JP6937071B2 - Fuel cell external restraint and method of manufacturing fuel cells using it - Google Patents

Description

The present invention relates to a fuel cell external restraint material and a method for manufacturing a fuel cell using the same.

The fuel cell stack mounted on a vehicle or the like includes a laminated body in which a plurality of single cells are laminated. If a large impact is applied to this fuel cell stack due to a vehicle collision or the like, the stacking position of the single cells may shift significantly, the air supply system may be damaged, hydrogen gas or the like may leak, and the power generation function of the fuel cell may stop. there were.

In order to prevent the stacking position of the single cell from being displaced due to such an impact, Japanese Patent Application Laid-Open No. 2017-50211 (Patent Document 1) provides for impact mitigation provided between the fuel cell stack and the stack case. As an intervening layer, the first corner portion of the outer shape of the stack when the fuel cell stack is viewed along the stacking direction of the single cells and the second corner portion diagonally related to the first corner portion of the outer shape of the stack. Only with respect to, the fuel cell stack is arranged on the side surface of the first stack and the side surface of the second stack forming the first corner portion so as to sandwich the first corner portion and extends in the stacking direction. The second corner portion is formed on the shaft-shaped first intervening layer and the second intervening layer, and the third stack side surface and the fourth stack side surface forming the second corner portion. A shaft-shaped third intervening layer and a fourth intervening layer that are arranged so as to be sandwiched and extend in the stacking direction and restrain the fuel cell stack from the outside are provided, and the first corner portion in the outer shape of the stack is provided. On the side of the adjacent corners of the side surface of the first stack forming the corners adjacent to the stack, the fuel cell stack extends in the stacking direction at least in the central region of the fuel cell stack in the stacking direction. A fuel cell having a shaft-shaped fifth intervening layer that is restrained from the outside has been proposed. Further, Japanese Patent Application Laid-Open No. 2017-110138 (Patent Document 2) proposes an external restraining material made of a cured product of a silicone rubber composition as a member to be arranged between the fuel cell stack and the stack case.

JP-A-2017-50211 JP-A-2017-110138

However, in the conventional fuel cell, when the fuel cell stack is restrained in the stack case by using an intervening layer or an external restraining material, the fuel cell stack is intervened with the fuel cell stack from the viewpoint of workability when the fuel cell stack is inserted into the stack case. Since it is necessary to provide a certain amount of gap between the layer and the external restraint material, or between the intervening layer and the external restraint material and the stack case, it is necessary to use a stack case with a lid having a large opening. rice field. Further, when a conventional general rubber material (elastic body) is used as an intervening layer or an external restraining material, even if the rubber material is compressed to provide a gap, the rubber is inserted while the fuel cell stack is inserted into the stack case. Since the material returns to its original size (particularly the thickness) and there is no gap, stress is applied to the single cell from the rubber material, the single cell bends, and the power generation function of the fuel cell may stop. Further, when a conventional general cushioning material (viscous material) is used as an intervening layer or an external restraining material, the gap provided by compressing the cushioning material is retained even while the fuel cell stack is inserted into the stack case. However, since the cushioning material does not easily return to its original size (particularly the thickness), the gap between the fuel cell stack or the stack case and the cushioning material is sufficiently filled after the fuel cell stack is housed in the stack case. Therefore, it was not possible to sufficiently prevent the displacement of the stacking position of the single cells.

The present invention has been made in view of the above-mentioned problems of the prior art, and is excellent in workability when inserting the fuel cell stack into the stack case, and the fuel cell in which the displacement of the stacking position of the single cell is sufficiently prevented. It is an object of the present invention to provide a method for producing a fuel cell, and a fuel cell external restraining material used for the method.

As a result of diligent research to achieve the above object, the present inventors have obtained a silicone rubber member made of a cured product of a silicone rubber composition having a storage elasticity E'and a loss tangent tan δ in a specific range. When the fuel cell external restraint material sandwiched between film-shaped or sheet-shaped members whose adhesive force to the surface of the rubber member is within a specific range is compressed, for a while (for example, 10 minutes) after the applied pressure is released. It has been found that the compressed state is maintained and returns to the original size (particularly the thickness) after a long period of time (for example, after 24 hours), and further, when the fuel cell is manufactured, the compressed fuel is used. While inserting the fuel cell stack into the stack case (eg, 10 minutes) by placing the fuel cell external restraint around the fuel cell stack or on the inner wall of the stack case and inserting the fuel cell stack into the stack case, the figure. As shown in 1 (a) or FIG. 2 (a), the compressed state of the fuel cell external restraint material 1 is maintained, so that there is sufficient space between the fuel cell external restraint material 1 and the fuel cell stack 2 or the stack case 3. A gap is formed so that the fuel cell stack 2 can be easily inserted into the stack case 3, and after the fuel cell stack 2 is housed in the stack case 3 (for example, after 24 hours), FIG. 1 (b) ) Or as shown in FIG. 2B, so that the fuel cell external restraint material 1 returns to its original size (particularly the thickness), so that between the fuel cell external restraint material 1 and the fuel cell stack 2 or the stack case 3. We have found that the gap between the two cells can be sufficiently filled and the displacement of the stacking position of the single cell 2a can be sufficiently prevented, and the present invention has been completed.

That is, the fuel cell external restraint material of the present invention is a silicone having a storage elastic modulus of 2.1 to 24 MPa and a loss tangent tan δ of 0.16 to 0.43, which is determined by dynamic viscoelasticity measurement. A silicone rubber member made of a cured product of the rubber composition and a film-like or sheet-like member are provided.
Two more members are obtained by sandwiching the two-layered film-shaped or sheet-shaped member between the two silicone rubber members (the size of the contact portion between the film-shaped or sheet-shaped member and the silicone rubber member: 20 mm × 20 mm). A test piece for measurement was prepared by sandwiching it between the film-shaped or sheet-shaped members (the size of the contact portion between the silicone rubber member and the film-shaped or sheet-shaped member: 20 mm × 20 mm), and from the completion of the test piece preparation. After 1 minute has passed, the test piece is stretched at a speed of 30 mm / min using a tensile tester, and the load at the time of stretching by 5 mm is measured using a load cell to obtain the silicone rubber member and the film. is obtained as an interface to the stress of the Jo or sheet-like member, the adhesive strength of the film-like or sheet-like member to the surface of said silicone rubber member is 10KPa～1MPa,
The silicone rubber member is sandwiched between the two film-shaped or sheet-shaped members.

In the fuel cell external restraint material of the present invention, it is preferable that a plurality of the silicone rubber members are arranged on the surface of the film-shaped or sheet-shaped member in a state of being separated from each other.

Further, in the first method for manufacturing a fuel cell of the present invention, the fuel cell external restraining material of the present invention is attached in a compressed state around a fuel cell stack in which a plurality of single cells are laminated, and then the fuel cell is described. It is characterized by inserting the stack into the stack case.

Further, in the second method for manufacturing a fuel cell of the present invention, a fuel cell stack in which a plurality of single cells are laminated is attached to the inner wall of the stack case in a compressed state. It is characterized by being inserted.

