Abstract:
A molded product and a method of manufacturing the same are disclosed, in which the insulating layer of uniform thickness is formed in a narrow clearance between plural metal bodies. Surroundings of metal plates spaced at specified intervals are covered with insulating polymer to insulate them electrically. A spacer polymer which consists of insulating polymer whose melting point is T1 is arranged between the metal plates, and a molded part which consists of insulating polymer whose melting point is T2 (&lt;T1) covers surroundings of the metal plates and the spacer polymer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional application of U.S. application Ser. No. 11/497,338, filed Aug. 2, 2006, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a molded product and a method of manufacturing the same, in which surroundings of each of metal bodies spaced at a constant interval is covered with insulating polymer to insulate plural metal plates electrically. 
         [0003]    The technique by which metal bodies are covered with a molded part comprised of insulating polymer is generally used to secure the reliability over the long term when insulating between metal bodies of relatively high average electric field strength of hundreds of V/mm or more with insulating polymer. As a technique by which the molding coating is done, the technique by which insulating polymer is injection-molded or extrusion-molded to obtain a target shape with the part to be exposed of metal bodies held is most frequently used. 
         [0004]    As shown in  FIG. 10A , two metal plates  101 ,  102  which have plural terminal parts  101   a,    102   a  are coated with molded part  103  in usual molded product  100 . Terminal parts  101   a  and  102   a  of metal bodies  101 ,  102  can be exposed from molded part  103 . As shown in  FIG. 10B  and  FIG. 10C , metal bodies  101 ,  102  are spaced at specified intervals and insulated to each other. 
         [0005]    Metal bodies  101 ,  102  are set in cavity  113  of injection molding die  110  as shown in  FIG. 11 , and fixed in cavity  113  with terminal part  101   a,    102   a  placed between upper dies  111  and lower dies  112 . Afterwards, molten resin  116  is supplied to cavity  113  from at least one shooting head  115  connected fluidly thereto. After the supply of molten resin  116  is completed, molded part  103  is formed by cooling molten resin  116  to solidify, and molded product  100  shown in  FIG. 10  is obtained. 
         [0006]    The prior art described above is disclosed, for example, in Japanese Patent Application Laid-Open No. 2003-143868. 
       SUMMARY OF THE INVENTION 
       [0007]    There are three main problems when the insulative molded product described above is molded by injection molding. 
         [0008]    (a) When the resin with a high melt viscosity is used, or when the areas of metal plates  101 ,  102  are large, it is difficult to decrease the clearance  105  (insulation thickness) between the metal bodies. 
         [0009]    When clearance  105  between metal bodies  101 ,  102  becomes narrow to the areas of metal bodies  101 ,  102 , the injection molding material (molten resin  116 ) becomes hard to enter between metal bodies  101 ,  102 . Therefore, it is difficult to form an insulating layer not defective between metal bodies  101 ,  102 . Although nylon which has small viscosity at melting is used to perform the injection molding with a high degree of accuracy, the clearance  105  where desirable injection molding can be performed to metal bodies  101 ,  102 , one side length of which is about 200 mm is about 0.5 mm. Molten resin  116  does not spread to the edge of cavity  113  (every corner) when clearance  105  is smaller than the value. Therefore, problem may occur in such a case. Inflow shortage of such a material causes the decrease in the insulating property between metal bodies  101 ,  102 . 
         [0010]    (b) It is difficult to maintain clearance  105  between metal plates  101 ,  102  uniformly. 
         [0011]    It is difficult to hold metal bodies  101 ,  102  when tried to insulate relatively thin metal plates  101 ,  102  spaced at specified intervals, and cover the outside of metal bodies  101 ,  102  with molded part  103 . As a result, metal bodies  101 ,  102  are transformed by the pressure of injected molten resin  116 , and the homogeneity of clearance  105  is lost. When the homogeneity of clearance  105  is lost, the electric field concentrates on the part with a narrow interval, the defect part of the insulation structure when the voltage is applied to metal bodies  101 ,  102 . As a result, long-term reliability of the article is spoiled (c) It is difficult to make insulating material (insulating polymer) and metal bodies  101 ,  102  stick. 
