbon powder may be surface-treated with a surface-treating agent such as titanate type, aluminum type and silane type. Further, it is also possible to use a granulated product in order to improve the workability of melt-kneading with a resin.

The blending amount of the thermoplastic resin and the filler used in the present invention is, with respect to the total amount of the thermoplastic resin and the filler, in view of the characteristics of the filler to be used and the balance with the melt processability. The thermoplastic resin is 1 to 40% by volume, the filler is 99 to 60% by volume, the thermoplastic resin is preferably 2 to 25% by volume, and the filler is 98 to 75% by volume, and further the thermoplastic resin is 3% by volume or more and 15% by volume. Less than,
The filler content is preferably 97% by volume or more and more than 85% by volume.

The filler-filled thermoplastic resin composition for molding the fuel cell separator of the present invention comprises:
Other components within a range that does not impair the effects of the present invention, for example, antioxidants and heat stabilizers (hindered phenol-based, hydroquinone-based, phosphite-based and substitution products thereof, etc.),
Weathering agents (resorcinol-based, salicylate-based, benzotriazole-based, benzophenone-based, hindered amine-based, etc.), release agents and lubricants (montanic acid and its metal salts, their esters, their half esters, stearyl alcohol, stearamide, various bisamides, bis Urea and polyethylene wax, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black for coloring, etc.), dyes (nigrosine, etc.), crystal nucleating agents (talc, silica, kaolin, clay, etc.), plasticizers (octyl p-oxybenzoate) , N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate) , Both betaine Antistatic agents), flame retardants (e.g.,
Red phosphorus, phosphoric acid ester, melamine cyanurate, hydroxides such as magnesium hydroxide and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated PPO
(Polyphenylene ether), brominated PC (polycarbonate), brominated epoxy resin or a combination of these brominated flame retardants and antimony trioxide, conductive polymers (for example, polyaniline, polypyrrole, polyacetylene, poly (paraphenylene), Other polymers such as polythiophene and polyphenylene vinylene) can be added.

The method for producing the fuel cell separator of the present invention comprises mixing one or more thermoplastic resins selected from liquid crystalline polyester resins and / or polyphenylene sulfide resins and fillers using a Banbury mixer, a kneader or a roll. Then, use a single-screw or twin-screw extruder (preferably a twin-screw extruder from the viewpoint of the uniformity of the resulting filler-filled resin composition) equipped with a die head having an opening having a shape with a small retention portion. Can be manufactured by. A die head that is normally used has a structure that has a plurality of ejection openings that linearly penetrate through the end wall surface on the most downstream side of the resin flow path. The molten resin stays in the portion other than the discharge port near the wall surface of the portion, which makes extrusion difficult. On the other hand, by using a die head having an opening having a shape with a small retention portion, stable extrusion becomes possible. The specific shape of the opening having such a small number of retention portions is a shape that does not hinder the flow of the molten resin toward the discharge port.

At this time, it is preferable that the shape of the die at the tip of the extruder has a structure for reducing the retention of the composition as much as possible (for example, it has a taper shape from the screw side to the tip of the discharge port).

For example, the taper-shaped flow path having a small amount of staying portion is branched in the middle of the flow direction, and each flow path portion reaching the discharge port after branching is also directed to the corresponding discharge port. A die head having a taper-shaped structure is used. Particularly, it is preferable that the branch portion is formed in a substantially sharp shape toward the upstream side in the flow direction. If the die head has one resin inlet from the screw side with respect to one discharge port, the branch passage is unnecessary.

Conventionally, it was difficult to cut the resin composition discharged from the die head into pellets, but the resin composition discharged from the die head having the above structure can be easily cut into pellets. Like

Further, since the filler-filled thermoplastic resin composition to be discharged is inferior in stretchability at the time of take-up due to the high filling of the filler, there is a suitable range for the discharge port size, and if it is too large or too small. If too much, pelletization becomes difficult. Specifically, for example, with the diameter or short diameter of the discharge port,
It is preferably within the range of 2 to 10 mm. However,
The shape of the discharge port is not particularly limited, and specific examples thereof include a circle, an ellipse, and a quadrangle or more polygon.

