WO2018225468A1 - Method for manufacturing anisotropic filler-containing sheet - Google Patents

Method for manufacturing anisotropic filler-containing sheet Download PDF

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Publication number
WO2018225468A1
WO2018225468A1 PCT/JP2018/018755 JP2018018755W WO2018225468A1 WO 2018225468 A1 WO2018225468 A1 WO 2018225468A1 JP 2018018755 W JP2018018755 W JP 2018018755W WO 2018225468 A1 WO2018225468 A1 WO 2018225468A1
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anisotropic filler
sheet
film
anisotropic
resin
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PCT/JP2018/018755
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French (fr)
Japanese (ja)
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染谷　昌男
朋佳 萩谷
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三菱瓦斯化学株式会社
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Priority to JP2019523422A priority Critical patent/JP7120229B2/en
Publication of WO2018225468A1 publication Critical patent/WO2018225468A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets

Definitions

  • the present invention relates to a method for producing an anisotropic filler-containing sheet, that is, a sheet comprising an anisotropic filler having an anisotropic particle shape (different in diameter depending on the direction) and a resin.
  • Anisotropic fillers that are anisotropic in particle shape often have anisotropy in their physical properties, and using these properties, sheets containing anisotropic fillers and resins are used in various applications.
  • one direction specifically, the major axis direction (plane direction)
  • the other direction specifically, the minor axis direction (thickness direction), such as scaly hexagonal boron nitride.
  • a heat conductive sheet using an anisotropic filler having a higher thermal conductivity than that of) is known.
  • the anisotropic filler is oriented so that the major axis direction is parallel to the direction in which the thermal conductivity is required (that is, the thickness direction of the sheet) (hereinafter referred to as “longitudinal orientation”). It is preferable that However, when a composition containing an anisotropic filler and a resin serving as a binder is simply applied in a sheet shape with a doctor blade or the like, the major axis direction of each particle is oriented parallel to the surface direction of the sheet (hereinafter referred to as “horizontal”). It is sometimes referred to as “orientation”.), So a sheet having high thermal conductivity cannot be obtained.
  • Patent Document 1 discloses that boron nitride particles are aggregated to form pseudo-isotropic particles (aggregated particles) with respect to thermal conductivity, and a thermal conductive sheet is produced using this. ing.
  • this method requires the preparation of aggregated particles.
  • a heat conductive sheet having a sufficiently high conductivity cannot be obtained.
  • Non-Patent Document 1 a paste containing hexagonal boron nitride particles and a resin is dropped using a discharge nozzle to form one point potting, and a large number of this potting is repeatedly formed to form an aggregate.
  • Patent Document 2 discloses that a primary sheet in which the major axis direction of hexagonal boron nitride particles is oriented parallel to the plane direction is laminated to obtain a laminate, and then 0 with respect to the normal line coming out of the primary sheet surface. It is disclosed that a sheet in which hexagonal boron nitride particles are longitudinally oriented is prepared by slicing the laminate at ⁇ 30 degrees.
  • these methods have a complicated sheet manufacturing method and have a problem in mass productivity.
  • an object of the present invention is to efficiently manufacture an anisotropic filler-containing sheet in which an anisotropic filler is oriented as much as possible by a simple method.
  • the present inventors apply high-frequency vibrations to the membrane. It was found that anisotropic fillers (primary particles) were randomly rearranged, and as a result, the proportion of those that were longitudinally aligned increased, and the present invention was completed using such knowledge.
  • the present invention is as follows.
  • [4] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [3], wherein an aspect ratio of the anisotropic filler is 2 or more.
  • [5] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [4], wherein the anisotropic filler includes scaly boron nitride particles.
  • [6] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [5], wherein the anisotropic filler contains hexagonal boron nitride particles.
  • a coating film of an ink containing an anisotropic filler and a resin is formed, and by imparting high-frequency vibrations thereto, lateral orientation of the anisotropic filler is prevented, and the anisotropic filler is randomly selected.
  • An oriented or longitudinally oriented sheet can be efficiently produced by a simple method. Therefore, according to this invention, a heat conductive sheet with high heat conductivity can be efficiently manufactured by a simple method.
  • FIG. 3 is an FE-SEM image of a cross section of an anisotropic filler-containing sheet (C sheet) obtained in Example 2.
  • FIG. 3 is an FE-SEM image of a cross section of an anisotropic filler-containing sheet (C sheet) obtained in Comparative Example 1.
  • FIG. 3 is an FE-SEM image of a cross section of an anisotropic filler-containing sheet (C sheet) obtained in Comparative Example 1.
  • the present embodiment a mode for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in more detail.
  • the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. Deformation is possible.
  • the method of this embodiment includes a step of forming an ink coating film containing an anisotropic filler and a resin on a support.
  • the anisotropic filler is a particle having an anisotropic shape (the diameter varies depending on the direction), for example, an inorganic compound such as carbon, an inorganic oxide, an inorganic nitride, an inorganic carbide, a resin, or the like.
  • hexagonal boron nitride particles are preferable from the viewpoint of thermal conductivity, and examples of the shape include flat shape, scale shape, plate shape, linear shape, flat plate shape, granular shape, fibrous shape, whisker shape, and the like.
  • the shape is preferably flaky, plate-like or linear, more preferably flaky or plate-like, and particularly preferably flaky.
  • anisotropic filler may be used, or two or more types of anisotropic fillers may be contained within a range that does not impair the effects of the present invention.
  • boron nitride particles and other anisotropic fillers can be used in combination.
  • the aspect ratio (the ratio of the longest diameter to the thickness) is not limited, but is preferably 2 or more, more preferably 5 or more. More preferably, it is the above. Although there is no upper limit to the aspect ratio, it is usually 1000 or less.
  • seat when used as a heat conductive sheet, especially when incorporating in a heat-emitting electronic component etc., it may be used under the high temperature of 180 degreeC or more.
  • the average longest diameter of the anisotropic filler is set to It is preferable that it is 1/2 or less of the thickness of this, and it is more preferable that it is 1/3 or less.
  • the anisotropic filler protrudes on the surface of the sheet, the surface shape of the sheet deteriorates, and the adhesion when producing a laminated sheet with other members is reduced. In addition, the withstand voltage characteristics may deteriorate.
  • the average longest diameter of the anisotropic filler is too small, the probability that the heat conduction path is connected from the top to the bottom in the thickness direction of the heat conduction sheet is reduced, and the heat conductivity in the thickness direction of the heat conduction sheet is insufficient. It may become.
  • the particle size of the anisotropic filler is not limited, but the average longest diameter is preferably 0.1 to 500 ⁇ m, more preferably 0.5 to 200 ⁇ m, and 1 to 100 ⁇ m. It is particularly preferred that Even in the case of having the average longest diameter as described above, there may be a very large number in the raw material that does not affect the average longest diameter. Therefore, in the present embodiment, it is preferable that the anisotropic filler is used after a material having a predetermined particle size or more is removed from the raw material by a sieve or the like in advance.
  • the anisotropic filler may be primary particles in the ink or may be in the form of aggregated particles (secondary particles) in which the primary particles are aggregated.
  • aggregated particles depending on the vibration application conditions (frequency, application time, etc.) in the high-frequency vibration application process, the rearrangement of fillers may not be sufficiently achieved, or there may be voids in the finally obtained sheet. May remain. Therefore, it is preferable to use an anisotropic filler that exists in the form of primary particles.
  • the shape, particle size and aspect ratio of the anisotropic filler can be determined by observing the particles with an electron microscope. Specifically, 200 or more particles were randomly selected from an image taken with a scanning electron microscope (SEM) (for example, FE-SEM-EDX (SU8220): manufactured by Hitachi High-Technology Corporation), Judging from its shape. The longest diameter is the length of the long side of the rectangle with the smallest area circumscribing the particles. In the case of a scale-like or flat-plate anisotropic filler, 200 or more particles showing the plane direction are selected at random, and the longest diameter is obtained. As for the aspect ratio, 200 particles or more are randomly selected from the image, and the average value of each of the longest diameter and the thickness is selected. It can be determined by calculating and determining the ratio.
  • SEM scanning electron microscope
  • the volume fraction of the anisotropic filler in the film (ink) (the content of the anisotropic filler in the solid content) can be appropriately set according to the application, for example, 10 to 90% by volume. This can be done. If the anisotropic filler is less than 10% by volume, the anisotropic filler may be too small to obtain desired characteristics (for example, thermal conductivity). On the other hand, when the content of the anisotropic filler exceeds 90% by volume, the amount of the anisotropic filler may be too much, the sheet may become brittle, or the electrical insulation of the sheet may be reduced. In addition, the viscosity of the ink increases, and it may be difficult to obtain a thin and flat sheet.
  • the volume of the anisotropic filler is a value obtained from the specific gravity of the material (compound) constituting the anisotropic filler and the mass of the anisotropic filler contained in the ink.
  • the resin contained in the ink is not limited.
  • a thermoplastic resin for example, polyolefin, vinyl chloride resin, methyl methacrylate resin, nylon, fluorine resin, etc.
  • a curable resin for example, an epoxy resin
  • Phenol resin Phenol resin
  • urea resin urea resin
  • melamine resin unsaturated polyester resin
  • silicon resin and the like
  • synthetic rubber synthetic rubber.
  • curable resins are preferable, and thermosetting resins are particularly preferable.
  • the curable resin may be added to the concavo-convex film in the form of a resin composition mixed with a curing agent or a curing catalyst, and further, a corresponding raw material (a precursor of monomer, dimer, oligomer, etc.). Body) may be added.
  • thermosetting resins examples include polyimide resins, polyaminobismaleimide (polybismaleimide) resins, bismaleimide / triazine resins, polyamideimide resins, polyetherimide resins, and other polyimide resins; polybenzoxazole resins; polyethers Resins; benzocyclobutene resins; silicone resins; epoxy resins such as phenolic epoxy resins and alcoholic epoxy resins.