The fuel cell external restraint material of the present invention retains the compressed state for a while (for example, 10 minutes) after the applied pressure is released (excellent in the continuity of the compressed state), and after a long time (for example). , 24 hours later), the reason why it returns to the original size (particularly the thickness) (excellent in recoverability) is not always clear, but the present inventors speculate as follows. As shown in FIG. 3A, the fuel cell external restraint material of the present invention is a silicone rubber member 1a made of a cured product of a silicone rubber composition sandwiched between film-shaped or sheet-shaped members 1b. When pressure is applied to the fuel cell external restraining material 1 from the surface of the film-shaped or sheet-shaped member 1b to compress it, as shown in FIG. 3B, the silicone rubber member 1a is deformed by compression. Adheres to the film-like or sheet-like member 1b. After that, when the applied pressure is released, the silicone rubber member 1a having the storage elastic modulus E'and the loss tangent tan δ in a specific range has the original size (particularly the thickness) as shown in FIG. 3 (c). Restoring force is generated to return to. However, since an adhesive force in the shear direction is generated at the interface between the silicone rubber member 1a and the film-shaped or sheet-shaped member 1b, this adhesive force becomes a resistance force against restoration. As a result, the restoration of the silicone rubber member 1a is further delayed, the compressed state is maintained for a while after the applied pressure is released, and then a long time elapses, so that the silicone rubber member 1a has the original size (particularly). , Thickness) is estimated to recover.

According to the present invention, it is possible to provide a method for manufacturing a fuel cell which is excellent in workability when the fuel cell stack is inserted into the stack case and whose stacking position of a single cell is sufficiently prevented from being displaced.

It is a schematic cross-sectional view which shows one preferable embodiment of the manufacturing method of the fuel cell of this invention, (a) shows the state while inserting a fuel cell stack into a stack case, (b) is a state in which a fuel cell stack is inserted. The state after being housed in the stack case (for example, after 24 hours) is shown. It is a schematic cross-sectional view which shows another preferable embodiment of the manufacturing method of the fuel cell of this invention, (a) shows the state while inserting the fuel cell stack into a stack case, (b) is a fuel cell. Indicates that the stack is housed in a stack case. It is a schematic cross-sectional view which shows one preferable embodiment of the fuel cell external restraint material of this invention, (a) shows the state before compression, (b) shows the compressed state, (c) is , Indicates the state after pressure release. It is a schematic cross-sectional view (the unit of the numerical value indicating a size: mm) which shows the test piece for adhesiveness measurement used in an Example and a comparative example.

Hereinafter, the present invention will be described in detail according to the preferred embodiment thereof.

[Fuel cell external restraint material]
First, the fuel cell external restraint material of the present invention will be described. The fuel cell external restraint material of the present invention is a silicone rubber composition having a storage elastic modulus of 2.1 to 24 MPa and a tan δ of 0.16 to 0.43, which is determined by dynamic viscoelasticity measurement. A silicone rubber member made of a cured product and a film-shaped or sheet-shaped member having an adhesive force to the surface of the silicone rubber member of 10 kPa to 1 MPa are provided, and the silicone rubber member is two sheets of the film-shaped or sheet. It is sandwiched between the shaped members.

(Silicone rubber composition)
As the silicone rubber composition used in the present invention, the cured product has a storage elastic modulus E'at a frequency of 1 Hz in the range of 2.1 to 24 MPa, which is determined by dynamic viscoelasticity measurement, and has a loss tangent tan δ. There is no particular limitation as long as it is in the range of 0.16 to 0.43, and examples thereof include known silicone rubber compositions containing polysiloxane and particles. The cured product of such a silicone rubber composition exhibits a viscoelastic response (delayed elasticity) in which the size (particularly the thickness) is not immediately restored even when the applied pressure is released, but is restored with a delay.

On the other hand, when the storage elastic modulus E'is less than the lower limit, the cured product of the silicone rubber composition has a weak restoring force to return to the original size (particularly the thickness). The size (especially the thickness) is not fully restored over time (recoverability is reduced). On the other hand, when the storage elastic modulus E'exceeds the upper limit, the cured product of the silicone rubber composition has a strong restoring force to return to the original size (particularly the thickness), so that the applied pressure is released immediately. The size (especially the thickness) is restored (compression state continuity is reduced). The storage elastic modulus E'is preferably 3 MPa or more, more preferably 4 MPa or more, and preferably 20 MPa or less from the viewpoint of further improving the continuity of the compressed state from the viewpoint of further improving the recoverability. , 15 MPa or less is more preferable.

Further, when the loss tangent tan δ is less than the lower limit, the cured product of the silicone rubber composition has a high contribution of elasticity (close to an elastic body), so that the continuity of the compressed state is lowered. On the other hand, when the loss tangent tan δ exceeds the upper limit, the cured product of the silicone rubber composition has a high contribution of viscosity (becomes close to a viscous body), so that the recoverability is lowered. The loss tangent tan δ is preferably 0.20 or more, more preferably 0.25 or more, from the viewpoint of further improving the continuity of the compressed state, and 0. 42 or less is preferable, and 0.41 or less is more preferable.

Examples of the silicone rubber composition exhibiting such delayed elasticity include a silicone rubber composition containing an organopolysiloxane, an organohydrogenpolysiloxane, and a filler, and among them, a silicone rubber composition containing a filler.
(A) An organopolysiloxane having a viscosity at 25 ° C. of 1.0 to 100 Pa · s and having at least one alkenyl group bonded to a silicon atom in one molecule.
(B) The following formula (1):

[In the above formula, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ² independently represents an alkyl group, an alkoxyalkyl group, an alkenyl group, and the like. Alternatively, it represents an acyl group, n is an integer of 2 to 100, and a is an integer of 1 to 3. ]
Organopolysiloxane, represented by
(C) The following formula (2):

[In the above formula, R ³ independently represents an alkyl group having 1 to 6 carbon atoms, and p and q are 10 ≦ p + q ≦ 100 and 0.01 ≦ p / (p + q) ≦ 0.5. It is a positive integer that satisfies. ]
Organohydrogenpolysiloxane, represented by
(D) The following formula (3):

[In the above formula, R ⁴ independently represents an alkyl group having 1 to 6 carbon atoms, and m is an integer of 5 to 1000. ]
Organohydrogenpolysiloxane, represented by
(E) Filler,
(F) Catalyst,
(G) Reaction control agent,
Is preferable.

(A) Ingredient:
The component (A) is an organopolysiloxane having at least one alkenyl group bonded to a silicon atom in one molecule. The structure of such an organopolysiloxane is not particularly limited, and may be linear or branched. Further, if at least one alkenyl group bonded to the silicon atom is present in one molecule of the organopolysiloxane, it is present at one or both of the terminal and the middle of the molecular chain of the organopolysiloxane. Although it may be used, it is preferable that it exists only at both ends from the viewpoint of flexibility. As the alkenyl group bonded to such a silicon atom, an alkenyl group having 2 to 10 carbon atoms is preferable, and an alkenyl group having 2 to 8 carbon atoms is more preferable. Specific examples thereof include a vinyl group, an allyl group, a 1-butenyl group, a 1-hexenyl group and the like. One of these alkenyl groups may be contained in one molecule of the organopolysiloxane, or two or more of these alkenyl groups may be contained. Further, among such alkenyl groups, a vinyl group is preferable from the viewpoint of ease of synthesis and cost.

Further, in the organopolysiloxane, examples of the organic group other than the alkenyl group bonded to the silicon atom are unsubstituted or substituted monovalents having 1 to 20 carbon atoms (more preferably 1 to 10 carbon atoms). Hydrocarbon groups are preferred. Here, the "substituted monovalent hydrocarbon group" means a group in which a part or all of hydrogen atoms of an unsubstituted monovalent hydrocarbon group is substituted with another atom or a substituent. Examples of such an unsubstituted or substituted monovalent hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-hexyl group and an n-dodecyl group, and a phenyl group. An aryl group such as a group, an aralkyl group such as a 2-phenylpropyl group, and a group in which some or all of these unsubstituted monovalent hydrocarbon groups are substituted with halogen atoms such as chlorine, fluorine and bromine ( For example, an alkyl halide group such as a fluoromethyl group, a bromomethyl group, a chloromethyl group, a 3,3,3-trifluoropropyl group) and the like can be mentioned. One of these other organic groups may be contained alone or two or more thereof may be contained in one molecule of the organopolysiloxane, but from the viewpoint of ease of synthesis and cost, these other organic groups may be contained. It is preferable that 90 mol% or more of all other organic groups are methyl groups.