         [0012]    Although surroundings of metal plates  101 ,  102  or clearance  105  between them becomes a part on which the electric field concentrates when the voltage is applied to metal bodies  101 ,  102 , the insulation performance decreases when flaking off is caused on the interfaces of metal bodies  101 ,  102  and the insulating material by the heating and cooling repeated by the change of the turn-on environment (or, system requirements) or by “shrinkage” when the insulating material is molded, and the possibility that the dielectric breakdown is caused rises. A partial electric discharge may occur on the interface of metal bodies  101 ,  102  and the insulating material, and lifetime may be remarkably decreased. Therefore, it is necessary to bond insulating material and metal bodies  101 ,  102  strongly, and mold release characteristics deteriorate when the insulating material contains the adhesive. In addition, the viscosity of molten resin  116  rises, and the formability deteriorates. Further, there is a possibility that the adhesive flows by the injection pressure of the insulating material when the adhesive is spread on metal bodies  101 ,  102  beforehand, and the bonding power varies. 
         [0013]    In consideration of the above-mentioned circumstances, an object of the present invention is to provide a molded product and a method of manufacturing the same, in which the insulating layer of uniform thickness is formed in a narrow clearance between plural metal bodies. 
         [0014]    To achieve the above-mentioned object, the present invention in one aspect resides in a molded product, in which surroundings of metal plates spaced at specified intervals are covered with insulating polymer to insulate them electrically comprises a spacer polymer arranged between said metal plates, which consists of insulating polymer whose melting point is T1, and a molded part, which covers surroundings of said metal plates and said spacer polymer, and consists of insulating polymer whose melting point is T2 (&lt;T1). 
         [0015]    Preferably, the principal ingredient of said insulating polymer of melting point T1 is aromatic polymer, and the principal ingredient of said insulating polymer of melting point T2 is polyolefine. 
         [0016]    Optionally, the bonding layer composed of the adhesive that melting point T3 is in the relation of T3&lt;T1 is provided between said metal plates and said spacer polymer, and between said metal plates and said molded part. Preferably, the first and second bonding layers composed of the adhesive that melting point T3is in the relation of T3&lt;T1 are provided between said metal plates and said spacer polymer, and between said metal plates and said molded part, respectively, and each adhesive which composes said first and second bonding layers has high compatibility. 
         [0017]    In another aspect, the present invention resides in a method of manufacturing a molded product, in which surroundings of metal plates spaced at specified intervals are covered with insulating polymer to insulate them electrically, comprises the steps of arranging a first sheet material composed of insulating polymer whose melting point is T1 between said metal plates spaced at specified intervals, arranging a second sheet material composed of insulating polymer whose melting point is T2 (&lt;T1) outside of the outermost metal plates, hot-pressing molding a laminate of the metal plates, the first sheet material, and the second sheet material at a temperature higher than T2 but lower than T1, melting the second sheet material while securing the interval between the metal plates by the first sheet material, and covering the surroundings of the metal plates and the first sheet material with the molded part composed of insulating polymer whose melting point is T2. 
         [0018]    In a further aspect, the present invention resides in a method of manufacturing a molded product, in which surroundings of metal plates spaced at specified intervals are covered with insulating polymer to insulate them electrically, comprises the steps of arranging a first sheet material composed of insulating polymer whose melting point is T1 between said metal plates spaced at specified intervals, arranging a laminate of the metal plates and the first sheet material in the cavity of the injection mold, injecting insulating polymer whose melting point is T2 (&lt;T1) heated and melted at a temperature higher than T2 but lower than T1 into the cavity, and covering the surroundings of the metal plates and the first sheet material with the molded part composed of insulating polymer whose melting point is T2 while securing the interval between the metal plates by the first sheet material. 
         [0019]    Optionally, a plurality of said first sheet materials are arranged between the metal plates. 