From the viewpoint of compositional uniformity and kneading properties of the obtained composition, it is particularly preferable to use the thermoplastic resin to be reduced in diameter or processed into a powder in the same manner as the filler to be used.

At this time, the thermoplastic resin to be blended is
If the composition can be produced, either pellets or powder may be used, but when the filler content is large, it is preferable to use a pellet having a small diameter or powder. The thermoplastic resin has a normal pellet shape (about 2
mmφ × 3 mm length), it is cooled and pulverized, preferably frozen and pulverized into powder, or repelleted using a strand die having a small diameter,
It is possible to use a reduced diameter.

In consideration of the compositional variation between pellets obtained from the filler-filled thermoplastic resin composition, the solidification property of the pellets, the melt processability, the surface appearance of the obtained molded article, etc., the thermoplastic resin is generally Specifically, about 2mmφ × 3
It is used as a pellet having a length of mm, but when the size is measured based on a sieving test method based on JIS-K0069, it is preferable that the size of the pellet pass through a sieve corresponding to 1000 μm, and more preferable. Is preferably one that passes through a sieve corresponding to 800 μm, and particularly one that passes through a sieve corresponding to 500 μm. Further, with respect to the lower limit, a sieve which does not substantially pass through a sieve corresponding to 5 μm is preferable from the viewpoint of handling. Here, "substantially does not pass" means that 95% by weight of the sieved filler
It means that the above does not pass. Such filler may be selected from commercially available fillers or may be crushed before use. It is also possible to classify using a sieve and take out a desired size to use. If necessary, two or more kinds having different particle sizes may be used in combination.

The size of the filler is 1000 μm when measured by the sieving test method based on JIS-K0069.
It is preferable that it passes through a sieve corresponding to, more preferably, it passes through a sieve corresponding to 800 μm,
In particular, it is preferable to pass through a sieve corresponding to 500 μm. Further, with respect to the lower limit, a sieve which does not substantially pass through a sieve corresponding to 5 μm is preferable from the viewpoint of handling. Here, "substantially does not pass" means that 95% by weight or more of the sieved filler does not pass. Such a filler may be selected from commercially available ones, or may be classified by using a sieve and taken out to have a required size and used. Also,
Regarding the shape of the filler to be used, from the obtainability of the pellets of the composition, fibrous, plate-like, scale-like and crushed products are preferably used, and fibrous or plate-like in terms of the strength of the molded product obtained in the production. The shape and scale are preferred. Furthermore, two or more kinds having different particle sizes may be used in combination depending on the required characteristics.

In the present invention, in the case of blending other components that can be blended as necessary, the blending method is not particularly limited and can be added at any stage.

By the above method, it becomes possible to obtain a filler-filled composition which could not be obtained conventionally, and it is possible to produce the fuel cell separator according to the present invention using the composition.

From the viewpoint of uniform mixing of the thermoplastic resin and the filler, the specific gravity of the filler is preferably 3.5 or less, more preferably 3 or less. In addition,
When using a plurality of types of fillers, it is preferable that the specific gravity of at least one of the fillers having the largest amount of compounding is within the above range.

The resin composition thus obtained can be melt-molded by injection molding, extrusion molding, press molding, injection press molding or the like, and can be processed into a fuel cell separator.

The resin composition thus obtained can be molded into a fuel cell separator having a target shape by making the most of the characteristics of the filler to be used and making it possible to perform melt molding. Among them, it is particularly useful for a fuel cell separator that requires high conductivity. Since the fuel cell separator is particularly required to have conductivity as described above, it is preferable to use, for example, a carbon-based material such as graphite, carbon fiber, carbon black or carbon nanotube, or a metal oxide such as aluminum oxide as the filler. .

[0071]

The present invention will be described in detail below with reference to examples, but the gist of the present invention is not limited to the following examples.

