JP5233600B2 - Method for producing particle-containing resin - Google Patents

Description

The present invention relates to a method of manufacturing a particle-containing resin.

  A film obtained by dispersing fine particles having conductivity in a resin has various uses such as a conductive film and a heat diffusion film.

  For example, in recent years, carbon nanotubes (hereinafter referred to as “CNT” when indicating a single carbon nanotube, or “CNTs” when indicating a plurality or aggregate, as required) are the core of nanotechnology. In the spotlight. CNTs are generally carbon materials having an elongated fibrous (columnar) particle shape with a diameter of about 0.5 to 100 nm and a length of about 50 nm to several mm. Applications of these CNTs to conductive films that can be used for transparent electrodes of image display devices such as electronic paper, flexible display boards, and flat panel displays are being studied.

As such a conductive film using CNTs, for example, a film formed by adding CNTs to a resin such as a thermoplastic polyimide resin and extruding it is known (see Patent Document 1). .
JP 2004-346143 A

  For example, when the conductive film using CNTs described above is applied as a transparent conductive film, it is necessary to add a certain amount or more of CNTs in order to obtain sufficient conductivity. However, since CNTs are black and absorb visible light, if too much is added, sufficient transparency of the film cannot be obtained. Therefore, when applying CNTs as a transparent conductive film, it is necessary to make the addition amount of CNTs as small as possible to ensure sufficient transparency while simultaneously obtaining sufficient conductivity.

  However, the conventional method such as Patent Document 1 described above simply mixes resin and CNTs and forms the film. Therefore, for example, when producing a transparent conductive film, it is necessary to add a large amount of CNTs in order to reliably obtain conductivity, while still a sufficient conductivity cannot be obtained if the amount of CNTs added is reduced. It tends to be difficult to achieve both sufficient transparency and electrical conductivity. Also, in this case, the dispersion of CNTs is likely to be non-uniform, such as a partial increase in the ratio of CNTs, and the conductivity of the film is not uniform over the entire surface. There is also a disadvantage that the image is easily displayed.

  Thus, in a film obtained by dispersing particles in a resin, conventionally, it has been difficult to obtain sufficient film characteristics while reducing the amount of particles added.

The present invention has been made in view of these circumstances, a manufacturing how the particle-containing resin can be obtained particle-containing resin even with a small amount of particles can exhibit sufficient properties The purpose is to do.

  In order to achieve the above object, a method for producing a particle-containing resin according to the present invention is a first method in which a raw material mixture containing particles and a resin or a resin precursor is disposed between a pair of electrodes disposed to face each other. A step of applying a voltage between the pair of electrodes to orient the particles in the raw material mixture in the direction of the electric field; and a step of solidifying the resin or resin precursor while applying a voltage between the pair of electrodes. 3 steps, and the distance between the pair of electrodes is larger than the distance in the first step during the second step.

  The method for producing a particle-containing resin of the present invention includes a first step of arranging a raw material mixture containing particles and a resin or a resin precursor between a pair of electrodes arranged to face each other, and a pair of A second step of applying a voltage between the electrodes to orient the particles in the raw material mixture in the direction of the electric field, and applying a voltage between the pair of electrodes, while the resin or resin precursor not solidified, The third step of solidifying the one near one of the electrodes and not solidifying the one near the other electrode, widening the distance between the pair of electrodes, while applying a voltage between the pair of electrodes, And a fourth step of solidifying all unsolidified resin or resin precursor.

  In the method for producing a particle-containing resin of the present invention, it is preferable to increase the distance between the pair of electrodes while measuring the current value between the electrodes. Thus, when the distance between the pair of electrodes is increased, it is more preferable that the current value after the distance between the electrodes is not made smaller than the value before the distance is increased.

  In the second step, it is preferable to orient the particles in the raw material mixture by moving them in a direction where the electric field is strong.

  Furthermore, as the particles to be contained in the raw material mixture, fibrous particles are preferable. Here, the fibrous particle is defined as a ratio of the major axis to the minor axis (aspect ratio) exceeding 10. The particles may contain a combination of fibrous particles and spherical particles.

According to the present invention, it is possible to provide a manufacturing how the particle-containing resin capable of obtaining a particle-containing resin even with a small amount of particles can exhibit sufficient characteristics.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[First Embodiment]
First, 1st Embodiment of the manufacturing method of particle-containing resin of this invention is described. In the method for producing a particle-containing resin according to the first embodiment, a first step of arranging a raw material mixture containing particles and a resin or a resin precursor between a pair of electrodes arranged to face each other, a pair A second step of applying a voltage between the electrodes to orient the particles in the raw material mixture in the electric field direction, and a third step of solidifying the resin or resin precursor while applying a voltage between the pair of electrodes. It carries out in this order.

(First step)
First, the first step will be described. FIG. 1 is a diagram schematically showing a cross-sectional configuration of a production apparatus used in the method for producing a particle-containing resin of the present embodiment. In the manufacturing apparatus 100 shown in FIG. 1, a pair of electrodes 101 are arranged to face each other, the upper electrode 101 is supported by a support wall 102, and the lower electrode 101 is supported by a stage 105.