         [0020]    Optionally, the method of manufacturing a molded product further comprises the steps of providing as one first bonding layers and second bonding layers which consist of adhesive whose melting point T3 is in the relation of T3&lt;T1on surfaces of the first sheet material and surfaces on the metal body sides of the second sheet materials, respectively, and after hot-pressing molding, bonding the first sheet material to said metal plates by the first bonding layers, and said molded part to said metal plates by the second bonding layers. Preferably, in the method of manufacturing a molded product, each adhesive which composes the first bonding layer and the second bonding layer has compatibility, and the first bonding layer are bonded to the second bonding layer. 
         [0021]    Optionally, the method of manufacturing a molded product further comprises the steps of providing as one first bonding layers which consist of adhesive whose melting point T3 is in the relation of T3&lt;T1 on surfaces of the first sheet material, and after hot-pressing molding, bonding the first sheet material to said metal plates by the first bonding layers. 
         [0022]    Plural metal plates can be coated with insulating polymer according to the present invention. Moreover, it is possible to insulate between plural metal plates by a thin and uniform insulating layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a sectional view of the spacer polymer sheet used for a manufacturing method of the molded product according to a preferred embodiment of the present invention. 
           [0024]      FIG. 2  is a sectional view of mold polymer sheet used for a manufacturing method of the molded product according to a preferred embodiment of the present invention. 
           [0025]      FIG. 3A  and  FIG. 3B  are structural drawings of the molded product according to a preferred embodiment of the present invention.  FIG. 3A  is a plan view, and  FIG. 3B  is a sectional view taken along the line  3 B- 3 B of  FIG. 3A . 
           [0026]      FIG. 4  is a view showing the lamination state of a laminate used to manufacture the molded product according to a preferred embodiment of the present invention. 
           [0027]      FIG. 5  is a view showing the state where the laminate of  FIG. 4  is arranged between hot pressing plates of a hot pressing machine. 
           [0028]      FIG. 6  is a view showing the state where the hot pressing mold was performed to the laminate of  FIG. 5 . 
           [0029]      FIG. 7  is a sectional view of a first modification of  FIG. 6 . 
           [0030]      FIG. 8A  and  FIG. 8B  are views showing the modification of the frame body used for a manufacturing method of the molded product according to a preferred embodiment of the present invention.  FIG. 8A  is a plan view, and  FIG. 8B  is a view seen from a direction of arrow  8 B of  FIG. 8A . 
           [0031]      FIG. 9  is an explanatory drawing of a manufacturing method of the molded product according to another preferred embodiment of the present invention. 
           [0032]      FIG. 10A ,  FIG. 10B  and  FIG. 10C  are structural drawings of a general bus bar.  FIG. 10A  is a plan view,  FIG. 10B  is a view seen from a direction of arrow  10 B of  FIG. 10A  and  FIG. 10C  are a sectional view taken along the line  10 C- 10 C of  FIG. 10A . 
           [0033]      FIG. 11  is an explanatory drawing of the conventional manufacturing method of a molded product. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Hereafter, a preferred embodiment of the present invention will be explained based on attached drawings. 
         [0035]      FIG. 3  is structural drawing of the molded product according to a preferred embodiment of the present invention.  FIG. 3A  is a plan view, and  FIG. 3B  is a sectional view taken along the line  3 B- 3 B of  FIG. 3A . 
         [0036]    Surroundings of plural metal plates  31  and  32  (two metal plates in  FIG. 3B ) are covered with molded part  33  in a mold article according to this embodiment as shown in  FIG. 3A  and  FIG. 3B . 
         [0037]    Spacer polymer part  34  composed of insulating polymer of melting point T1 and adhesive of melting point T3 (T3&lt;T1) is provided between metal plates  31  and  32 . Surroundings of spacer polymer part  34  and metal plates  31  and  32  are covered with molded part  33  composed of insulating polymer of melting point (or softening point) T2 (&lt;T1). Projection parts (terminal part)  31   a  and  32   a  projects from molded part  33 . 
         [0038]    A method of manufacturing a molded product according to this embodiment will be explained based on attached drawings. 
