JP2010269572A - Manufacturing process for molding, mold and molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process for a molding for inhibiting the generation of chips when forming a protrusion on a surface using a mold, the mold and the molding. <P>SOLUTION: A plurality of mold protrusions 33 extending in straight lines are formed with a plurality of intervals while mold recessions 34 adjoining the mold protrusions 33 and extending in straight lines are formed with a plurality of intervals on a mold 30 so as to shape a protrusion 11 and a recess 13. The mold protrusion 33 is formed of a side face 331, an end face 332 and a planar slat face 333 which connects the side face 331 and the end face 332. In other words, the mold protrusion 33 has a shape chamfered (or C plane cut) planar by the planar slant face 333. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a molded product having a concavo-convex shape on the surface, a mold and a molded product.

Conventionally, various methods are used as a method for producing a molded product. For example, an injection molding method, an extrusion molding method, and the like are known. As a molded product to be molded by such a molding method, there is a molded product in which a large amount of filler is mixed with a thermoplastic resin. For example, a separator for a fuel cell in which a filler such as graphitic carbon and carbon fiber is mixed with a thermoplastic resin as a filler can be used.
The separator for a fuel cell includes a solid electrolyte of a fuel cell (especially a polymer electrolyte fuel cell (PEFC)), and a fuel electrode and an oxidation electrode (also anode and cathode) formed on both sides of the solid electrolyte. And a membrane / electrode assembly (MEA). Oxygen is supplied to one side of the MEA and hydrogen is supplied to the other side from a groove formed in the fuel cell separator.

  In addition, since the separator for a fuel cell has a current collecting function from the electrode as a product surface, high conductivity (electric conductivity) is required, and a lot of fuel gas etc. pass through the surface. The flow path (groove) requires various properties such as gas impermeability, thermal conductivity, compressive strength, mechanical strength, electrolyte (phosphoric acid, sulfuric acid, etc.), corrosion resistance against ions, and the shape itself. However, high dimensional accuracy is required.

  There is known a method of molding a molded article that is such a fuel cell separator by an injection molding method (see, for example, Patent Document 1). In Patent Document 1, a polyphenylene sulfide (PPS) resin composition containing a large amount of fillers such as graphitic carbon and carbon fiber is injected and filled into a cavity space in a mold having a fine shape, and after filling, The fuel cell separator is formed by closing and compression-molding.

  On the other hand, a separator molded with a resin containing a large amount of filler is very fragile, and troubles such as cracking during mold release are likely to occur. Therefore, in order to prevent this trouble, a technique is known in which the outer peripheral portion of the fuel cell separator body is reinforced with a frame material such as metal, resin, or wood (see, for example, Patent Document 2). In addition, in order to prevent cracking due to the surface pressure applied to the separator during operation of the fuel cell, the size of the connecting surface in which the groove bottom surface and the groove side surface of the fluid flow path are curved surfaces or inclined surfaces according to the surface pressure. Is known (see, for example, Patent Document 3).

JP 2006-19227 A JP 2002-358773 A JP 2003-36885 A

However, in Patent Document 1, although a high-quality fuel cell separator that satisfies various characteristics required for PEFC can be obtained efficiently, when compression molding is performed by injection molding, stress concentration in the mold is reduced. Due to the influence, a chipped portion was generated in the groove portion forming the flow path, and it was difficult to obtain a satisfactory molded product.
Moreover, since the method described in Patent Document 2 only reinforces the outer peripheral portion of the separator, it cannot prevent the occurrence of chipping of the groove portion in the mold.
Furthermore, in Patent Document 3, although a structure for preventing cracking of the separator due to surface pressure during fuel cell operation is described, a method for preventing cracking in the mold is not described. It is not possible to prevent the occurrence of a chipped portion.

  The objective of this invention is providing the manufacturing method of a molded article, a mold, and a molded article which prevent generation | occurrence | production of a chip | tip, when forming uneven | corrugated shape on the surface using a metal mold | die.

  The method for producing a molded product according to the present invention is a method for producing a molded product that uses a mold to produce a molded product having a concavo-convex shape on the surface. The mold includes a plurality of mold convex portions, A mold concave portion adjacent to the mold convex portion, and the mold convex portion has a chamfered portion that is chamfered at the tip portion, and contains a filler of 50% by mass or more and 90% by mass or less. An injection filling step of injecting and filling the resin composition into the cavity space of the mold, and a compression shaping step of closing the cavity space and compressing the resin composition. And

In the present invention, a resin composition containing 50% by mass or more and 90% by mass or less of filler as a material of a molded product is an object. When the content of the filler is less than 50% by mass, the phenomenon that the convex portion is missing hardly occurs even when a conventional mold is used. The present invention prevents a molded article that has become brittle by containing 50 mass% or more and 90 mass% or less of filler.
Moreover, in this invention, a metal mold | die is used in order to shape | mold the molded article which has an uneven | corrugated shape on the surface. The mold has a concavo-convex shape corresponding to the concavo-convex shape formed in the molded product. That is, the concave and convex shape of the mold is formed by a plurality of mold convex portions and a plurality of mold concave portions adjacent to the mold convex portions. The shapes of the mold convex part and the mold concave part may be appropriately adjusted according to the use of the molded product, and may be linear or curved, or may be formed in an island shape. .
The mold convex part has a chamfered part that is chamfered at the tip part. That is, it is formed in a state where the tip portion does not have a corner portion.

In this invention, after the resin composition containing the filler is injected and filled into the cavity space of such a mold (injection filling process), the cavity space is closed and the injection-filled resin composition is subjected to compression molding. Perform (compression shaping process).
According to this, since the chamfered portion is formed at the tip portion of the mold convex portion (that is, there is no corner portion), the stress applied to the tip portion of the mold convex portion is relieved during the compression molding process. can do. Therefore, it is possible to prevent the molded product from being cracked in the mold during the manufacturing process, and it is possible to accurately mold a molded product having a fine shape.

  In the method for manufacturing a molded product according to the present invention, the chamfered portion is a planar connecting surface that connects a side surface portion that forms the side surface of the mold convex portion and an end surface portion that forms the tip of the mold convex portion. Preferably there is.

In this invention, the side part which forms the side surface of a metal mold | die convex part, and the end surface part which forms the front end surface of a metal mold | die convex part are connected with the planar connection surface. That is, the corner portion where the side surface portion and the end surface portion intersect each other is chamfered with a planar connecting surface.
According to this, in the compression molding process, stress is not concentrated on the corner portion at the tip of the mold convex portion, so that it is possible to prevent the occurrence of chipping of the molded product in the mold.

In the method for producing a molded product according to the present invention, the height h of the mold convex part, the width d1 of the root part of the mold convex part, the width d2 of the end face part, and the angle formed by the chamfered part and the end face part It is preferable that θ1 and the distance l from the intersection of the extension line of the side surface part and the extension line of the end face part to the end face part satisfy the following relationship.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
110 ° ≦ θ1 ≦ 160 °
0 <l ≦ 0.5mm

  In this invention, the angle θ1 formed between the chamfered portion and the end surface portion forming the mold convex portion and the distance l from the intersection of the extension line of the side surface portion and the extension line of the end surface portion to the end surface portion are within the above range. Therefore, since stress is not concentrated more in the compression molding process, it is possible to reliably prevent the molded product from being chipped.

  In the method for manufacturing a molded product according to the present invention, the chamfered portion is a curved connecting surface that connects a side surface portion that forms the mold convex portion and an end surface portion that forms the tip of the mold convex portion. Is preferred.

In this invention, the side surface part which forms the side surface of a metal mold | die convex part, and the end surface part which forms the front end surface of a metal mold | die convex part are connected by the curved-shaped connection surface. That is, the corner portion where the side surface portion and the end surface portion intersect is chamfered by a curved connecting surface.
According to this, in the compression molding process, stress is not concentrated on the corner portion at the tip of the mold convex portion, so that it is possible to prevent the occurrence of chipping of the molded product in the mold.