In the component (A), the viscosity of the organopolysiloxane at 25 ° C. is 1.0 to 100 Pa · s. When the viscosity of the organopolysiloxane is less than the lower limit, the dilatant property of the cured product of the silicone rubber composition tends to decrease, while when the viscosity exceeds the upper limit, the fluidity of the silicone rubber composition tends to decrease. It is in. The viscosity of such an organopolysiloxane is preferably 2.0 Pa · s or more from the viewpoint of further improving the dilatant property of the cured product of the silicone rubber composition, and the fluidity of the silicone rubber composition is further improved. From the viewpoint of this, 10 Pa · s or less is preferable. The viscosity of the organopolysiloxane is a value measured at 25 ° C. with a rotational viscometer.

As the component (A), there is no particular limitation as long as it is an organopolysiloxane having a predetermined amount of an alkenyl group bonded to a silicon atom and the viscosity at 25 ° C. is within the above range, and a known organopolysiloxane is used. However, among them, an organopolysiloxane having both ends sealed with a dimethylvinylsilyl group is preferable, and a dimethylpolysiloxane having both ends sealed with a dimethylvinylsilyl group is particularly preferable. Further, as the component (A), an organopolysiloxane having a predetermined amount of an alkenyl group to be bonded to a silicon atom and having a viscosity at 25 ° C. within the above range may be used alone, but is bonded to a silicon atom. Two or more kinds of organopolysiloxanes having a predetermined amount of alkenyl groups and having different viscosities may be mixed and used so that the viscosity at 25 ° C. is within the above range.

(B) Ingredient:
The component (B) has the following formula (1):

It is an organopolysiloxane represented by, and has a function of lowering the viscosity of the silicone rubber composition and imparting fluidity. The organopolysiloxane represented by the formula (1) may be used alone or in combination of two or more.

^{R 1} in the formula (1) is an independently substituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms). Represents. Here, the "substituted monovalent hydrocarbon group" means a group in which a part or all of hydrogen atoms of an unsubstituted monovalent hydrocarbon group is substituted with another atom or a substituent. Examples of such an unsubstituted or substituted monovalent hydrocarbon group include a linear alkyl group, a branched alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkyl halide group and a cyanoalkyl group. The group etc. can be mentioned.

Examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-hexyl group, an n-octyl group and the like, and examples of the branched alkyl group include an isopropyl group and an isobutyl group. Examples thereof include a tert-butyl group and a 2-ethylhexyl group. Examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group, and examples of the alkenyl group include a vinyl group and an allyl group. Examples of the group include a phenyl group, a tolyl group and the like, and examples of the aralkyl group include a 2-phenylethyl group and a 2-methyl-2-phenylethyl group. Examples of the alkyl halide group include 3,3,3-trifluoropropyl group, 2- (nonafluorobutyl) ethyl, 2- (heptadecafluorooctyl) ethyl group and the like, and examples of the cyanoalkyl group include cyanoalkyl groups. For example, a cyanoethyl group and the like can be mentioned. Among these unsubstituted or substituted monovalent hydrocarbon groups, a linear alkyl group, an alkenyl group and an aryl group are preferable, and a methyl group, a vinyl group and a phenyl group are more preferable.

^{In addition, R 2} in the formula (1) independently represents an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. The carbon number of these groups is not particularly limited, but is preferably 1 to 10, more preferably 1 to 6, and particularly preferably 1 to 3. Examples of the alkyl group include a linear alkyl group, a branched alkyl group and a cyclic alkyl group, and examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group and an n-hexyl. Examples of the branched alkyl group include an isopropyl group, an isobutyl group, a tert-butyl group and a 2-ethylhexyl group, and examples of the cyclic alkyl group include a cyclopentyl group. , Cyclohexyl group and the like. Examples of the alkoxyalkyl group include a methoxyethyl group and a methoxypropyl group, examples of the alkenyl group include a vinyl group and an allyl group, and examples of the acyl group include an acetyl group and an octanoyl group. Can be mentioned. Among these groups, an alkyl group is preferable, and a methyl group and an ethyl group are more preferable.

Further, n in the formula (1) is an integer of 2 to 100, preferably an integer of 5 to 80. Further, a in the formula (1) is an integer of 1 to 3, preferably 3.

In the component (B), the viscosity of the organopolysiloxane represented by the formula (1) at 25 ° C. is not particularly limited, but is preferably 0.005 to 10 Pa · s, preferably 0.005 to 1 Pa · s. More preferred. When the viscosity of the organopolysiloxane represented by the formula (1) is less than the lower limit, oil bleeding is likely to occur from the silicone rubber composition, and the adhesive strength may decrease with time, while the above-mentioned If it exceeds the upper limit, the viscosity of the silicone rubber composition tends to increase and the fluidity tends to decrease. The viscosity of the organopolysiloxane represented by the formula (1) is a value measured at 25 ° C. with a rotational viscometer.

Suitable specific examples of the organopolysiloxane represented by the formula (1) include the following formulas (1-1) to (1-4):

Organopolysiloxane represented by, but not limited to these.

The blending amount of the component (B) is preferably 1 to 100 parts by mass, more preferably 1 to 50 parts by mass with respect to 100 parts by mass of the component (A). When the blending amount of the component (B) is less than the lower limit, the viscosity of the silicone rubber composition tends to increase and the fluidity tends to decrease, while when the amount exceeds the upper limit, the silicone rubber composition is hard to cure. It tends to be.

Ingredient (C):
The component (C) has the following formula (2):

It is an organohydrogenpolysiloxane represented by, and has a function of curing a liquid silicone rubber composition. The organohydrogenpolysiloxane represented by the formula (2) may be used alone or in combination of two or more.

^{Each of R 3} in the formula (2) independently represents an alkyl group having 1 to 6 carbon atoms. The structure of such an alkyl group may be linear, branched or cyclic. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group n-hexyl group. These alkyl groups may contain one kind alone or two or more kinds in one molecule of the organohydrogenpolysiloxane represented by the above formula (2), but they are synthesized. from ease and cost aspects, it is preferable more than 90 mole% of all R ³ is a methyl group.

Further, p and q in the above equation (2) are positive integers and satisfy 10 ≦ p + q ≦ 100. When p + q is less than the lower limit, the organohydrogenpolysiloxane represented by the formula (2) tends to become a volatile component, which may cause contact failure in the fuel cell. On the other hand, when p + q exceeds the upper limit, the above-mentioned The viscosity of the organohydrogenpolysiloxane represented by the formula (2) becomes high, and it tends to be difficult to handle. The p + q is preferably 20 or more from the viewpoint that the organohydrogenpolysiloxane represented by the formula (2) is less likely to volatilize, and the organohydrogenpoly represented by the formula (2). From the viewpoint of reducing the viscosity of siloxane, 60 or less is preferable.

Further, p and q in the formula (2) satisfy 0.01 ≦ p / (p + q) ≦ 0.5. When p / (p + q) is less than the lower limit, the reticulation of the silicone rubber composition by cross-linking tends to be difficult to proceed, while when it exceeds the upper limit, unreacted Si—H groups remain at the initial stage of curing. It is easy, and the cross-linking reaction between the remaining Si—H group and water proceeds excessively, and the flexibility of the cured product of the silicone rubber composition tends to decrease. As p / (p + q), 0.05 ≦ p / (p + q) ≦ 0.4 is satisfied from the viewpoint that the cross-linking reaction proceeds appropriately and a cured product of the silicone rubber composition having excellent flexibility can be obtained. Is preferable.

