Abstract:
A cartridge applied to a fuel cell is provided with: a fuel including at least two selected from the group of an organic compound having an ether linkage, an organic compound having an O—H linkage, and water; and a container to house the fuel, the container including one selected from the group of a casing of a resin including naphthalate system polyester and a casing of a metal having an inner coating of a resin including naphthalate system polyester.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2005-070061 (filed Mar. 11, 2005); the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a container for containing a fuel for a fuel cell and the fuel cell using the fuel supplied from the container to generate electricity.  
         [0004]     2. Description of the Related Art  
         [0005]     In the recent past, development of fuel cells has been emphasized on stationary fuel cells. For the last few years, there is increasing interest in development of a portable fuel cell, which will be applicable to various portable information equipments such as a cellular phone, a notebook PC, etc.  
         [0006]     A direct methanol fuel cell (DMFC, hereinafter), in which methanol aqueous solution is directly used as a fuel for power generation, is now proposed to be a preferable type of the portable fuel cell. In the meantime, a reformed hydrogen fuel cell (RHFC, hereinafter) is preferable for generation of relatively high power.  
         [0007]     To carry about the portable fuel cell, a compact cartridge for containing and supplying a fuel to the fuel cell is required. Japanese Patent Unexamined Publications S52-45466, H11-166725 and H11-321837 respectively disclose arts of containers or materials preferably applied to containers for containing a fuel.  
         [0008]     The cartridge may be required to have the following properties. The cartridge is required to sufficiently protect leakage and permeation of ingredients of the fuel so as to prevent composition change, which leads to change in output power of the fuel cell. The cartridge should be chemically stable against the ingredients of the fuel because it greatly influences safety. Moreover the cartridge preferably has transparency to some degree to show the remaining amount of the fuel to its user. These issues and solutions thereof are not disclosed in the above publications.  
       SUMMARY OF THE INVENTION  
       [0009]     According to an aspect of the present invention, a container for containing a fuel including at least two selected from the group of an organic compound having an ether linkage, an organic compound having an O—H linkage, and water, is provided with: a casing of a metal; and an inner coating of a resin including naphthalate system polyester.  
         [0010]     According to another aspect of the present invention, a cartridge is provided with: a casing of a resin including naphthalate system polyester; and a fuel including at least two selected from the group of an organic compound having an ether linkage, an organic compound having an O—H linkage, and water.  
         [0011]     According to still another aspect of the present invention, a container for containing a fuel including at least two selected from the group of an organic compound having an ether linkage, an organic compound having an O—H linkage, and water, is provided with: a casing; and a sealing member of a rubber selected from the group of butyl rubber and perfluoro rubber. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a perspective view of a cartridge in accordance with an embodiment of the present invention;  
         [0013]      FIG. 2  is an exploded perspective view of the cartridge;  
         [0014]      FIG. 3  is a cross sectional view of the cartridge;  
         [0015]      FIG. 4  is an enlarged cross sectional view of the cartridge;  
         [0016]      FIG. 5  is a schematic diagram of a fuel cell system in accordance with an embodiment of the present invention; and  
         [0017]      FIG. 6  is a cross sectional view of a cartridge in accordance with another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     An embodiment of the present invention will be described hereinafter with reference to  FIGS. 1 through 6 .  
         [0019]     As mentioned in the above DESCRIPTION OF THE RELATED ART, a cartridge applied to a fuel cell is required to sufficiently protect leakage and permeation of ingredients of the fuel so as to prevent composition change, be chemically stable against the ingredients of the fuel, and be transparent to some degree. To satisfy the properties, the present inventors have carried out keen studies on materials for the cartridge as described hereinafter.  
         [0000]     (A) SEARCH OF MATERIAL  
         [0020]     The present inventors have searched materials preferably applied to the cartridge and found that naphthalate system polyester resins such as polyethylene naphthalate (PEN) or polybutylene naphthalate (PBN) are preferably applied to a casing of the cartridge and butyl rubber and perfluoro rubber are preferably applied to a sealing member of the cartridge.  