  • an epoxy resin, a polyether resin, a benzocyclobutene resin, and a silicone resin are preferable because of high thermal conductivity and good solubility in an organic solvent, and an epoxy resin is particularly preferable.
  • These resins may be used alone or in combination of two or more in any combination and ratio.
  • the ink can contain a solvent or a dispersion medium as necessary.
  • a solvent or a dispersion medium when a thermosetting resin is used as the resin, it is preferable to contain a solvent or a dispersion medium.
  • the type of the solvent (dispersion medium) is not particularly limited, and examples thereof include ketones such as acetone, methyl ethyl ketone, methyl cellosolve, and cyclopentanone; aromatic hydrocarbons such as toluene and xylene; cyclohexane, cyclopentane, and the like.
  • Cycloalkanes ; alcohols such as methanol, ethanol and n-butyl alcohol; esters such as ethyl acetate, propyl acetate and butyl acetate; amides such as dimethylformamide; organic solvents such as propylene glycol monomethyl ether and its acetate It is done.
  • a solvent may be used individually by 1 type, or may use 2 or more types together.
  • the viscosity of the ink is adjusted to be constant, and after applying high-frequency vibration, a solvent whose evaporation rate is 4.5 times or less that of butyl acetate is used from the viewpoint of quickly drying the ink. It is preferable to use it.
  • the evaporation rate is too high, a large amount of solvent volatilizes during film formation or high frequency vibration application, and the viscosity of the ink changes. On the other hand, if the evaporation rate is too slow, drying of the solvent becomes difficult and drying at a high temperature for a long time is required. However, when such drying is performed, the curing proceeds when a thermosetting resin is used as the resin. End up. From such a viewpoint, it is more preferable to use a solvent having a butyl acetate evaporation rate of 0.05 to 4.5 times.
  • the content of the solvent is not limited, and can be appropriately determined in consideration of, for example, the viscosity of the ink, and is usually about 10 to 50% by mass of the ink.
  • the amount of the solvent is insufficient, it is difficult to form a film having a uniform thickness, and unevenness may occur on the film surface.
  • the amount of the solvent is excessive, the orientation retention of the anisotropic filler in the film after application of high-frequency vibration may be inferior.
  • the ink may further contain various additives that are conventionally used depending on the application.
  • additives include a coupling agent for improving adhesion between the anisotropic filler and the resin, the above-described curing agent and curing catalyst, resin curing accelerator, viscosity modifier, and dispersion.
  • Stabilizers, surfactants, emulsifiers, low elasticity agents, diluents, antifoaming agents, ion trapping agents and the like can be mentioned. Any of these may be used alone or in a combination of two or more in any combination and ratio.
  • aminosilanes such as ⁇ -aminopropyltriethoxysilane and N- ⁇ - (aminoethyl) - ⁇ -aminopropyltrimethoxylane; ⁇ -glycidoxypropyltrimethoxysilane, ⁇ - (3,4 Epoxy silanes such as epoxycyclohexyl) ethyltrimethoxysilane; Vinylsilanes such as ⁇ -methacryloxypropyltrimethoxysilane and vinyl-tri ( ⁇ -methoxyethoxy) silane; N- ⁇ - (N-vinylbenzylaminoethyl)- Examples include cationic silanes such as ⁇ -aminopropyltrimethoxysilane hydrochloride; silane coupling agents such as phenylsilane.
  • silane coupling agents can be used alone or in combination of two or more.
  • the coupling agent is preferably added in an amount of 0.01 to 10% by mass, more preferably 1 to 2% by mass relative to the anisotropic filler.
  • the coupling agent can be added to the anisotropic filler in advance, and the method is not limited.
  • the coupling agent stock solution is uniformly dispersed in the anisotropic filler that is stirred at high speed by a stirrer. And a wet method in which an anisotropic filler is immersed in a dilute solution of a coupling agent and stirred.
  • the viscosity of the ink there is no limitation on the viscosity of the ink.
  • the viscosity may be 0.1 to 100 Pa ⁇ s, and may be 5 to 20 Pa ⁇ s.
  • the method for preparing the ink is not particularly limited, and each component may be mixed. In that case, in order to mix each component uniformly, well-known processes, such as stirring, mixing, and a kneading
  • the membrane is formed on a support.
  • a support having a strength capable of holding a film and withstanding high-frequency vibration and having good releasability when peeled later is preferable.
  • Specific examples include metal foils such as copper and aluminum, metal plates, plastic films, plastic plates, and the like.
  • the support may be peeled off after forming the sheet.
  • the support has characteristics that are not suitable for the use of the sheet (for example, in the case where the sheet is a heat conductive sheet for an insulating layer of an electronic circuit, a conductive material such as a metal foil as the support) In the case of using the above, it is preferable to peel the support from the sheet.
  • the support does not necessarily have to be peeled off, and it is also possible to use a laminate with the support remaining finally as a sheet.
  • the support is peeled from the sheet, there is no limitation on the timing of the peeling step, but it is preferable that the film is cured to some extent and can become independent.
  • the method for forming the above-described ink film on such a support there is no limitation on the method for forming the above-described ink film on such a support.
  • rolls such as gravure coating, roll coating, bar coating, die coating, dipping, and knife coating are used.
  • the resin is a thermoplastic resin, it can be melt coated such as hot melt coating.
  • a method for forming a coating film can be selected.
  • the thickness of the coating film can be appropriately determined according to the application, purpose, etc., and can be, for example, 10 to 5000 ⁇ m.
  • the manufacturing method of this embodiment has the process of giving the vibration which has a frequency of 5 kHz or more to a film
  • the anisotropic fillers are rearranged, and even if they are laterally oriented, they can approach random orientation and further longitudinal orientation. found. Such rearrangement is presumed to be due to the action of a shock wave when bubbles generated by the cavitation phenomenon generated by applying high-frequency vibrations, but the mechanism does not depend on this.
  • the film to which vibration is applied needs to be flowable, ie, liquid (including liquid (including sol and gel)) so as to allow rearrangement of the anisotropic filler.
  • the ink does not contain a solvent or a dispersion medium and the resin is a thermoplastic resin (when the ink is a hot melt ink)
  • the film formation method is melt coating.
  • the film is formed after the film is formed. May be cooled and hardened (solidified). Therefore, in such a case, the film can be flowed in the high frequency vibration application process by continuously heating the film to maintain the flowable state or by heating the cured film once again to return to the liquid state. To be in.
  • vibration can be applied to the coating film via a support that holds the coating film using an ultrasonic generator.
  • the frequency of vibration is 5 kHz or more and there is no upper limit, but it may be, for example, 10 to 1000 kHz or 15 to 1000 kHz.
  • vibration having a single frequency may be applied, vibration that changes in frequency over time may be used, and a plurality of vibrations having different frequencies may be used. Use in combination (sweep vibration) is also effective.
  • the appropriate frequency varies depending on the shape and size of the anisotropic filler.
  • a lower frequency is suitable as the particle size of the filler is larger, and a higher frequency is suitable as the particle size is smaller. That is, since the impact force of high-frequency vibration (ultrasonic waves) increases as the frequency decreases, increasing the frequency tends to cause large anisotropic fillers to be randomly oriented. On the other hand, since the standing wave interval is narrower as the frequency is higher, lowering the frequency is effective for randomly orienting small anisotropic fillers.
  • the time for applying the high-frequency vibration can be appropriately determined according to the frequency and film thickness of the vibration. For example, it can be 1 to 300 seconds.
  • a step of pressing the film in which the anisotropic fillers are rearranged as described above may be further included, whereby the voids contained in the film can be removed. If there are voids in the film, the thermal conductivity may decrease. Therefore, such a press is particularly effective when the sheet is used as a heat conductive sheet.
  • the pressing conditions pressure, temperature, time, atmosphere, etc.
  • the arrangement of anisotropic fillers in the film in consideration of the types of anisotropic fillers and resins, the filler content in the film, etc. What is necessary is just to determine suitably the conditions which can remove a space
  • the pressing pressure can be, for example, 0.01 to 20 MPa, may be 10 MPa or less, and usually 5 MPa or less is sufficient.
  • the film may be semi-cured by removing some or all of the solvent from the film prior to the pressing step.
  • methods such as vacuum drying and heat drying can be appropriately employed.
  • the film formed as described above can be appropriately dried and / or cured as necessary.
  • curing there is no limitation on the curing method, and curing can be performed by heating or light irradiation according to the type of resin.
  • the thickness of the anisotropic filler-containing sheet may be appropriately determined according to the application, and may be, for example, 10 to 1000 ⁇ m.
  • the thermal conductivity in the thickness direction of the sheet is. It is preferably 0 W / m ⁇ K or more, more preferably 7.0 W / m ⁇ K or more, and still more preferably 10.0 W / m ⁇ K or more.
  • the thermal conductivity There is no upper limit to the thermal conductivity, and the larger the better. According to the manufacturing method of the present embodiment, it is possible to manufacture a heat conductive sheet having such a high thermal conductivity.
  • the thermal conductivity (W / m ⁇ K) was calculated from the product of (2) Orientation Strength Ratio
  • I (002) diffraction line 26.5 °
  • I (100) diffraction line 41.5 °
  • the ratio (I (002) / I (100) is the orientation of the particles present in the vicinity of the surface of the sheet.
  • the thickness direction of the hexagonal boron nitride primary particles coincides with the crystallographic I (002) diffraction line, that is, the c-axis direction, and the in-plane direction coincides with the I (100) diffraction line, that is, the a-axis direction.
  • the boron nitride primary particles constituting the boron nitride particle aggregate have a completely random orientation (non-orientation), (I (002) / I (100)) ⁇ 6.7 (“JCPDS [powder X Line Diffraction Database] ”No. 34-0421 [BN] crystal density value [Dx]).
  • the smaller (I (002) / I (100)) means that the a-axis direction of hexagonal boron nitride particles is oriented in the thickness direction.