In the method for manufacturing a molded product according to the present invention, the height h of the mold convex part, the width d1 of the root part of the mold convex part, the width d2 of the end face part, and the radius R of the circle whose arc is the chamfered part Preferably satisfies the following relationship.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
0.2mm ≦ R ≦ h / 2mm

  In the present invention, since the radius of the curved chamfered portion that forms the mold convex portion is within the above range, stress is not concentrated more in the compression molding process, so that it is possible to reliably prevent the molded product from being chipped. can do.

In the method for manufacturing a molded article of the present invention, it is preferable that the following relationship is satisfied, where c1 is the width of the bottom surface part forming the mold recess.
0.2mm ≦ c1 ≦ 5mm

  In the present invention, by setting the parameters of the mold convex portion and the mold concave portion formed in the mold within the above ranges, it is possible to reliably prevent the molded product from being chipped.

In the method for producing a molded article of the present invention, the resin composition containing the filler is a polyarylene sulfide resin composition, and the polyarylene sulfide resin composition comprises (A) a polyarylene sulfide resin and (B). The conductive filler contains (b1) graphite and (b2) carbon fiber, and (C) a polyolefin wax, and (B) the content of the conductive filler is 75% by mass or more and 85% by mass of the entire resin composition. (B2) The carbon fiber content is 1.0% by mass or more and 5.0% by mass or less of the entire resin composition, and (C) polyolefin wax / ((A) polyarylene sulfide resin + ( C) polyolefin wax) is from 0.05 to 0.3, and (A) the polyarylene sulfide resin has a melt viscosity of 300 ° C. In rate 2000 sec ^-1 or less 20Pa · sec, (b1) average particle diameter (D50%) of the graphite is at 50μm or 150μm or less, a bulk density of 0.6 g / cm ³ or more 1.0 g / cm ³ or less Preferably there is.

The polyarylene sulfide (PAS) resin composition contains a polyarylene sulfide (PAS) resin, graphite and carbon fiber as a conductive filler, and a polyolefin wax, and the conductive filler and carbon fiber are contained in the entire resin composition. Similarly, the ratio of the polyolefin wax to the resin component (polyarylene sulfide (PAS) resin and polyolefin wax) is set to a specific range, and the melting of the polyarylene sulfide (PAS) resin. A configuration in which the viscosity and the average particle diameter (D50) and bulk density of graphite are in a specific range is adopted.
As a result, a conductive filler such as graphite or carbon fiber is contained at a high content rate (75% by mass or more and 85% by mass or less of the entire resin composition), so that the resin composition is excellent in conductivity, and at the time of melt kneading It is possible to provide a resin composition that can be molded into a desired shape with high dimensional accuracy. In addition, the resin composition having such a structure is widely used as a molding material for a fuel cell separator (particularly, a polymer electrolyte fuel cell separator) in which a conductive filler is dispersed in a high content ratio with respect to a resin component. Can be used.
The particularly preferable PAS resin composition used in the present invention can be easily produced because each component is dispersed in a well-balanced manner, has high productivity, and can be produced at low cost.

  In the method for producing a molded product according to the present invention, it is preferable that the molded product is a fuel cell separator, and the plurality of mold convex portions are linearly formed at equal intervals.

The fuel cell separator is formed by a mold having the above-described shape. In this mold, linear mold convex portions are formed at equal intervals. Here, the linear shape may be a linear shape or a curved shape. The groove formed on the surface of the separator for the fuel cell by the convex portion of the mold serves as a flow path for supplying oxygen and hydrogen to the fuel cell. Further, the equal interval means that two linear mold convex portions adjacent to each other are installed at an equal distance.
According to the present invention, the same operational effects as described above can be achieved. That is, it is possible to manufacture a highly accurate fuel cell separator that does not cause chipping.
Since the fuel cell using such a separator can control the supply amount of hydrogen and oxygen with high accuracy, the performance of the fuel cell can be improved.

In addition, when a resin composition having a high content of conductive fillers such as graphite and carbon fiber and efficiently dispersed with respect to the resin component is used as a material, conductivity (electric conductivity), gas impermeability, thermal conductivity, Various properties such as compressive strength, mechanical strength, and corrosion resistance can be provided. For example, as electrical conductivity, volume resistivity is 20 mΩ · cm or less (preferably 10 mΩ · cm or less), mechanical strength As described above, various properties such as a flexural modulus of 50 MPa or more (preferably 70 MPa or more) can be suitably provided.
In addition, when the above-mentioned polyarylene sulfide (PAS) resin composition is used as a material for a fuel cell separator, it is possible to provide a fuel cell separator with excellent moldability and productivity and good mass productivity at low cost. .

  The mold of the present invention is a mold for molding a molded product having an uneven shape on the surface, and includes a plurality of mold convex portions and a mold concave portion adjacent to the mold convex portion, and the mold The mold convex portion has a chamfered portion having a chamfered end portion.

  According to the present invention, since the chamfered portion is formed at the tip of the mold convex portion formed on the surface of the mold, when the molded product is compression-molded using this mold, the mold convex portion It is possible to relieve the stress applied to the corners of the tip of the dies and prevent the molded product from being chipped. As a result, a molded product having a desired shape can be manufactured with high accuracy.

  In the mold of the present invention, the mold is preferably a mold for molding a resin composition containing a filler of 50 mass% or more and 90 mass% or less.

  This invention is a metal mold | die for shape | molding the resin composition which contains 50 to 90 mass% of fillers. The resin composition containing 50% by mass or more and 90% by mass or less of the filler is brittle, and when compression molding is performed on this resin composition, the molded product is likely to crack, but it should be molded with the mold of the present invention. As a result, it is possible to prevent the molded product from being cracked in the mold during the manufacturing process, and it is possible to accurately mold a molded product having a fine shape.

In the mold of the present invention, the resin composition comprises (A) a polyarylene sulfide resin, (B) (b1) graphite and (b2) carbon fibers as conductive fillers, and (C) a polyolefin wax. And (B) the content of the conductive filler is 75% by mass or more and 85% by mass or less of the entire resin composition, and (b2) the content of the carbon fiber is 1.0% by mass or more and 5% by mass of the entire resin composition. 0.0% by mass or less, and (C) polyolefin wax / ((A) polyarylene sulfide resin + (C) polyolefin wax) is from 0.05 to 0.3, and (A) polyarylene sulfide resin melt viscosity of a resin temperature of 300 ° C., or less 20 Pa · sec at a shear rate 2000 sec ^-1, (b1) average particle diameter (D50%) of graphite 50μm more than 15 and a μm or less, it is preferred bulk density of 0.6 g / cm ³ or more 1.0 g / cm ³ or less.

  According to the present invention, as described above, since the conductive filler such as graphite or carbon fiber is contained at a high content (75% by mass or more and 85% by mass or less of the entire resin composition), the resin composition having excellent conductivity. The product has good fluidity at the time of melt-kneading and also has good dispersibility such as graphite, and can be molded into a desired shape with high dimensional accuracy.

In the mold of the present invention, the chamfered portion is a planar connecting surface that connects a side surface portion that forms the side surface of the mold convex portion and an end surface portion that forms the tip of the mold convex portion, The height h of the mold convex portion, the width d1 of the root portion of the mold convex portion, the width d2 of the end surface portion, the angle θ1 formed by the chamfered portion and the end surface portion, and the extension line of the side surface portion and the It is preferable that the distance l from the intersection with the extended line of the end surface portion to the end surface portion satisfies the following relationship.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
110 ° ≦ θ1 ≦ 160 °
0 <l ≦ 0.5mm

  In this invention, since the parameter of each part of the mold convex portion is in the above range, stress is not concentrated more in the compression molding process, so that it is possible to reliably prevent the molded product from being chipped.