  Further, in the manufacturing apparatus 100, each of the electrodes 101 has a configuration in which the surface electrode 202 is provided on the substrate 201, and the pair of electrodes 101 face each other so that the surface electrodes 202 face each other. Has been placed. A power source 104 is connected to the surface electrodes 202 of these electrodes 101 via lead wires 103 so that a voltage can be applied between the surface electrodes 202 facing each other.

  The outer shape of the electrode 101 is not particularly limited, and is appropriately selected from a square shape, a circular shape, and the like. For example, a glass substrate is used as the substrate 201 in the electrode 101. Moreover, the surface electrode 202 will not be restrict | limited especially if comprised from the electrically-conductive material normally used for an electrode etc., For example, gold | metal | money is preferable. Note that the electrode 101 does not necessarily have such a laminated structure, and may be a single layer that can function as an electrode.

  In the manufacturing apparatus 100, the raw material mixture R can be accommodated between the pair of electrodes 101. Although not shown, the side of the region between the pair of electrodes 101 may be blocked by a spacer or the like so that the internal raw material mixture does not leak. The support wall 102 may also serve as this spacer. Further, the manufacturing apparatus 100 is provided with a supply device that can supply a resin component or a raw material mixture in accordance with the spread of the region between the electrodes when the pair of electrodes 101 are separated in the second step described later. It is preferable.

  The stage 105 is configured such that the support column 105a can be taken in and out in the vertical direction (the arrow direction in the figure). Accordingly, the lower electrode 101 supported by the column 105a can be moved up and down, and the distance between the pair of electrodes 101 facing each other can be adjusted.

  The power source 104 is a power source capable of applying an alternating current between the pair of electrodes 101 (surface electrode 202). Any known power source can be used as the power source 104 as long as it has such a function. However, from the viewpoint of satisfactorily generating dielectrophoresis described later, alternating current having a frequency in the range of 1 GHz to 1 kHz is applied. A high-frequency power supply that can be used is preferable.

  In the first step, the raw material mixture R of the particle-containing resin is supplied and arranged between the pair of electrodes 101 in such a manufacturing apparatus 100. The raw material mixture R includes particles and a liquid resin or a liquid resin precursor.

  The particles can be appropriately selected according to the properties required for the use of the particle-containing resin. For example, when used as a conductive film, conductive particles are used. Examples of such particles include carbon nanotubes, carbon nanofibers, carbon nanotwists, carbon nanocoils, carbon microcoils, carbon fibers, metal and semiconductor nanofibers or nanorods, and one or two of these. More than one species may be used. In addition to such fibrous particles, spherical particles made of the above materials can also be used.

  As the particles, at least fibrous particles are preferably used, and it is also suitable to use a combination of fibrous particles and spherical particles. For example, when the particle-containing resin is applied to a conductive film, particularly a transparent conductive film, carbon nanotubes or carbon nanofibers that can provide high conductivity are preferable.

  As the carbon nanotubes (CNTs), single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), triple-walled carbon nanotubes (3WCNTs), and other multi-walled carbon nanotubes (MWCNTs) can be used without particular limitation. As the carbon nanofiber, a carbon nanofiber having a large diameter (about 100 to 300 nm) or a carbon nanofiber having a spiral shape can be applied. In order to improve the dispersibility in the resin or the resin precursor, the surface of these carbon nanotubes and carbon nanofibers may be modified with a predetermined functional group such as a carboxyl group or a nitro group. In the case of using CNTs as the particles, for example, the size is preferably about 1 nm to several tens of nm in diameter and about 1 μm in length.

  On the other hand, the resin or the resin precursor can also be appropriately selected according to the characteristics required for the use of the particle-containing resin, and one kind can be used alone or two or more kinds can be used in combination. Here, the resin precursor is a precursor compound that can form a resin after solidification, which will be described later, and examples thereof include monomers and oligomers that can be polymerized to form a resin upon solidification. As the resin, a thermosetting resin, a thermoplastic resin, a photocurable resin, or the like can be applied without particular limitation. For example, when the particle-containing resin is used as a transparent conductive film, a resin that is transparent to visible light in a solidified state can be applied, and an acrylic resin, a urethane acrylate resin, an epoxy resin, or the like is preferable.

  Further, the resin or the resin precursor is preferably one having such a property that the raw material mixture R becomes liquid. By arranging the raw material mixture R in a liquid state, the particles in the raw material mixture R can be favorably oriented when a voltage is applied after the electrodes are disposed between the electrodes 101. Examples of such a resin or resin precursor include those that are themselves liquid and those that can be dissolved in a solvent to become liquid.

  In addition to the particles and the resin or the resin precursor described above, the raw material mixture R further includes, as necessary, a solvent for making the raw material mixture a liquid and various components capable of obtaining characteristics required for the use of the particle-containing resin. You may go out. For example, it may further contain conductive colloidal particles such as Au colloidal particles or polyaniline having a function as a binder between the particles.

  The mixing ratio of each component in the raw material mixture R is not particularly limited, and can be appropriately selected according to the characteristics required for the particle-containing resin. For example, when carbon nanotubes are used as the particles and the particle-containing resin is applied to the transparent conductive film, the particle content is 0.001 to 10% by mass in the total amount of the resin or the resin precursor and the particles. It is preferable to make it 0.01 to 0.1% by mass.