  • a test piece (5 mm ⁇ 5 mm ⁇ thickness 0.2 mm) was cut out from the sheets obtained in Examples and Comparative Examples, and “Fully Automatic Horizontal Multipurpose X-ray Diffractometer SmartLab” (manufactured by Rigaku Corporation, X X-rays are irradiated in the thickness direction of the test piece using a radiation source: CuK ⁇ ray, tube voltage: 45 kV, tube current: 360 mA), and intensity of I (002) diffraction line and I (100) diffraction line Was measured.
  • Example 1 A sheet containing scaly boron nitride particles and a resin was produced using the method of the present invention. 100 parts by mass of a triphenylmethane type epoxy resin (“EPPN-501H” manufactured by Nippon Kayaku), 63 parts by mass of a curing agent (phenonovolak-based curing agent, “DL-92” manufactured by Meiwa Kasei), and a curing catalyst (2-phenylimidazole) , Shikoku Chemicals) 0.01 parts by mass was mixed to prepare a resin composition. The mixing ratio of the epoxy resin and the curing agent was such that the functional group of the epoxy resin / curing agent was 1.0 in terms of equivalent ratio.
  • EPPN-501H triphenylmethane type epoxy resin
  • DL-92 phenonovolak-based curing agent
  • 2-phenylimidazole 2-phenylimidazole
  • Shikoku Chemicals Shikoku Chemicals
  • boron nitride primary particles (“PT110” manufactured by Momentive Performance) having an average particle diameter of 45 ⁇ m as an anisotropic filler and 3-glycoxide propyltrimethoxylane (manufactured by Tokyo Chemical Industry Co., Ltd.) as a coupling agent are used. 1.5 parts by mass were dropped, and the mixture was stirred with a rotation / revolution mixer (Sinky AR-100). Subsequently, in 50 parts by mass of a solvent (methyl ethyl ketone), 39% by volume of the resin composition and 50 parts by mass in total of 61% by volume of boron nitride primary particles to which the coupling agent was added were mixed to prepare an ink. .
  • a solvent methyl ethyl ketone
  • This ink was coated on a support (copper foil) with an applicator (Imoto Seisakusho Co., Ltd.) (gap: about 1.5 mm) to form a flat coating film. Subsequently, this was placed on an aluminum plate, the vibration element of an ultrasonic generator (Ultrasonic Homogenizer US-600T manufactured by Nippon Seiki Seisakusho Co., Ltd.) was applied to the aluminum plate, and the coating was applied to the coating film via the aluminum plate and copper foil. Ultrasonic vibration was applied for a minute and then allowed to stand. Subsequently, the said coating film was dried at 120 degreeC for 10 minutes, the solvent was removed, and the semi-hardened sheet (B sheet) (about 1.5 mm thickness) was produced. This was vacuum-pressed at 180 ° C. for 2 hours under the condition of 10 MPa, cured, and finally the copper foil was peeled off to produce an anisotropic filler-containing sheet (C sheet).
  • an ultrasonic generator Ultrasonic Homogen
  • Example 2 An anisotropic filler-containing sheet was obtained in the same manner as in Example 1 except that the pressing pressure during vacuum pressing on the semi-cured sheet was 5 MPa.
  • Example 3 In 50 parts by mass of a solvent (methyl ethyl ketone), an ink was prepared by mixing 30% by volume of the resin composition and 50 parts by mass in total of 70% by volume of boron nitride primary particles to which the coupling agent was added (ink solids).
  • An anisotropic filler-containing sheet was produced in the same manner as in Example 1 except that the ratio of the anisotropic filler in the minute was changed.
  • Example 4 An anisotropic filler-containing sheet was prepared in the same manner as in Example 1, except that boron nitride primary particles having an average particle diameter of 12 ⁇ m (“ ⁇ BN-S03” manufactured by Tokuyama) were used as the anisotropic filler. (Example 5) An anisotropic filler-containing sheet was obtained in the same manner as in Example 4 except that the pressing pressure during vacuum pressing on the semi-cured sheet was 5 MPa. (Example 6) In 50 parts by mass of a solvent (methyl ethyl ketone), an ink was prepared by mixing 30% by volume of the resin composition and 50 parts by mass in total of 70% by volume of boron nitride primary particles to which the coupling agent was added (ink solids). An anisotropic filler-containing sheet was produced in the same manner as in Example 4 except that the proportion of the anisotropic filler in the minute was changed.
  • a solvent methyl ethyl ketone
  • Table 1 shows the thermal conductivity of the anisotropic filler-containing sheets prepared in Examples 1 to 6 and Comparative Examples 1 to 6 and the orientation strength ratio (I (002) / I (100)) of the boron nitride primary particles. Show.
  • the sheets of Examples 1 and 2 use the same ink, and the orientation strength ratio I (002) / I (100) is small (in the case of random orientation) as compared with Comparative Example 1 prepared without applying high-frequency vibration. Nearly the theoretical value of 6.7), the thermal conductivity was about 2-3 times higher.
  • the orientation strength ratio of the particles in the vicinity of the sheet surface evaluated by the X-ray diffraction method is compared with that before pressing (B sheet) after pressing (C sheet).
  • the sheet of Example 4 has a larger orientation strength ratio than the sheet of Comparative Example 5 produced in the same manner except that aggregated boron nitride particles were used as the anisotropic filler and high frequency vibration was not applied. However, the porosity was low, resulting in a high thermal conductivity.
  • the sheet of Example 6 uses aggregated boron nitride particles as an anisotropic filler, and the orientation strength ratio is the same as that of the sheet of Comparative Example 6 prepared in the same manner except that high frequency vibration is not applied. Although large, the porosity was low, resulting in high thermal conductivity.
  • the anisotropic filler-containing sheet produced by the production method of the present invention can be used for various applications.
  • the anisotropic filler-containing sheet produced by the production method of the present invention can be used as a thermal conductive sheet when a thermally conductive material is used as the anisotropic filler, and particularly has high thermal conductivity and insulation.
  • various applications that require thermal conductivity and insulation for example, materials for heat-dissipating insulating layers and adhesive layers in heat-generating electronic components such as circuit boards for power equipment and semiconductor power devices).

Abstract

Provided is a method for manufacturing an anisotropic filler-containing sheet including: a step of forming, on a support, a film of an ink that comprises an anisotropic filler and a resin; and a step of imparting vibrations having a frequency of 5 kHz or higher to the film while the film is flowable.

Description

異方性フィラー含有シートの製造方法Method for producing anisotropic filler-containing sheet
　本発明は、異方性フィラー含有シート、すなわち、粒子形状に異方性のある（方向によって径の異なる）異方性フィラーと樹脂を含むシートの製造方法に関する。 The present invention relates to a method for producing an anisotropic filler-containing sheet, that is, a sheet comprising an anisotropic filler having an anisotropic particle shape (different in diameter depending on the direction) and a resin.
　粒子形状に異方性のある異方性フィラーは、その物性にも異方性を有することが多く、その性質を利用して、各種用途において異方性フィラーと樹脂を含むシートが利用されている。
　代表的な例として、鱗片状六方晶窒化ホウ素のように、ある方向（具体的には、長径方向（面方向））の方が他の方向（具体的には、短径方向（厚み方向））よりも熱伝導率が高い異方性フィラーを用いた熱伝導シートが知られている。このような熱伝導シートにおいては、異方性フィラーが、長径方向が熱伝導性の求められる方向（すなわち、シートの厚み方向）に対して平行となるように配向（以下、「縦配向」ということがある。）していることが好ましい。
　しかし、異方性フィラーとバインダとなる樹脂を含む組成物をドクターブレード等で単純にシート状に塗工したのでは、各粒子の長径方向はシートの面方向に平行に配向（以下、「横配向」ということがある。）してしまうため、熱伝導率の高いシートが得られない。 Anisotropic fillers that are anisotropic in particle shape often have anisotropy in their physical properties, and using these properties, sheets containing anisotropic fillers and resins are used in various applications. Yes.
As a typical example, one direction (specifically, the major axis direction (plane direction)) is in the other direction (specifically, the minor axis direction (thickness direction), such as scaly hexagonal boron nitride. A heat conductive sheet using an anisotropic filler having a higher thermal conductivity than that of) is known. In such a heat conductive sheet, the anisotropic filler is oriented so that the major axis direction is parallel to the direction in which the thermal conductivity is required (that is, the thickness direction of the sheet) (hereinafter referred to as “longitudinal orientation”). It is preferable that
However, when a composition containing an anisotropic filler and a resin serving as a binder is simply applied in a sheet shape with a doctor blade or the like, the major axis direction of each particle is oriented parallel to the surface direction of the sheet (hereinafter referred to as “horizontal”). It is sometimes referred to as “orientation”.), So a sheet having high thermal conductivity cannot be obtained.
　この点、特許文献１には、窒化ホウ素粒子を凝集させて、熱伝導性に関し疑似的に等方性な粒子（凝集粒子）とし、これを利用して熱伝導シートを製造することが開示されている。
　しかしながら、この方法では、凝集粒子の調製が必要となる。加えて、凝集粒子中には空隙が混入することが避けられないところ、シート中に空隙が存在するとその熱伝導率は低下してしまうため、異方性フィラーの横配列が防げたとしても熱伝導率が十分に高い熱伝導シートは得られない。 In this regard, Patent Document 1 discloses that boron nitride particles are aggregated to form pseudo-isotropic particles (aggregated particles) with respect to thermal conductivity, and a thermal conductive sheet is produced using this. ing.
However, this method requires the preparation of aggregated particles. In addition, it is inevitable that voids are mixed in the agglomerated particles, but if there are voids in the sheet, the thermal conductivity decreases, so even if the anisotropic fillers can be prevented from being laterally arranged, heat is not generated. A heat conductive sheet having a sufficiently high conductivity cannot be obtained.