In the mold of the present invention, the chamfered portion is a curved connecting surface that connects a side surface portion and an end surface portion forming the mold convex portion, and the height h of the mold convex portion, the mold It is preferable that the width d1 of the base portion of the convex portion, the width d2 of the end surface portion, and the radius R of the circle whose arc is the chamfered portion satisfy the following relationship.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
0.2mm ≦ R ≦ h / 2mm

  In this invention, since the parameter of each part of the mold convex portion is in the above range, stress is not concentrated more in the compression molding process, so that it is possible to reliably prevent the molded product from being chipped.

The molded product of the present invention is manufactured by the above-described method for manufacturing a molded product.
According to this invention, as described above, since it is manufactured using a mold having a chamfered portion at the tip of the mold convex portion, chipping does not occur and a molded product having a desired shape is reliably provided. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the polymer electrolyte fuel cell (PEFC) using the separator for fuel cells concerning 1st Embodiment of this invention. Sectional drawing which shows the metal mold | die which shape | molds the separator for fuel cells concerning 1st Embodiment of this invention. It is the figure which showed the injection compression unit which implements the manufacturing method of the separator for fuel cells concerning 1st Embodiment of this invention, Comprising: The schematic which shows the state which opened the metal mold | die (state which is performing injection filling). In FIG. 3, the schematic which shows the state which closed the metal mold | die (state which is performing the compression shaping). Sectional drawing which shows the metal mold | die which shape | molds the separator for fuel cells concerning 2nd Embodiment of this invention.

Hereinafter, although embodiment of this invention is described, this invention is not limited to this.
[First Embodiment]
In the first embodiment, a polymer electrolyte fuel cell (PEFC) is exemplified, and an example in which a separator used for PEFC is a molded product will be described with reference to FIGS. 1 to 4.
[1. Configuration of fuel cell]
FIG. 1 is a schematic view showing a basic configuration example of a fuel cell 100 using a fuel cell separator made of a molded product obtained by the injection compression molding method of the present invention.
A fuel cell 100 shown in FIG. 1 includes a fuel electrode 21, an electrolyte membrane (electrolyte plate) 22, an oxidation electrode 23 (which forms a membrane / electrode assembly (MEA) 20), and a fuel cell separator 10 (hereinafter referred to as “fuel cell separator”). Simply “separator 10”).

[2. Configuration of Fuel Cell Separator 10]
The separator 10 is formed in a substantially flat plate shape with dimensions of length × width × thickness of 150 mm × 150 mm × 2 mm. A plurality of linear protrusions 11 are formed on one surface of the separator 10 at equal intervals, and the other surface of the separator 10 extends in a direction orthogonal to the protrusions 11 formed on one surface. A plurality of linear protrusions 12 are formed at equal intervals. Thereby, the recessed part 13 adjacent to the convex part 11 is formed, and an uneven | corrugated shape is formed in one surface of the separator 10. FIG. Moreover, the recessed part 14 adjacent to the convex part 12 is formed, and an uneven | corrugated shape is formed in the other surface of the separator 10. FIG. The convex portions 11 and 12 are formed in a substantially trapezoidal cross section, and the dimensions of these concave and convex shapes are the same as the shape of the mold 30 described later.
In addition, the shape of the convex parts 11 and 12 is not restricted to a cross-sectional substantially trapezoid shape, You may form in the cross-sectional rectangle shape which an adjacent surface cross | intersects at right angle.

  Such a separator 10 has various properties such as conductivity (electric conductivity), gas impermeability, thermal conductivity, compressive strength, mechanical strength, electrolyte (phosphoric acid, sulfuric acid, etc.), and corrosion resistance against ions. As the conductivity (electric conductivity), for example, the volume resistivity is preferably 20 mΩ · cm or less, and more preferably 10 mΩ · cm or less. In addition, as the mechanical strength, for example, the flexural modulus is preferably 50 MPa or more, and more preferably 70 MPa or more.

As a resin composition satisfying such conditions, for example, a polyarylene sulfide (PAS) resin composition containing a high amount of conductive filler such as graphite or carbon fiber can be cited.
The PAS resin composition contains (A) polyarylene sulfide (PAS) resin, (B) conductive fillers (b1) graphite and (b2) carbon fibers, and (C) polyolefin wax as basic components. It will be.

(A) Polyarylene sulfide (PAS) resin:
PAS resin is an engineering plastic having excellent heat resistance, chemical resistance, flame retardancy, electrical properties, and mechanical properties, and is used as a molding material in various applications such as electrical, electronic parts, and automotive parts. As the PAS resin, it is preferable to use a resin in which the repeating unit of the structure represented by the formula (1) (unit structure of (para) phenylene sulfide) is contained in an amount of 70 mol% or more of the entire resin, and is contained in an amount of 90 mol% or more. It is more preferable to use one. When the repeating unit having the structure represented by the formula (1) is less than 70 mol% of the entire resin, the heat resistance of the obtained PAS resin composition may be remarkably deteriorated.

  Moreover, as another repeating unit, for example, at least one selected from compounds represented by the following formulas (2) to (4) may be contained, but is represented by the formula (1) ( A polymer that is mainly composed of para) phenylene sulfide and does not substantially contain the units represented by the formulas (2) to (4), and is generally referred to as poly (para) phenylene sulfide (PPS). Arylene sulfide (PAS) is preferred.

The melt viscosity of the (A) PAS resin is 20 Pa · sec or less, preferably 10 Pa · sec or less, at a resin temperature of 300 ° C. and a shear rate of 2000 sec ⁻¹ . (A) By setting the melt viscosity of the PAS resin to 20 Pa · sec or less, the fluidity of the PAS resin composition can be maintained in a good state, and a molded article such as a fuel cell separator made of the PAS resin composition. The moldability or mass productivity can be made excellent.

(B) Conductive filler:
As the conductive filler (B) constituting the PAS resin composition, (b1) graphite and (b2) carbon fiber are used.

(B1) Graphite:
As graphite, conventionally known various graphites can be used, for example, crystalline carbon particles having a graphite structure, natural graphite excavated and purified as a natural mineral, petroleum pitch, etc. at 2000 ° C. or more, for example. Artificial graphite obtained by firing and crystallization at a temperature, and then pulverizing and classifying can be used. In addition, expanded graphite obtained by heat-treating a graphite intercalation compound obtained by treating a graphite material with a strong acid and an oxidizing agent may be used.
Here, the shape of the graphite can be various shapes such as a scaly shape, an irregular particle shape, and a spherical shape, and is preferably a shape close to a spherical shape.

The content of graphite in the PAS resin composition is relatively large, and therefore, it aggregates in the resin composition to increase thixotropic properties. Depending on the form (average particle diameter (D50%) and bulk density), the fluidity However, it is difficult to knead and prepare the resin composition.
Accordingly, the particle form of graphite may be an average particle diameter (D50%) of 50 μm or more and 150 μm or less and a bulk density of 0.6 g / cm ³ or more and 1.0 g / cm ³ or less. Is more preferably 80 μm or more and 120 μm or less, and the bulk density is 0.8 g / cm ³ or more and 1.0 g / cm ³ or less. By setting the average particle diameter (D50%) and bulk density of graphite in such a range, it is possible to suppress a decrease in fluidity in the kneading preparation of the resin composition.

The graphite may be a blend of graphite particles having two particle size distributions. In order to improve fluidity, two monodisperse graphite particles having an average particle diameter (D50%) different by 5 times or more are used. You may make it blend and use.
The average particle size (D50%) is an average particle size corresponding to a particle size corresponding to 50% of the weight by converting the weight of fine particles, and the particle size of such a powder. The distribution can be easily measured by a known method such as gravitational sedimentation or centrifugal sedimentation. Moreover, the value measured based on JIS K6891 can be used for the bulk density of (b1) graphite, for example.

