Abstract:
An apparatus for manufacturing an anisotropic formed body in which functional, magnetic fine particles are oriented in a specific direction within a matrix and in which anisotropy is given to properties attributable to the functional fine particles. The apparatus allows use of a wide variety of materials as the functional fine particles and realizes an anisotropy which is parallel and of a uniform interval within a large area. Further, a method for manufacturing an anisotropic formed body, includes applying, by using a superconducting magnet device, a uniform and parallel magnetic field with magnetic lines of force at equal intervals and parallel to each other, to a mold in which the matrix is filled with a liquid molding material containing functional, magnetic fine particles, to orient the functional fine particles in a direction of the magnetic lines of force, whereby the liquid molding material subsequently hardens.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and method for manufacturing an anisotropic formed body having anisotropy to exhibit in specific directions within a matrix various properties, such as electrical conductivity, heat conductivity, expansion coefficient, light transmittance, magnetism, hardness, elasticity, water absorption, dielectric constant, gas permeability, piezoelectric characteristics, and vibration absorption. In particular, the present invention relates to an apparatus and method for manufacturing an anisotropic formed body in which anisotropy is imparted by utilizing a magnetic field. 
   2. Description of the Related Art 
   As an example of an anisotropic formed body as mentioned above, an anisotropic conductive device is known. For example, an anisotropic conductive connector for electrical connection of a microphone and a printed circuit board contained in a mobile phone is known. As an example of such an anisotropic conductive connector, there is known a formed body composed of a disc-shaped main body portion with a continuous conductive portion formed therein. The main body portion uses electrically insulating silicone rubber as a matrix. Conductive, magnetic fine particles are oriented in a specific direction to form the continuous conductive portion. This formed body is generally obtained as follows: A mold with conductive fine particles arranged therein is filled with liquid silicone rubber, and the conductive fine particles are oriented by a parallel magnetic field generated by permanent magnets embedded in the upper and lower portions of the mold so as to be opposed to each other. Then, the silicone rubber is crosslinked. 
   As a prior-art technical document disclosing a technique in which an anisotropic formed body is formed by utilizing the parallel magnetic field of such permanent magnets, the applicant of the present invention has referred to the following patent document. 
   However, in the method of forming an anisotropic formed body by utilizing the magnetic field of permanent magnets, there are limitations regarding the intensity of the magnetic field that can be generated. Thus, the functional fine particles allowing orientation and exhibiting properties such as conductivity are restricted to ferromagnetic materials such as nickel or iron. With paramagnetic materials, such as aluminum, platinum, palladium, titanium, and manganese, and diamagnetic materials, such as gold, silver, copper, metal oxide, metal nitride, metal carbide, metal hydroxide, carbon, organicpolymer, protein, and DNA, it is difficult to effect orientation so as to attain the intended anisotropy. Further, due to its weak magnetic force and unevenness in magnetic field generated by its surface irregularities, it is rather difficult for a permanent magnet to generate a uniform parallel magnetic field in a large space. Thus, it is very difficult to produce an anisotropic formed body exhibiting an anisotropy which is parallel and of a uniform interval within a large area. 
   SUMMARY OF THE INVENTION 
   In view of the above problem in the prior art, it is an object of the present invention to provide an anisotropic formed body allowing use of a wider variety of materials as the functional fine particles and realizing an anisotropy which is parallel and of a uniform interval within a large area. 
   To achieve the above object, the present invention basically adopts a technical concept according to which a superconducting magnet device generates a uniform and parallel magnetic field in which magnetic lines of force are arranged at equal intervals so as to be parallel to each other and a mold is placed in this uniform and parallel magnetic field to orient the functional fine particles therein. This helps to realize a uniform and parallel orientation along the magnetic lines of force constituting the uniform and parallel magnetic field even with functional fine particles that are difficult to orient by conventional permanent magnets, thus making it possible to use a wider variety of materials for the functional fine particles. Thus, it is possible to obtain an anisotropic formed body that can be used as a functional material exhibiting, uniformly and in parallel, various properties inherent in the functional fine particles, such as electrical conductivity, heat conductivity, expansivity, light transmittance, magnetism, hardness, elasticity, water absorption, dielectric constant, gas permeability, piezoelectric characteristics, and vibration absorption, and to use the anisotropic formed body in various technical fields. 