　また、非特許文献１には、六方晶窒化ホウ素粒子と樹脂を含むペーストを吐出ノズルを用いて滴下することにより１点のポッティングを成形し、このポッティングを繰り返し多数形成して集合体にすることで、六方晶窒化ホウ素粒子が縦配向したシートを作成することが開示されている。さらに、特許文献２には、六方晶窒化ホウ素粒子の長径方向が面方向に対して平行に配向した一次シートを積層して積層体を得た後、一次シート面から出る法線に対して０～３０度で積層体をスライスすることによって、六方晶窒化ホウ素粒子が縦配向したシートを作成することが開示されている。
　しかしながら、これらの方法はシートの製造方法が複雑で、量産性に課題がある。 In Non-Patent Document 1, a paste containing hexagonal boron nitride particles and a resin is dropped using a discharge nozzle to form one point potting, and a large number of this potting is repeatedly formed to form an aggregate. Thus, it is disclosed that a sheet in which hexagonal boron nitride particles are longitudinally oriented is prepared. Furthermore, Patent Document 2 discloses that a primary sheet in which the major axis direction of hexagonal boron nitride particles is oriented parallel to the plane direction is laminated to obtain a laminate, and then 0 with respect to the normal line coming out of the primary sheet surface. It is disclosed that a sheet in which hexagonal boron nitride particles are longitudinally oriented is prepared by slicing the laminate at ˜30 degrees.
However, these methods have a complicated sheet manufacturing method and have a problem in mass productivity.
特開２０１５－６９８０号公報Japanese Patent Laid-Open No. 2015-6980 特開２０１２－３８７６３号公報JP 2012-38763 A
　本発明は、上記のような問題に鑑み、異方性フィラーがなるべく縦配向している異方性フィラー含有シートを、簡易な方法で効率よく製造することを課題とする。 In view of the above problems, an object of the present invention is to efficiently manufacture an anisotropic filler-containing sheet in which an anisotropic filler is oriented as much as possible by a simple method.
　本発明者らは、異方性フィラーと樹脂を含む膜（層）が流動性を有している間に（すなわち、流動可能である間に）、該膜に高周波数の振動を与えると、異方性フィラー（一次粒子）がランダムに再配列し、その結果、縦配向したものの割合が高まることを見出し、このような知見を利用して本発明を完成させた。 When the membrane (layer) containing the anisotropic filler and the resin has fluidity (that is, while the membrane can flow), the present inventors apply high-frequency vibrations to the membrane. It was found that anisotropic fillers (primary particles) were randomly rearranged, and as a result, the proportion of those that were longitudinally aligned increased, and the present invention was completed using such knowledge.
　すなわち、本発明は、以下のとおりである。
［１］支持体上に、異方性フィラーと樹脂を含むインクの膜を形成する工程、及び
　前記膜が流動可能である間に、前記膜に５ｋＨｚ以上の周波数を有する振動を与える工程、
　を含む、異方性フィラー含有シートの製造方法。
［２］前記振動の周波数が、１０～１０００ｋＨｚである、［１］に記載の異方性フィラー含有シートの製造方法。
［３］前記異方性フィラーの平均最長径が、０．５μｍ～２００μｍである、［１］又は［２］に記載の異方性フィラー含有シートの製造方法。
［４］前記異方性フィラーのアスペクト比が、２以上である、［１］～［３］のいずれかに記載の異方性フィラー含有シートの製造方法。
［５］前記異方性フィラーが、鱗片状の窒化ホウ素粒子を含む、［１］～［４］のいずれかに記載の異方性フィラー含有シートの製造方法。
［６］前記異方性フィラーが、六方晶窒化ホウ素粒子を含む、［１］～［５］のいずれかに記載の異方性フィラー含有シートの製造方法。
［７］前記膜中の前記異方性フィラーの体積率が、１０～９０体積％である、［１］～［６］のいずれかに記載の異方性フィラー含有シートの製造方法。
［８］前記樹脂が熱硬化性樹脂を含む、［１］～［７］のいずれかに記載の異方性フィラー含有シートの製造方法。
［９］さらに、前記膜をプレスする工程を含む、［１］～［８］のいずれかに記載の異方性フィラー含有シートの製造方法。 That is, the present invention is as follows.
[1] A step of forming an ink film containing an anisotropic filler and a resin on a support, and a step of applying vibration having a frequency of 5 kHz or more to the film while the film is flowable.
The manufacturing method of an anisotropic filler containing sheet | seat containing.
[2] The method for producing an anisotropic filler-containing sheet according to [1], wherein the vibration frequency is 10 to 1000 kHz.
[3] The method for producing an anisotropic filler-containing sheet according to [1] or [2], wherein an average longest diameter of the anisotropic filler is 0.5 μm to 200 μm.
[4] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [3], wherein an aspect ratio of the anisotropic filler is 2 or more.
[5] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [4], wherein the anisotropic filler includes scaly boron nitride particles.
[6] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [5], wherein the anisotropic filler contains hexagonal boron nitride particles.
[7] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [6], wherein the volume fraction of the anisotropic filler in the film is 10 to 90% by volume.
[8] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [7], wherein the resin contains a thermosetting resin.
[9] The method for producing an anisotropic filler-containing sheet according to any one of [1] to [8], further comprising a step of pressing the film.
　本発明によれば、異方性フィラーと樹脂を含むインクの塗膜を形成し、これに高周波の振動を付与するだけで、異方性フィラーの横配向を防ぎ、異方性フィラーがランダムに配向、或は、縦配向したシートを簡易な方法で効率よく製造することができる。
　したがって、本発明によれば、熱伝導率の高い熱伝導シートを簡易な方法で効率よく製造することができる。 According to the present invention, a coating film of an ink containing an anisotropic filler and a resin is formed, and by imparting high-frequency vibrations thereto, lateral orientation of the anisotropic filler is prevented, and the anisotropic filler is randomly selected. An oriented or longitudinally oriented sheet can be efficiently produced by a simple method.
Therefore, according to this invention, a heat conductive sheet with high heat conductivity can be efficiently manufactured by a simple method.
実施例２で得られた異方性フィラー含有シート（Ｃシート）の断面のＦＥ－ＳＥＭ画像である。3 is an FE-SEM image of a cross section of an anisotropic filler-containing sheet (C sheet) obtained in Example 2. FIG. 比較例１で得られた異方性フィラー含有シート（Ｃシート）の断面のＦＥ－ＳＥＭ画像である。3 is an FE-SEM image of a cross section of an anisotropic filler-containing sheet (C sheet) obtained in Comparative Example 1. FIG.
　以下、本発明を実施するための形態（以下、「本実施形態」という。）についてさらに詳細に説明するが、本発明はこれに限定されるものではなく、その要旨を逸脱しない範囲で様々な変形が可能である。 Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in more detail. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. Deformation is possible.
　本実施形態の方法は、支持体上に、異方性フィラーと樹脂を含むインクの塗膜を形成する工程を含む。
　本実施形態において、異方性フィラーとは、異方性形状を有する（方向によって径が異なる）粒子であり、例えば、カーボン、無機酸化物、無機窒化物、無機炭化物等の無機化合物や樹脂等からなり、具体例としては、窒化ホウ素、窒化アルミニウム、酸化アルミニウム、酸化亜鉛、炭化ケイ素、水酸化アルミニウムなどの金属酸化物、金属窒化物、金属炭化物、金属水酸化物；金属や合金；グラファイト、黒鉛、ダイヤモンドなどの炭素材料；高熱伝導性樹脂等からなる、繊維状、針状、鱗片状、ウィスカー状などの粒子が挙げられる。
　中でも、熱伝導性の観点から六方晶窒化ホウ素粒子が好ましく、その形状としては、例えば、偏平状、鱗片状、板状、線状、平板状、顆粒状、繊維状、ウィスカー状などが挙げられ、好ましくは、鱗片状、板状又は線状であり、より好ましくは鱗片状又は板状であり、とりわけ好ましくは、鱗片状である。
　本実施形態においては、異方性フィラーは１種類のみを用いてもよいし、本発明の効果を損なわない範囲で、２種以上の異方性フィラーを含有してもよい。例えば、窒化ホウ素粒子と、それ以外の異方性フィラーとを組み合わせて用いることもできる。 The method of this embodiment includes a step of forming an ink coating film containing an anisotropic filler and a resin on a support.
In the present embodiment, the anisotropic filler is a particle having an anisotropic shape (the diameter varies depending on the direction), for example, an inorganic compound such as carbon, an inorganic oxide, an inorganic nitride, an inorganic carbide, a resin, or the like. Specific examples include boron nitride, aluminum nitride, aluminum oxide, zinc oxide, silicon carbide, aluminum hydroxide and other metal oxides, metal nitrides, metal carbides, metal hydroxides; metals and alloys; graphite, Examples thereof include carbon materials such as graphite and diamond; and particles such as fibers, needles, scales, and whiskers made of a highly thermally conductive resin.
Among these, hexagonal boron nitride particles are preferable from the viewpoint of thermal conductivity, and examples of the shape include flat shape, scale shape, plate shape, linear shape, flat plate shape, granular shape, fibrous shape, whisker shape, and the like. The shape is preferably flaky, plate-like or linear, more preferably flaky or plate-like, and particularly preferably flaky.
In the present embodiment, only one type of anisotropic filler may be used, or two or more types of anisotropic fillers may be contained within a range that does not impair the effects of the present invention. For example, boron nitride particles and other anisotropic fillers can be used in combination.
　異方性フィラーが鱗片状や平板状である場合、そのアスペクト比（厚さに対する最長径の比）に限定はないが、２以上であることが好ましく、５以上であることがより好ましく、１０以上であることがさらに好ましい。アスペクト比に上限はないが、通常、１０００以下である。 When the anisotropic filler is scale-like or flat, the aspect ratio (the ratio of the longest diameter to the thickness) is not limited, but is preferably 2 or more, more preferably 5 or more. More preferably, it is the above. Although there is no upper limit to the aspect ratio, it is usually 1000 or less.