  With such a ratio, the production method of the present embodiment provides sufficient transparency because the particle content is small, and sufficient conductivity is also obtained. According to this embodiment, since a particle-containing resin having sufficient characteristics can be obtained with a small amount of added particles, the content of such particles is compared with the value required in the case of the conventional manufacturing method. Is much smaller.

  The raw material mixture R described above can be obtained by mixing a resin or resin precursor, particles, and other necessary components. Mixing can be performed, for example, by ultrasonic agitation in order to improve particle dispersion.

  In the first step, the method of supplying the raw material mixture R to the region between the pair of electrodes 101 in the manufacturing apparatus 100 described above includes, for example, a method of injecting a raw material compound between the pair of electrodes 101. The raw material mixture R is preferably filled so as to fill a region sandwiched between the electrodes 101, and may protrude from this region. By disposing the raw material mixture between the electrodes 101 so as to be in contact with at least both of the opposing electrodes 101 (surface electrodes 202), the later-described dielectrophoresis can be surely generated.

(Second step)
Next, the second step will be described. In the second step, a voltage is applied by a power source 104 between the pair of electrodes 101 with the raw material mixture R sandwiched therebetween, and the particles in the raw material mixture R are oriented in the electric field direction (second step). Further, during the second step, the distance between the pair of electrodes 101 is increased while causing such orientation.

  FIG. 2 is a schematic cross-sectional view showing the state of the electrode and the raw material mixture in the second step. In FIG. 2, for ease of explanation, a pair of electrodes 101 and a raw material mixture R are shown, and a specific configuration of the manufacturing apparatus 100 is omitted. In the second step shown in FIG. 2, a voltage is applied between the opposed surface electrodes 202. The applied voltage is set within a range of 1 to 100 Vpp, for example. The higher the applied voltage, the greater the force of dielectrophoresis on the particles, and the alignment can be completed quickly. However, if the voltage is high and the electric field strength becomes too strong, bubbles may be generated due to electrolysis or the like, and the characteristics of the obtained particle-containing resin may be deteriorated. Therefore, a high voltage is applied to the extent that the bubbles are not generated. It is preferable. The applied voltage is preferably alternating current, particularly high frequency alternating current having a frequency in the range of 1 GHz to 1 kHz.

  An electric field is generated between the electrodes 101 by applying a voltage, preferably high-frequency alternating current, between the electrodes 101 (surface electrode 202). As a result, as shown in FIG. 2, the particles 204 dispersed in the resin or resin precursor (hereinafter collectively referred to as “resin component 203”) in the raw material mixture undergo dielectrophoresis and are oriented.

  Here, the principle of dielectrophoresis will be described.

Usually, when an electric field is applied to a dispersion obtained by dispersing particles in a solvent, an induced dipole moment is generated due to a difference in polarizability between the solvent and the particles. Then, the difference in the electric field strength formed on both sides of the particle becomes the difference in force exerted by the induced dipole, resulting in the force acting on the particle, and the particle moving in the direction of this force. It is known that the dielectrophoretic force F _DEP acting at this time is expressed by the following equation (1).
^{_{F DEP = 2πε m a 3 Re}} [(ε p - ε m) / (ε p +2 ε m)] ∇E 2 ... (1)

In the formula (1), a represents the particle radius [m], ε represents the dielectric constant [F / m], and the subscripts p and m represent the values of the particle and the solvent, respectively. E is an electric field (V / m), and Re [f (x)] is an operator that extracts only the real part of the complex number f (x). ε is a complex dielectric constant defined by the following equation (2).
ε = ε− (σ / ω) j (2)

Also, σ represents conductivity [S / m], ω (= 2πf) represents angular frequency [Hz], f represents applied frequency [Hz], and j is an imaginary unit. The expression in square brackets represented by Re [([ epsilon] _p- [ epsilon] _m ) / ([ epsilon ] _p + 2 [ epsilon ] _m )] in the expression (1) is expressed by Clausius-Mossotti as represented by the following expression (3). It is called a factor (CM factor: K (ω)) and represents the degree of polarization.
_{K (ω) = (ε p} - ε m) / (ε p +2 ε m) ... (3)

  From the above formulas (2) and (3), this CM factor takes a value of −0.5 to 1.0 depending on the conductivity and dielectric constant of the solvent and particles and the frequency applied. From the above formula (1), the direction of the dielectrophoretic force depends on the CM factor. That is, when the real part of the CM factor is positive, the dielectrophoretic force is positive, and positive dielectrophoresis that induces particles acts on the one with the larger electric field strength. On the other hand, if it is negative, the dielectrophoretic force becomes negative, and the negative dielectrophoretic force that induces particles acts on the one where the electric field strength is weak.

  By applying a voltage between the electrodes 101 to cause such dielectrophoresis, the particles 204 in the raw material mixture R exhibit the following behavior. Here, the case where SWCNTs in which positive dielectrophoretic force acts is used as the particle 204 will be described as an example. That is, in the raw material mixture R, since the resin component 203 is before solidification, the particles 204 can move freely within the resin component 203 to some extent. Therefore, when the dielectrophoretic force as described above acts, the particle 204 first starts moving in the direction in which the dielectrophoretic force acts, and moves to the surface electrode 202 having the highest electric field strength. At this time, since SWCNTs are fibrous particles and are polarized in the major axis direction, one end of the major axis direction is in contact with the surface electrode 202 and the major axis direction is arranged along the electric field direction.