         [0021]     Here, the naphthalate system polyester resins mean any resins having the following general chemical formula;  
                         
 
 where m and n represent arbitrary integers. Representative examples of the naphthalate system polyester resins are polyethylene naphthalate (PEN) and polybutylene naphthalate (PBN) respectively represented by the following chemical formulae;  
                         
 
         [0022]     A fuel cartridge (fuel container)  1  for containing a fuel is provided with a casing  2  having an opening at an end thereof and a lid  10  attached to the opening as shown in  FIG. 1 . The casing  2  may be formed by injection molding and is applied to fuel storage therein as shown in  FIGS. 1 and 2 .  
         [0023]     The lid  10  is provided with a housing  11  fixedly attached to the opening of the casing  2 , a spring  12  attached to the housing  11 , a gasket  13 , a stem  14  and a guide screw  15  as shown in  FIGS. 2 and 3 .  
         [0024]     The housing  11  is provided with a frame portion  11   a  fitting in the opening of the casing  2  and a cylinder portion  11   b  housing the spring  12 . The cylinder portion  11   b  has an aperture at a bottom thereof and a through hole  11   c  at a side wall thereof, which link the interior of the casing  2  with an interior of an inner hollow of the cylinder portion  11   b  to allow the fuel contained in the casing  2  flowing.  
         [0025]     The housing  11  is welded with the opening of the casing  2  by ultra-sonic welding. The spring  12  is fit in and on the bottom of the inner hollow of the cylinder portion  11   b . The stem  14  to which the gasket  13  made of rubber is attached is disposed on the spring  12 .  
         [0026]     The housing  11  has a support  11   d  on which the gasket  13  is disposed. The guide screw  15  is screwed in the housing  11  so as to hold an outer periphery of the gasket  13  between the guide screw  15  and the support  11   d.    
         [0027]     The guide screw  15  is provided with a through hole substantially at a center thereof, in which the stem  14  is movably supported. When the fuel cartridge  1  is installed in the fuel cell, the stem  14  is pressed into the fuel cartridge  1 , namely downward in accordance with illustration by  FIG. 3 . When pressing down the stem  14 , deformation of an inner periphery of the gasket  13  and compression of the spring  12  allow the stem  14  receding into the interior of the inner hollow of the cylinder portion  11   b . Then a hole  14   b  formed on the side wall of the stem  14  links the interior of the inner hollow of the cylinder portion  11   b  with the exterior of the fuel cartridge  1  via a hollow  14   a  of the stem  14 .  
         [0028]     Then the fuel in the cylinder portion  11   b  poured from the casing  2  flows through the hole  14   b  and the hollow  14   a  of the stem  14  and flows out of an outer end of the stem  14 . The discharged fuel is supplied to the fuel cell. When the fuel cartridge  1  is detached from the fuel cell, the stem  14  protrudes upward in view of  FIG. 4  by repulsive force of the compressed spring  12  and the gasket  13  recovers into the original state so that the hole  14   b  of the stem  14  comes to be closed.  
         [0029]     Meanwhile, the casing  2  may be formed in a triangular or polygonal prism shape.  
         [0000]     (1) MATERIAL OF CASING  
         [0030]     General properties of the resins had been tested and disclosed already, as indicated in left columns of Table 1. However, resistance of these resins to DME is not fully known. In particular, a chemical system including DME has a considerable tendency to permeate a resin because DME has a vapor pressure of several MPa in the room temperature and hence gives excess pressure to the system. This leads to increased difficulty in estimation of the properties of the resins in the chemical system including DME.  
         [0031]     The present inventor has carried out some tests to estimate resistance of some of the resins to a fuel system including DME and water. The tests are carried out under the following two conditions.  
         [0000]     (a) 65 degrees C. - 4 hr. test  
         [0032]     A test fuel of 9.45 g is produced by adding 3 mol water to 1 mol DME and further adding 10 vol % methanol thereto. The test fuel is poured in a casing subject to the test and left at 65 degrees C. for 4 hours. Weight is measured before and after the test and the external appearance is observed.  