　また、異方性フィラー含有シートが熱伝導シートとして使用される場合、特に発熱性電子部品等に組み込まれる場合などには、１８０℃以上の高温下で使用されることがある。このような１８０℃以上の高温下での使用でも、周辺部材の寿命を延ばし、高熱伝導性および耐電圧特性などの信頼性を確保するためには、異方性フィラーの平均最長径は、シートの厚みの１／２以下であることが好ましく、１／３以下であることがより好ましい。
　平均最長径がシートの厚みの１/２を超えると、シートの表面に異方性フィラーが突出して、シートの表面形状が悪化し、他部材との張り合わせシートを作製する際の密着性が低下し、耐電圧特性が低下することがある。
　一方で、異方性フィラーの平均最長径が小さ過ぎると、熱伝導パスが熱伝導シートの厚み方向に上から下まで繋がる確率が小さくなり、熱伝導シートの厚み方向の熱伝導率が不十分となることがある。
　以上のような観点から、異方性フィラーの粒径に限定はないものの、平均最長径は０．１～５００μｍであることが好ましく、０．５～２００μｍであることがより好ましく、１～１００μｍであることが特に好ましい。
　なお、上記のような平均最長径を有する場合であっても、平均最長径には影響を与えない程度の個数で非常に大きいものが原料中に存在していることもある。そこで、本実施形態においては、異方性フィラーは、予め、ふるいなどで所定以上の粒径のものを原料から除去してから用いることが好ましい。 Moreover, when an anisotropic filler containing sheet | seat is used as a heat conductive sheet, especially when incorporating in a heat-emitting electronic component etc., it may be used under the high temperature of 180 degreeC or more. In order to extend the life of peripheral members and ensure reliability such as high thermal conductivity and withstand voltage characteristics even when used at such a high temperature of 180 ° C. or higher, the average longest diameter of the anisotropic filler is set to It is preferable that it is 1/2 or less of the thickness of this, and it is more preferable that it is 1/3 or less.
When the average longest diameter exceeds 1/2 of the thickness of the sheet, the anisotropic filler protrudes on the surface of the sheet, the surface shape of the sheet deteriorates, and the adhesion when producing a laminated sheet with other members is reduced. In addition, the withstand voltage characteristics may deteriorate.
On the other hand, if the average longest diameter of the anisotropic filler is too small, the probability that the heat conduction path is connected from the top to the bottom in the thickness direction of the heat conduction sheet is reduced, and the heat conductivity in the thickness direction of the heat conduction sheet is insufficient. It may become.
In view of the above, the particle size of the anisotropic filler is not limited, but the average longest diameter is preferably 0.1 to 500 μm, more preferably 0.5 to 200 μm, and 1 to 100 μm. It is particularly preferred that
Even in the case of having the average longest diameter as described above, there may be a very large number in the raw material that does not affect the average longest diameter. Therefore, in the present embodiment, it is preferable that the anisotropic filler is used after a material having a predetermined particle size or more is removed from the raw material by a sieve or the like in advance.
　異方性フィラーは、インク中において一次粒子であってもよいし、一次粒子が凝集した凝集粒子（二次粒子）の状態であってもよい。もっとも、凝集粒子である場合には、高周波振動付与工程における振動付与条件（周波数、付与時間等）によっては、フィラーの再配列が十分に達成されないことや、最終的に得られるシート中に空隙が残存することがある。そのため、異方性フィラーとしては、一次粒子の状態で存在しているものを用いることが好ましい。 The anisotropic filler may be primary particles in the ink or may be in the form of aggregated particles (secondary particles) in which the primary particles are aggregated. However, in the case of aggregated particles, depending on the vibration application conditions (frequency, application time, etc.) in the high-frequency vibration application process, the rearrangement of fillers may not be sufficiently achieved, or there may be voids in the finally obtained sheet. May remain. Therefore, it is preferable to use an anisotropic filler that exists in the form of primary particles.
　異方性フィラーの形状、粒径及びアスペクト比は、電子顕微鏡により粒子を観察することによって決定できる。
　具体的には、走査型電子顕微鏡（ＳＥＭ）（例えば、ＦＥ－ＳＥＭ－ＥＤＸ（ＳＵ８２２０）：株式会社日立ハイテクノロジー社製）で撮影された画像から、粒子を２００個以上無作為に選択し、その形状から判断する。
　最長径は、粒子に外接する面積が最小の長方形の長辺の長さとする。なお、鱗片状又は平板状の異方性フィラーの場合は、面方向が写っている粒子２００個以上ずつ無作為に選択し、最長径を求める。
　また、アスペクト比は、画像の中から、面方向が写っている粒子及び厚さが写っている粒子を、各々、２００個以上ずつ無作為に選択し、最長径と厚さ各々の平均値を算出し、その比を求めることにより決定できる。 The shape, particle size and aspect ratio of the anisotropic filler can be determined by observing the particles with an electron microscope.
Specifically, 200 or more particles were randomly selected from an image taken with a scanning electron microscope (SEM) (for example, FE-SEM-EDX (SU8220): manufactured by Hitachi High-Technology Corporation), Judging from its shape.
The longest diameter is the length of the long side of the rectangle with the smallest area circumscribing the particles. In the case of a scale-like or flat-plate anisotropic filler, 200 or more particles showing the plane direction are selected at random, and the longest diameter is obtained.
As for the aspect ratio, 200 particles or more are randomly selected from the image, and the average value of each of the longest diameter and the thickness is selected. It can be determined by calculating and determining the ratio.
　本実施形態において、膜中（インク）の異方性フィラーの体積率（固形分中の異方性フィラーの含有量）は、用途に応じて適宜設定することができ、たとえば１０～９０体積％以上とすることができる。
　異方性フィラーが１０体積％未満であると、異方性フィラーが少なすぎて所望の特性（例えば、熱伝導性）が得られないこともある。
　逆に、異方性フィラーの含有量が９０体積％を超えると、異方性フィラーが多すぎてシートが脆くなったり、シートの電気絶縁性が低下したりすることがある。加えて、インクの粘度が高くなり、薄く且つ平坦なシートを得にくくなることがある。
　ここで、異方性フィラーの体積は、異方性フィラーを構成する材料（化合物）の比重とインクに含まれる異方性フィラーの質量とから求められる値とする。 In the present embodiment, the volume fraction of the anisotropic filler in the film (ink) (the content of the anisotropic filler in the solid content) can be appropriately set according to the application, for example, 10 to 90% by volume. This can be done.
If the anisotropic filler is less than 10% by volume, the anisotropic filler may be too small to obtain desired characteristics (for example, thermal conductivity).
On the other hand, when the content of the anisotropic filler exceeds 90% by volume, the amount of the anisotropic filler may be too much, the sheet may become brittle, or the electrical insulation of the sheet may be reduced. In addition, the viscosity of the ink increases, and it may be difficult to obtain a thin and flat sheet.
Here, the volume of the anisotropic filler is a value obtained from the specific gravity of the material (compound) constituting the anisotropic filler and the mass of the anisotropic filler contained in the ink.
　本実施形態において、インクに含まれる樹脂に限定はないが、例えば、熱可塑性樹脂（例えば、ポリオレフィン、塩化ビニル樹脂、メタクリル酸メチル樹脂、ナイロン、フッ素樹脂等）、硬化性樹脂（例えば、エポキシ樹脂、フェノール樹脂、尿素樹脂、メラミン樹脂、不飽和ポリエステル樹脂、ケイ素樹脂等）、合成ゴムなどが挙げられる。中でも硬化性樹脂が好ましく、熱硬化性樹脂が特に好ましい。
　また、本実施形態において硬化性樹脂は、硬化剤や硬化触媒と混合した樹脂組成物の形で凹凸膜中に添加してもよいし、さらに、対応する原料（モノマー、ダイマー、オリゴマー等の前駆体）の形で添加してもよい。 In the present embodiment, the resin contained in the ink is not limited. For example, a thermoplastic resin (for example, polyolefin, vinyl chloride resin, methyl methacrylate resin, nylon, fluorine resin, etc.), a curable resin (for example, an epoxy resin) Phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicon resin, and the like) and synthetic rubber. Of these, curable resins are preferable, and thermosetting resins are particularly preferable.
In the present embodiment, the curable resin may be added to the concavo-convex film in the form of a resin composition mixed with a curing agent or a curing catalyst, and further, a corresponding raw material (a precursor of monomer, dimer, oligomer, etc.). Body) may be added.
　熱硬化性樹脂としては、例えば、ポリイミド樹脂、ポリアミノビスマレイミド（ポリビスマレイミド）樹脂、ビスマレイミド・トリアジン樹脂、ポリアミドイミド樹脂、ポリエーテルイミド樹脂等のポリイミド系樹脂；ポリベンゾオキサゾール系樹脂；ポリエーテル樹脂；ベンゾシクロブテン樹脂；シリコーン系樹脂；フェノール系エポキシ樹脂、アルコール系エポキシ樹脂等のエポキシ系樹脂等が挙げられる。
　中でも、高熱伝導性で、有機溶剤への溶解性も良好であることから、エポキシ樹脂やポリエーテル樹脂、ベンゾシクロブテン樹脂、シリコーン樹脂が好ましく、特にエポキシ樹脂が好ましい。
　これらの樹脂は１種を単独で用いてもよく、２種以上を任意の組合せ及び比率で併用してもよい。 Examples of thermosetting resins include polyimide resins, polyaminobismaleimide (polybismaleimide) resins, bismaleimide / triazine resins, polyamideimide resins, polyetherimide resins, and other polyimide resins; polybenzoxazole resins; polyethers Resins; benzocyclobutene resins; silicone resins; epoxy resins such as phenolic epoxy resins and alcoholic epoxy resins.
Among them, an epoxy resin, a polyether resin, a benzocyclobutene resin, and a silicone resin are preferable because of high thermal conductivity and good solubility in an organic solvent, and an epoxy resin is particularly preferable.
These resins may be used alone or in combination of two or more in any combination and ratio.