  When the movement of the particles 204 occurs to some extent, the electric field strength of the portion of the particles 204 (particles 204a in FIG. 2) previously attached to the surface electrode 202 is large, so that other particles 204 (dispersed in the raw material mixture ( In FIG. 2, 204 b) moves toward the particles 204 a attached to the surface electrode 202. In the case of fibrous particles such as SWCNTs, the electric field strength is greatest near the ends in the major axis direction, so that the particles 204a and 204b come close to each other in the vicinity of these ends. Further, when the particles 204b adhere to the particles 204a to some extent, the other particles 204b dispersed in the raw material mixture move toward the particles 204b attached to the particles 204a. Attach to touch. Then, when the movement of the particles 204 due to such dielectrophoresis occurs sequentially, as shown in FIG. 2, the particles 204 are continuously arranged so as to be in contact with each other at the ends in the major axis direction, and the electric field Arranged in a substantially straight line along the direction. And the particle | grain 204 will be connected so that the surface electrodes 202 may be bridge | crosslinked finally by being orientated in this way.

  By using fibrous particles such as particles 204 made of SWCNTs as the particles, in the second step, the long axis direction of the particles can be continuously arranged along the electric field direction as described above. Therefore, according to such fibrous particles, good conductivity and thermal conductivity as described later can be obtained even with a smaller amount of added particles. In addition, since the particle density is relatively small in the direction perpendicular to the orientation direction, the transparency in the orientation direction tends to be further improved. However, even when spherical particles are used as particles instead of such fibrous particles, spherical particles can be oriented so as to be continuous along the electric field direction. Can get to.

  In addition, when a combination of fibrous particles and spherical particles is used, the fibrous particles may be oriented in the above-described form, and the spherical particles may be interposed between adjacent fibrous particles. is there. And when such an orientation state is formed, it exists in the tendency for the contact property of particle | grains to become favorable rather than the case where fibrous particle | grains contact | connect directly between the edge parts. As a result, the effects of conductivity and thermal conductivity as described later may be obtained even better.

  The orientation described above corresponds to this electric field strength by arranging the raw material mixture that becomes the particle-containing resin as it is after solidification between the pair of electrodes 101, so that the electric field strength near the electrode is maximized. This is possible because orientation can be produced. Therefore, for example, in a method in which a predetermined film or the like is disposed between the electrodes and the raw material is moved toward the film, the distribution of the electric field strength becomes completely different, so that the orientation as in the present invention cannot be generated at all. .

  Here, with reference to FIG. 3, the distribution of the electric field strength in the present embodiment will be described. FIG. 3 is a diagram showing an example of an electric field intensity distribution obtained when a raw material compound is arranged between a pair of electrodes.

  In FIG. 3, E arranged above and below indicates a pair of electrodes, and the raw material compound is filled between the electrodes E. And the line attached | subjected to the area | region of the raw material compound in FIG. 3 partitions this area | region according to the grade of an electric field strength, and the number attached | subjected to the area | region divided into this line is so small that the area | region of that area | region. Indicates that the electric field strength is high. As shown in FIG. 3, in the example in which only the raw material compound is disposed between a pair of electrodes as in the present invention, the distribution of the electric field strength increases as the distance from the electrodes approaches. Therefore, the particles in the raw material compound can cause the above-described orientation. On the other hand, when a film such as a porous film is arranged in the raw material compound, the electric field strength of the film portion increases, and in this case, the particles in the raw material compound are directed not to the electrodes but to the pores of the porous film. Therefore, the orientation as in the present invention cannot be produced.

  In the second step, in addition to the above-described orientation by dielectrophoresis, an operation of increasing the distance between the pair of electrodes 101 during the step is performed. FIG. 4 is a cross-sectional view schematically showing an operation of increasing the distance between the electrodes in the second step. As shown in FIG. 4, in the second step, the lower electrode 101 is moved to a lower position by lowering the column 105a of the stage 105 (moving it in the direction of the arrow in the figure), thereby a pair of electrodes 101. Increase the distance between. At this time, a resin component or a raw material mixture may be supplied to the region between the electrodes 101 in accordance with the spread of the region.

  In this way, by increasing the distance between the electrodes 101 during the second step, the thickness of the raw material mixture R disposed between the electrodes 101 can be increased while causing the orientation of particles by dielectrophoresis. As a result, it becomes possible to produce a particle-containing resin having a large thickness. This is because, as described above, when the orientation of the particles by dielectrophoresis occurs, the electric field strength increases at the tip portion of the structure formed by connecting the particles so as to extend from the electrode 101 (surface electrode 202). In this case, even when the distance between the electrodes 101 is such that normally no electric field is formed, an electric field is formed between the tip portions of the above-described structures extending from the opposing electrodes 101, thereby preventing the resin from being oriented. Dielectric migration can be sufficiently generated in the particles 204 remaining dispersed in the components. On the other hand, if the distance between the electrodes 101 is excessively increased from the beginning of the second step, that is, before the dielectrophoresis starts, an electric field between the electrodes 101 is not formed in the first place. The particles cannot be oriented.