         [0039]    First of all, as shown in  FIG. 1 , first bonding layers  12   a,    12   b  composed of the adhesive whose melting point T3 is in the relation of T3&lt;T1 are provided as one on the surface (upper and lower sides in  FIG. 1 ) of first sheet material  11  composed of insulating polymer whose melting point is T1 to make spacer polymer sheet  10 . Optionally, first bonding layer can be provided only on one side of first sheet material  11 . Further, first bonding layer need not necessarily provide. 
         [0040]    On the other hand, as shown in  FIG. 2 , second bonding layer  22  composed of the adhesive whose melting point T3 is in the relation of T3&lt;T1 is provided as one on the surface on metal body side (under face in  FIG. 2 ) of second sheet material  21  composed of insulating polymer whose melting point is T2(&lt;T1) to make mold polymer sheet  20 . Further, the second bonding layer need not necessarily provide. 
         [0041]    Next, as shown in  FIG. 4 , laminate  40  is formed by placing spacer polymer sheet  10  between metal plates  31  and  32 , and laminating mold polymer sheet  20  on metal plates  31  and  32  so that the surface of the side of second bonding layer  22  may contact the metal sheet. At this time, the lamination is performed so that a part of metal plates  31  and  32  may protrude beyond laminate  40 . The points of metal plates  31  and  32  which protrude from laminate  40  become terminal parts  31   a  and  32   a.  Optionally, a plurality of spacer polymer sheets  10  can be placed between metal plates  31  and  32 . The clearance between metal plates  31 ,  32  of molded product  30  described later can be freely adjusted by adjusting the number of spacer polymer sheets  10 . When the number of metal plates is three sheets or more, mold polymer sheets  20  are arranged only outside of two outermost metal plates. 
         [0042]    Laminate  40  is arranged between hot pressing plates  41  and  42  of the hot pressing machine. Terminal part  31   a  is supported by upper dies  43  and lower dies  44  as shown in the  FIG. 5 , and positioned on step part  44   a  of lower dies  44 . Moreover, terminal part  32   a  is supported by upper dies  45  and lower dies  46 , and positioned on step part  45   a  of upper dies  45 . At least one of hot pressing plates  41  and  42  is connected with a cylinder etc. (not shown) of an oil pressure piston, and can move freely in directions of arrows A 1  and A 2 , that is, in a direction where laminate  40  is compressed. 
         [0043]    Next, the hot pressing mold is carried out to laminate  40  at a temperature higher than T2, but lower than T1. The pressure when the hot pressing mold is carried out is the pressure by which molten polymer  63  (described later), second sheet material  21  melted, can be transformed and drifted sufficiently, and is not limited to the specified value. 
         [0044]    As shown in the  FIG. 6 , first sheet material  11  of spacer polymer sheet  10  is not melted when the hot pressing mold is carried out, and the shape is maintained. Therefore, the interval (clearance) corresponding to the thickness of first sheet material  11  can be almost secured between metal plates  31  and  32 . Moreover, this clearance becomes uniform over the direction of the surface of metal plates  31  and  32 . Further, second sheet material  21  of each mold polymer sheet  20  is melted by the hot pressing processing, and becomes molten polymer  63 . This molten polymer  63  flows so as to bury space  61  formed by hot pressing plates  41 ,  42 , dies  43 ,  44 , and dies  45 ,  46 . Moreover, each adhesive which composes first bonding layers  12   a ,  12   b,  and second bonding layers  22  is melted partially by the hot pressing processing because melting point T3 is less than T1 as well as T2,and flowed along with molten polymer  63 . Temperature T3 can be either one of T3≦T2 and T3≧T2. 
         [0045]    Metal plate article  30  shown in  FIG. 7  is obtained by molten polymer  63  spread in space  61  being cooled, and being solidified. First sheet material  11  and each of metal plates  31 ,  32  are bonded through remaining first bonding layers  12   a  and  12   b.  Moreover, the major part of molding sides (under face in  FIG. 7 ) of metal plate  31  and molded part  33 , and the major part of molding sides (top face in  FIG. 7 ) of metal plate  32  and molded part  33  are bonded through remaining second bonding layers  22 . Spacer polymer part  34  comprises first sheet material  11  and remaining first bonding layers  12   a  and  12   b.  When the first bonding layer is not provided on first sheet material  11 , the first sheet material itself becomes spacer polymer part  34 . 