Reference Example 1 (Thermoplastic resin) PPS (polyphenylene sulfide, linear type): M2588 (manufactured by Toray) is crushed by a sample mill (SK-M type manufactured by Kyoritsu Riko), and sieved to 60 mesh. Number average particle size is 200 after sorting with 150 mesh on pass
.mu.m was obtained. LCP1 (Liquid Crystal Polymer 1): "Ciberus" L201E
(Toray Co., Ltd.) is immersed in liquid nitrogen, pulverized with a sample mill (SK-M type, manufactured by Kyoritsu Riko Co., Ltd.), and classified with a sieve of 80 mesh and 150 mesh to obtain a number average particle diameter of 150.
.mu.m was obtained. LCP2 (liquid crystal polymer 2): 994 parts by weight of p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl 16
8 parts by weight, 150 parts by weight of terephthalic acid, 173 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl / g and 1011 parts by weight of acetic anhydride were charged into a reaction vessel equipped with a stirring blade and a distilling tube. The temperature is raised from room temperature to 150 ° C and the reaction is performed for 3 hours.
The temperature is raised from 250 ° C. to 335 ° C. in 1.5 hours, and then 6.5 × 10 ⁻³ in 335 ° C. and 1.5 hours.
The pressure was reduced to Pa, and the reaction was continued for about 0.25 hours to carry out polycondensation. As a result, 80 mol equivalents of aromatic oxycarbonyl units,
A melting point of 328 ° C. consisting of 10 molar equivalents of aromatic dioxy units, 10 molar equivalents of ethylenedioxy units, and 20 molar equivalents of aromatic dicarboxylic acid units, melt viscosity 18 (338 ° C., orifice 0.5 mm diameter × 10 mm, shear rate 1,000) (1
/ Sec)) pellets were obtained. LCP3 (Liquid Crystal Polymer 2): LCP2 was dipped in liquid nitrogen, crushed with a sample mill (SK-M type manufactured by Kyoritsu Riko Co., Ltd.), and classified with a sieve of 60 mesh and 150 mesh to obtain a number average particle diameter. 220 μm was obtained.

Reference Example 2 (Filler) Carbon fiber (CF): MLD30 (fibrous filler, fiber diameter 7 μm, manufactured by Toray) Graphite (KS44): KS-44 (scaly filler, manufactured by Timcal Japan) Graphite ( KS150): KS-150 (scaly filler, manufactured by Timcal Japan Co., Ltd.) The filler sizes in the tables below are on a sieve when a 500 g sample is taken and classified using a sieve having a roughness corresponding to that size. It means that it did not remain.

Example 1 A twin-screw extruder having 14% by volume of LCP1 of Reference Example 1 and 86% by volume of graphite (KS150) shown in Reference Example 2 blended with a ribbon blender and equipped with a die head 1 shown in FIG. (PCM30; manufactured by Ikegai Tekko Co., Ltd.) was discharged at a resin temperature of 360 ° C. at a screw rotation speed of 100 rpm, and pelletized to obtain a composition. FIG. 1 is a side view, a top view and a front view showing the outline of the die head 1 described above. A tapered flow passage 2 in which a resin flow passage is tapered from a screw head A side toward a die tip end side B. And the flow path 2 is branched into a W shape on the way,
The branched flow path 2a is also formed in a taper shape that tapers toward the corresponding ejection port 3 at the tip of the die head.
The W-shaped branch portion 4 is formed sharply toward the upstream side in the flow direction, and the resin is prevented from staying at the sharp branch portion 4. Further, since the branched flow paths 2a are connected to the corresponding discharge ports 3 by the tapered flow paths, they do not stay even immediately before the discharge ports 3. Therefore, the structure is such that resin does not accumulate inside the die head. The opening forming the flow path in the die head has a chamfered rectangle with a width of 12 mm and a height of 5 mm on the die tip side, and two circular portions with a diameter of 30 mm are connected on the screw head side to form an eyebrows with a width of 55 mm. It is formed in a shape.