  In order to cause dielectrophoresis in the second step, it is desirable that the distance between the electrodes 101 is 1000 μm or less at least at the start of the second step. Beyond this, dielectrophoresis does not occur sufficiently and the particles may not be oriented. For example, in the first step, the distance between the electrodes 101 is preferably 1000 μm or less, more preferably 1 to 1000 μm, and in the second step, dielectrophoresis is started at the distance between the electrodes 101, and thereafter It is preferable to increase the distance between the electrodes 101 so as to increase. Thereby, even if the distance between the electrodes 101 finally exceeds 1000 μm, the orientation by dielectrophoresis can be sufficiently generated.

  In the second step, the distance between the pair of electrodes 101 may be gradually increased or may be increased stepwise over a plurality of times. At this time, the distance between the electrodes 101 may be widened so that, for example, the structures in which particles are connected from the opposing electrodes 101 once contact each other, and then the structures are in contact with each other. May be spread out before

  However, if the distance between the electrodes 101 is excessively increased, the electrodes 101 are separated before the particles are sufficiently aligned by dielectrophoresis, and a sufficient electric field is formed by the structures in which the particles are connected to the electrodes 101. As a result, no further dielectrophoresis can occur. Therefore, in order to prevent such inconvenience, in the second step, it is preferable to increase the distance between the electrodes 101 so as to satisfy the following conditions.

  For example, first, in the second step, the structure formed by the orientation of particles by dielectrophoresis is observed, and the distance between the tips of these structures extending from the opposing electrode 101 is preferably 100 μm or more, more preferably 10 μm. There is a method of increasing the distance between the electrodes 101 so as not to become above. By doing so, a sufficient electric field strength can be obtained near the tip of the above structure, and orientation by dielectrophoresis can be sufficiently generated.

  If the observation is difficult, for example, the distance between the electrodes 101 can be increased while measuring the current value between the electrodes 101 facing each other. If dielectrophoresis has occurred, the particles are oriented so as to connect the electrodes 101. Therefore, even if the current value after increasing the distance between the electrodes 101 decreases once, the particles are oriented by dielectrophoresis. growing. Therefore, by increasing the distance between the electrodes 101 while confirming the current value in this way, it is possible to reliably cause orientation by dielectrophoresis. That is, immediately after the distance between the electrodes 101 is increased, the cross-linked structure in which the oriented particles are connected may be cut to temporarily reduce the current value. In this case, if dielectrophoresis occurs, the particles This causes the current value to increase again. Therefore, even when the current value once decreases, the distance between the electrodes 101 may be increased while confirming that the current value increases again.

  In the second step, the distance between the opposing electrodes 101 can be increased in a range of preferably 50 μm or less, more preferably 20 μm or less. In the second step, it is only necessary that the distance between the electrodes 101 is finally larger than that in the first step. For example, when sufficient dielectrophoresis does not occur on the way, the distance between the electrodes 101 is temporarily increased. The distance between the electrodes 101 may be increased again after reducing the distance so that dielectrophoresis occurs sufficiently.

(Third step)
In this way, after the particles 204 are oriented in the second step and set to a desired distance between the electrodes 101, the resin component 203 (resin or resin precursor) is solidified while applying a voltage between the electrodes 101. (Third step). Thus, the particles 204 are fixed in the solidified resin component 203 while maintaining the orientation generated in the second step.

  In this third step, the resin component 203 is solidified by, for example, curing by heating or light irradiation when using heat or photocurable resin. Further, when the resin component 203 is a precursor of a thermoplastic resin, the polymerization of the precursor (monomer, oligomer, etc.) may be advanced by appropriately heating and the like to produce a solidified thermoplastic resin. . Furthermore, a monomer or an oligomer that is a precursor of a curable resin may be used, and polymerization and curing may be caused together at the time of solidification.

  In this way, after the resin component 203 in the raw material mixture is solidified, the electrode 101 is removed as necessary to obtain a particle-containing resin in which the particles 204 are dispersed and contained in the solidified resin component 203. . Note that the electrode 101 does not necessarily have to be removed from the particle-containing resin. Depending on the application, the electrode 101 may be left, or only the substrate 201 may be removed to leave the surface electrode 202.

  In the method for producing the particle-containing resin of the present embodiment having the first to third steps described above, first, in the second step, since an electric field is applied to the raw material mixture containing the resin (or precursor) and the particles, In FIG. 1, the force of dielectrophoresis acts on the particles, and the particles are oriented along the direction of the electric field, and are continuously arranged so as to be continuous in this direction, for example. In the third step, since the resin (or precursor) is solidified while applying a voltage, the particle-containing resin is formed while maintaining the orientation of the particles.

  Therefore, according to the above production method, a particle-containing resin in which particles are arranged in a specific direction as described above by orientation is obtained. Therefore, the particle-containing resin has conductivity and heat in a direction along the particle orientation direction. The conductivity is enhanced, and even with a small amount of particles, these properties are sufficiently excellent. As a result, when the particle-containing resin is applied to a conductive film, sufficient conductivity can be obtained by the above-described orientation even if the particles are reduced to obtain good transparency. Moreover, when it is set as a heat conductive film, sufficient thermal conductivity comes to be obtained, reducing particle | grains.

  In the manufacturing method of this embodiment, in the second step, the distance between the electrodes is increased while causing the orientation of particles by dielectrophoresis. Therefore, even when the distance between the electrodes is such that dielectrophoresis could not be caused conventionally, the orientation of the particles can be continuously caused. As a result, even if a thick particle-containing resin is formed by increasing the distance between the electrodes, the orientation in a specific direction by the particles can be obtained well, and the excellent characteristics can be obtained with the small amount of particles as described above. You can get enough.