Preferable specific examples of the organohydrogenpolysiloxane represented by the formula (2) include the following formulas (2-1) to (2-2):

Organohydrogenpolysiloxane represented by, but not limited to these.

Ingredient (D):
The component (D) has the following formula (3):

It is an organohydrogenpolysiloxane represented by, and has a function of lowering the hardness of a cured product of a silicone rubber composition to develop and improve dilatant properties. The organohydrogenpolysiloxane represented by the formula (3) may be used alone or in combination of two or more.

^{Each of R 4} in the formula (3) independently represents an alkyl group having 1 to 6 carbon atoms. The structure of such an alkyl group may be linear, branched or cyclic. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group n-hexyl group. These alkyl groups may contain one type alone or two or more types in one molecule of the organohydrogenpolysiloxane represented by the above formula (3), but they are synthesized. from ease and cost aspects, it is preferable more than 90 mole% of all R ³ is a methyl group.

Further, m in the above formula (3) is an integer of 5 to 1000. When m is less than the lower limit, the organohydrogenpolysiloxane represented by the formula (3) tends to become a volatile component, which may cause contact failure in the fuel cell. On the other hand, when m exceeds the upper limit, the above-mentioned The viscosity of the organohydrogenpolysiloxane represented by the formula (3) becomes high, and it tends to be difficult to handle. The m is preferably 10 or more from the viewpoint that the organohydrogenpolysiloxane represented by the formula (3) is less likely to volatilize, and the organohydrogenpoly represented by the formula (3). From the viewpoint of reducing the viscosity of siloxane, 100 or less is preferable.

Preferable specific examples of the organohydrogenpolysiloxane represented by the formula (3) include the following formulas (3-1) to (3-2):

Examples include, but are not limited to, the organohydrogenpolysiloxanes represented.

The blending amount of the component (C) and the component (D) is in the component (C) and the component (D) with respect to the total number of alkenyl groups in the component (A) and the component (B). Ratio of total number of Si—H groups ([total number of Si—H groups in (C) and (D) components] / [total number of alkenyl groups in (A) and (B) components] ]) Is preferably an amount satisfying 0.6 to 1.5, and more preferably an amount satisfying 0.7 to 1.4. If the ratio of the total number of Si—H groups to the total number of alkenyl groups is less than the lower limit, a sufficient network structure is not formed in the cured product of the silicone rubber composition, so that the hardness tends to be insufficient, while the hardness tends to be insufficient. If the upper limit is exceeded, the hardness tends to be too high.

The blending amount of the component (C) and the component (D) is the ratio of the number of Si—H groups in the component (D) to the number of Si—H groups in the component (C) ([(. D) Number of Si—H groups in the component] / [Number of Si—H groups in the component (C)]) is preferably an amount satisfying 1 to 10, and is an amount satisfying 2 to 9. Is more preferable. When the ratio of the number of Si—H groups is less than the lower limit, the dilatant property of the cured product of the silicone rubber composition tends to decrease, while when the ratio exceeds the upper limit, the hardness of the cured product of the silicone rubber composition tends to decrease. Tends to run short.

(E) Ingredient:
The component (E) is a filler and is a powder (particle) having a function of imparting dilatant properties to a cured product of a silicone rubber composition. Such a filler is not particularly limited, and aluminum powder, copper powder, silver powder, nickel powder, gold powder, alumina powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, boron nitride powder, silicon nitride powder, etc. Conventionally known metal powders such as diamond powder, carbon powder, indium powder, and gallium powder, and metal compound powders can be used. Such a filler may be used alone or in combination of two or more. The shape of such a filler is not particularly limited, but a spherical shape is preferable.

The average particle size of the filler is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm. When the average particle size of the filler is less than the lower limit, the particles tend to aggregate with each other and the fluidity of the silicone rubber composition tends to decrease. On the other hand, when the average particle size exceeds the upper limit, the cured product of the silicone rubber composition tends to be agglomerated. The dilatant characteristics tend to decrease. The average particle size of the filler is a value measured as a volume average value D ₅₀ (that is, a particle size or a median diameter when the cumulative volume becomes 50%) in the particle size distribution measurement by the laser light diffraction method.

The blending amount of the component (E) is preferably 200 to 1000 parts by mass, more preferably 300 to 800 parts by mass with respect to 100 parts by mass of the component (A). If the blending amount of the component (E) is less than the lower limit, it may not be possible to impart the desired dilatant property to the cured product of the silicone rubber composition, while if it exceeds the upper limit, the silicone rubber composition may be released. It does not become liquid and tends to decrease in fluidity.

(F) Ingredient:
The component (F) is a catalyst and promotes an addition reaction between an alkenyl group such as the component (A) and a Si—H group of the component (C) and the component (D). Examples of such a catalyst include platinum group metal catalysts.

The platinum group metal catalyst is not particularly limited as long as it promotes the addition reaction, and a known platinum group metal catalyst can be used. Specifically, platinum group metals such as platinum (including platinum black), rhodium, and palladium; H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaHPtCl ₆ · nH ₂ O, KH PtCl ₆・ NH ₂ O, Na ₂ PtCl ₆・ nH ₂ O, K ₂ PtCl ₄・ nH ₂ O, PtCl ₄・ nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄・ nH ₂ O (However, n in the chemical formula is 0. Platinum chloride, chloroplatinic acid and chloroplatinate; alcohol-modified chloroplatinic acid; complex of chloroplatinic acid and olefin; platinum black, palladium. A catalyst in which a platinum group metal such as is supported on a carrier such as alumina, silica, or carbon; a rhodium-olefin complex; a Wilkinson catalyst [chlorotris (triphenylphosphine) rhodium]; Examples thereof include a complex with a vinyl group-containing siloxane. These platinum group metal catalysts may be used alone or in combination of two or more. Further, among these platinum group metal catalysts, platinum and platinum compounds are preferable.

The blending amount of the component (F) is particularly limited as long as it is an effective amount as a catalyst, that is, an amount capable of promoting the reaction between the component (A) and the like and the component (C) and the component (D). However, it can be appropriately set according to the desired curing rate. For example, with respect to 100 parts by mass of the component (A), the blending amount of the component (F) ^{is preferably 1 × 10 -5 to} 7 × 10 ^-1 part by mass in terms of platinum group metal atoms, and is 1 × 10. ^{-4 to} 6 × 10 ^-1 parts by mass is more preferable. If the blending amount of the component (F) is less than the lower limit, the reaction may not be sufficiently promoted. Further, even if an amount of the catalyst exceeding the above upper limit is blended, improvement in the curing rate may not be expected.

(G) component:
The component (G) is a reaction control agent and has a function of suppressing the progress of the curing reaction at room temperature and extending the shell life and pot life of the silicone rubber composition. The reaction control agent is not particularly limited as long as it can suppress the catalytic activity of the component (F), and a known reaction control agent can be used. Specific examples thereof include acetylene compounds having hydroxyl groups such as 1-ethynyl-1-cyclohexanol and 3-butin-1-ol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds. These reaction control agents may be used alone or in combination of two or more. Further, among these reaction control agents, an acetylene compound having a hydroxyl group is preferable from the viewpoint of not being corrosive to metals. Such a reaction control agent may be added as it is, but in order to improve the dispersibility in the silicone rubber composition, it is diluted with an organic solvent such as toluene, xylene or isopropyl alcohol and added to the polysiloxane. Is preferable.