   As an apparatus for manufacturing an anisotropic formed body providing the action and effect based on the above technical concept, the present invention provides an apparatus for manufacturing an anisotropic formed body in which functional, magnetic fine particles are oriented in a specific direction within a matrix and in which anisotropy is given to properties attributable to the functional fine particles. The apparatus includes a super conducting magnet device that has a cylindrical super conducting coil and generates a uniform and parallel magnetic field in which magnetic lines of force at equal intervals and parallel to each other extend through a mold arranged in a barrel axis of the superconducting coil. 
   Further, the present invention provides a method for manufacturing an anisotropic formed body, in which a superconducting magnet device applies a uniform and parallel magnetic field with magnetic lines of force at equal intervals and parallel to each other to a mold, in which a matrix is filled with a liquid molding material containing functional, magnetic fine particles, to orient the functional fine particles in a direction of the magnetic lines of force which subsequently harden in the liquid molding material. 
   In the above-described manufacturing apparatus of the present invention, the cylindrical superconducting coil is composed of an upper superconducting coil and a lower superconducting coil vertically spaced apart from each other, and a gap between the coils constitutes a transfer opening for the mold. By thus using the gap between the coils as the transfer opening for the mold, it is possible to advantageously utilize the portion usually constituting a dead space of a split type superconducting magnet device equipped with upper and lower superconducting coils, thereby rationally simplifying the construction of the device. Thus, there is no need to separately form a transfer opening or to provide a transfer mechanism leading to a separate transfer opening. 
   The above-described manufacturing apparatus of the present invention may be equipped with a heating device for heating in the mold the liquid molding material with functional fine particles contained in the matrix. In this arrangement, it is possible to further soften through heating a synthetic resin material, such as a thermoplastic resin or a thermosetting resin, natural rubber, synthetic rubber, or an elastomer material, such as thermoplastic elastomer, so that the orientation of functional fine particles by the uniform and parallel magnetic field is facilitated. Further, in the case of using natural rubber or synthetic rubber, it is possible to crosslink the molding material. 
   The above-described manufacturing apparatus of the present invention may be equipped with a drive device for driving at least one of the mold and the heating device in the barrel axis direction of the superconducting coil. In this drive device, the mold and the heating device are driven in the barrel axis direction of the superconducting coil, so that it is possible to significantly utilize the internal space of the superconducting coil, making it possible to rationally simplify the construction of the device. 
   The above-described manufacturing apparatus of the present invention may be equipped with an injection molding device using an injection mold as the mold. Further, the manufacturing apparatus of the present invention may be equipped with a photo-setting molding device using a photo-setting mold as the mold. This makes it possible to obtain anisotropic formed bodies of various configurations and materials in which functional fine particles are oriented by a uniform parallel magnetic field. 
   In the above-described manufacturing apparatus of the present invention, the superconducting magnet device is equipped with a heat insulating portion. Thus, the cooling of the superconducting coil is not hindered by the heat due to the heat generating mechanism such as the heating device or the injection molding device. 
   Incidentally, as stated above, the functional, magnetic fine particles to be contained in the matrix are endowed with anisotropy with respect to properties, such as electrical conductivity, heat conductivity, expansion coefficient, light transmittance, magnetism, hardness, elasticity, water absorption, dielectric constant, gas permeability, piezoelectric characteristics, and vibration absorption. Specific examples of the functional fine particles include nickel, iron, cobalt, aluminum, platinum, palladium, titanium, manganese, gold, silver, copper, metal oxide, metal nitride, metal carbide, metal hydroxide, a carbon material, such as carbon fiber, graphite, or carbon nanotube, organic polymer, protein, and DNA. Examples of conductive functional fine particles include magnetic conductors, such as nickel, iron, or cobalt, or an alloy using these as main components, conductor particles consisting of copper, aluminum, gold, or silver plated with a magnetic conductor, magnetic conductor particles plated with a conductor as mentioned above, and carbon materials, such as carbon fiber, graphite, or carbon nanotube. Further, examples of functional fine particles with heat conductivity include, in addition to the above-mentioned carbon materials, metal oxide, metal nitride, metal carbide, and metal hydroxide. According to the present invention, to orient these functional fine particles by a superconducting magnet device, a uniform parallel magnetic field with a magnetic flux density of 1 to 10 T is generated. Generally speaking, it is difficult to obtain a high magnetic field of 1 T or more by using permanent magnets. Regarding the above-mentioned functional fine particles, it is possible to achieve the requisite and sufficient anisotropic orientation with a magnetic flux density of 1 to 10 T. Further, in this case, it is possible to achieve the requisite cooling of the superconducting coil by using a refrigerator cooling system that can achieve a forced-flow cooling or a conduction cooling, and an immersion cooling system, which involves immersion in a large amount of liquid helium, is not required. Thus, a superconducting magnet device of a simpler device construction suffices. In the present invention, this high magnetic field generated by the superconducting magnet device is a uniform parallel magnetic field having a diameter of 300 to 1000 mm. Thus, it is possible to obtain an anisotropic formed body and exhibiting anisotropy with respect to properties, such as electrical conductivity, heat conductivity, expansion coefficient, light transmittance, magnetism, hardness, elasticity, water absorption, dielectric constant, gas permeability, piezoelectric characteristics, and vibration absorption within a large area. 