         [0000]     (b) 45 degrees C. - 3 days test  
         [0033]     A test fuel of 9.45 g is produced by adding 3 mol water to 1 mol DME and further adding 10 vol % methanol thereto. The test fuel is poured in a casing subject to the test and left at 45 degrees C. for 3 months. Weight is measured before and after the test and the external appearance is observed.  
         [0034]     Test results are summarized in Table 1. The test results teach that PEN and PBN are preferable in view of weight change and appearance change.  
                                                                                                                                                               TABLE 1                           test results                general properties                    water           after exposure   after exposure               absorption   resis-       to 65° C.-4 hr   to 45° C.-3 months                    resis-   (%) after   tance           weight       weight   ap-               sym-   tance   24 hr/   to meth-   resitance       reduction   appearance   reduction   pearance       resins   bols   to DME   20° C.   anol   to mixture   adhesivity   (%)[IIR]   change   (%)[IIR]   change   overall                    polyethylene terephthalate   PET   poor   0.3   good   poor   middle       whitened       whitened   inferior                                       with cracks       with                                               cracks       polyethylene naphthalate   PEN   poor   0.2   good   good   good   0.11   whitened to   4.78   whitened   superior                                       some extent       to some                                               extent       polybuthylene terephthalata   PBT   middle   0.03   good   middle   good   0.08   no   13.48   no   middle                                       abnormality       abnor-                                               mality       polybutylene naphthalate   PBN   good   0.1   good   excellent   good   0.07   no   3.88   no   ex-                                       abnormality       abnor-   cellent                                               mality       polyamide   PA   good   1-2   middle   poor   middle                   inferior       polycarbonate   PC   poor   0.23   poor   poor   good                   inferior       polyacetal   POM   middle   0.7   good   middle   good                   middle       polypropylene   PP   middle   &lt;0.01   good   middle   poor                   inferior       acrylonitrile.styrene   AS   poor   0.2-0.3   poor   poor   good                   inferior       acrylonitrile.butadiene.styre   ABS   poor    0.2-0.35   poor   poor   good                   inferior                  
 
         [0035]     Appearance abnormality is also checked, where appearance abnormality is defined as degree of whitening of resin.  
         [0036]     PBN is inherently white and hence incapable of showing clear appearance change in view of whitening. However, PET, PET+PEN and PEN are inherently transparent and hence capable of showing clear change of degree of whitening. In these test, any of PET, PET+PEN and PEN shows progress in degree of whitening. Further, these resins are subject to an infrared spectroscopic analysis and show great change in infrared spectra.  
         [0037]     It is considered that bridges of terephthalate in PET are in part subject to hydrolysis by permeation of DME and water and heating. In contrast, naphthalate is considered insusceptible to hydrolysis.  
         [0038]     The casing of any of the resins may be produced by any publicly known production method.  
         [0039]     Polyethylene naphthalate (PEN) and polybutylene naphthalate (PBN) may be mixed to be applied. Such a mixture has transparency of PEN and chemical resistance and thermal resistance of PBN and provides these preferable properties for the casing.  
         [0000]     (2) MATERIAL OF SEAL MEMBER  
         [0040]     Because DME is excellent in permeation as described above, any preferable rubber for a seal member resistive to DME has not been known. In particular, any rubber insusceptible to a chemical system including DME and water has not been known as in the case with the material for the casing.  
         [0041]     In view of the above issue, some rubbers having resistance to ketones are selected and tested with respect to resistance to the fuel system including DME and water as described hereinafter.  
         [0042]     The tests are carried out under the following two conditions.  
         [0000]     (a) immersion test  
         [0043]     Test pieces respectively made of the rubbers are immersed in a test fuel of 9.45 g, in which 3 mol water is added to 1 mol DME and 10 vol % methanol is further added thereto, and left at 65 degrees C. for 4 hours. The rubber test pieces are made to be 2.0 mm in thickness and 14 mm in diameter. Weight change and appearance change after 4 hours are tested.  
         [0000]     (b) fuel permeation test  
         [0044]     A test fuel of 9.45 g is produced by adding 3 mol water to 1 mol DME and further adding 10 vol % methanol thereto. The test pieces are sandwiched in a test container and compressed by 20%. Next the test fuel is poured in the test container and left at 65 degrees C. for 4 hours. Weight reduction is measured and transparency is observed.  