　本実施形態において、インクには必要に応じて溶剤や分散媒を含有させることができる。特に、樹脂として熱硬化性樹脂を用いる場合には、溶剤や分散媒を含有させることが好ましい。
　溶剤（分散媒）の種類には、特に限定はなく、例えば、アセトン、メチルエチルケトン、メチルセルソルブ、シクロペンタノンなどのケトン類；トルエン、キシレンなどの芳香族炭化水素類；シクロヘキサン、シクロペンタンなどのシクロアルカン類；メタノール、エタノール、ｎ―ブチルアルコールなどのアルコール類；酢酸エチル、酢酸プロピル、酢酸ブチルなどのエステル類；ジメチルホルムアミドなどのアミド類；プロピレングリコールモノメチルエーテル及びそのアセテートなどの有機溶剤が挙げられる。溶剤は、１種を単独で用いても、２種以上を併用してもよい。
　膜形成中及び高周波振動付与中にはインクの粘度を一定に調整し、高周波振動付与後にはインクを迅速に乾燥させる観点から、その蒸発速度が、酢酸ブチルの４．５倍以下である溶剤を用いることが好ましい。蒸発速度が速すぎると膜形成中や高周波振動付与中に溶剤が多く揮発し、インクの粘度が変化してしまう。一方、蒸発速度が遅すぎると溶剤の乾燥が困難になり高温長時間の乾燥が必要となるところ、そのような乾燥を行うと、樹脂として熱硬化性樹脂を使用した場合にその硬化が進んでしまう。このような観点から、酢酸ブチルの蒸発速度の０．０５倍～４．５倍の溶剤を用いることがより好ましい。
　溶剤（分散媒）の含有量に限定はなく、例えば、インクの粘度等を考慮して適宜決定することができ、通常、インクの１０～５０質量％程度である。溶剤量が不足すると、均一の厚さを有する膜の形成が難しく、膜表面にムラが生じることもある。逆に溶剤量が過剰になると、高周波振動付与後の膜中の異方性フィラーの配向保持性が劣ることがある。 In this embodiment, the ink can contain a solvent or a dispersion medium as necessary. In particular, when a thermosetting resin is used as the resin, it is preferable to contain a solvent or a dispersion medium.
The type of the solvent (dispersion medium) is not particularly limited, and examples thereof include ketones such as acetone, methyl ethyl ketone, methyl cellosolve, and cyclopentanone; aromatic hydrocarbons such as toluene and xylene; cyclohexane, cyclopentane, and the like. Cycloalkanes; alcohols such as methanol, ethanol and n-butyl alcohol; esters such as ethyl acetate, propyl acetate and butyl acetate; amides such as dimethylformamide; organic solvents such as propylene glycol monomethyl ether and its acetate It is done. A solvent may be used individually by 1 type, or may use 2 or more types together.
During film formation and during application of high-frequency vibration, the viscosity of the ink is adjusted to be constant, and after applying high-frequency vibration, a solvent whose evaporation rate is 4.5 times or less that of butyl acetate is used from the viewpoint of quickly drying the ink. It is preferable to use it. If the evaporation rate is too high, a large amount of solvent volatilizes during film formation or high frequency vibration application, and the viscosity of the ink changes. On the other hand, if the evaporation rate is too slow, drying of the solvent becomes difficult and drying at a high temperature for a long time is required. However, when such drying is performed, the curing proceeds when a thermosetting resin is used as the resin. End up. From such a viewpoint, it is more preferable to use a solvent having a butyl acetate evaporation rate of 0.05 to 4.5 times.
The content of the solvent (dispersion medium) is not limited, and can be appropriately determined in consideration of, for example, the viscosity of the ink, and is usually about 10 to 50% by mass of the ink. When the amount of the solvent is insufficient, it is difficult to form a film having a uniform thickness, and unevenness may occur on the film surface. On the contrary, when the amount of the solvent is excessive, the orientation retention of the anisotropic filler in the film after application of high-frequency vibration may be inferior.
　本実施形態において、インクには、異方性フィラー、樹脂及び溶剤／分散媒に加えて、さらに、用途等に応じて従来使用される各種添加剤等を含有させることもできる。
　このような添加剤としては、例えば、異方性フィラーと樹脂との間の接着性を改良するためのカップリング剤や、上述の硬化剤及び硬化触媒、樹脂硬化促進剤、粘度調整剤、分散安定剤、界面活性剤、乳化剤、低弾性化剤、希釈剤、消泡剤、イオントラップ剤等が挙げられる。これらは、いずれも１種を単独で用いてもよく、２種以上を任意の組み合わせ及び比率で混合して用いてもよい。 In the present embodiment, in addition to the anisotropic filler, resin, and solvent / dispersion medium, the ink may further contain various additives that are conventionally used depending on the application.
Examples of such additives include a coupling agent for improving adhesion between the anisotropic filler and the resin, the above-described curing agent and curing catalyst, resin curing accelerator, viscosity modifier, and dispersion. Stabilizers, surfactants, emulsifiers, low elasticity agents, diluents, antifoaming agents, ion trapping agents and the like can be mentioned. Any of these may be used alone or in a combination of two or more in any combination and ratio.
　前記カップリング剤としては、一般に異方性フィラーの表面処理に使用されているものを好適に用いることができ、その種類は特に限定されない。具体的には、γ－アミノプロピルトリエトキシシラン、Ｎ－β－（アミノエチル）－γ－アミノプロピルトリメトキシランなどのアミノシラン系；γ－グリシドキシプロピルトリメトキシシラン、β－（３，４－エポキシシクロヘキシル）エチルトリメトキシシランなどのエポキシシラン系；γ－メタアクリロキシプロピルトリメトキシシラン、ビニルートリ（β－メトキシエトキシ）シランなどのビニルシラン系；Ｎ－β－（Ｎ－ビニルベンジルアミノエチル）－γ－アミノプロピルトリメトキシシラン塩酸塩などのカチオニックシラン系；フェニルシラン系などのシランカップリング剤が挙げられる。
　これらのシランカップリング剤は、１種を単独で又は２種以上を組み合わせて用いることができる。
　上記カップリング剤は、異方性フィラーの表面積にもよるが、異方性フィラーに対して、０．０１～１０質量％添加することが好ましく、１～２質量％添加することがより好ましい。
　カップリング剤は、予め異方性フィラーに付加しておくことができ、その方法に限定はないが、例えば、攪拌機によって高速攪拌している異方性フィラーにカップリング剤原液を均一に分散させて処理する乾式法やカップリング剤希薄溶液に異方性フィラーを浸漬し攪拌する湿式法等が挙げられる。 As said coupling agent, what is generally used for the surface treatment of an anisotropic filler can be used suitably, The kind is not specifically limited. Specifically, aminosilanes such as γ-aminopropyltriethoxysilane and N-β- (aminoethyl) -γ-aminopropyltrimethoxylane; γ-glycidoxypropyltrimethoxysilane, β- (3,4 Epoxy silanes such as epoxycyclohexyl) ethyltrimethoxysilane; Vinylsilanes such as γ-methacryloxypropyltrimethoxysilane and vinyl-tri (β-methoxyethoxy) silane; N-β- (N-vinylbenzylaminoethyl)- Examples include cationic silanes such as γ-aminopropyltrimethoxysilane hydrochloride; silane coupling agents such as phenylsilane.
These silane coupling agents can be used alone or in combination of two or more.
Depending on the surface area of the anisotropic filler, the coupling agent is preferably added in an amount of 0.01 to 10% by mass, more preferably 1 to 2% by mass relative to the anisotropic filler.
The coupling agent can be added to the anisotropic filler in advance, and the method is not limited. For example, the coupling agent stock solution is uniformly dispersed in the anisotropic filler that is stirred at high speed by a stirrer. And a wet method in which an anisotropic filler is immersed in a dilute solution of a coupling agent and stirred.
　インクの粘度に限定はなく、例えば、０．１～１００Ｐａ・ｓとすることができ、５～２０Ｐａ・ｓとしてもよい。
　なお、インクの調製方法に特に限定はなく、各成分を混合すればよい。その際、各成分を均一に混合させるため、攪拌、混合、混練処理などの公知の処理を行うことができる。 There is no limitation on the viscosity of the ink. For example, the viscosity may be 0.1 to 100 Pa · s, and may be 5 to 20 Pa · s.
The method for preparing the ink is not particularly limited, and each component may be mixed. In that case, in order to mix each component uniformly, well-known processes, such as stirring, mixing, and a kneading | mixing process, can be performed.
　本実施形態において、膜は支持体上に形成される。支持体としては、膜を保持し、高周波振動に耐える強度を有し、後に剥離する場合には離型性のよいものが好ましい。具体例としては、銅やアルミニウム等の金属箔や金属板、プラスチックフィルムやプラスチック板等が挙げられる。
　支持体は、シート形成後に剥離してもよい。特に、支持体がシートの用途にふさわしくない特性を有している場合（例えば、シートが、電子回路の絶縁層用の熱伝導シートであるような場合において、支持体として金属箔等の導電性のものを利用した場合）には、支持体をシートから剥離することが好ましい。一方、上述のような事情がない場合には、支持体は必ずしも剥離する必要はなく、最終的に支持体を残したままの積層体をシートとして利用することもできる。
　支持体をシートから剥離する場合、その剥離工程のタイミングに限定はないが、膜がある程度硬化して、自立できるようになった後であることが好ましい。 In this embodiment, the membrane is formed on a support. As the support, a support having a strength capable of holding a film and withstanding high-frequency vibration and having good releasability when peeled later is preferable. Specific examples include metal foils such as copper and aluminum, metal plates, plastic films, plastic plates, and the like.
The support may be peeled off after forming the sheet. In particular, when the support has characteristics that are not suitable for the use of the sheet (for example, in the case where the sheet is a heat conductive sheet for an insulating layer of an electronic circuit, a conductive material such as a metal foil as the support) In the case of using the above, it is preferable to peel the support from the sheet. On the other hand, when there is no such situation as described above, the support does not necessarily have to be peeled off, and it is also possible to use a laminate with the support remaining finally as a sheet.