(B2) Carbon fiber:
The carbon fiber is not particularly limited, and examples thereof include conventionally known carbon fibers such as coal-based or petroleum-based pitch-based carbon fibers, polyacrylonitrile (PAN: abbreviation of Poly Acrylo Nitrile) -based carbon fibers, and rayon-based carbon fibers. Carbon fibers such as so-called chopped carbon fibers or milled carbon fibers may be used as the fiber production mode.

  Further, vapor grown carbon fibers (VGCF), which are crystalline carbon fibers produced by a gas phase method, and carbon nanofibers, which have been developed recently, may be used. This vapor grown carbon fiber (VGCF) is more preferable than the above-mentioned general carbon fiber from the viewpoint of conductivity, but it is preferably used in combination with these general carbon fibers because the reinforcing effect is small.

In general, carbon fibers having a fiber diameter of 10 μm or less can be used. The carbon fiber serves as a reinforcing material in the PAS resin composition and also serves to impart conductivity to the resin composition, and it is preferable to use carbon fiber having a relatively small fiber diameter.
For this reason, the carbon fiber is a polyacrylonitrile (PAN) carbon fiber having a fiber diameter of 10 μm or less, preferably 8 μm or less, or a fiber diameter of 0.05 μm or more and 0.5 μm or less, preferably 0.07 μm or more and 0.2 μm. It is desirable to use the following vapor grown carbon fiber (VGCF). By using these carbon fibers, the reinforcing effect of the mechanical strength in the PAS resin composition or a molded product molded using the resin composition is further improved. Moreover, the electroconductivity of a resin composition etc. and the dispersibility of the carbon fiber in these become favorable.

  In addition, when using polyacrylonitrile (PAN) type | system | group carbon fiber, electroconductivity can further be improved if the thing which coat | covered metals, such as nickel, by plating etc. is used.

  The fiber length of the carbon fiber is not particularly limited, but is generally preferably 0.05 mm or more and 1.0 mm or less, and particularly preferably 0.1 mm or more and 0.5 mm or less.

(C) Polyolefin wax:
The polyolefin-based wax improves the fluidity of the PAS resin composition as an additive to the (A) PAS resin, and improves the dispersibility of the (b1) graphite. Moreover, the heat resistance of the PAS resin composition is improved by the addition of (C) polyolefin wax.
This polyolefin wax is an artificial wax produced by polymerization, and for example, polyethylene wax, polypropylene wax, vinyl acetate-ethylene copolymer wax and the like can be used. Also, oxidized polyolefin waxes such as oxidized polyethylene wax, oxidized polypropylene wax, MAH copolymerized polypropylene wax, vinyl acetate-ethylene copolymer wax, and the like can be used.

  Among these, as the polyolefin wax, it is preferable to use an oxidized polyolefin wax, and it is particularly preferable to use an oxidized polyethylene wax obtained by oxidizing a polyethylene polymer. Thereby, the fluidity of the PAS resin composition and the dispersibility of (b1) graphite in the resin composition are further improved, and the heat resistance of the PAS resin composition is also improved. In particular, oxidized polyethylene wax is excellent in heat resistance even at a standard temperature (320 ° C. or higher and 340 ° C. or lower) when processing a PAS resin composition, and whitening due to phase separation hardly occurs. (A) PAS resin In particular, it is an excellent additive.

In addition, an oxidized polyolefin wax such as an oxidized polyethylene wax generally has higher heat resistance as the average molecular weight increases, and becomes more polar as the degree of oxidation increases (A) PAS resin or (B) conductive filler The compatibility of is improved.
As the average molecular weight of the oxidized polyolefin wax, the weight average molecular weight (M _w ) measured by GPC (Gel Permeation Chromatography) method is preferably 4000 or more, particularly preferably 10,000 or more.
The degree of oxidation is preferably 10 or more, and particularly preferably 15 or more. The “degree of oxidation” in the present invention indicates the number of milligrams of potassium hydroxide (KOH) necessary for neutralizing 1 g of polyolefin wax.

  In addition, in the resin composition comprised from the essential component of said (A)-(C), a conventionally well-known coupling agent, mold release agent, and plasticizer as needed in the range which does not impair the effect of this invention. In addition, additives such as antistatic agents, impact improving resins such as elastomers (rubbers), inorganic fillers, and the like may be added as appropriate.

  The content of the conductive filler (B) in the PAS resin composition is preferably 75% by mass or more and 85% by mass or less, and more preferably 80% by mass or more and 84% by mass or less of the entire resin composition. When the content of the conductive filler (B) with respect to the entire PAS resin composition is less than 75% by mass, the conductivity required for the separator when a fuel cell separator is produced using the PAS resin composition (for example, , The volume resistivity becomes 100 mΩ · cm or less). On the other hand, when the content of the conductive filler (B) exceeds 85% by mass, the ratio of (A) polyarylene sulfide (PAS) resin to the entire PAS resin composition is reduced, and (C) polyolefin wax is added. However, the fluidity is not improved, it becomes difficult to obtain a PAS resin composition by melt kneading or the like, and the manufacturability of the resin composition is greatly deteriorated.

  In addition, the content of (b2) carbon fiber in the PAS resin composition is preferably 1.0% by mass or more and 5.0% by mass or less, and 2.0% by mass or more and 5.0% by mass of the entire PAS resin composition. It is more preferable that the amount is not more than mass%. When the content of (b2) carbon fiber relative to the entire PAS resin composition is less than 1.0% by mass, the effect of reinforcing the conductivity and mechanical strength of the resin composition cannot be expected. On the other hand, when the content of the carbon fiber exceeds 5.0% by mass, the fluidity of the PAS resin composition is deteriorated and, in addition, the fuel cell separator is manufactured using the PAS resin composition. Warpage may occur in the separator. In addition, since carbon fiber is an expensive material, the raw material cost increases, resulting in inferior cost performance as a constituent material of the separator, and the versatility of the obtained fuel cell separator is lost, which is not preferable.

  The ratio of (C) polyolefin wax in the resin component (component other than (B) conductive filler) is (C) polyolefin wax / ((A) polyarylene sulfide (PAS) resin + (C) polyolefin type. Wax) is preferably 0.05 or more and 0.3 or less, and more preferably 0.1 or more and 0.25 or less. If the ratio of the polyolefin wax in the resin component is within such a range, (A) the melt viscosity of the PAS resin is reduced, and (B) the dispersibility of the conductive filler and the productivity of the PAS resin composition are improved. be able to. On the other hand, if the ratio of the (C) polyolefin wax to the resin component is less than 0.05, these effects cannot be expected, and the ratio of the (C) polyolefin wax to the resin component exceeds 0.3. As a result, gas generation from the wax increases, resulting in increased venting during melt kneading and poor appearance of the resulting fuel cell separator.

There is no restriction | limiting in particular as a means to obtain such a PAS resin composition, A well-known method is used. That is, after the raw material components including the essential components (A) to (C) described above are dry-blended in advance with a stirrer such as a Henschel mixer, a single or multi-screw extruder, a mixing roll, and a kneader having sufficient kneading ability For example, it can be easily produced by a method of melting or kneading.
Moreover, when using an extruder when obtaining a PAS resin composition, a part of raw material component can also be mix | blended by feeding (side feed) from the middle of an extruder. For example, components other than carbon fiber are dry-blended in advance, continuously metered and fed to a twin-screw extruder kneader, and carbon fiber is side-fed to an intermediate position of the extruder and continuously kneaded. A method of producing by degassing under reduced pressure can be mentioned.