   The present invention is not restricted to what has been described above. The objectives, advantages, features, and usages of the invention will be further clarified by the following description given with reference to the accompanying drawings. It should be understood that all appropriate modifications made without departing from the gist of this invention are within the scope of this invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
       FIG. 1  is a schematic sectional view of an anisotropic formed body manufacturing apparatus according to an embodiment of the present invention; 
       FIG. 2  is a schematic plan view taken along the line  2 - 2  of  FIG. 1 ; 
       FIG. 3  is a schematic explanatory view of a uniform parallel magnetic field generated by a superconducting coil provided in the manufacturing apparatus of  FIG. 1 ; 
       FIG. 4  is a schematic sectional view of an anisotropic formed body manufacturing apparatus according to another embodiment of the present invention; and 
       FIG. 5  is a schematic sectional view of an anisotropic formed body manufacturing apparatus according to still another embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An embodiment of the present invention will now be described with reference to the drawings. 
   An anisotropic formed body manufacturing apparatus  1  according to this embodiment has an upper superconducting coil  2   a  and a lower superconducting coil  2   b , which are respectively accommodated in hollow and annular sealed containers  3   a  and  3   b  that are substantially evacuated. These sealed containers  3   a  and  3   b  are respectively accommodated in an upper casing  4   a  and a lower casing  4   b , which are hollow and annular in configuration. The upper casing  4   a  is secured to an upper frame  5   a , and the lower casing  4   b  is secured to a lower frame  5   b . Between the upper casing  4   a  and the lower casing  4   b , there is provided a spacer  6 , and the upper casing  4   a  mounted to the upper frame  5   a  are supported by the spacer  6 . 
   The split type superconducting coils  2   a  and  2   b  composed of upper and lower portions are formed into an annular configuration using, e.g., NbTi. For improved productivity, ones with a large diameter are desirable. Thus, the coils have an inner diameter of at least 200 mm or more, and more preferably, an inner diameter of 300 mm or more. These superconducting coils  2   a  and  2   b  generate a uniform and parallel magnetic field in which the magnetic lines of force are at equal intervals and parallel to each other. The magnetic flux density thereof is at least 1 to 10 T. Further, the difference in magnetic flux density in the transverse direction of the uniform and parallel magnetic field is within a range of ±1%. Further, the diameter of the uniform and parallel magnetic field is 300 to 1000 mm. An example of the specific construction of the superconducting coils  2   a  and  2   b , generating such a uniform and parallel magnetic field, is disclosed in JP2001-264402A invented by Kiyoshi et al. filed on Mar. 17, 2000 in Japan, and it is possible to realize the superconducting coils based on this example. The teachings described in this patent application are hereby incorporated by reference. Refrigerators  7   a  and  7   b  are respectively mounted to the superconducting coils  2   a  and  2   b . The refrigerators are supplied with refrigerants provided from a pressure feeding device (not shown) to cool the superconducting coils  2   a  and  2   b . That is, the superconducting coils  2   a  and  2   b  of this embodiment are cooled by using a refrigerator which can achieve a forced-flow cooling or a conduction cooling. 
   Between the upper superconducting coil  2   a  and the lower superconducting coil  2   b , and more specifically, between the upper casing  4   a  and the lower casing  4   b  (slidable receiving plate  12 ), there is formed, by means of the spacer  6 , a gap d whose height is larger than that of a mold described below. In the manufacturing apparatus  1  of this embodiment, this gap d is utilized as a “transfer opening” for the mold. 