The blending amount of the component (G) is preferably 0.01 to 1.0 parts by mass, more preferably 0.05 to 0.9 parts by mass with respect to 100 parts by mass of the component (A). If the blending amount of the component (G) is less than the lower limit, the shell life and pot life of the silicone rubber composition may not be sufficiently extended. On the other hand, if the amount exceeds the upper limit, the silicone rubber composition becomes fragile. It tends to be difficult to cure.

Other ingredients:
A known additive may be further added to the silicone rubber composition containing the components (A) to (G) as long as the object of the present invention is not impaired. Examples of such additives include hindered phenolic antioxidants, reinforcing or non-reinforcing fillers such as calcium carbonate, and colorants such as polyols, pigments and dyes as thixotropy improvers.

(Silicone rubber member)
The silicone rubber member used in the present invention is made of a cured product of the silicone rubber composition. In the fuel cell external restraint material according to the present invention, the silicone rubber member is sandwiched between two film-shaped or sheet-shaped members. The shape of the contact surface of the silicone rubber member with the film-shaped or sheet-shaped member is not particularly limited, and may be any shape such as a square, a rectangle, a perfect circle, and an ellipse.

The ratio of the vertical length (major axis length in the case of an ellipse) to the horizontal length (minor axis length in the case of an ellipse) of the contact surface of the silicone rubber member with the film-like or sheet-like member ( The aspect ratio) is preferably 1 to 8, more preferably 1 to 4, and particularly preferably 1 to 2. When the aspect ratio of the contact surface exceeds the upper limit, the adhesive force does not act uniformly on the contact surface with the film-like or sheet-like member, so that the continuity of the compressed state tends to decrease.

As the area of the contact surface between the film-like or sheet-like member of said silicone rubber member before compression, preferably 64～10000Mm ^2, more preferably 81~8100mm ^2, 100~6400mm ² is particularly preferred. If the area of the contact surface before compression is less than the lower limit, sufficient adhesive force cannot be obtained on the contact surface with the film-like or sheet-like member, so that the silicone rubber member is released from the applied pressure. The size (particularly the thickness) tends to be restored immediately (the continuity of the compressed state is reduced), and on the other hand, if the upper limit is exceeded, the adhesive force on the contact surface with the film-like or sheet-like member is too strong. The size (particularly, the thickness) of the silicone rubber member tends not to be sufficiently restored (recoverability is lowered) even when a long time has passed after the applied pressure is released.

Further, the thickness of the silicone rubber member is preferably 1 mm to 10 cm, more preferably 2 mm to 5 cm, and particularly preferably 3 mm to 1 cm. When the thickness of the silicone rubber member is less than the lower limit, it tends to be difficult to sufficiently prevent the stacking position of the single cell from being displaced due to impact, while when the thickness exceeds the upper limit, the film-like or sheet-like member tends to be difficult to sufficiently prevent. Since the adhesive force does not act uniformly on the contact surface with the silicone rubber member, the size (particularly the thickness) of the silicone rubber member tends to be restored (the continuity of the compressed state is reduced) as soon as the applied pressure is released. be.

Such a silicone rubber member can be produced, for example, by cutting a cured product (for example, a silicone rubber sheet) of the silicone rubber composition into a predetermined size and shape.

(Film-shaped or sheet-shaped member)
The film-shaped or sheet-shaped member used in the present invention has an adhesive force with respect to the surface of the silicone rubber member in the range of 10 kPa to 1 MPa. By sandwiching the silicone rubber member between the film-shaped or sheet-shaped members whose adhesive force to the surface of the silicone rubber member is within the range, the silicone rubber member can be further recovered from the compressed state. Due to the delay, the continuity of the compressed state is improved. When the adhesive force of the film-shaped or sheet-shaped member is less than the lower limit, sufficient adhesive force cannot be obtained on the contact surface with the silicone rubber member. Therefore, when the applied pressure is released to the silicone rubber member, the silicone rubber member is released. The size (especially the thickness) is restored immediately (the continuity of the compressed state is reduced). On the other hand, when the adhesive force of the film-shaped or sheet-shaped member exceeds the upper limit, the adhesive force on the contact surface with the silicone rubber member is too strong, so that the silicone rubber member becomes long after the applied pressure is released. The size (especially the thickness) is not fully restored over time (recoverability is reduced). The adhesive force of the film-like or sheet-like member to the surface of such a silicone rubber member is preferably 15 kPa to 500 kPa, more preferably 20 kPa to 200 kPa, from the viewpoint of further improving the continuity of the compressed state.

The material of the film-like or sheet-like member is not particularly limited as long as the adhesive force to the surface of the silicone rubber member is within the above range. For example, polypropylene, polyethylene, polyvinyl chloride, polyvinyl alcohol, polyester. , Polypropylene, polystyrene, polymethylmethacrylate, polyacrylonitrile, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, polyamide, acrylic resin and the like.

The thickness of the film-shaped or sheet-shaped member is preferably 0.05 to 5 mm, more preferably 0.1 to 4 mm, and particularly preferably 0.1 to 3 mm. If the thickness of the film-shaped or sheet-shaped member is less than the lower limit, the film-shaped or sheet-shaped member is deformed by compression, so that the compressed state of the silicone rubber member may not be maintained. On the other hand, if the thickness exceeds the upper limit. , When a single cell comes into contact with a film-shaped or sheet-shaped member, stress may be applied to bend the single cell.

The size of the film-shaped or sheet-shaped member is not particularly limited as long as the silicone rubber member does not protrude when compressed. For example, the film of the silicone rubber member before compression. The area of the contact surface with the shaped or sheet-shaped member is preferably 2 to 30 times, more preferably 3 to 20 times, and particularly preferably 4 to 10 times. When the size of the film-shaped or sheet-shaped member exceeds the upper limit, the area ratio of the silicone rubber member to the film-shaped or sheet-shaped member becomes small, so that the deviation of the stacking position of the single cell cannot be sufficiently prevented. There is.

(Fuel cell external restraint material)
The fuel cell external restraining material of the present invention includes the silicone rubber member and two film-shaped or sheet-shaped members, and is composed of two film-shaped or sheet-shaped members and one silicone rubber. Although the members may be sandwiched, it is preferable to sandwich a plurality of the silicone rubber members. When a plurality of the silicone rubber members are sandwiched, the respective silicone rubber members are arranged apart from each other on the surface of the film-shaped or sheet-shaped member so that the adjacent silicone rubber members do not interfere with each other due to compression. Is preferable. As for the spacing between adjacent silicone rubber members, the spacing in the stacking direction of the single cells of the fuel cell stack is 0.1 to 20 times the length of the silicone rubber members in the vertical direction (longitudinal direction in the case of an ellipse). It is preferably present, and more preferably 0.2 to 10 times. Further, the interval in the direction perpendicular to the stacking direction of the single cells of the fuel cell stack is not particularly limited, and the silicone rubber members can be arranged at arbitrary intervals. By arranging the plurality of the silicone rubber members at intervals (preferably at the intervals), the silicone rubber members are sufficiently expanded by compression, and the silicone rubber members and the film-like or sheet-like members are sufficiently expanded. Since the contact surface with the surface becomes large, the adhesive force becomes strong and the continuity of the compressed state is improved. On the other hand, when a plurality of the silicone rubber members are arranged without being separated from each other, the silicone rubber members do not expand sufficiently when compressed, and the contact surface between the silicone rubber members and the film-shaped or sheet-shaped members becomes large. Therefore, sufficient adhesive strength cannot be obtained, and the continuity of the compressed state tends to decrease.