         [0045]     The test results are summarized in Table 2.  
                                                                           TABLE 2                           test results                shortened   weight   size   fuel               RUBBER   symbol   reduction   change   permeation   elution   overall                    butyl rubber   IIR   15.25%   6.05%   1.20%   small   good       polyurethane   UR   20.99%   11.46%   4.00%   small   poor       rubber (esters)       hydrogenated   HNBR   19.33%   9.36%   3.10%   small   poor       nitrile butadiene rubber       perfluoro rubber   FFKM   13.08%   10.19%   2.20%   small   middle                  
 
         [0046]     As long as judging by the weight change and the size change, although it is hard to say that any rubber is excellent in resistance to the fuel system including DME and water, butyl rubber and perfluoro rubber are superior.  
         [0047]     Volume increase and fuel permeation in a system including water and alcohol as well as DME may not be analogically estimated from the above results. Therefore imbibition and permeation tests are carried out. Further resistance tests are carried out with respect to selected materials.  
       (B) APPLICABILITY  
       [0000]     (1) composition change of fuel  
         [0048]     Fuel cartridges as mentioned above (see  FIG. 1 ) made of any of the aforementioned resins and rubbers are practically produced and subject to tests in which decrease and composition change of fuel contained therein are tested.  
         [0049]     Conditions of the tests are as same as the tests of the resins and the rubbers. Test results are summarized in Table 3.  
                                           TABLE 3                           Test results                    weight increase       resin   rubber   ratio                    PEN   UR   9.81%       PEN   IIR   4.78%       PBN   IIR   3.88%       PBT   IIR   13.48%                  
 
         [0050]     More specifically, the composition changes in the cartridges to which the present embodiment of the present invention is applied are in the range of 3 to 5 wt %. Therefore, the fuel cartridge in accordance with the present embodiment of the present invention may provide small change in the fuel composition and stable output for a fuel cell.  
         [0051]     In particular, the rubber applied to the fuel cartridge preferably excludes plasticizer, because elution of any component of plasticizer, such as dioctyl phtalate (DOP), does not occur. Needless to say, plasticizer is not limited to DOP but may include phtalate esters, adipate esters, phosphoric esters, trimellitate esters, citric esters, epoxy system compounds and polyesters. For general rubber whose hardness is 70, about from 10 to 20 parts of plasticizer is added to 100 parts of rubber, though the appropriate ratio depends on its purpose and application.  
         [0052]     As being understood from the above description, the phrase “excluding plasticizer” means that any plasticizer is not added to rubber with the intention, to the extent that would affect the basic and novel characteristics of the product, in the course of production of the rubber. However, the phrase should not be interpreted as excluding small amount of, for example 0.1%, plasticizer mixed as an unintended impurity come from an environment of the production. Either excluding or including may be estimated by either inclusion of 1% or less plasticizer or not, which can be measured by quantitative analysis by any publicly known analyzing method such as a FT-IR or a liquid or gas chromatograph carried out after thermal pressurized cracking or solvent extraction.  
         [0053]     In contrast, in a case where another combinations of resins such as PBT and rubbers are applied to the cartridges, the composition changes reaches 10 wt % or such. If the fuel cell is operated with any of these cartridges, DME as a component of the fuel leaks away and is reduced in concentration, which leads to troubles.  
         [0054]     Concrete troubles are as follows.  
         [0055]     (a) Greater energy is required to compensate heat of vaporization at a time of heating the fuel as the water content per unit volume becomes relatively great.  
         [0056]     (b) Smaller amount of hydrogen is gained in a reforming reaction of the fuel because of the reduced concentration of DME.  
         [0057]     (c) The smaller amount of hydrogen leads to insufficient temperature increase, thereby a CO shift reaction and a methanation reaction of the fuel insufficiently progress. This results in production of few to few hundreds ppm of CO (carbon monoxide).  
         [0058]     (d) This produced CO deteriorates a catalyst of Pt in cells for electricity generation.  