[Second Embodiment]
Next, 2nd Embodiment of the manufacturing method of particle-containing resin of this invention is described.

  In the present embodiment, the operation of increasing the inter-electrode distance in the second step in the first embodiment described above and the solidification of the resin or resin precursor in the third step are performed in parallel. That is, a first step of arranging a raw material mixture containing particles and a resin or a resin precursor between a pair of electrodes arranged to face each other, a voltage is applied between the pair of electrodes, and the raw material mixture The second step of orienting the particles in the electric field direction, applying a voltage between the pair of electrodes, solidifying the resin or resin precursor not solidified near one of the pair of electrodes And the third step of expanding the distance between the pair of electrodes, and applying a voltage between the pair of electrodes while applying a voltage between the pair of electrodes, and all the unsolidified resin or resin precursor. The 4th process to solidify is implemented in this order.

  Since such 2nd Embodiment can be performed using the material and manufacturing apparatus 100 similar to 1st Embodiment mentioned above, it abbreviate | omits about these description. In 2nd Embodiment, a raw material mixture is arrange | positioned in a 1st process, and the particle | grains in a raw material mixture are orientated to an electric field direction in a 2nd process. These can be performed in the same manner as in the first embodiment.

  Next, in the third step, first, a voltage is applied between the pair of electrodes, and the resin component 203 in the vicinity of one of the pair of electrodes is maintained while maintaining the orientation of the particles 204 generated in the second step. (Resin or resin precursor) is solidified. That is, in the third step in the second embodiment, not all the resin components 203 in the raw material mixture R are solidified, but are solidified only in the vicinity of one electrode and are not solidified in the vicinity of the other electrode. To. By carrying out like this, operation which extends the distance between electrodes mentioned later can be performed, solidifying resin component 203 partially.

  The solidification of the resin component 203 can be performed in the same manner as in the first embodiment. However, in this embodiment, for example, by shielding a region that is not solidified, only the region where heat or light for solidification should be solidified is used. Do to reach. In the second embodiment, in particular, by using a photo-curable resin as the resin component 203 and solidifying by light irradiation, the above-described shielding solidified region and unsolidified region can be favorably separated. .

  In the raw material mixture R, the region where the resin component 203 is solidified is, first, when only one (lower) electrode 101 is movable as in the manufacturing apparatus 100, the region near the non-moving side electrode 101. A region is preferable. By doing so, since the raw material mixture R in the vicinity of the moving electrode 101 is not solidified, the shape is easily deformed with the movement of the electrode 101, and an operation for increasing the distance between the electrodes 101 described later can be performed satisfactorily. It becomes.

  In the third step, after the resin component 203 in the raw material mixture R is partially solidified in this way, an operation of increasing the distance between the pair of electrodes 101 is performed. Such an operation can be performed in the same manner as in the first embodiment. At this time, the solidified region in the raw material mixture R is maintained in a solidified shape, while the non-solidified region causes the orientation of particles by dielectrophoresis in accordance with the spread of the region between the electrodes 101. The resin component or raw material mixture supplied as it is or separately is mixed and stretched.

  Such a series of operations in the third step may be performed only once or repeatedly. That is, in the third step, when the resin component 203 in the raw material mixture R after the second step is partially solidified and then the distance between the electrodes 101 is increased, the raw material mixture R is not solidified. The area will remain. Therefore, in such an unsolidified region, partial solidification and an operation of increasing the distance between the electrodes 101 are repeatedly performed so that the solidified region is gradually increased while the distance between the electrodes 101 is increased. Good.

  In the third step, when the above series of operations is repeated, the region in which the raw material mixture R is solidified in each operation is as much as possible with respect to the distance between the electrodes 101 at the beginning (at the end of the second step). If it is made smaller, the distance between the electrodes 101 can be increased while maintaining the orientation of the particles 204 in the resin component 203 well.

  In the second embodiment, after the third step, the resin or resin precursor in the raw material mixture R that has not yet been solidified is solidified (fourth step). After that, the particle-containing resin is obtained by removing the electrode 101 as necessary.

  Also in the second embodiment, after causing the orientation of particles by dielectrophoresis in the second step, in the third step, the solidification is promoted while maintaining this orientation and the distance between the electrodes is increased. Therefore, even when the distance between the electrodes cannot conventionally cause dielectrophoresis, the orientation of the particles can be continuously generated. As a result, even if a thick particle-containing resin is formed by increasing the distance between the electrodes, the orientation in the specific direction by the particles can be obtained well, and the effect of obtaining excellent characteristics with a small amount of particles can be sufficiently obtained. Can do.

[Particle-containing resin]
Next, an example of the configuration of the particle-containing resin obtained by the production method of the present invention as described above will be described. FIG. 2 is a diagram showing a cross-sectional configuration of the second step in the case of using SWCNTs or the like that are fibrous particles that undergo positive dielectrophoresis, and the particle-containing resin obtained thereby also has a cross-section shown in FIG. The configuration is maintained as it is.