         [0046]    Here, the manufacturing of molded product  30  comes to be easy and to stabilize as the difference between the melting point of insulating polymer whose melting point is T2 which composes first bonding layers  12   a,    12   b  and that of insulating polymer whose melting point is T1 which composes second bonding layers  22  becomes large. 
         [0047]    Polymer material which contains aromatic polymer as a principal ingredient is suitable for insulating polymer whose melting point is T1. Moreover, polymer material or various elastomers which contains polyolefine as a principal ingredient is suitable for insulating polymer whose melting point is T2. In a word, it is desirable that the first polymer which has first adhesion mechanism by which strong bonding for the aromatic polymer material is obtained is used for insulating polymer whose melting point is T1. On the other hand, it is desirable that the second polymer which has second adhesion mechanism by which strong bonding for the metallic material is obtained is used for insulating polymer whose melting point is T2. It is more desirable that each polymer has high compatibility. When second bonding layers  22  are provided on the sides of spacer polymer sheet  10  of metal plates  31 ,  32 , first bonding layers  12   a,    12   b,  and second bonding layers  22  are adjacent. At this time, first bonding layers  12   a,    12   b,  and second bonding layers  22  are strongly bonded when first polymer and second polymer have high compatibility, and metal plates  31 ,  32 , and first sheet material  11  can be bonded more strongly consequently. 
         [0048]    In the first adhesion mechanism, styrenic elastomer (polymer) which has styren block with high compatibility with aromatic polymer is used as an adhesive. The styren block part and the aromatic polymer in the adhesive are melted into each other when the adhesive and the aromatic polymer material are heated and pressurized. As a result, the adhesive and the aromatic polymer material are bonded strongly. Here, the aromatic polymer means polymer which has an aromatic ring in the principal chain. For instance, polyphenylene ether (PPE), polyetherimide (PEI), polycarbonate (PC), polyether sulphone, polyimide, polyphenylene sulfide, polysulfone, polyether ether ketone, etc. can be used, but it is not limited to the above substances. On the other hand, as styrenic elastomer which has the styren block, styrene ethylene butylene styrene copolymer (SEBS), styrene ethylene propylene styrene copolymer (SEPS), triblock copolymer such as styrene butylene styrene copolymer (SBS), diblock copolymer such as styrene butadiene rubber hydrogenised can be used. 
         [0049]    Moreover, in the second adhesion mechanism, the epoxy radical part or the acid radical part of polymer produces hydrogen bond with the water molecule or the oxide of the metal surface by using the acid-modified or epoxy-modified polymer as an adhesive. As a result, the adhesive and the metal are bonded strongly. Maleic acid modification in the acid modification of polymer is typical acid-modification. There are, for instance, elastomer polyethylene (PE) such as SBS, SEBS, polyisobutylene (PIB), etc. and polymer of olefinic system such as polypropylene as acid-denaturated polymer. On the other hand, there are substance obtained by changing the copolymer of polyethylene and polystyrene to glycidyl, and substance obtained by changing the copolymer of ethylene glycidyl methacrylate copolymer (EGMA) and polystyrene (PS) as polymer which has the epoxy radical. 
         [0050]    Spacer polymer part  34  (see  FIG. 3B ) which is a thin insulating layer can be uniformly formed by coating molded part  33  with spacer polymer sheet  10  arranged between metal plates  31  and  32  according to a manufacturing method of a molded product according to this embodiment. In a word, it is possible to coat metal plates  31 ,  32  with molded part  33 . Moreover, it is possible to insulate metal plates  31  and  32  through a thin, uniform insulating layer. The formation of this spacer polymer  34  is influenced by neither the size of the areas of metal plates  31  and  32  nor the size of the clearance between metal plates  31  and  32 . Further, the thickness of spacer polymer  34 , that is, the clearance between metal plates  31  and  32  is uniform in a direction of the surface of the metal plates. 