         [0000]     (2) safety  
         [0059]     Fuel cartridges made of any of the aforementioned resins and rubbers are practically produced and subject to a strength test. As a result, the cartridge in accordance with the present embodiment of the present invention is superior in durability to the cartridge of PET which allows greater DEM permeation and is more susceptible to hydrolysis.  
         [0000]     (3) another effects: first—easier visible check  
         [0060]     For users of portable fuel cells, it is important to easily check a remaining fuel level, as they need to know how long the battery lasts to enjoy trouble-free user interface of their mobile equipments.  
         [0061]     However, to provide the fuel cell system with a detection system for detecting a remaining fuel level may be somewhat troublesome in view of cost, weight and/or size because such a system requires large-scale devices, surveillance systems and controllers. Moreover, the detection system may cause malfunction and result in provision of wrong information.  
         [0062]     In contrast, if a fuel cartridge allows users to visibly check the remaining fuel level, these problems may not occur. Such a fuel cartridge provides simpleness, compactness and high reliability.  
         [0063]     Regarding this issue, whitening of PEN is slower than that of PET, thereby the fuel cartridge of PEN keeps to allow visible check for 8 hours in a high temperature condition as an imitation of the vehicle interior in summer.  
         [0064]     It is possible to mix and apply polyethylene naphthalate and polybutylene naphthalate to the fuel cartridge. It is preferable to mix these resins in a proper ratio to give preferable properties to the fuel cartridge in view of transparency originated from PEN and chemical resistance, thermal resistance and gas barrier property originated from PBN.  
         [0065]     Fuel cartridges made of various mixtures of PEN and PBN in various mixing ratios are practically produced with thickness of 2 mm and subject to a thermal resistance test in which the test pieces are left at 65 degrees C. for 4 hours and 8 hours. Test results are summarized in Table 4.  
                                                                                                                                                                                                                                                                 TABLE 4                           test results                after exposure to 65° C.-4 hr   after exposure to 65° C.-8 hr            mixing   initial state   diame-   infla-       defor-       infla-       defor-                ratio       diameter       ter   tion   inflation   mation       diameter   tion   inflation   mation                PEN   PBN   portion   (mm)   visibility   (mm)   (mm)   rate (%)   at bottom   visibility   (mm)   (mm)   rate (%)   at bottom   visibility                    80   20   upper   20.8   excellent   20.9   0.10   0.5   small   minimum   22   1.20   5.8   small   minimum               central   21.4       21.4   0.00   0.0           21.5   0.10   0.5               bottom   20.7       20.6   −0.10   −0.5           20.8   0.10   0.5       70   30   upper   21.8   excellent   22   0.20   0.9   small   minimum   22   0.20   0.9   large   minimum               central   21.4       21.55   0.15   0.7           21.7   0.30   1.4               bottom   20.7       20.85   0.15   0.7           20.9   0.20   1.0       60   40   upper   21.8   excellent   22   0.20   0.9   small   good   22.2   0.40   1.8   large   good               central   21.4       21.6   0.20   0.9           21.85   0.45   2.1               bottom   20.7       20.9   0.20   1.0           20.9   0.20   1.0       50   50   upper   21.85   excellent   22.1   0.25   1.1   large   good   22.15   0.30   1.4   large   good               central   21.4       21.9   0.50   2.3           21.95   0.55   2.6               bottom   20.8       20.8   0.00   0.0           20.8   0.00   0.0       40   60   upper   20.8   good   22.3   1.50   7.2   large   good   22.4   1.60   7.7   large   minimum               central   21.35       22.3   0.95   4.4           22.6   1.25   5.9               bottom   20.75       20.9   0.15   0.7           20.95   0.20   1.0       30   70   upper   21.7   poor   21.8   0.10   0.5   small   poor   21.85   0.15   0.7   small   poor               central   21.2       21.6   0.40   1.9           21.9   0.70   3.3               bottom   21.75       20.45   −1.30   −6.0           21.75   0.00   0.0                  
 
         [0066]     In a condition just after production, the cartridges including less than 70 wt % PBN, particularly including 60 wt % or less PBN, assure enough transparency to allow visible check of remaining fuel level from the exterior. However, the cartridges including 70 wt % or more PBN have insufficient transparency so that visible check is impossible.  