   Between the outer side surfaces of the sealed containers  3   a  and  3   b  and the inner side surfaces of the casings  4   a  and  4   b , there are mounted heat insulating materials  8   a  and  8   b  consisting of glass wool, hard urethane, or the like to insulate the sealed containers  3   a  and  3   b  from heat generated by heating devices  9   a  and  9   b.    
   The superconducting magnet device of this embodiment is constructed as described above. 
   Next, the heating devices of this embodiment will be described. The upper heating device  9   a  is mounted to the lower end of a column  10  extending vertically downwards through the cylindrical interior of the upper casing  4   a , and is adapted to heat the mold  11  from above. The lower heating device  9   b  is mounted to the upper end of a slide  12 , which extends through the cylindrical interior of the lower casing  4   b  and serves as a “drive device” driven by a hydraulic cylinder, an electric motor, or the like. The lower heating device  9   b  is adapted to heat the mold  11  from below. Thus, the lower heating device  9   b  is vertically movable, and capable of moving toward and away from the upper heating device  9   a . The lower heating device  9   b  is upwardly displaced with the mold  11  placed thereon to thereby bring the mold  11  into contact with the upper heating device  9   a . To thus place the mold  11  on the lower heating device  9   b , the mold  11  is brought from outside the manufacturing apparatus  1  onto an annular, disc-like slidable receiving plate  13  mounted to the upper surface of the lower casing  4   b , and the mold is caused to slide thereon to be placed on the lower heating device  9   b.    
   Next, an anisotropic formed body manufacturing method according to an embodiment, using the above manufacturing apparatus  1 , will be described. In this embodiment, the anisotropic formed body to be obtained is a sheet-like anisotropic conductive connector. This anisotropic conductive connector uses silicone rubber as the matrix and nickel particles as the functional fine particles. 
   First, the mold  11  is previously filled with a liquid molding material composed of liquid silicone rubber containing nickel particles. More specifically, the mold  11  is composed of upper and lower mold portions, and the cavity to form the outer contour of the anisotropic conductive connector, formed in the lower mold portion  11   b , is filled with the liquid molding material. The upper mold portion  11   a  is used as a lid for closing the lower mold portion  11   b.    
   Next, as shown in  FIG. 2 , this mold  11  is pushed by a transfer device  14   a  composed of a straight feeder or the like provided in the manufacturing apparatus  1 , and is transferred to the interior of the manufacturing apparatus  1 . During this transfer, the mold  11  is caused to slide on the slide recipient plate  13  through a transfer plate  15   a . The height of the lower heating device  9   b  is previously adjusted by the vertically movable slide  12  such that its upper surface is substantially flush with the upper surface of the slide recipient surface  13  (See  FIG. 1 ). When the mold  11  has been placed at a predetermined position on the lower heating device  9   b , the transfer device  14   a  retreats, and the lower heating device  9   b  is caused to ascend by the slide  12  until the mold  11  comes into contact with the upper heating device  9   a.    
   Then, the mold  11  is heated for a predetermined period of time while being sandwiched between the upper heating device  9   a  and the lower heating device  9   b , and the liquid silicone rubber is further softened. In the meantime, the upper superconducting coil  2   a  and the lower superconducting coil  2   b  form a uniform and parallel magnetic field  16 , in which, as shown in  FIG. 3 , the magnetic lines of force  16   a  are at equal intervals and are parallel to each other in a planar direction. As a result, in the mold  11 , the nickel particles constituting the functional fine particles are easily oriented in the vertical direction along the uniform and parallel magnetic field  16  within the liquid silicone rubber further softened by being heated by the heating devices  9   a  and  9   b , whereby an anisotropic conductive portion is formed. Thereafter, heating is performed at still higher temperature to crosslink the liquid silicone rubber, thereby fixing the orientation of the nickel particles in the anisotropic conductive portion. After the completion of this molding process, the lower heating device  9   b  is lowered by the slide  12  until its upper surface becomes substantially flush with the upper surface of the slide recipient plate  13 . Then, as shown in  FIG. 2 , the mold  11  is pulled by a transfer device  14   b  composed of a straight feeder or the like provided in the manufacturing apparatus  1 , and is brought to the exterior of the manufacturing apparatus  1  by means of a transfer plate  15   b.    