Further, the fuel cell external restraint material of the present invention can be used by being attached to the periphery of the fuel cell stack or the inner wall of the stack case as a member independent of the fuel cell stack or the stack case when manufacturing the fuel cell. However, one of the two film-shaped or sheet-shaped members constituting the fuel cell external restraint material constitutes the inner wall of the stack case, and the fuel cell external restraint material of the present invention is fixed to the inner wall of the stack case. It can also be used in.

Such a fuel cell external restraint material of the present invention is excellent in compression state continuity. Specifically, the thickness of the silicone rubber member in the fuel cell external restraint material of the present invention before compression is set to t _0, and the thickness of the silicone rubber member of this fuel cell external restraint material is 30% of the thickness before compression. When compressed to (0.30 × t ₀ ) and the applied pressure is released, the thickness of the silicone rubber member 10 minutes after the pressure is released becomes 70% of the thickness before compression (0.70). Less than × t ₀ ) (preferably less than 60% thickness (0.60 × t ₀ )), that is, the thickness of the silicone rubber member is 70% of the thickness before compression (0.70 × t ₀ ). (Preferably, it takes 10 minutes or more to return to the thickness of 60% (0.60 × t _0)). By using such a fuel cell external restraint material having excellent continuity in the compressed state, workability when inserting the fuel cell stack into the stack case is improved.

Further, the fuel cell external restraint material of the present invention is also excellent in recoverability. Specifically, in the same manner as described above, the external restraint material for the fuel cell of the present invention was compressed and applied until _{the thickness of the silicone rubber member became 30% of the thickness (0.30 × t 0) before compression.} When the pressure is released, the thickness of the silicone rubber member at 24 hours after the pressure is released is 94% _{or more (0.94 × t 0} ) before compression (preferably 98% thickness (0)). .98 x t ₀ ) or more), that is, the thickness of the silicone rubber member is 94% before compression (0.94 x t ₀ ) (preferably 98% thickness (0.98 x t _0)). )) It takes less than 24 hours to return. By using such a fuel cell external restraint material having excellent recoverability, it is possible to sufficiently prevent the displacement of the stacking position of the single cell.

[Fuel cell manufacturing method]
Next, the method for manufacturing the fuel cell of the present invention will be described. In the first method for manufacturing a fuel cell of the present invention, the fuel cell external restraining material of the present invention is attached in a compressed state around a fuel cell stack in which a plurality of single cells are laminated, and then the fuel cell stack is attached. This is a method of inserting into a stack case. Further, in the second method for manufacturing a fuel cell of the present invention, a fuel cell stack in which a plurality of single cells are laminated is attached to the inner wall of the stack case in a compressed state. This is the method of inserting.

In these methods, the fuel cell external restraint when affixed to the periphery of the fuel cell stack or to the inner wall of the stack case is compressed so that a sufficient gap is formed when the fuel cell stack is inserted into the stack case. If so, the compression ratio is not particularly limited, but for example, the outside of the fuel cell is such that the thickness of the silicone member is 30% or less (more preferably 20% or less) of the thickness of the silicone member before compression. It is preferable to compress the restraint material. This improves workability when inserting the fuel cell stack into the stack case.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. The components used and the method for preparing the silicone sheet are shown below.

(Component A)
Dimethylpolysiloxane (component B) with both ends sealed with a dimethylvinylsilyl group and a viscosity of 5.0 Pa · s at 25 ° C.
Organopolysiloxane represented by the following formula (1-3)

(C component)
Organohydrogenpolysiloxane represented by the following formula (2-2)

(D component)
Organohydrogenpolysiloxane represented by the following formula (3-1)

（Ｅ成分）
平均粒径４．０μｍ、比表面積０．５０ｍ^２／ｇの球状アルミナ粉末
（Ｆ成分）
白金−ジビニルテトラメチルジシロキサン錯体のジメチルポリシロキサン（前記Ａ成分）溶液（白金原子として１質量％含有）
（Ｇ成分）
１−エチニル−１−シクロヘキサノール
（調製例１〜４）
容量５Ｌのプラネタリーミキサー（株式会社井上製作所製）に、表１に示す量の前記Ａ成分、前記Ｂ成分及び前記Ｅ成分を入れた後、減圧下、２５℃で２時間攪拌した。その後に、表１に示す量の前記Ｆ成分を加えて２５℃で３０分間攪拌し、さらに、表１に示す量の前記Ｇ成分を加えて、２５℃で３０分間攪拌した。最後に、表１に示す量の前記Ｃ成分及び前記Ｄ成分を加えて、２５℃で３０分間撹拌して均一に混合し、シリコーンゴム組成物１〜４を得た。得られるシリコーンゴムシートの厚さｔ_０が３．０〜１０ｍｍの範囲内となるように、前記シリコーンゴム組成物１〜４をそれぞれ１２０℃で１０分間プレス硬化させ、さらに、１２０℃のオーブン中で５０分間加熱して、シリコーンゴムシート１〜４を作製した。

(E component)
Spherical alumina powder with an average particle size of 4.0 μm and a specific surface area of 0.50 m ² / g (F component)
Didimethylpolysiloxane (component A) solution of platinum-divinyltetramethyldisiloxane complex (containing 1% by mass as platinum atom)
(G component)
1-ethynyl-1-cyclohexanol (Preparations 1-4)
After putting the A component, the B component and the E component in the amounts shown in Table 1 into a planetary mixer having a capacity of 5 L (manufactured by Inoue Seisakusho Co., Ltd.), the mixture was stirred at 25 ° C. for 2 hours under reduced pressure. Then, the amount of the F component shown in Table 1 was added and stirred at 25 ° C. for 30 minutes, and further, the amount of the G component shown in Table 1 was added and stirred at 25 ° C. for 30 minutes. Finally, the amounts of the C component and the D component shown in Table 1 were added, and the mixture was stirred uniformly at 25 ° C. for 30 minutes to obtain silicone rubber compositions 1 to 4. The silicone rubber compositions 1 to 4 are press-cured at 120 ° C. for 10 minutes so that _{the thickness t 0} of the obtained silicone rubber sheet is within the range of 3.0 to 10 mm, and further, in an oven at 120 ° C. Silicone rubber sheets 1 to 4 were prepared by heating with.

<Dynamic viscoelasticity measurement>
_{A test piece (thickness: t 0} ) having a size of 10 mm × 10 mm was cut out from each of the silicone rubber sheets obtained in Preparation Examples 1 to 4, and a dynamic viscoelasticity measuring device (IT Measurement Control Co., Ltd. “DVA-” 220 ”) was used to measure the storage elastic modulus E'and the loss elastic modulus E'in the frequency range of 0.1 to 50 Hz under the conditions of compression mode, strain amplitude 0.1%, and room temperature, and loss positive contact tan δ ( = E "/ E') was calculated. Table 1 shows the storage elastic modulus E'and the loss tangent tan δ at the measurement frequency of 1 Hz. Table 1 also shows the storage elastic modulus E'and the loss tangent tan δ at a measurement frequency of 1 Hz, which were measured for the following commercially available silicone rubber sheets.
α-gel: Heat-dissipating α-gel sheet (“λGEL COH-1019LVC-T2.0” manufactured by Taica Corporation, hardness (needle insertion degree (1/10 mm)): 90, thickness t ₀ : 5.0 mm)
A90: Silicone rubber sheet ("A90" manufactured by Kyowa Kogyo Co., Ltd., thickness t ₀ : 5.0 mm)
A10: Ultra-low hardness silicone rubber sheet ("A10" manufactured by Kyowa Kogyo Co., Ltd., thickness t ₀ : 5.0 mm)

(Example 1)
_{A silicone rubber member (thickness: t 0} ) having a size of 20 mm × 20 mm was cut out from the silicone rubber sheet 2 (storage elasticity E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, and this was cut out. A laminated structure composed of a PET film / silicone rubber-like member / PET film by sandwiching a silicone rubber-like member between two PET films (“Lumilar T” manufactured by Toray Co., Ltd., 50 mm × 50 mm, thickness: 0.3 mm). External restraint material was prepared.