         [0067]     The cartridges including 40 wt % or less PBN, namely 60 wt % or more PEN, become clouded originated by whitening of PEN after exposure to a high temperature environment for few hours, thereby visible check from the exterior comes to be difficult. More specifically, albeit it depends on the environmental conditions such as temperature, the content of PBN is preferably 0 wt % or more and 70 wt % or less, more preferably 40 wt % or more and 70 wt % or less, and further preferably 40 wt % or more and 60 wt % or less, to assure visible check from the exterior.  
         [0068]     Thermal deformation is most prominent in a case of 60 wt % PBN. More specifically, the content of PBN is preferably 0 to 50 wt % or 70 to 100 wt %, more preferably 0 to 40 wt % or 70 to 100 wt %, to prevent thermal deformation.  
         [0069]     Meanwhile, the mixture of PEN and PBN may be produced as a pellet in which polymerization partly progresses, or the mixture may be left in a state of monomers, dimers or trimers and, after production of a pellet, polymerized. Mixing of PEN and PBN is preferably carried out in a low molecular state because mixing after polymerization may cause lack of uniformity and decrease in strength thereof.  
         [0070]     A preferable range of mixing ratios in view of visible check differs from another preferable range in view of thermal deformation as described above. The mixing ratios may be preferably selected depending on conditions of environments in which the cartridge is used. Moreover, the cartridge may be reinforced so as to endure thermal deformation by introducing any reinforcing structure, for example reinforcement plates or ribs made of steel or stainless steel. Alternatively fillers are in advance mixed in the mixture of resins. Thereby thermal deformation may be prevented with assuring visible check from the exterior if the content of PBN is 40 to 60 wt %.  
         [0071]     A fuel cell system  21  with the fuel cartridge (fuel container)  1  may be constituted as described hereinafter. The fuel cell system  21  is provided with a fuel cell  23  as illustrated in  FIG. 5 . The fuel cell  23  is provided with a solid polymer electrolyte membrane  23 A, a fuel electrode  23 B (including an anodic catalyst) layered on one side of the membrane  23 A and an air electrode  23 C (including a cathodic catalyst) layered on another side of the membrane  23 A.  
         [0072]     The fuel cartridge  1  is linked with the fuel electrode  23 B via a flow path, in which a fuel supply regulator  25 , an evaporator  27 , a reforming portion  29  and a CO removal portion  31  intervene in this order. The fuel supply regulator  25  is configured to regulate a flow rate of the fluid supplied to the fuel cell  23  and for example provided with a flow regulation valve. The evaporator  27  receives heat generated at a catalytic combustion portion  33  to evaporate the fuel flowing from the fuel cartridge  1 .  
         [0073]     The reforming portion  29  is provided with an internal flow path for conducting the evaporated fuel and a reforming catalyst for promoting a reforming reaction of the fuel, which generates a reformed gas including hydrogen. The CO removal portion  31  receives the reformed gas and removes carbon monoxide (CO) contained therein, which is generated as a by-product of the reforming reaction. The catalytic combustion portion  33  is linked with the fuel electrode  23 B so as to receive the exhaust gas therefrom and further linked with a pump  35  so as to receive air. The catalytic combustion portion  33  is configured to bring about catalytic combustion of hydrogen left unreacted in the exhaust gas with oxygen in the air.  
         [0074]     An air flow path  37  to supply the outside air to the air electrode  23 C and the catalytic combustion portion  33  is provided with a heat exchanging portion  41  configured to exchange heat between the air flowing in the air flow path  37  and an exhaust air exhausted from the air electrode  23 C and flowing in an air exhaust path  39 . Therefore the air is in advance heated before being supplied to the air electrode  23 C and the catalytic combustion portion  33 .  