  In the case of producing a fuel cell separator using this PAS resin composition, the PAS resin composition may then be molded into pellets by a known method and used as a molding material, or Subsequently, it may be used as it is in a molding process such as a roll press.

[3. Structure of fuel cell separator mold]
Next, the structure of the metal mold | die used in order to manufacture the separator 10 for fuel cells is demonstrated. FIG. 2 is a cross-sectional view of a mold for molding the fuel cell separator according to the first embodiment.
As shown in FIG. 2, a plurality of linearly extending mold protrusions 33 are formed at equal intervals in the mold 30 in order to form the above-described protrusions 11 and recesses 13. Mold recesses 34 extending linearly adjacent to the mold protrusions 33 are formed at equal intervals.

The mold convex portion 33 is formed in a substantially trapezoidal cross section by a side surface portion 331, an end surface portion 332, and a planar inclined surface portion 333 that connects the side surface portion 331 and the end surface portion 332. As shown in FIG. 2, the mold convex portion 33 has a shape that is chamfered (or C-plane cut) into a flat shape by the slope portion 333.
The mold concave portion 34 is formed in a substantially trapezoidal cross section by a side surface portion 331 that forms the mold convex portion 33 and a bottom surface portion 341.

  In FIG. 2, h is the height of the mold convex portion 33, d1 is the width of the root portion of the mold convex portion 33, that is, the bottom surface portion of the next mold concave portion 34 from the end of the bottom surface portion 341 of the mold concave portion 34. The distance to the end of 341, d2 is the width of the end surface portion 332 of the mold convex portion 33, c1 is the width of the bottom surface portion 341 of the mold concave portion 34, θ1 is the angle formed by the end surface portion 332 and the inclined surface portion 333, l Is the distance from the end portion 332A of the end surface portion 332 to the intersection 331A on the extension line of the side surface portion 331 and the end surface portion 332. In forming the fuel cell separator 10 in the present embodiment, the above parameters are defined as follows.

0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
0.2mm ≦ c1 ≦ 5mm
110 ° ≦ θ1 ≦ 160 °
0 <l ≦ 0.5mm

  Here, if h, d2, and c1 are smaller than 0.2 mm, the groove formed in the separator 10 becomes too small, and the function as the flow path cannot be sufficiently exhibited. On the other hand, when h is larger than 5 mm, the thickness becomes thick and it becomes difficult to mold, and the fuel cell stack becomes large. Furthermore, if d2 is larger than d1, the cross-sectional shape of the convex part 11 of the separator 10 becomes a trapezoid whose width at the root part is smaller than the tip part, resulting in an undercut, so that the molded product cannot be released from the mold. . And when c1 is larger than 5 mm, since the space | interval of the adjacent metal mold | die convex part 33 becomes large too much, a sufficient number of flow paths cannot be formed in the surface of the separator 10. FIG. Moreover, since the cross-sectional area of the base part of the convex part of the molded product where cracks occur increases, cracks are less likely to occur. On the other hand, if θ1 is smaller than 110 °, stress tends to be concentrated during compression molding, and the separator 10 is cracked. On the other hand, if θ1 is larger than 160 °, the function as chamfering is not sufficiently exhibited. If l is 0, the effect of reducing the concentration of stress is small, and cracking occurs during compression molding. On the other hand, if l is larger than 0.5 mm, the flow path area decreases and the flow pressure loss of the fuel gas increases.

In the present embodiment, the above parameters are the following numerical values.
h = 0.4mm
c1 = 1.5mm
d1 = 1.5mm
d2 = 0.9mm
θ1 = 135 °
l = 0.3mm

[4. Manufacturing method of fuel cell separator]
In the present embodiment, a method for molding the fuel cell separator 10 by an injection compression molding method will be described. The injection compression molding method is a kind of injection molding method. A mold with a slide mechanism is used and the mold is opened slightly in advance, and a resin composition is prepared using a normal injection molding unit. Inject only the specified amount. Next, immediately before or after completion of the injection process, the compression core is moved by the compression unit to apply pressure to a part of the cavity (compression core). The movement of the compressed core is a method in which the cavity volume is reduced, whereby a high pressure is applied to the resin, and the resin is cooled and solidified to form a predetermined shape.

  As an advantage of such injection compression molding method, since the cavity thickness is large and the flow resistance is low in the injection process, it is possible to form a thin molded product with a large area, and it can be compressed and shaped by clamping, so it is uniform For example, a large molding pressure is applied, and warping and deformation of the molded product are small. Therefore, this injection compression molding method is particularly effective in manufacturing the grooved fuel cell separator 10 in the polymer electrolyte fuel cell 100 having the structure as shown in FIG. It can be used effectively.

An example of a method for forming the fuel cell separator 10 by injection compression molding using the mold 30 described above will be described with reference to FIGS.
FIG. 3 is a view showing an injection compression molding unit 50 for carrying out the method for manufacturing the fuel cell separator 10. The movable mold 31 and the fixed mold 32 are opened, and the PAS resin composition 70 is injected and filled. FIG. 4 is a schematic view showing a state, and FIG. 4 shows a state where the movable mold 31 and the fixed mold 32 are closed in the injection compression molding unit 50 of FIG. 3 and the resin composition 70 is compressed and shaped. It is the shown schematic diagram.

  First, as shown in FIG. 3, the compression unit 51 is moved backward, and the mating surfaces 31 a and 32 a of the movable mold 31 and the fixed mold 32 are opened, and the cavity space 35 (hereinafter simply referred to as “space 35”). The PAS resin composition 70 is injection-filled from the injection unit 60 into the space 35 ((1) injection / filling step).

  Here, the interval between the cavity spaces 35 formed by the mating surfaces 31a and 32a of the movable mold 31 and the fixed mold 32 is preferably 0.5 mm or more and 5.0 mm or less, and 3.0 mm or more and 5.0 mm or less. More preferably. By setting the interval to such a range, it is possible to suitably inject and fill the PAS resin composition 70 in a molten state, and it is also suitable as a compression margin in the subsequent step (2) compression and shaping step.・ The shaping process is performed well.

  In addition, the heating method of the mold 30 (the movable mold 31 and the fixed mold 32) is not particularly limited, and the movable mold 31 and the fixed mold 32 are placed before filling the PAS resin composition 70 using a conventionally known heater. What is necessary is just to set it as a heating state. For example, an energization heating body is provided on the surfaces of the movable mold 31 and the fixed mold 32, and the energization heating body is energized before filling the resin so that the movable mold 31 and the fixed mold 32 are heated to a predetermined temperature. Also good. Examples of the electric heating body include silicon nitride, titanium nitride, aluminum nitride, and zirconia oxide.

  The mold temperature may be determined according to the type of the PAS resin composition 70, but may be 150 ° C. or higher and 250 ° C. or lower. In this embodiment, unlike the conventional injection compression molding method, it is not necessary to set the mold temperature to a high temperature state (for example, 270 ° C. or higher and 300 ° C. or lower), so that the molded product is smoothly cooled and injection compression is performed. Molding can be performed easily.

  Next, when the injection filling of the predetermined amount of the resin composition 70 is completed, as shown in FIG. 4, the compression unit 51 is advanced (moved in the direction of the arrow in FIG. 4), and the movable mold 31 and the fixed mold 31 are fixed. The mold 32 is closed and a clamping force is applied to compress and shape the filled PAS resin composition 70 to obtain the fuel cell separator 10 having a predetermined shape ((2) compression / loading) Forming process).

  In addition, although the start of the (2) compression / shaping process is when the filling of the PAS resin composition 70 is completed, this is not only when the filling is completely completed, but also immediately before or immediately after the filling is completed (for example, It may be 0.1 to 0.5 seconds before completion of filling or 0.1 to 0.5 seconds after completion).