         [0051]    Moreover, molded part  33  and spacer polymer part  34  of the molded product according to this embodiment are formed not by the injection molding like the conventional manufacturing method shown in the  FIG. 11  but by the hot pressing mold. In a word, molded part  33  and spacer polymer part  34  can be manufactured by using simple frame body composed of dies  43 ,  44 , dies  45 ,  46  and hot pressing plates  41 ,  42  shown in  FIG. 6 . Namely, an expensive dies for an injection molding need not be used. Therefore, molded product  30  can be manufactured cheaply. 
         [0052]    The shape and the thickness of second sheet material  21  used to manufacture molded product  30  according to this embodiment are adjusted for the volume to increase more than at least necessary amounts of the volume only by 10-40% in consideration of the volume of final molded part  33 . In other words, the shape and the thickness of second sheet material  21  are adjusted so that the amount of the overflow of molten polymer  63  may be 10% to 40% of the actual amount of volume of molded part  33 . The shape reproducibility of molded part  33  can be improved by taking the amount of the overflow of molten polymer  63  enough. 
         [0053]    Moreover, when metal plates  31  and  32  are coated with molded part  33 , the bond strength between metal plates  31 ,  32  and molded part  33 , that is, the magnitude of peel strength between metal plates  31 ,  32  and molded part  33  becomes a main factor which determines the insulation performance of molded product  30 . Therefore, metal plates  31 ,  32  and molded part  33  are bonded through the adhesive in molded product  30  according to this embodiment. Concretely, the bonding layers are formed on the surfaces of first sheet material  11  and second sheet material  21 , the surfaces of metal plates  31 ,  32  or the surfaces of first sheet material  11 , second sheet material  21 , and metal plates  31 ,  32  beforehand. As a result, metal plates  31 ,  32  and molded part  33  can be bonded uniformly and strongly. It is possible to maintain excellently the insulation performance of molded product  30  over a long period of time. 
         [0054]    The bond strength of adhesive of insulating polymer whose melting point is T2 and metal plates  31 ,  32  can be freely adjusted by adjusting an amount of the acid modification (or, epoxy modification) of acid modification (or, epoxy modification) polymer. Moreover, the bond strength of adhesive of insulating polymer whose melting point is T1 and first sheet material  11  can be freely adjusted by adjusting an amount of the styrene in the styren block part of styrenic elastomer. 
         [0055]    For instance, molded product  30  according to this embodiment is suitable for a mold type power supply bus bar. 
         [0056]    Further, although molded part  33  is formed by using frame body composed by hot pressing plates  41 ,  42 , dies  43 ,  44 , and dies  45 ,  46  in this embodiment as shown in  FIG. 6 , the present invention is not limited to such structure. Optionally, it is possible to form molded part  33  by using lower metal frame  81  and upper metal frame (not shown) shown in  FIG. 8A  and  FIG. 8B  as a frame body. Lower metal frame  81  corresponds to the one that hot pressing plate  42 , and lower dies  44 ,  46  are integrated, and mold polymer sheet  20 , metal plate  31 , and spacer polymer sheet  10  are accommodated in space part  82  of lower metal frame  81 . On the other hand, upper metal frame corresponds to the one that hot pressing plate  41  and upper dies  43 ,  45  are integrated, and metal plate  32  and mold polymer sheet  20  are accommodated in the space part of the upper metal frame. 
         [0057]    Next, another embodiment of the present invention will be explained with reference to attached drawings. 
         [0058]    In the manufacturing method of a molded product according to the above-mentioned embodiment, the molded part is formed by the hot pressing process. On the other hand, the molded part is formed by an injection molding process in the manufacturing method of a molded product according to this embodiment. 
         [0059]    Concretely, spacer polymer sheet  10  is made by providing first bonding layers  12   a,    12   b  composed of the adhesive whose melting point T3 is in the relation of T3&lt;T1 on the surfaces (upper and lower surfaces in  FIG. 1 ) of first sheet material  11  composed of insulating polymer whose melting point is T1 first shown in  FIG. 1 . 