  That is, in the particle-containing resin obtained in this example, the particles 204 are continuously arranged so that adjacent ones are sequentially in contact with each other in the vicinity of the end in the long axis direction. The direction in which the particles 204 are continuous (that is, the orientation direction) coincides with the direction of the electric field applied in the second step. Therefore, in the particle-containing resin, the particles 204 are continuously arranged so as to connect both surfaces that have been in contact with the electrode in the second step. Further, in the vicinity of the surface in contact with the electrode, the particle 204 has one end in contact with the surface, and the major axis direction rises substantially perpendicularly from the surface.

  The thus-configured particle-containing resin has conductivity in the direction in which the particles 204 are oriented, and may have so-called anisotropic conductivity having insulation in a direction perpendicular thereto. Moreover, it has a high thermal conductivity in the orientation direction of the particles 204, and has a thermal conductivity lower than that in the orientation direction in a direction perpendicular thereto. Furthermore, since the particles 204 are not randomly oriented but are oriented so as to be continuously arranged in one direction, the particles 204 can also have high transparency in the orientation direction. That is, the particle-containing resin obtained through the second step shown in FIG. 2 has high conductivity, thermal conductivity, and transparency in the film thickness direction. In addition, even if it is a case where what is not a fibrous particle is used as particle | grains, the same effect will fully be acquired by orientation.

  The particle-containing resin produced as described above can be used as a conductive film, for example, when conductive particles are used as the particles. In particular, a resin or resin precursor that is transparent after curing is used. If it is, it can be applied as a transparent conductive film. Such a conductive film or the like can be obtained as it is or by appropriately processing the film-like particle-containing resin obtained by the above production. Moreover, the structure which provided the layer of particle-containing resin on a predetermined | prescribed board | substrate (transparent substrate etc.) may be sufficient.

  Such a transparent conductive film can be suitably used as a transparent electrode for electronic paper, flexible display, flat panel display, and the like. Since the particle-containing resin constituting the transparent conductive film is obtained by the manufacturing method as described above, it has a small amount of added particles and has sufficient transparency, and also has sufficient conductivity. It will be.

  The particle-containing resin can be applied to a thermal diffusion film having thermal conductivity. When applied to a thermal diffusion film, transparency is rarely required, so the content of particles can be increased. However, according to the manufacturing method of the above-described embodiment, the particle content is the same as the conventional one. However, since a particle-containing resin having excellent thermal conductivity is obtained, it becomes easy to provide a particle-containing resin suitable for a heat diffusion film.

  Such a heat diffusion film can be applied to various uses, and is suitable for application to, for example, a high-frequency high-power amplifier. In order to realize a high-performance high-frequency output amplifier for a wireless communication system for the next and subsequent households, for example, in a face-up amplifier, a metal wire that electrically connects an electrode of a transistor chip and an electrode of a package The inductance is a problem. As a solution, a flip chip structure is proposed in which the transistor chip is turned over and the chip electrode and the package electrode are connected by a short metal bump (projection electrode) such as gold. However, conventional metal bumps are still insufficient in terms of heat dissipation to release a large amount of heat generated in high-power transistors used in high-frequency and high-power amplifiers.

  Therefore, it has been attempted to simultaneously realize heat dissipation and high amplification factor by using CNTs instead of metal bumps. In this technique, conventionally, CNTs are grown so as to be oriented perpendicular to the electrodes, and the CNTs bumps and the flip chip are joined. However, when the CNTs are directly grown on the electrode in this way, the orientation can be unified, but the shape of the CNTs that can be formed may be limited depending on the properties of the electrode. Further, in this case, since the electrode is exposed to high temperature carbon deposition conditions, there is a problem that the material of the electrode is deteriorated.

  On the other hand, according to the thermal diffusion film to which the particle-containing resin obtained according to the present invention is applied, by using CNTs as particles and setting the content within an appropriate range, the anisotropic conductivity described above is aligned in the alignment direction. High thermal conductivity can be obtained. Moreover, even if the thickness of the film is increased, a sufficiently good effect can be obtained. Therefore, if such a heat diffusion film is applied to a high-frequency high-power amplifier and the flip chip is supported on the electrode of the package via this heat diffusion film, it is possible to obtain a high amplification factor with excellent heat dissipation. It becomes possible.

  The preferred embodiments of the particle-containing resin and the method for producing the same according to the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and may be appropriately changed without departing from the spirit of the present invention. Is possible.

  For example, in the first and second embodiments described above, in the first step, the pair of electrodes are spaced apart from each other, and then the raw material mixture is introduced between them. After applying the raw material mixture to one electrode in advance, the other electrode may be bonded to this.

  In the first embodiment, after the second step, the resin or resin precursor is solidified in the third step. However, the second step and the third step may overlap. That is, while applying a voltage between a pair of electrodes to orient the particles, the distance between the electrodes may be increased (second step), and the resin or resin precursor may be solidified (third step). . However, from the viewpoint of causing sufficient orientation of the particles, it is preferable to cause solidification in the third step after a desired interelectrode distance is obtained in the second step.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

[Example 1]
Single-walled carbon nanotubes (SWCNTs) 25 mg and 3M nitric acid were mixed, and this was ultrasonically stirred for 20 minutes. Next, after the obtained mixture was diluted with a large amount of pure water, it was heated to 110 ° C. to evaporate the water and dried. By this treatment, SWCNTs whose surface was modified with a nitro group or the like were obtained.