<Measurement of compression state continuity and recoverability>
The obtained external restraining material is sandwiched between two compression plates, and the thickness of the silicone rubber member becomes 30% (0.30 × t ₀ ) before compression at a pressure of 1 MPa using a manual hydraulic press. Compressed. After holding this compressed state at room temperature (20 to 24 ° C.) for 10 minutes, the pressure was released. After that, the external restraining material is held at room temperature (20 to 24 ° C.), and the thickness of the external restraining material after 10 minutes and 24 hours from the pressure release is measured using a thickness gauge (manufactured by Mitutoyo Co., Ltd.). Then, the thickness of the silicone rubber member was calculated in consideration of the thickness (0.3 mm) of the two PET films. Table 2 shows the ratio [%] of the thickness of the silicone rubber member after 10 minutes and 24 hours from the pressure release to _{the thickness t 0 before compression.}

Further, the smaller the ratio of the thickness of the external restraint material after the lapse of 10 minutes, the higher the continuity of the compressed state, and the larger the ratio of the thickness of the external restraint material after the lapse of 24 hours, the more the recovery. Since it means that the properties are high, the obtained external restraining material is used for continuity in the compressed state (ratio of the thickness of the _{silicone rubber member 10 minutes after the pressure is released to the thickness t 0 before compression).} And the recoverability (the ratio of the thickness after 24 hours from the pressure release to _{the thickness t 0} before compression of the silicone rubber member) was evaluated according to the following criteria. The results are shown in Table 2.

(comprehensive evaluation)
A: Compressed state continuity is less than 60% and recoverability is 98% or more.
B: Compressed state continuity is less than 70% and recoverability is 94% or more (except when compressed state continuity is less than 60% and recoverability is 98% or more).
C: Compressed state continuity is 70% or more or recoverability is less than 94%.

<Adhesive measurement>
_{Two silicone rubber members (thickness: t 0} ) having a size of 20 mm × 20 mm were cut out from the silicone rubber sheet 2 obtained in Preparation Example 2, and these two silicone rubber members and a PET film having a length of 80 mm (stocks) were cut out. Company Toray "Lumirror T", width: 42 mm, thickness: 0.3 mm) 2 sheets and 60 mm long PET film (Toray Co., Ltd. "Lumirror T", width: 42 mm, thickness: 0.3 mm) 2 A test piece for measuring adhesiveness shown in FIG. 4 was prepared using a sheet and a spacer block (manufactured by Misumi Co., Ltd., material: stainless steel, 20 mm × 30 mm, thickness: 2 × (t _{0 + 0.3) mm).}

One minute after the completion of preparation of the test piece, both ends of the test piece were attached to the chuck of a tensile tester (universal tester manufactured by Instron), and the test piece was extended at a speed of 30 mm / min to 5 mm. The load at the time of elongation is measured using a load cell having a rated capacity of 100 N, the stress applied to the interface between the silicone rubber member and the PET film is obtained, and this is determined as the adhesive force of the PET film to the surface of the silicone rubber member. bottom. The results are shown in Table 2.

(Example 2)
Instead of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, the silicone rubber sheet 3 (storage elastic modulus E': 10) obtained in Preparation Example 3 An external restraint was prepared in the same manner as in Example 1 except that .2 MPa, tan δ: 0.34) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the silicone rubber sheet 3 obtained in Preparation Example 3 was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and silicone was prepared. The adhesive force of the PET film on the surface of the rubber member was determined. These results are shown in Table 2.

(Example 3)
Instead of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, the silicone rubber sheet 4 (storage elastic modulus E': 12) obtained in Preparation Example 4 An external restraint was prepared in the same manner as in Example 1 except that .5 MPa, tan δ: 0.37) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the silicone rubber sheet 4 obtained in Preparation Example 4 was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and silicone was prepared. The adhesive force of the PET film on the surface of the rubber member was determined. These results are shown in Table 2.

(Example 4)
Instead of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, the silicone rubber sheet 1 (storage elastic modulus E': 7) obtained in Preparation Example 1 An external restraint was prepared in the same manner as in Example 1 except that 1 MPa, tan δ: 0.39) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the silicone rubber sheet 1 obtained in Preparation Example 1 was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and silicone was prepared. The adhesive force of the PET film on the surface of the rubber member was determined. These results are shown in Table 2.

(Example 5)
_{Using a silicone rubber member (thickness: t 0} ) cut out to a size of 10 mm × 10 mm from the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2. An external restraining material was produced in the same manner as in Example 1 except that a PET film having a size of 30 mm × 30 mm (“Rubber T” manufactured by Toray Co., Ltd., thickness: 0.3 mm) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. The results are shown in Table 2. The adhesive force of the PET film on the surface of the silicone rubber member does not depend on the size of the silicone rubber member (the same applies hereinafter).

(Example 6)
_{A silicone rubber member (thickness: t 0} ) cut out to a size of 14 mm × 20 mm from the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2 was used. An external restraining material was produced in the same manner as in Example 1 except that a PET film having a size of 36 mm × 41 mm (“Rubber T” manufactured by Toray Co., Ltd., thickness: 0.3 mm) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. The results are shown in Table 2.

(Example 7)
_{A silicone rubber member (thickness: t 0} ) cut out to a size of 10 mm × 20 mm from the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2 was used. An external restraining material was produced in the same manner as in Example 1 except that a PET film having a size of 30 mm × 41 mm (“Rubber T” manufactured by Toray Co., Ltd., thickness: 0.3 mm) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. The results are shown in Table 2.

(Example 8)
_{A silicone rubber member (thickness: t 0} ) cut out to a size of 10 mm × 40 mm from the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2 was used. An external restraining material was produced in the same manner as in Example 1 except that a PET film having a size of 30 mm × 61 mm (“Rubber T” manufactured by Toray Co., Ltd., thickness: 0.3 mm) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. The results are shown in Table 2.

(Example 9)
_{A disc-shaped silicone rubber member (thickness: t 0} ) having a radius of 11.3 mm was cut out from the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2. An external restraining material was prepared in the same manner as in Example 1 except that a PET film having a size of 50 mm × 50 mm (“Rubber T” manufactured by Toray Co., Ltd., thickness: 0.3 mm) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. The results are shown in Table 2.

(Example 10)
An external restraining material was produced in the same manner as in Example 5 except that an acrylic plate having a size of 30 mm × 30 mm (manufactured by Misumi Co., Ltd., thickness: 3 mm) was used instead of the PET film. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, instead of the PET film, two 80 mm long acrylic plates (manufactured by Misumi Co., Ltd., width: 42 mm, thickness: 3 mm) and 60 mm long acrylic plates (manufactured by Misumi Co., Ltd., width: 42 mm, thickness: 3 mm) ) Using two sheets, the adhesiveness measurement test piece shown in FIG. 4 was prepared in the same manner as in Example 1 except that the thickness of the spacer block _{was changed to 2 × (t 0 + 3) mm, and the silicone rubber member was prepared.} The adhesive strength of the acrylic plate to the surface was determined. These results are shown in Table 2.