         [0060]    Next, laminate  97  shown in  FIG. 9  is formed by placing spacer polymer sheet  10  between metal plated  31  and  32  and laminating them. At this time, the lamination is performed so that a part of metal plates  31 ,  32  may protrude beyond the laminate  97 . Points of metal plates  31 ,  32  which protrude beyond laminate  97  forms terminal parts  31   a,    32   a.  Further, optionally, it is possible to place a plurality of spacer polymer sheets  10  between metal plates  31  and  32 . The clearance between metal plates  31  and  32  as described later can be freely adjusted by adjusting the number of spacer polymer sheets  10  to be placed. 
         [0061]    After laminate  97  is arranged between hot pressing plates of the hot pressing molding machine, the heating processing is carried out. As a result, first bonding layers  12   a,    12   b  is melted, and metal plates  31 ,  32  and first sheet material  11  are bonded through first bonding layers  12   a,    12   b.  Then, bonded laminate  97  is set in cavity  93  of injection molding dies  90 . Metal plates  31  and  32  are fixed in cavity  93  with terminal parts  31   a ,  32   a  placed between upper dies  92  and lower dies  91 . Then, molten polymer  96  is supplied to cavity  93  from at least one injection head  95  connected fluidly to cavity  93 . Molten polymer  96  is the polymer made by heating insulating polymer whose melting point is T2 (&lt;T1) at a temperature higher than T2 but lower than T1 and melting it. 
         [0062]    First sheet material  11  of spacer polymer sheet  10  does not melt at this injection molding processing, and thus its shape is maintained. Therefore, the interval (clearance) for the thickness of first sheet material  11  is almost secured between metal plates  31  and  32 . This clearance becomes uniform over a direction of the surfaces of metal plates  31 ,  32 . Further, molten polymer  96  flows so as to fill in the space of cavity  93 . Moreover, a part of the adhesive which composes first bonding layers  12   a,    12   b  melts by the temperature at the injection molding processing because melting point T3 is in the relation of T3&lt;T1, and flows along with molten polymer  96 . 
         [0063]    Molded product  30  (refer to  FIG. 3 ) in which surroundings of metal plates  31 ,  32  and first sheet material  11  are covered with molded part  33  is obtained by molten polymer  96  spread in cavity  93  being cooled, and being solidified. First sheet material  11  and metal plates  31 ,  32  are bonded through remaining first bonding layers  12   a,    12   b.    
         [0064]    Because in the manufacturing method of a molded product according to this embodiment, the molded part is formed by an injection molding process, an expensive injection molding dies is needed, differing from the manufacturing method of a molded product according to the above-mentioned embodiment. However, because in the manufacturing method of a molded product according to this embodiment, the mold coating is performed to laminate  90  of at least three-layer structure, mold polymer sheet  20  shown in  FIG. 2  is not needed. Therefore, the formation process of the laminate can be simplified compared with the manufacturing method of a molded product according to the previous embodiment in which laminate  40  of at least five layer-structure is coated with molding material. 
       EMBODIMENT   
       [0065]    Two sheet of coppers (200 mm×280 mm and thickness t is 1 mm) were prepared as a metal plate. Lap width L was 210 mm and the clearance between sheet coppers was 0.4 mm as shown in  FIG. 3B , and the molding area (240 mm×250 mm) which includes the lap area was coated with molding. 
       Embodiment 1  
       [0066]    PPE sheet (Asahi Kasei Corporation, Zairon 540Z, and thickness t is 0.4 mm) where the heat-hardening bonding layer had been spread on both sides as shown in  FIG. 1  was prepared. The sheet was cut into the size (220 mm×230 mm) whose length and breadth is 10 mm larger than the lap area of two sheet coppers. Moreover, flame-resistant PE resin sheet (UBE INDUSTRIES, LTD. Z555, and thickness t is 2.5 mm) which the hot melt adhesive layer was spread on one side as shown in  FIG. 2  was prepared. The flame-resistant PE resin sheet was cut (220 mm×230 mm×2.5 mm) so that the volume of two flame-resistant PE resin sheet may become more than the value obtained by subtracting the volume of the sheet copper and the PPE sheet from the volume of the molded product of 240 mm×250 mm×5 km. Further, a frame body composed of lower metal frame  81  shown in  FIG. 8  and an upper metal frame which makes couple with lower metal frame  81  was prepared. 