         [0075]     When the fuel cartridge  1  discharges the fuel contained therein, the fuel including dimethyl ether and water is evaporated at the evaporator  27 , and subsequently reformed to be a reformed gas including hydrogen at the reforming portion  29 . Carbon monoxide contained in the reformed gas is removed at the CO removal portion  31 , and the reformed gas with reduced carbon monoxide is supplied to the fuel electrode  23 B of the fuel cell  23 . In the meantime, air is introduced by the pump  35  and exchanges heat with the exhaust air from the air electrode  23 C of the fuel cell  23 . The air thereby pre-heated is supplied to the air electrode  23 C and the catalytic combustion portion  33 .  
         [0076]     Next, unreacted hydrogen contained in the exhaust gas from the fuel electrode  23 B is subject to catalytic combustion with oxygen contained in the air supplied from the pump  35  and hence generates heat. The generated heat is used to heating the evaporator  27 , the reforming portion  29  and the CO removal portion  31 . At the fuel cell  23 , hydrogen supplied to the fuel electrode  23 B and oxygen supplied to the air electrode  23 C are reacted with each other and results in generation of electricity.  
         [0077]     Some working examples in accordance with the present embodiment of the present invention will be described hereinafter. In the following description, if not otherwise noticed, rubbers exclude any plasticizer.  
       EXAMPLE 1  
     PEN-IIR (DME:water=1:4)  
       [0078]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0079]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0080]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 2  
     PEN-IIR (DME:water=1:3)  
       [0081]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 4.14 g was filled as a fuel in the casing.  
         [0082]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0083]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 3  
     PEN-FFKM  
       [0084]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and FFKM to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0085]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0086]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 4  
     PBN-IIR  
       [0087]     A fuel cartridge as shown in  FIG. 1  was produced by applying PBN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0088]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
       EXAMPLE 5  
     PBN-FFKM  
       [0089]     A fuel cartridge as shown in  FIG. 1  was produced by applying PBN to its casing and FFKM to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0090]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
       EXAMPLE 6  
     methanol (CH 3 OH)  
       [0091]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0092]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0093]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 7  
     ethanol (C 2 H 5 OH)  
       [0094]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and ethanol of 1. 37 g was filled as a fuel in the casing.  
         [0095]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0096]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 8  
     propanol (C 3 H 7 OH)  
       [0097]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and propanol of 1.78 g was filled as a fuel in the casing.  
         [0098]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0099]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 9  
     IPA (isopropyl alcohol, (CH 3 ) 2 CHOH)  
       [0100]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and isopropyl alcohol of 1.37 g was filled as a fuel in the casing.  
         [0101]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0102]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 10  
     PEN-IIR  
       [0103]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 4.05 g and water of 4.755 g was filled as a fuel in the casing.  
         [0104]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0105]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 11  
     PEN-IIR  
       [0106]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13. 5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0107]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. In this test, the reformed hydrogen fuel cell system is provided with a concentration sensor and a pressure valve controlled thereby at an inlet of the reforming portion. By the sensor and the pressure valve, the ratio of DME to water was constantly regulated to be 1 to 3 or less. The test showed stable output of 20 W for 30 min with 15 ppm or less carbon monoxide concentration.  
         [0108]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 12  
     PEN-IIR  
       [0109]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13. 5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0110]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 12 ppm or less carbon monoxide concentration.  
         [0111]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 13  
     PEN-IIR  
       [0112]     A fuel cartridge as shown in  FIG. 1  was produced by applying an aluminum can with an internal coating of PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0113]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 12 ppm or less carbon monoxide concentration.  
       EXAMPLE 14  
     PEN-IIR  
       [0114]     A fuel reforming system to which a reforming step, a CO shifting step, a methanation step and a combustion step are installed is combined with an electricity generation portion. Further a control system for regulation of them, a thermal system and a safety system are combined therewith to form a fuel cell system as shown in  FIG. 5 . A test of reforming the fuel using the fuel cell system was carried out.  
         [0115]     The test showed stable output of 20 W for 30 min with 12 ppm or less carbon monoxide concentration.  
       EXAMPLE 15  
     PEN-PBN-IIR  
       [0116]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 50 wt % PBN and 50 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0117]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0118]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 16  
     PEN-PBN-IIR  
       [0119]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 30 wt % PBN and 70 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0120]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0121]     In the course of and even after the test, the fuel could be visibly checked from the exterior though visibility was inferior to cases where ratios of PBN/PEN fall in a range of 40/60 to 60/40, which are described in the above and below examples 15, 18 and 19.  