(Comparative Example 1)
Instead of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, the heat-dissipating α gel sheet (storage elastic modulus E': 2.0 MPa, tan δ: 0. An external restraining material was produced in the same manner as in Example 1 except that 44) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the heat-dissipating α-gel sheet was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and the PET on the surface of the silicone rubber member was prepared. The adhesive strength of the film was determined. These results are shown in Table 2.

(Comparative Example 2)
Instead of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, the silicone rubber sheet "A90" (storage elastic modulus E': 24.5 MPa, tan δ) An external restraint was prepared in the same manner as in Example 1 except that 0.15) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was produced in the same manner as in Example 1 except that the silicone rubber sheet "A90" was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and the surface of the silicone rubber member was prepared. The adhesive strength of the PET film was determined. These results are shown in Table 2.

(Comparative Example 3)
Instead of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2, the ultra-low hardness silicone rubber sheet "A10" (storage elastic modulus E': 0. An external restraint was prepared in the same manner as in Example 1 except that 81 MPa, tan δ: 0.15) was used. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the ultra-low hardness silicone rubber sheet "A10" was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and the silicone rubber was prepared. The adhesive force of the PET film on the surface of the member was determined. These results are shown in Table 2.

(Comparative Example 4)
The surface of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2 is coated with water-resistant abrasive paper (Noritake Coated Abrasive Co., Ltd. "C947H # 1000"). After rubbing 30 times with the product, it was washed with a detergent. The same as in Example 1 except that the surface-polished silicone rubber sheet (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) was used in place of the silicone rubber sheet 2 obtained in Preparation Example 2. An external restraint material was prepared. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the silicone rubber sheet after surface polishing was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and the silicone rubber member was prepared. The adhesive strength of the PET film to the surface was determined. These results are shown in Table 2.

(Comparative Example 5)
A lubricant (“KE-1051J (A)” manufactured by Shinetsu Silicone) was thinly applied to the surface of the silicone rubber sheet 2 (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) obtained in Preparation Example 2. .. The same as in Example 1 except that the silicone rubber sheet (storage elastic modulus E': 9.3 MPa, tan δ: 0.35) after this lubrication coating was used in place of the silicone rubber sheet 2 obtained in Preparation Example 2. An external restraint material was prepared. The compression state continuity and recoverability of this external restraint were measured in the same manner as in Example 1. Further, a test piece for measuring adhesiveness was prepared in the same manner as in Example 1 except that the silicone rubber sheet after the lubricating coating was used instead of the silicone rubber sheet 2 obtained in Preparation Example 2, and the silicone rubber member was prepared. The adhesive strength of the PET film to the surface was determined. These results are shown in Table 2.

As is clear from the results shown in Table 2, a silicone rubber member having a storage elastic modulus and tan δ within a predetermined range, and a film-like or sheet-like member having an adhesive force to the surface of the silicone rubber member within a predetermined range. The fuel cell external restraint material (Examples 1 to 10) of the present invention, which comprises a member and the silicone rubber member is sandwiched between the two film-shaped or sheet-shaped members, has a compression state continuity and It was confirmed that it was excellent in recoverability. This is because the fuel cell external restraint material of the present invention exhibits delayed elasticity (a viscoelastic response in which the size (particularly the thickness) is not immediately restored even when the applied pressure is released, but is restored with a delay). , And it is considered that the recovery from the compressed state is further delayed due to the adhesiveness between the silicone rubber member and the film-like or sheet-like member.

On the other hand, when the storage elastic modulus of the silicone rubber member is 2.0 MPa or less and tan δ is 0.44 or more, the restoring force of the silicone rubber is weak and the silicone rubber becomes a viscous body, so that the recoverability of the external restraint is improved. It was found to be extremely low (Comparative Example 1). Further, when the storage elastic modulus of the silicone rubber member is 24.5 MPa or more and tan δ is 0.15 or less, the restoring force of the silicone rubber is strong and the silicone rubber becomes an elastic body, so that the compressed state of the external restraining material is continued. It was found that the sex was extremely low (Comparative Example 2). Further, even if the storage elastic modulus of the silicone rubber member is 2.0 MPa or less, when tan δ is 0.15 or less, the contribution of elasticity in the silicone rubber is higher than the contribution of viscosity, so that the external restraining material is in a compressed state. It was found that the continuity was low (Comparative Example 3).

Further, even when the storage elastic modulus and tan δ of the silicone rubber member are within a predetermined range, when the adhesive force of the film-like or sheet-like member to the surface of the silicone rubber member is less than 10 kPa, the silicone rubber member Was not constrained by the film-shaped or sheet-shaped member, so that the continuity of the compressed state of the external restraining material was found to be low (Comparative Examples 4 to 5).

From the above results, the fuel cell external restraint material of the present invention is maintained in a compressed state while the fuel cell stack is inserted into the stack case (for example, for 10 minutes), and after the fuel cell stack is housed in the stack case (for example). For example, after 24 hours, it was confirmed that the original size (particularly the thickness) was restored.

As described above, the fuel cell external restraint material of the present invention is maintained in a compressed state while the fuel cell stack is inserted into the stack case (for example, for 10 minutes), and after the fuel cell stack is housed in the stack case. After 24 hours (for example, after 24 hours) it will be possible to restore the original size (particularly the thickness).

Therefore, since the fuel cell manufacturing method of the present invention uses such the fuel cell external restraint material of the present invention, the workability when inserting the fuel cell stack into the stack case is excellent, and the obtained fuel can be obtained. The battery is also one in which the deviation of the stacking position of the single cell is sufficiently prevented.

1: Fuel cell external restraint material 1a: Silicone rubber member 1b: Film-like or sheet-like member 2: Fuel cell stack 2a: Single cell 3: Stack case A: Silicone rubber member B: Film-like or sheet-like member (length: 60mm)
C: Film-shaped or sheet-shaped member (length: 80 mm)
D: Spacer block E: Upper chuck grip part F: Lower chuck grip part

Claims (4)

A silicone rubber member made of a cured product of a silicone rubber composition having a storage elastic modulus at a frequency of 1 Hz and a loss positive contact tan δ of 0.16 to 0.43, which is determined by dynamic viscoelasticity measurement. , A film-like or sheet-like member,
Two more members are obtained by sandwiching the two-layered film-shaped or sheet-shaped member between the two silicone rubber members (the size of the contact portion between the film-shaped or sheet-shaped member and the silicone rubber member: 20 mm × 20 mm). A test piece for measurement was prepared by sandwiching it between the film-shaped or sheet-shaped members (the size of the contact portion between the silicone rubber member and the film-shaped or sheet-shaped member: 20 mm × 20 mm), and from the completion of the test piece preparation. After 1 minute has passed, the test piece is stretched at a speed of 30 mm / min using a tensile tester, and the load at the time of stretching by 5 mm is measured using a load cell to obtain the silicone rubber member and the film. is obtained as an interface to the stress of the Jo or sheet-like member, the adhesive strength of the film-like or sheet-like member to the surface of said silicone rubber member is 10KPa～1MPa,
A fuel cell external restraining material, wherein the silicone rubber member is sandwiched between two film-shaped or sheet-shaped members. The fuel cell external restraint material according to claim 1, wherein a plurality of the silicone rubber members are arranged on the surface of the film-shaped or sheet-shaped member in a state of being separated from each other. The fuel cell external restraint according to claim 1 or 2 is attached around a fuel cell stack in which a plurality of single cells are stacked in a compressed state, and then the fuel cell stack is inserted into a stack case. How to manufacture a fuel cell. Manufacture of a fuel cell, wherein the fuel cell external restraining material according to claim 1 or 2 is attached to the inner wall of the stack case in a compressed state, and then a fuel cell stack in which a plurality of single cells are laminated is inserted. Method.

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