Then, using a press molding machine at a resin temperature of 360 ° C. and a pressing pressure of 7 MPa, 105 mm × 105 m
A plate-shaped molded product having a thickness of m × 3 mm was molded, and the volume resistivity was measured by the four-terminal method. The result was 0.008 Ωcm.

Example 2 25% by volume of LCP3 of Reference Example 1 and 75% by volume of graphite (KS150) shown in Reference Example 2 were blended with a ribbon blender, and a twin-screw extruder equipped with a die head shown in FIG. PCM30; manufactured by Ikegai Tekko Co., Ltd.) was used to obtain a composition at a screw rotation speed of 100 rpm and a resin temperature of 360 ° C. Then, using a press molding machine at a resin temperature of 360 ° C. and a pressing pressure of 7 MPa, 105 mm × 105 m
A plate-shaped molded product having a thickness of m × 3 mm was molded, and the volume resistivity was measured by the 4-terminal method, and the result was 0.010 Ωcm.

Example 3 25% by volume of LCP2 of Reference Example 1 and 75% by volume of graphite (KS44) shown in Reference Example 2 were blended with a ribbon blender, and a twin-screw extruder equipped with a die head as shown in FIG. PCM30; manufactured by Ikegai Tekko Co., Ltd.) was used to obtain a composition at a screw rotation speed of 100 rpm and a resin temperature of 360 ° C. Then, using a press molding machine at a resin temperature of 360 ° C. and a pressing pressure of 7 MPa, 105 mm × 105 mm
A plate-shaped molded product having a thickness of 3 mm was molded, and the volume resistivity was measured by the four-terminal method. The result was 0.022 Ωcm.

Example 4 14% by volume of PPS of Reference Example 1 and 86% by volume of graphite (KS150) shown in Reference Example 2 were blended with a ribbon blender, and a twin-screw extruder equipped with a die head shown in FIG. 1 ( PCM30; manufactured by Ikegai Tekko Co., Ltd.) to obtain a composition at a screw rotation speed of 100 rpm and a resin temperature of 350 ° C. Then, using a press molding machine at a resin temperature of 350 ° C. and a pressing pressure of 7 MPa, 105 mm × 105 mm
A plate-shaped molded product having a thickness of 3 mm was molded, and the volume resistivity was measured by the four-terminal method, and the result was 0.009 Ωcm.

Comparative Examples 1 and 2 The thermoplastic resin of Reference Example 1 and a predetermined amount of the filler shown in Reference Example 2 were blended with a ribbon blender, and the die head 11 for 4 mmφ × 3 holes for strand shown in FIG.
(Because it is a conventional die head 11 in which a common tapered flow path 12 is formed toward all of the three-hole discharge ports 13, there is a possibility that stagnation may occur on the inner surface near the discharge ports 13) When a melt-kneading study was conducted using a twin-screw extruder PCM30 (manufactured by Ikegai Tekko Co., Ltd.) at a screw rotation speed of 100 rpm and a resin temperature shown in Table 1, no composition was obtained. The results are shown in Table 1.

[0080]

[Table 1]

As is clear from the results shown in Table 1, since the filler-filled thermoplastic resin composition of the present invention can obtain the characteristics of the region which have not been obtained conventionally and can be melt-processed, It is clear that it will be possible to develop new applications such as metal replacement used for weight reduction purposes. In particular, by adding a conductive filler, a molded product with significantly improved conductivity can be obtained, so it is clear that a molded product useful as a separator of a fuel cell or the like can be obtained.

[0082]

EFFECTS OF THE INVENTION According to the fuel cell separator and the method for producing the same of the present invention, melt processing is possible, and the obtained fuel cell separator can exhibit the characteristics of the filler used with high efficiency. Thus, it becomes possible to give the resin composition a characteristic that could not be obtained in the past, so that a particularly highly conductive separator for a fuel cell can be efficiently produced.

[Brief description of drawings]

FIG. 1 is a diagram showing a side surface, a top surface, and a front surface of a die head used in an example of the present invention.