When the support is peeled from the sheet, there is no limitation on the timing of the peeling step, but it is preferable that the film is cured to some extent and can become independent.
　本実施形態において、このような支持体上に、上述のインクの膜を形成する方法に限定はなく、例えば、グラビアコーティング、ロールコーティング、バーコーティング、ダイコーティング、ディッピング、ナイフコーティング等のロールを利用した各種コーティング；スプレーコーティング；ブレードコーティング；スピンコーティング；スクリーン印刷等の各種印刷等の各種アプリケーターによる塗工が挙げられる。また、樹脂が熱可塑性樹脂である場合には、ホットメルトコーティング等の溶融塗工することもできる。
　本実施形態の製造方法においては、後に続く高周波振動付与工程において膜中の異方性フィラーを再配列させるので、膜形成の際に決まる異方性フィラーの配向状態を考慮する必要はなく、自由に塗膜形成方法を選択することができる。
　塗膜の厚さは、用途、目的等に応じて適宜決定することができ、例えば、１０～５０００μｍとすることができる。 In the present embodiment, there is no limitation on the method for forming the above-described ink film on such a support. For example, rolls such as gravure coating, roll coating, bar coating, die coating, dipping, and knife coating are used. Spray coating; blade coating; spin coating; and coating with various applicators such as screen printing. Further, when the resin is a thermoplastic resin, it can be melt coated such as hot melt coating.
In the manufacturing method of this embodiment, since the anisotropic filler in the film is rearranged in the subsequent high-frequency vibration applying step, it is not necessary to consider the orientation state of the anisotropic filler determined at the time of film formation. A method for forming a coating film can be selected.
The thickness of the coating film can be appropriately determined according to the application, purpose, etc., and can be, for example, 10 to 5000 μm.
　本実施形態の製造方法においては、膜形成工程に続いて、膜に５ｋＨｚ以上の周波数を有する振動を与える工程を有する。本発明者らの研究によれば、膜に高周波振動を与えると、異方性フィラーが再配列し、仮に横配向していたような場合でも、ランダム配向、さらには、縦配向に近づくことが判明した。このような再配列は、高周波振動付与により発生するキャビテーション現象で生じる泡が弾けるときの衝撃波の作用によると推測されるが、機序はこれによらない。
　この際、振動を付与する対象である膜は、異方性フィラーの再配列を許すよう、流動可能、すなわち、液状（液体（ゾル状及びゲル状を含む））、であることが必要である。
　インクが溶剤や分散媒を含まず、樹脂が熱可塑性樹脂である場合（インクが熱溶融インクである場合）には、膜の形成方法は溶融塗工となるが、その場合、膜形成後に膜が冷却されて硬化（固化）してしまうことがある。したがって、そのような場合には、膜を加熱し続けて流動可能状態を維持したり、いったん硬化した硬化膜を加熱して再び液状に戻すなどして、高周波振動付与工程において膜が流動可能状態にあるようにする。 In the manufacturing method of this embodiment, it has the process of giving the vibration which has a frequency of 5 kHz or more to a film | membrane following a film | membrane formation process. According to the study by the present inventors, when high-frequency vibration is applied to the film, the anisotropic fillers are rearranged, and even if they are laterally oriented, they can approach random orientation and further longitudinal orientation. found. Such rearrangement is presumed to be due to the action of a shock wave when bubbles generated by the cavitation phenomenon generated by applying high-frequency vibrations, but the mechanism does not depend on this.
At this time, the film to which vibration is applied needs to be flowable, ie, liquid (including liquid (including sol and gel)) so as to allow rearrangement of the anisotropic filler. .
When the ink does not contain a solvent or a dispersion medium and the resin is a thermoplastic resin (when the ink is a hot melt ink), the film formation method is melt coating. In this case, the film is formed after the film is formed. May be cooled and hardened (solidified). Therefore, in such a case, the film can be flowed in the high frequency vibration application process by continuously heating the film to maintain the flowable state or by heating the cured film once again to return to the liquid state. To be in.
　塗膜に高周波振動を付与する方法に限定はなく、例えば、超音波発生装置を利用して、塗膜を保持する支持体を介して塗膜に振動を付与することができる。
　振動の周波数は、５ｋＨｚ以上であり、上限はないが、例えば、１０～１０００ｋＨｚ或いは１５～１０００ｋＨｚとしてもよい。
　また、用いる周波数の種類に限定はなく、単一の周波数を有する振動を付与してもよいし、経時的に周波数が変わる振動を用いてもよいし、さらに、異なる周波数を有する複数の振動を組み合わせて用いること（スイープ振動）も効果的である。
　適切な周波数は、異方性フィラーの形状、大きさに応じて変わり、一般に、フィラーの粒径が大きいほど低い周波数が、粒径が小さいほど高い周波数が適している。すなわち、高周波振動（超音波）の衝撃力は周波数が低いほど大きいため、周波数を高くすると、大きな異方性フィラーがランダムに配向する傾向がある。一方、定常波間隔は周波数が高いほど狭いため、周波数を低くすると、小さな異方性フィラーをランダムに配向させるのに効果的である。
　高周波振動を付与する時間に限定はなく、振動の周波数、膜厚に応じて適宜決定することができ、例えば、１秒～３００秒とすることができる。 There is no limitation on the method of applying high-frequency vibration to the coating film. For example, vibration can be applied to the coating film via a support that holds the coating film using an ultrasonic generator.
The frequency of vibration is 5 kHz or more and there is no upper limit, but it may be, for example, 10 to 1000 kHz or 15 to 1000 kHz.
Moreover, there is no limitation on the type of frequency to be used, vibration having a single frequency may be applied, vibration that changes in frequency over time may be used, and a plurality of vibrations having different frequencies may be used. Use in combination (sweep vibration) is also effective.
The appropriate frequency varies depending on the shape and size of the anisotropic filler. In general, a lower frequency is suitable as the particle size of the filler is larger, and a higher frequency is suitable as the particle size is smaller. That is, since the impact force of high-frequency vibration (ultrasonic waves) increases as the frequency decreases, increasing the frequency tends to cause large anisotropic fillers to be randomly oriented. On the other hand, since the standing wave interval is narrower as the frequency is higher, lowering the frequency is effective for randomly orienting small anisotropic fillers.
There is no limitation on the time for applying the high-frequency vibration, and it can be appropriately determined according to the frequency and film thickness of the vibration. For example, it can be 1 to 300 seconds.
　本実施形態においては、さらに、以上のようにして異方性フィラーを再配列させた膜をプレスする工程を含んでもよく、これにより膜中に含まれる空隙を除去することができる。膜中に空隙が存在しているとその熱伝導率が低下することがある。そのため、シートを熱伝導シートとして利用する場合には、このようなプレスは特に有効である。
　その際のプレス条件（圧力、温度、時間、雰囲気等）に限定はなく、異方性フィラーや樹脂の種類、膜中のフィラーの含有量等を考慮して膜中の異方性フィラーの配列に影響を与えることなく空隙を除去できるような条件を適宜決定すればよい。プレス圧は、例えば、０．０１～２０ＭＰａとすることができ、１０Ｍｐａ以下でもよく、通常は５ＭＰａ以下でも十分である。
　なお、膜を構成するインクの粘度が低く、そのままではプレスするのが難しい場合などには、プレス工程に先立ち、膜から溶剤の一部又は全てを除去して、膜を半硬化させてもよい。その際の溶剤の除去方法に限定はなく、例えば、真空乾燥、加熱乾燥等の方法を適宜採用することができる。 In the present embodiment, a step of pressing the film in which the anisotropic fillers are rearranged as described above may be further included, whereby the voids contained in the film can be removed. If there are voids in the film, the thermal conductivity may decrease. Therefore, such a press is particularly effective when the sheet is used as a heat conductive sheet.
There are no limitations on the pressing conditions (pressure, temperature, time, atmosphere, etc.) at that time, and the arrangement of anisotropic fillers in the film in consideration of the types of anisotropic fillers and resins, the filler content in the film, etc. What is necessary is just to determine suitably the conditions which can remove a space | gap, without affecting this. The pressing pressure can be, for example, 0.01 to 20 MPa, may be 10 MPa or less, and usually 5 MPa or less is sufficient.
In addition, when the viscosity of the ink constituting the film is low and it is difficult to press as it is, the film may be semi-cured by removing some or all of the solvent from the film prior to the pressing step. . There is no limitation on the method of removing the solvent at that time, and for example, methods such as vacuum drying and heat drying can be appropriately employed.
　以上のようにして形成した膜は、必要に応じて適宜乾燥及び／又は硬化させることができる。硬化させる場合、硬化方法に限定はなく、樹脂の種類に応じて加熱や光照射を行うなどして硬化させることができる。 The film formed as described above can be appropriately dried and / or cured as necessary. In the case of curing, there is no limitation on the curing method, and curing can be performed by heating or light irradiation according to the type of resin.
　本実施形態において、異方性フィラー含有シートの厚さは用途に応じて適宜決定すればよく、例えば、１０～１０００μｍとすることができる。
　また、異方性フィラー含有シートが熱伝導シートである場合、シートの厚み方向の熱伝導率は．０Ｗ／ｍ・Ｋ以上であることが好ましく、７．０Ｗ／ｍ・Ｋ以上であることがより好ましく、１０．０Ｗ／ｍ・Ｋ以上であることがさらに好ましい。熱伝導率に上限はなく、大きいほど好ましい。本実施形態の製造方法によれば、このような高熱伝導率の熱伝導シートの製造も可能である。 In the present embodiment, the thickness of the anisotropic filler-containing sheet may be appropriately determined according to the application, and may be, for example, 10 to 1000 μm.
When the anisotropic filler-containing sheet is a heat conductive sheet, the thermal conductivity in the thickness direction of the sheet is. It is preferably 0 W / m · K or more, more preferably 7.0 W / m · K or more, and still more preferably 10.0 W / m · K or more. There is no upper limit to the thermal conductivity, and the larger the better. According to the manufacturing method of the present embodiment, it is possible to manufacture a heat conductive sheet having such a high thermal conductivity.