  The compression speed in the (2) compression / shaping step is preferably 1.0 mm / second or more and 20 mm / second or less, and more preferably 5.0 mm / second or more and 20 mm / second or less. By setting the compression speed within such a range, the injection-filled PAS resin composition 70 can be suitably compressed and shaped. On the other hand, if the compression speed is less than 1 mm / second, the thickness of the resulting molded product The continuous formability may be adversely affected, for example, the distribution may be deteriorated (for example, the gate side is thick and the flow end is thin) or the number of short shots is increased. On the other hand, when the speed is higher than 20 mm / second, the quality of the separator 10 as a molded product is stabilized, but the load on the molding machine and the mold is large, and the molding machine and the like are heavily consumed. May occur.

  Furthermore, the compression pressure in the (2) compression / shaping step is preferably 10 MPa or more, and more preferably 50 MPa. The mold clamping pressure at that time is preferably about 60 tons, more preferably about 300 tons. If the compression pressure is 10 MPa or more, the compression and shaping are sufficiently performed and the separator 10 having a good appearance can be obtained. On the other hand, if the compression pressure is less than 10 MPa, the pressure is not sufficient and the appearance of the separator 10 is In this case, sink marks and warpage may occur, resulting in poor appearance.

When the compression unit 51 is advanced in this way, the movable mold 31 and the fixed mold 32 are closed and a clamping force is applied to compress and shape the filled PAS resin composition 70, and then the movable mold 31 and the fixed mold 32 are compressed. The PAS resin composition 70 inside the movable mold 31 and the fixed mold 32 is cooled and solidified. The cooling conditions are not particularly limited, but the cooling temperature is 160 ° C. or higher and 250 ° C. or lower (more preferably 180 ° C. or higher and 230 ° C. or lower), and the cooling time is 30 seconds or longer and 90 seconds or shorter (more preferably 50 seconds). 70 seconds or less). And if the said resin composition 70 is cooled and solidified, the separator 10 in which the electroconductive filler was disperse | distributed uniformly can be obtained by opening the movable mold | type 31 and the fixed mold | type 32, and taking out a molded article.
The separator 10 thus obtained is molded into a shape having the same dimensions as the ranges of the parameters of the mold 30 described above.

[5. Effects of First Embodiment]
As described above, in the present embodiment, the following operational effects can be achieved.
In the above embodiment, the mold convex portion 33 formed on the mold 30 is formed with the inclined surface portion 333 that connects the side surface portion 331 and the end surface portion 332. The angle θ1 formed by the inclined surface portion 333 and the end surface portion 332 is 135 °, and is within a specified range of 110 ° or more and 160 ° or less. Therefore, the resin is injected and filled into the cavity by injection compression molding, and compression molding is performed. When performing, the stress which the front-end | tip part of the metal mold | die convex part 33 gives to the PAS resin composition 70 is relieved.
Therefore, it is possible to prevent the separator 10 from being chipped during the manufacturing process of the separator 10. As a result, a finely shaped flow path can be formed with high accuracy, so that the separator 10 having excellent moldability can be provided.
Since the fuel cell 100 using the separator 10 in which the flow path (concave portion 13) having a highly accurate shape is formed as described above can control the supply amount of hydrogen and oxygen with high accuracy, the performance of the fuel cell 100 is improved. Can be made.

  Moreover, in the said embodiment, the separator 10 for fuel cells was obtained by the injection compression molding method. When the PAS resin composition as described above is used as a material, the resin composition often has a high melt viscosity. However, according to the injection compression molding method, even if the resin composition has insufficient fluidity, dimensions Highly accurate molded products can be produced efficiently.

  Further, in the above embodiment, the cavity is formed by the mating surfaces 31a and 32a of the movable mold 31 and the fixed mold 32 having a mold temperature of 150 ° C. or more and 250 ° C. or less, and the interval is 0.5 mm or more and 5.0 mm or less. An injection / filling step of injecting and filling the PAS resin composition 70 into the space 35, and after completion of the filling, the cavity space 35 is closed, and the compression speed of the PAS resin composition 70 filled in the space 35 is set to 1. The flow rate of the resin composition 70 during the molding process is very good because it is composed of a compression / shaping process in which the compression pressure is 10 MPa or higher and the compression pressure is 10 MPa or higher. A fuel cell separator 10 filled with a conductive filler at a high content and having various required properties can be efficiently molded with good productivity. How to and capable of providing.

In the above embodiment, the PAS resin composition is used as the material of the fuel cell separator 10. Since the PAS resin composition contains a conductive filler such as graphite or carbon fiber at a high content (75% by mass or more and 85% by mass or less of the entire resin composition), it becomes a resin composition excellent in conductivity, Good fluidity during melt-kneading, good dispersibility of graphite, etc., and can be molded into a desired shape, so various characteristics of fuel cell separators (particularly solid polymer fuel cell separators) Can be fully demonstrated.
The PAS resin composition is a molding material that can be easily manufactured because the components (A) to (C) are dispersed in a well-balanced manner, and can be produced with high productivity and reduced cost. It becomes.

  And the separator 10 for fuel cells of the structure shown, for example in the structure shown in FIG. 1 obtained by the above-mentioned manufacturing method using the PAS resin composition is high in the conductive filler such as graphite and carbon fiber with respect to the resin component. A fuel cell having excellent conductivity required for the fuel cell separator 10 such as high conductivity, for example, volume resistivity of 20 mΩ · cm or less (preferably 10 mΩ · cm or less) because it is distributed in a balanced manner. In addition, the mechanical strength of the separator 10 for a fuel cell having the mechanical strength required for a separator for a fuel cell, for example, a flexural modulus of 50 MPa or more (preferably 70 MPa or more) is obtained. .

[Second Embodiment]
Next, a second embodiment will be described based on FIG. In the second embodiment, only the configuration of the mold of the fuel cell separator is different, and the other configurations and details of each process are the same as those of the first embodiment. Therefore, only the configuration of the mold of the fuel cell separator is used. explain.
FIG. 5 is a cross-sectional view of a mold for molding a fuel cell separator according to the second embodiment.
As shown in FIG. 5, a plurality of linearly extending mold protrusions 41 are formed at equal intervals on the mold 40, and the molds extend linearly adjacent to the mold protrusions 41. The recesses 42 are formed at equal intervals.

The mold convex portion 41 is formed in a substantially trapezoidal cross section by a side surface portion 411, an end surface portion 412, and a curved connection portion 413 that connects the side surface portion 411 and the end surface portion 412. That is, the mold convex portion 41 has a shape that is chamfered (or R-processed) into a curved surface by the connecting portion 413.
The mold concave portion 42 is formed in a substantially trapezoidal cross section by a side surface portion 411 that forms the mold convex portion 41 and a bottom surface portion 421.

  In FIG. 5, h is the height of the mold convex portion 41, d1 is the width of the root portion of the mold convex portion 41, that is, the bottom surface portion of the next mold concave portion 42 from the end of the bottom surface portion 421 of the mold concave portion 42. The distance to the end portion of 421, d2 is the width of the end surface portion 412 of the mold convex portion 41, and c1 is the width of the bottom surface portion 421 of the mold concave portion 42. R is an arc in contact with the two surfaces of the side surface portion 411 and the end surface portion 412 of the mold convex portion 41. In forming the fuel cell separator according to the second embodiment, the above parameters are defined as follows. Note that h, d1, d2, and c1 are the same as those in the first embodiment.

0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
0.2mm ≦ c1 ≦ 5mm
0.2 mm ≦ R ≦ h / 2

  Here, when R is smaller than 0.2 mm, stress tends to concentrate during compression molding, and the separator 10 is cracked. On the other hand, if R is larger than h / 2, the flow path cross-sectional area is reduced and the flow pressure loss of the fuel gas is increased. Moreover, the function as chamfering is not fully exhibited.