FIG. 2 is a diagram showing a side surface, a top surface, and a front surface of a die head used in a comparative example.

[Explanation of symbols]

1,11 Die head 2, 12 channels 2a Branch flow path 3, 13 outlet 4 branches

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 67/00 C08L 67/00 81/02 81/02 // B29K 67:00 B29K 67:00 81:00 81:00 105: 16 105: 16 (72) Inventor Yoshiki Makabe, 1-9-9 Oe-cho, Minato-ku, Nagoya-shi, Aichi Toray Industries, Inc. Nagoya business site F-term (reference) 4F071 AA44 AA62 AB03 AB06 AB07 AB08 AB09 AB10 AB12 AB19 AB28 AB29 AB30 AD01 AD02 AD05 AE17 AF13 AF37 AF44 AH15 BB03 BB05 BB06 BC03 4F201 AA24 AA34 AB11 AB13 AB18 AB24 AB25 AB27 AH42 BA02 BC01 BC02 BC37 BD02 BD04 BD05 BK02 BK27 BK27 BK02 BK02 BK02 BK02 CG02 CF01 CF01 CF03 4062 CF161 CF03 4062 CF161CF031 DA076 DA096 DA106 DA116 DC006 DE046 DE086 DE096 DE106 DE146 DE186 DE236 DG026 DG056 DH046 DJ006 DJ016 DJ036 DJ046 DJ056 DL006 DM006 FA016 FA041 FA046 FA086 GD00 GQ00 5H026 AA02 BB08 EE18 HH01 HH05

Claims (11)

[Claims] 1. A highly filled filler resin composition comprising 1 to 40% by volume of a thermoplastic resin selected from a liquid crystalline polyester resin and / or a polyphenylene sulfide resin and 99 to 60% by volume of a filler. A separator for a fuel cell, which is characterized in that 2. A thermoplastic resin containing at least 3% by volume and less than 15% by volume of one or more thermoplastic resins selected from liquid crystalline polyester resins and / or polyphenylene sulfide resins and a filler 9
The fuel cell separator according to claim 1, which is obtained by molding a highly filled filler resin composition containing 7% by volume or more and more than 85% by volume. 3. The fuel cell separator according to claim 1, wherein the specific gravity of the filler is 3.5 or less. 4. The fuel cell separator according to claim 1, wherein the filler is fibrous, plate-shaped or scale-shaped. 5. The fuel cell separator according to any one of claims 1 to 4, wherein the thermoplastic resin is a liquid crystalline polyester resin. 6. The liquid crystal polyester resin is a structural unit shown below.
The fuel cell separator according to claim 5, which is a liquid crystalline polyester resin comprising (I), (II), (III) and (IV). [Chemical 1] (However, R1 in the formula is R1 represents one or more groups selected from And one or more groups selected from However, in the formula, X represents a hydrogen atom or a chlorine atom. ) 7. A flow path reaching a discharge port when melt-kneading 1 to 40% by volume of one or more thermoplastic resins selected from a liquid crystalline polyester resin and / or polyphenylene sulfide resin and 99 to 60% by volume of a filler. 7. The fuel cell according to any one of claims 1 to 6, wherein a resin composition is produced by using a die head formed in a tapered shape having a small retention portion, and the resin composition is molded. Method for manufacturing separator. 8. The taper-shaped flow passage having a small amount of retention portion is branched midway in the flow direction, and each flow passage portion up to the discharge port after branching is also directed toward the corresponding discharge port. The method for manufacturing a fuel cell separator according to claim 7, wherein the separator is formed into a tapered shape. 9. The method for producing a fuel cell separator according to claim 8, wherein the branch portion is formed in a substantially sharp shape toward the upstream side in the flow direction. 10. The method for producing a fuel cell separator according to claim 7, wherein a thermoplastic resin which passes through a sieve corresponding to 1000 μm is used. 11. A separator for a fuel cell, which is produced by the method according to any one of claims 7 to 10 and is formed by molding cut pellets after being discharged from a die head.