  The SWCNTs after the modification treatment were mixed in a urethane acrylate UV curable resin (containing 3% by weight of Irgacure 184 as a polymerization initiator) so as to have a concentration of 0.025% by weight, and ultrasonically stirred for 1 hour. . Next, centrifugation was performed at 10,000 rpm for 30 minutes to obtain a raw material mixture in which SWCNTs were dispersed in the resin.

  Using this raw material mixture, a particle-containing resin was produced using a production apparatus 100 as shown in FIG. That is, first, the raw material mixture is applied to one electrode 101, and the other electrode 101 is overlaid thereon. Then, the raw material mixture is pressurized to 100 μm (that is, the distance between the electrodes 101 is 100 μm). The mixture was spread between the electrodes 101.

  Next, SWCNTs were oriented by applying a high frequency alternating current of 10 kHz and 20 Vpp between these electrodes 101 to cause dielectrophoresis. At this time, the current value between the opposing electrodes 101 was monitored and waited until the value hardly changed. Thereafter, while applying high-frequency alternating current, the column 105a on the stage 105 was gradually lowered to gradually widen the distance between the electrodes 101. The distance between the electrodes 101 was increased by 10 μm, and each time, the process waited until the current value between the monitored electrodes 101 hardly changed. This was repeated, and the distance between the electrodes 101 was finally set to 1030 μm. Note that when the distance between the electrodes 101 is increased, the diameter of the sandwiched raw material mixture becomes smaller. Therefore, the raw material mixture was appropriately added so as not to disturb the orientation of the SWCNTs.

Then, with the voltage applied between the electrodes 101, the raw material mixture was irradiated with UV light (wavelength range of 280 to 380 nm) at 10 mJ / cm ² for 200 seconds to cure the UV curable resin, A particle-containing resin (particle-containing resin film) was formed.

  Then, a wedge-shaped material was inserted between the electrodes 101 with respect to the laminate in which the particle-containing resin film was sandwiched between the electrodes 101, and the particle-containing resin film was peeled from one electrode 101. Subsequently, a razor was inserted between the other electrode and the particle-containing resin film, and the particle-containing resin film was slowly peeled off. Thereby, a particle-containing resin film in which SWCNTs were oriented in the film thickness direction as shown in FIG. 2 was obtained. When metal electrodes were formed on both surfaces of the film by sputtering, it was possible to energize between these electrodes (that is, in the film thickness direction).

[Example 2]
A particle-containing resin film was formed in the same manner as in Example 1 except that the concentration of SWCNTs after the modification treatment in the raw material mixture was changed to 0.05% by weight.

  When 50 nm gold electrodes were provided by sputtering gold on both surfaces of the obtained particle-containing resin film, it was possible to energize between these electrodes (that is, in the film thickness direction).

It is a figure which shows typically the cross-sectional structure of the manufacturing apparatus used for the manufacturing method of particle-containing resin. It is a schematic cross section which shows the state of the electrode and raw material mixture in a 2nd process. It is a figure which shows an example of distribution of the electric field strength obtained when it is set as the structure which has arrange | positioned the raw material compound between a pair of electrodes. It is sectional drawing which shows typically operation which expands the distance between electrodes in a 2nd process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Manufacturing apparatus, 101 ... Electrode, 102 ... Support wall, 103 ... Lead wire, 104 ... Power supply, 105 ... Stage, 105a ... Column, 201 ... Substrate, 202 ... Planar electrode, 203 ... Resin component, 204 ... Particles.

Claims (7)

A first step of disposing a raw material mixture containing particles and a resin or a resin precursor between a pair of electrodes disposed to face each other;
A second step of applying a voltage between the pair of electrodes to orient the particles in the raw material mixture in the electric field direction;
A third step of solidifying the resin or resin precursor while applying a voltage between the pair of electrodes,
At least during the second step, the distance between the pair of electrodes is made larger than the distance in the first step,
A method for producing a particle-containing resin. A first step of disposing a raw material mixture containing particles and a resin or a resin precursor between a pair of electrodes disposed to face each other;
A second step of applying a voltage between the pair of electrodes to orient the particles in the raw material mixture in the electric field direction;
While applying a voltage between the pair of electrodes, out of the resin or resin precursor not solidified, the one near the one electrode of the pair of electrodes is solidified, and the one near the other electrode is solidified. A third step of not solidifying the object and increasing the distance between the pair of electrodes;
A fourth step of solidifying all of the resin or resin precursor not solidified while applying a voltage between the pair of electrodes;
A process for producing a particle-containing resin characterized by comprising:   The method for producing a particle-containing resin according to claim 1, wherein the distance between the pair of electrodes is increased while measuring a current value between the electrodes.   2. When the distance between the pair of electrodes is increased, the current value after the distance between the electrodes is increased is prevented from becoming smaller than the value before the distance is increased. 3. A method for producing a particle-containing resin according to 3.   In the said 2nd process, the said particle | grains in the said raw material mixture are orientated by moving to the direction where an electric field is strong, The manufacture of the particle | grain containing resin as described in any one of Claims 1-4 characterized by the above-mentioned. Method.   The method for producing a particle-containing resin according to any one of claims 1 to 5, wherein the particles include fibrous particles.   The method for producing a particle-containing resin according to any one of claims 1 to 6, wherein the particles include fibrous particles and spherical particles.