   In the anisotropic conductive connector obtained by the above forming method, it is possible to form the anisotropic conductive portion in which the nickel particles are oriented with precision and in a fine pitch. Further, it is possible to form such a conductive portion in a large area. Thus, the connector can be used for connection, for example, between a liquid crystal display and a printed circuit board. 
   Instead of the mold  11  used in the above embodiment, it is possible to adopt a mold with a ferromagnetic substance embedded therein so that magnetic lines of force may be formed at desired positions in the mold. By thus realizing a magnetic circuit design in the mold, it is possible to make the intervals of the magnetic lines of force in the uniform and parallel magnetic field partially different. 
   While in the above embodiment a single mold  11  is supplied to the manufacturing apparatus  1 , it is also possible to supply the manufacturing apparatus  1  with a plurality of molds  11  stacked together or arranged in a planar direction, performing simultaneous molding with a plurality of molds. 
   While in the above embodiment silicone rubber is used as the matrix and nickel particles as the functional fine particles, these allow modifications according to the anisotropic formed body to be obtained. With such modifications, the period of time and temperature for the heating by the heating devices  9   a  and  9   b  are appropriately changed. 
   While in the above embodiment the superconducting coils  2   a  and  2   b  are cooled by the cooling system using the refrigerators  7   a  and  7   b  to thereby realize the manufacturing apparatus  1  in a generally simple construction, it is also possible to adopt the immersion cooling system if such simplification in apparatus construction is not desired. 
   While in the above embodiment the heat insulating portion has the heat insulating materials  8   a  and  8   b , it is also possible to provide a water cooling pipe for heat insulation. 
   Instead of the manufacturing apparatus  1  of the above embodiment, it is also possible, for example, to adopt manufacturing apparatuses as shown in  FIGS. 4 and 5 . In the manufacturing apparatus  1  shown in  FIG. 4 , an injection molding device is provided. This injection molding device is equipped with a cylinder  20 , a screw  21 , a drive source  22  for driving the screw  21  composed of an injection cylinder and a hydraulic motor or the like, a heater  23 , a bracket  24  accommodating the drive source  22 , a hopper  25 , an injection mold  26 , etc. The bracket  24  is fixed to the upper frame  5   a  through the intermediation of an angle member  27 , whereby the entire injection molding device is secured in position. The opening and closing of the mold  26  is effected through the vertical movement of the slide  12 , and the releasing of the anisotropic formed body is effected by an adsorption nozzle or the like (not shown). Thus, also with the anisotropic formed body manufacturing apparatus  1  shown in  FIG. 4 , it is possible to obtain, through injection molding, an anisotropic formed body in which the functional fine particles are oriented so as to be at equal intervals and parallel to each other by a uniform and parallel magnetic field generated by the upper superconducting coil  2   a  and the lower superconducting coil  2   b . In the manufacturing apparatus  1  shown in  FIG. 5 , a photo-setting molding device is provided inside the upper casing  4   a  and the lower casing  4   b . The photo-setting molding device is equipped with a photo-setting mold  30  formed of a transparent material such as acrylic resin or glass, and a light source device  31  using ultraviolet laser or the like. Reference numerals  32  and  33  indicate support members on which the photo-setting mold  31  is to be placed. Thus, also with the anisotropic formed body manufacturing apparatus  1  shown in  FIG. 5 , it is possible to obtain, through photo-setting molding, an anisotropic formed body in which the functional fine particles are oriented so as to be at equal intervals and parallel to each other by a uniform and parallel magnetic field generated by the upper superconducting coil  2   a  and the lower superconducting coil  2   b.    
   While in the above embodiment a split type superconducting coil composed of the upper superconducting coil  2   a  and the lower superconducting coil  2   b  are used as an example, it is also possible to use a unitary superconducting coil. 
   According to the apparatus and method for manufacturing an anisotropic formed body of the present invention, a uniform and parallel magnetic field, which can not be generated by permanent magnets, is used to orient functional fine particles at equal intervals and parallel to each other, which is difficult to effect with permanent magnets, whereby it is possible to obtain various anisotropic formed bodies exhibiting, uniformly and in parallel, various properties, such as electrical conductivity, heat conductivity, expansion coefficient, light transmittance, magnetism, hardness, elasticity, water absorption, dielectric constant, gas permeability, piezoelectric characteristics, and vibration absorption. The anisotropic formed bodies thus obtained can be used in a variety of technical fields.