In the present embodiment, the above parameters are the following numerical values.
h = 0.4mm
d1 = 1.5mm
d2 = 1.1mm
c1 = 1.5mm
R = 0.2mm

[Effects of Second Embodiment]
The fuel cell separator formed by the mold having such a configuration can exhibit the same effects as those of the first embodiment.
Further, in the second embodiment, since there is no corner in the mold convex portion 41 of the mold 40, when compressed by injection compression molding, stress can be dispersed efficiently, and chipping can be further prevented. it can.

[Modification]
In addition, this invention is not limited to the above-mentioned embodiment, The deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. are included in this invention.
For example, in the above-described embodiment, the shape of the mold convex portion is a substantially trapezoidal cross section, but the shape is not limited to this, and any shape may be used as long as the uneven shape is formed on the surface of the obtained molded product. For example, the cross-sectional rectangle shape in which the extension line of the side face part and the extension line of the end face part are orthogonal to each other can be mentioned. In addition to the rectangular cross-section, the same chamfering process as in the above embodiment is performed on the corner portion where the angle formed by two adjacent surfaces forming the mold convex portion is less than 110 °. When the angle formed by the two surfaces is 110 ° or more, the stress due to injection compression molding is dispersed, and the possibility of occurrence of chipping in the molded product is small.

  Moreover, in the said embodiment, although the mold structure which has several linear mold convex part and mold recessed part was illustrated as a metal mold | die of a molded article, the shape of a mold convex part and a mold recessed part is shown to this Not limited. For example, it may be formed in a curved shape or a combination of a linear shape and a curved shape. Further, it may be a serpentine type mold for molding a separator having a so-called serpentine type flow path that is bent so that the mold convex part and the mold concave part (flow path) meander in the middle.

  Furthermore, in the said embodiment, a polyarylene sulfide (PAS) resin composition is (B) graphite and (b2) which are (A) polyarylene sulfide (PAS) resin, and (B) electroconductive filler as a structural component. The carbon fiber and the (C) polyolefin-based wax were contained, but other fillers can be added to the PAS resin composition as long as the effects of the present invention are not impaired.

  Specific examples of the filler include glass fibers, potassium titanate whiskers, zinc oxide whiskers, aluminum borate whiskers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, metal fibers, and the like. Fillers, wollastonite, zeolite, sericite, kaolin, mica, clay, pyrophyllite, bentonite, asbestos, talc, alumina silicate, silicate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, oxidation Metal compounds such as iron, carbonates such as calcium carbonate, magnesium carbonate and dolomite, sulfates such as calcium sulfate and barium sulfate, hydroxides such as magnesium hydroxide, calcium hydroxide and aluminum hydroxide, glass beads, glass Flakes, ceramic beads, boron nitride, silicon carbide, such as a non-fiber-based fillers such as silica and the like, which may be a hollow body. Moreover, these may be used individually by 1 type and may be used in combination of 2 or more types. Furthermore, in order to obtain better mechanical strength, these fibrous fillers and non-fibrous fillers are used as isocyanate compounds, organic silane compounds, organic titanate compounds, organic borane compounds, epoxy compounds. You may make it use it by pre-processing with coupling agents, such as.

  In addition, for the PAS resin composition used in the present invention, in the range that does not interfere with the effects of the present invention, organic phosphorus compounds, crystal nucleating agents such as polyether ethers, coloring inhibitors such as hypophosphorous acid, Additives such as antioxidants such as hindered phenols and hindered amines, ultraviolet light inhibitors, colorants such as dyes and pigments, heat stabilizers, and lubricants can be appropriately added.

  In addition, the plurality of convex portions 11 and concave portions 13 formed on the fuel cell separator 10 are preferably formed at a time by the injection compression molding of the present embodiment from the viewpoint of labor and cost, but the shape of the separator 10 In some cases, a predetermined shape cannot be obtained by only one injection compression molding using a mold. In this case, as an additional process, the obtained molded product may be subjected to machining such as cutting, drilling, and threading.

  Further, the shapes of the polymer electrolyte fuel cell (PEFC) 100 and the separator 10 shown in FIG. 1 are merely examples, and the configuration of the polymer electrolyte fuel cell (PEFC) 100, the shape of the separator 10 and the like are required. It is not limited to the contents, and can have any configuration and shape.

  And when carrying out the method for producing a separator for a fuel cell of the present invention, it is preferable to predict the sink of the PAS resin composition in advance, and to design the mold, etc. Basically, the mold shape is directly reflected in the shape of the separator, and the dimensional accuracy in the thickness direction can be improved.

In addition, the constituent material of the fuel cell separator of the polymer electrolyte fuel cell (PEFC) is not limited to the above-described PAS resin composition. A thermoplastic resin containing a large amount of filler may be applied.
Furthermore, in the above-described embodiment, the polymer electrolyte fuel cell (PEFC) has been described as an example, but there is no problem even if it is applied to molding of a fuel cell separator other than PEFC.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all to the description content of these Examples.

[Examples 1-4 and Comparative Examples 1-2]
(Production of polyarylene sulfide (PAS) resin composition)
The components shown in the following (1) to (4) are blended in the proportions shown below, and after dry blending uniformly using a super floater mixer (vibration / stirring mixer) (manufactured by Kawata Corporation), biaxial A polyarylene sulfide (PAS) resin composition was produced by using a kneading extruder (TEM35B: manufactured by Toshiba Machine Co., Ltd.) and melt-kneading in a range of 300 ° C. to 330 ° C. and extruding into a pellet. .

(1) Poly (para) phenylene sulfide resin (17% by mass of the whole)
Grade: LR01G (manufactured by DIC EPS Corporation)
Melt viscosity: 10 Pa · sec (resin temperature 300 ° C.,
(Value at a shear rate of 2000 sec ^-1 )

(2) Graphite (conductive filler) (77% by mass of the whole)
Grade: Natural graphite CGC-100H (manufactured by Nippon Graphite Industry Co., Ltd.)
Average particle diameter (D50%): 100 μm
Bulk density: 0.7 g / cm ³ (measured according to JIS K6891)

(3) Carbon fiber (conductive filler) (3% by mass of the whole)
Grade: PAN-based milled carbon fiber HTA-CMF-0160E
(Toho Natex Co., Ltd.)
Fiber diameter: 7 μm
Fiber length: 160 μm

(4) Oxidized polyethylene wax (3% by mass of the total)
Grade: Rico wax PED191 (high density polyethylene (HDPE) oxide)
Yip, Clariant Japan Co., Ltd.)
M _w (weight average molecular weight): 12000
Oxidation degree: 17 mgKOH / g

(Mold configuration)
A hot runner mold was used as a mold for molding a fuel cell separator. The molten resin injected from the nozzle of the injection molding machine passes through the sprue, runner, and gate and is filled into the cavity. The hot runner mold is one in which the runner is always heated. The exit diameter of the runner was φ2.0 mm, and the gate was a 4-point fan gate with a width of 20 mm and a thickness of 2 mm.
This mold was set in an injection molding unit 50 as shown in FIG. The size of the cavity (space filled with resin) formed by the movable mold 31 and the fixed mold 32 is made larger than that of the finally obtained fuel cell separator. It is molded so as to be a flat plate having a width × thickness of 150 mm × 150 mm × 2 mm.
On the surface of the fixed mold 32 facing the movable mold 31, ten linear mold concave portions are formed at equal intervals, and eleven mold convex portions adjacent to these mold concave portions are formed at equal intervals. Yes.
On the surface of the movable mold 31 facing the fixed mold 32, there are 10 mold recesses formed on the surface of the movable mold 31 and 10 linear mold recesses extending in a direction perpendicular to the mold projections at equal intervals. 11 mold protrusions that are formed and are adjacent to these mold recesses are formed at equal intervals in the mold recess.
Table 1 below shows the shape of the mold irregularities formed on the surfaces of the movable mold 31 and the fixed mold 32. Here, h, θ, c1, d1, d2, and l are parameters shown in FIG.