         [0067]    The laminate piled up in order of a flame-resistant PE resin sheet, a resin sheet, a PPE sheet, a sheet copper, and a flame-resistant PE resin sheet was arranged in this frame body. This laminate was placed between hot pressing plates together with the frame body, and it was set in hot pressing molding machine heated to 130° C. The pressure of 0.5 MPa was applied after preheating enough, and the hot pressing processing was carried out. As a result, the molded product (sample 1) which has the structure shown in  FIG. 7  was obtained. 
         [0068]    As a result, in sample 1, a very thin and uniform insulating layer (spacer polymer) was formed between sheet coppers of 0.4 mm in the clearance and 200 mm in one side. Partial discharge generation disappearance (10 pC) voltage in sample 1 was measured, and the value of 8 kV or more was obtained. Moreover, the void which affects negatively on electrical insulation did not generate between sheet coppers of this molded product and around the sheet copper. 
         [0069]    Moreover, the partial discharge generation disappearance voltage was measured again after heat cycle of −25° C. to 105° C. was repeated 100 times to this sample 1, and the same value of 8 kV or more as one before providing the heat cycle were obtained. In a word, it was confirmed that even if the heat cycle is added, the void and flaking off are not occurred on the interface of the sheet copper and the PPE sheet, and the sheet copper and the PPE sheet are strongly bonded. 
       Embodiment 2   
       [0070]    The same PPE sheet as embodiment 1 was made. Moreover, injection molding dies  90  shown in  FIG. 9  as a frame body was prepared. 
         [0071]    The laminate piled up in order of a sheet copper, a PPE sheet and a sheet copper was placed between hot pressing plates of a hot pressing molding machine, and heated to 130° C. The bonding layer in the PPE sheet melted by this heating processing, and the sheet copper and the PPE sheet were bonded through the bonding layer. The injection molding processing was carried out by injecting the flame-resistant PE resin melted after having arranged this laminate in cavity  93  of injection molding dies  90 . Thereby, the molded product (sample 2) which has the structure shown in the  FIG. 7  was produced. 
         [0072]    As a result, in sample 2, a very thin and uniform insulating layer (spacer polymer) was formed between sheet coppers of 0.4 mm in the clearance and 200 mm in one side. Partial discharge generation disappearance (10 pC) voltage in sample 2 was measured, and the value of 8 kV or more was obtained. Moreover, the void which affects negatively on electrical insulation did not generate between sheet coppers of this molded product and around the sheet copper. 
         [0073]    Moreover, the partial discharge generation disappearance voltage was measured again after heat cycle of −25° C. to 105° C. was repeated 100 times to this sample 2, and the same value of 8 kV or more as one before providing the heat cycle were obtained. In a word, it was confirmed that even if the heat cycle is added, the void and flaking off are not occurred on the interface of the sheet copper and the PPE sheet, and the sheet copper and the PPE sheet are strongly bonded. 
       Comparison Example 1   
       [0074]    injection molding dies  110  shown in  FIG. 11  as a frame body was prepared. 
         [0075]    The injection molding processing was carried out by injecting polyphenyl ether (PPE, Asahi Kasei Corporation, Zairon 540Z) melted after arranging the sheet copper in cavity  113  of injection mold  110  in cavity  113 , and the molded product (sample 3) was made. 
         [0076]    Partial discharge generation disappearance (10 pC) voltage in sample 3 was measured, and the very low value less than 1 kV or more was obtained. This molded product was cut, and the section was observed. As a result, it was confirmed that the void which affects negatively on electrical insulation had generated between sheet coppers. 
         [0077]    Although the present invention has been illustrated and described with respect to exemplary embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omission and additions may be made therein and thereto, without departing from the spirit and scope of the present invention. Therefore, the present invention should not be understood as limited to the specific embodiment set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalent thereof with respect to the feature set out in the appended claims.