       EXAMPLE 17  
     PEN-PBN-IIR  
       [0122]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 70 wt % PBN and 30 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0123]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0124]     However, both before and after the test, the remaining fuel level could not be visibly checked from the exterior.  
       EXAMPLE 18  
     PEN-PBN-IIR  
       [0125]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 40 wt % PBN and 60 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0126]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0127]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 19  
     PEN-PBN-IIR  
       [0128]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 60 wt % PBN and 40 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0129]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0130]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 20  
     PEN/stainless steel-IIR  
       [0131]     A fuel cartridge as shown in  FIG. 6  was produced by applying JIS SUS304 stainless steel (correspondent to AISI 304 stainless steel) with an internal coating of PEN to its casing and IIR to its sealing member. The stainless steel casing is provided with a slit. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 5.53 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0132]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed stable output of 20 W for 30 min with 20 ppm or less carbon monoxide concentration.  
         [0133]     The remaining fuel level could be visibly checked from the exterior through the slit of the casing.  
         [0134]     In the above description, the fuel cartridge slightly differs from the fuel cartridge  1  as aforementioned. However, most of the constitutions are in common. Therefore the detailed description is omitted.  
       EXAMPLE 21  
     PEN-PBN-IIR  
       [0135]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 50 wt % PBN and 50 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 1.38 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0136]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel by supplying the fuel to the reforming portion of the reformed hydrogen fuel cell was carried out. The test showed stable output of 20 W for 30 min.  
         [0137]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       EXAMPLE 22  
     PEN-PBN-IIR  
       [0138]     A fuel cartridge as shown in  FIG. 1  was produced by applying a mixed resin of 50 wt % PBN and 50 wt % PEN to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g, water of 1.38 g and methanol of 0.95 g was filled as a fuel in the casing.  
         [0139]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of electricity generation by supplying the fuel to a direct solid oxide fuel cell (not shown) was carried out. The test showed stable output of 15 W for 30 min.  
         [0140]     In the course of and even after the test, the fuel could be visibly checked from the exterior.  
       COMPARATIVE EXAMPLE 1  
     PBT-IIR  
       [0141]     A fuel cartridge as shown in  FIG. 1  was produced by applying PBT to its casing and IIR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0142]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed output power did not reach 20 W and an average output for 30 min was 18 W though carbon monoxide concentration was 20 ppm or less.  
         [0143]     In the course of and even after the test, visible check of the fuel from the exterior was harder as compared with a case where PEN is applied to the casing and IIR to its sealing member.  
       COMPARATIVE EXAMPLE 2  
     PEN-ester system UR  
       [0144]     A fuel cartridge as shown in  FIG. 1  was produced by applying PEN to its casing and ester system UR to its sealing member. The casing was 20 mm in diameter, 71 mm in height, 2 mm in thickness and about 13.5 mL in capacity. A mixture of DME of 3.53 g and water of 5.53 g was filled as a fuel in the casing.  
         [0145]     The fuel cartridge containing the fuel had been left at 65 degrees C. for 8 hours. After this, a test of reforming the fuel using a reformed hydrogen fuel cell with this fuel cartridge as shown in  FIG. 5  was carried out. The test showed output power did not reach 20 W and an average output for 30 min was 19 W though carbon monoxide concentration was 20 ppm or less.  
         [0146]     As being understood from the above description, the fuel cartridge in accordance with the present embodiment of the present invention is prominently effective in generating pure hydrogen stably and for a long time, which is preferably applied to a fuel cell in particular.  
         [0147]     The fuel cartridge assures safety in particular in cases using flammable gases, as gas leakage is small at high temperatures over 60 degrees C.  
         [0148]     Moreover, the fuel cartridge enables visible check from the exterior by applying polyethylene naphthalate or a mixture of polyethylene naphthalate and polybutylene naphthalate to the casing so as to assure transparency. Thereby the remaining fuel level is stably enabled.  
         [0149]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.