(Molding condition)
An injection compression molding machine equipped with an injection compression molding unit (product name “AZ-70000”, manufactured by Nissei Plastic Industry Co., Ltd., mold clamping force 350) using the molds of the examples and comparative examples shown in Table 1. Ton (3430 kN)), the obtained PAS resin composition was injected and filled, and then compression and shaping were performed. Various molding conditions are as follows.
Cylinder temperature: 350 ° C
Mold temperature: 200 ℃
Compression force: 15 MPa
Compression speed: 15 mm / sec

(Evaluation methods)
About the obtained molded product, a fixed load was given to the side surface of the convex part formed in the molded product, and the presence or absence of the chip | tip in a convex part was confirmed. When the chipping was confirmed, the quality was evaluated using the number of the convex portions where the chipping occurred among the convex portions of the molded product as an index. That is, the closer the number of convex portions is to 0, the better. The evaluation results are shown in Table 1.

From the results in Table 1, it was confirmed that any of the molded products (fuel cell separators) obtained in Examples 1 to 4 had no chipped protrusions formed on the surface.
On the other hand, in Comparative Examples 1 and 2, chipping occurred in the plurality of convex portions, and a satisfactory molded product could not be obtained.

  The method for producing a molded article of the present invention is effective as a method for producing a molded article having a concavo-convex shape on the surface, particularly a fuel cell separator, using a resin containing a high content of filler.

10. Fuel cell separator (separator)
DESCRIPTION OF SYMBOLS 11, 12 ... Convex part 13, 14 ... Concave part 20 ... Membrane / electrode assembly (MEA)
DESCRIPTION OF SYMBOLS 21 ... Fuel electrode 22 ... Electrolyte membrane 23 ... Oxidation electrode 30 ... Mold 31 ... Movable type 32 ... Fixed type 35 ... Cavity space (space)
DESCRIPTION OF SYMBOLS 50 ... Injection compression molding unit 51 ... Compression unit 60 ... Injection unit 70 ... PAS resin composition 100 ... Fuel cell

Claims (14)

Using a mold, a method for producing a molded product that produces a molded product having an uneven shape on the surface,
The mold has a plurality of mold convex portions and a mold concave portion adjacent to the mold convex portions,
The mold convex portion has a chamfered portion chamfered at the tip,
An injection filling step of filling and filling the cavity space of the mold with a resin composition containing 50% by mass or more and 90% by mass or less filler;
A compression shaping step of closing the cavity space and performing compression shaping on the resin composition;
A method for producing a molded product, comprising: In the manufacturing method of the molded article according to claim 1,
The chamfered portion is a flat connecting surface that connects a side surface portion that forms the side surface of the mold convex portion and an end surface portion that forms the tip of the mold convex portion. Method. In the manufacturing method of the molded article according to claim 2,
A height h of the mold convex part, a width d1 of a root part of the mold convex part, a width d2 of the end face part, an angle θ1 formed by the chamfered part and the end face part, and an extension line of the side part A method for manufacturing a molded product, wherein a distance l from an intersection with an extension line of the end surface portion to the end surface portion satisfies the following relationship.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
110 ° ≦ θ1 ≦ 160 °
0 <l ≦ 0.5mm In the manufacturing method of the molded article according to claim 1,
The method of manufacturing a molded product, wherein the chamfered portion is a curved connecting surface that connects a side surface portion that forms the mold convex portion and an end surface portion that forms the tip of the mold convex portion. In the manufacturing method of the molded article according to claim 4,
The height h of the mold convex part, the width d1 of the root part of the mold convex part, the width d2 of the end face part, and the radius R of the circle having the chamfered part as an arc satisfy the following relationship: A method for manufacturing a molded product.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
0.2mm ≦ R ≦ h / 2mm In the manufacturing method of the molded article according to any one of claims 1 to 5,
A manufacturing method of a molded product characterized by satisfying the following relationship, where c1 is a width of a bottom surface portion forming the mold recess.
0.2mm ≦ c1 ≦ 5mm In the manufacturing method of the molded article according to any one of claims 1 to 6,
The resin composition containing the filler is a polyarylene sulfide resin composition,
The polyarylene sulfide resin composition contains (A) polyarylene sulfide resin, (B) (b1) graphite and (b2) carbon fibers as conductive fillers, and (C) a polyolefin wax,
(B) The content of the conductive filler is 75% by mass or more and 85% by mass or less of the entire resin composition,
(B2) The content of the carbon fiber is 1.0% by mass or more and 5.0% by mass or less of the entire resin composition,
(C) polyolefin wax / ((A) polyarylene sulfide resin + (C) polyolefin wax) is from 0.05 to 0.3,
(A) The melt viscosity of the polyarylene sulfide resin is 20 Pa · sec or less at a resin temperature of 300 ° C. and a shear rate of 2000 sec ⁻¹ ,
(B1) An average particle diameter (D50%) of graphite is 50 μm or more and 150 μm or less, and a bulk density is 0.6 g / cm ³ or more and 1.0 g / cm ³ or less. In the manufacturing method of the molded article according to any one of claims 1 to 7,
The molded article is a fuel cell separator,
The method for producing a molded product, wherein the plurality of mold convex portions are formed in a linear shape at regular intervals. A mold for molding a molded product having an uneven shape on the surface,
A plurality of mold protrusions, and a mold recess adjacent to the mold protrusions,
The mold convex portion has a chamfered portion with a chamfered end portion. The mold according to claim 9,
The mold is a mold for molding a resin composition containing a filler of 50% by mass or more and 90% by mass or less. The mold according to claim 10, wherein
The resin composition contains (A) a polyarylene sulfide resin, (B) (b1) graphite and (b2) carbon fibers as conductive fillers, and (C) a polyolefin-based wax,
(B) The content of the conductive filler is 75% by mass or more and 85% by mass or less of the entire resin composition,
(B2) The content of the carbon fiber is 1.0% by mass or more and 5.0% by mass or less of the entire resin composition,
(C) polyolefin wax / ((A) polyarylene sulfide resin + (C) polyolefin wax) is from 0.05 to 0.3,
(A) The melt viscosity of the polyarylene sulfide resin is 20 Pa · sec or less at a resin temperature of 300 ° C. and a shear rate of 2000 sec ⁻¹ ,
(B1) A mold having an average particle diameter (D50%) of graphite of 50 μm or more and 150 μm or less and a bulk density of 0.6 g / cm ³ or more and 1.0 g / cm ³ or less. The mold according to any one of claims 9 to 11,
The chamfered portion is a planar connecting surface that connects a side surface portion that forms the side surface of the mold convex portion and an end surface portion that forms the tip of the mold convex portion,
A height h of the mold convex part, a width d1 of a root part of the mold convex part, a width d2 of the end face part, an angle θ1 formed by the chamfered part and the end face part, and an extension line of the side part The mold 1 is characterized in that the distance l from the intersection with the extended line of the end surface portion to the end surface portion satisfies the following relationship.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
110 ° ≦ θ1 ≦ 160 °
0 <l ≦ 0.5mm The mold according to any one of claims 9 to 11,
The chamfered portion is a curved connecting surface that connects a side surface portion and an end surface portion forming the mold convex portion,
The height h of the mold convex part, the width d1 of the root part of the mold convex part, the width d2 of the end face part, and the radius R of the circle having the chamfered part as an arc satisfy the following relationship: Mold to be used.
0.2mm ≦ h ≦ 5mm
0.2 mm ≦ d2 ≦ d1
0.2mm ≦ R ≦ h / 2mm A molded article produced by the method for producing a molded article according to any one of claims 1 to 8.

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