　次に、本発明を実施例によりさらに詳細に説明するが、本発明は、これらの例によってなんら限定されるものではない。
　実施例及び比較例において作製した異方性フィラー含有シートの特性の測定方法を以下に示す。
＜各特性の評価方法＞
（１）熱伝導率
　実施例及び比較例で得られたシート（後述のＣシート）から試験片（１０ｍｍ×１０ｍｍ×厚さ１ｍｍ）を切り出し、この試験片についてＮＥＴＺＳＣＨ製キセノンフラッシュアナライザーＬＦＡ４４７型熱伝導率計を用いてレーザーフラシュで試験片の熱拡散率を測定した。
　以上のようにして得られた熱拡散率；密度測定器（メトラー・トレド株式会社製　ＭＳ－ＤＮＹ－４３）を用いて測定したシートの密度；及び；窒化ホウ素と樹脂（硬化物）各々の比熱（窒化ホウ素：０．８１J／ｇ・K、樹脂：０．８０J／ｇ・Ｋ）とのこれらのシート中での質量比ら算出（質量比に応じて按分した平均値）されるシートの比熱の積から熱伝導率（Ｗ／ｍ・Ｋ）を算出した。
（２）配向強度比
　シート中の窒化ホウ素一次粒子の配向性は、Ｘ線回折法によるＩ（００２）回析線（２θ＝２６．５°）の強度とＩ（１００）回析線（２θ＝４１．５°）の強度との比（Ｉ（００２）／Ｉ（１００））により評価した。ただし、Ｘ線回折法により評価されるのは、シートの表面付近の範囲に存在する粒子の配向性である。
　六方晶である窒化ホウ素一次粒子の厚み方向は結晶学的なＩ（００２）回析線すなわちｃ軸方向、面内方向はＩ（１００）回析線すなわちａ軸方向にそれぞれ一致している。窒化ホウ素粒子凝集体を構成する窒化ホウ素一次粒子が、完全にランダムな配向（無配向）で有る場合、（Ｉ（００２）／Ｉ（１００））≒６．７になる（「ＪＣＰＤＳ［粉末Ｘ線回折データベース］」Ｎｏ．３４－０４２１［ＢＮ］の結晶密度値［Ｄｘ］）。（Ｉ（００２）／Ｉ（１００））が小さいほど、六方晶の窒化ホウ素粒子のａ軸方向が厚さ方向に配向していることを意味する。
　具体的には、実施例及び比較例で得られたシートから試験片（５ｍｍ×５ｍｍ×厚さ０．２ｍｍ）を切り出し、「全自動水平型多目的Ｘ線回折装置　ＳｍａｒｔＬａｂ」（リガク社製、Ｘ線源：ＣｕＫα線、管電圧：４５ｋＶ、管電流：３６０ｍＡ）を用いて、Ｘ線を試験片の厚み方向に照射して、Ｉ（００２）回析線とＩ（１００）回析線の強度を測定した。 EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The measuring method of the characteristic of the anisotropic filler containing sheet | seat produced in the Example and the comparative example is shown below.
<Evaluation method of each characteristic>
(1) Thermal conductivity A test piece (10 mm × 10 mm × thickness 1 mm) was cut out from the sheet (C sheet described later) obtained in the examples and comparative examples, and the xenon flash analyzer LFA447 type manufactured by NETZSCH was used for this test piece. The thermal diffusivity of the test piece was measured with a laser flash using a rate meter.
Thermal diffusivity obtained as described above; sheet density measured using a density meter (MS-DNY-43 manufactured by METTLER TOLEDO Co., Ltd.); and; specific heat of each of boron nitride and resin (cured product) Specific heat of the sheet calculated from the mass ratio in these sheets (boron nitride: 0.81 J / g · K, resin: 0.80 J / g · K) (average value prorated according to the mass ratio). The thermal conductivity (W / m · K) was calculated from the product of
(2) Orientation Strength Ratio The orientation of the boron nitride primary particles in the sheet is determined by the intensity of I (002) diffraction line (2θ = 26.5 °) and I (100) diffraction line (2θ by X-ray diffraction method. = 41.5 °) and the ratio (I (002) / I (100)). However, what is evaluated by the X-ray diffraction method is the orientation of the particles present in the vicinity of the surface of the sheet.
The thickness direction of the hexagonal boron nitride primary particles coincides with the crystallographic I (002) diffraction line, that is, the c-axis direction, and the in-plane direction coincides with the I (100) diffraction line, that is, the a-axis direction. When the boron nitride primary particles constituting the boron nitride particle aggregate have a completely random orientation (non-orientation), (I (002) / I (100)) ≈6.7 (“JCPDS [powder X Line Diffraction Database] ”No. 34-0421 [BN] crystal density value [Dx]). The smaller (I (002) / I (100)) means that the a-axis direction of hexagonal boron nitride particles is oriented in the thickness direction.
Specifically, a test piece (5 mm × 5 mm × thickness 0.2 mm) was cut out from the sheets obtained in Examples and Comparative Examples, and “Fully Automatic Horizontal Multipurpose X-ray Diffractometer SmartLab” (manufactured by Rigaku Corporation, X X-rays are irradiated in the thickness direction of the test piece using a radiation source: CuKα ray, tube voltage: 45 kV, tube current: 360 mA), and intensity of I (002) diffraction line and I (100) diffraction line Was measured.
（実施例１）
　本発明の方法を用いて、鱗片状窒化ホウ素粒子と樹脂とを含むシートを作製した。
　トリフェニルメタン型エポキシ樹脂（日本化薬製「ＥＰＰＮ－５０１Ｈ」）１００質量部、硬化剤（フェノーノボラック系硬化剤、明和化成製「ＤＬ－９２」）６３質量部、及び硬化触媒（２フェニルイミダゾール、四国化成製）０．０１質量部を混合し、樹脂組成物を調製した。なお、エポキシ樹脂と硬化剤の配合比率は、エポキシ樹脂／硬化剤の官能基が当量比で１．０となるようにした。
　次に、異方性フィラーとして平均粒径４５μｍの窒化ホウ素一次粒子（モメンティブパフォーマンス製「ＰＴ１１０」）１００質量部に、カップリング剤として３－グリコキシドプロピルトリメトキシラン（東京化成工業株式会社製）１．５質量部を滴下し、自転公転ミキサー（シンキー　ＡＲ－１００）で攪拌した。
　続いて、溶剤（メチルエチルケトン）５０質量部中で、前記樹脂組成物３９体積％と、上記カップリング剤を付加した窒化ホウ素一次粒子６１体積％の合計５０質量部とを混合し、インクを調製した。
　このインクをアプリケーター（株式会社井元製作所製）（ギャップ約１．５ｍｍ）で支持体（銅箔）上に塗工し、平らな塗膜を形成した。続いて、これをアルミ板に載せ、超音波発生装置（株式会社日本精機製作所製　超音波ホモジナイザーＵＳ－６００Ｔ）の振動素子を上記アルミ板にあて、アルミ板、銅箔を介して塗膜に３分間超音波振動を付与し、その後静置した。
　次いで、上記塗膜を１２０℃１０分で乾燥させ溶剤を除去して、半硬化シート（Ｂシート）（約１．５ｍｍ厚）を作製した。
　これを１８０℃真空下で、２時間、１０ＭＰａの条件で真空プレスし、硬化させ、最後に銅箔を剥して異方性フィラー含有シート（Ｃシート）を作製した。 Example 1
A sheet containing scaly boron nitride particles and a resin was produced using the method of the present invention.
100 parts by mass of a triphenylmethane type epoxy resin (“EPPN-501H” manufactured by Nippon Kayaku), 63 parts by mass of a curing agent (phenonovolak-based curing agent, “DL-92” manufactured by Meiwa Kasei), and a curing catalyst (2-phenylimidazole) , Shikoku Chemicals) 0.01 parts by mass was mixed to prepare a resin composition. The mixing ratio of the epoxy resin and the curing agent was such that the functional group of the epoxy resin / curing agent was 1.0 in terms of equivalent ratio.
Next, 100 parts by mass of boron nitride primary particles (“PT110” manufactured by Momentive Performance) having an average particle diameter of 45 μm as an anisotropic filler and 3-glycoxide propyltrimethoxylane (manufactured by Tokyo Chemical Industry Co., Ltd.) as a coupling agent are used. 1.5 parts by mass were dropped, and the mixture was stirred with a rotation / revolution mixer (Sinky AR-100).
Subsequently, in 50 parts by mass of a solvent (methyl ethyl ketone), 39% by volume of the resin composition and 50 parts by mass in total of 61% by volume of boron nitride primary particles to which the coupling agent was added were mixed to prepare an ink. .
This ink was coated on a support (copper foil) with an applicator (Imoto Seisakusho Co., Ltd.) (gap: about 1.5 mm) to form a flat coating film. Subsequently, this was placed on an aluminum plate, the vibration element of an ultrasonic generator (Ultrasonic Homogenizer US-600T manufactured by Nippon Seiki Seisakusho Co., Ltd.) was applied to the aluminum plate, and the coating was applied to the coating film via the aluminum plate and copper foil. Ultrasonic vibration was applied for a minute and then allowed to stand.
Subsequently, the said coating film was dried at 120 degreeC for 10 minutes, the solvent was removed, and the semi-hardened sheet (B sheet) (about 1.5 mm thickness) was produced.
This was vacuum-pressed at 180 ° C. for 2 hours under the condition of 10 MPa, cured, and finally the copper foil was peeled off to produce an anisotropic filler-containing sheet (C sheet).
（実施例２）
　半硬化シートに対する真空プレス時のプレス圧力を５ＭＰａとした以外は実施例１と同様にして異方性フィラー含有シートを得た。
（実施例３）
　溶剤（メチルエチルケトン）５０質量部中で、前記樹脂組成物３０体積％と、前記カップリング剤を付加した窒化ホウ素一次粒子７０体積％の合計５０質量部とを混合してインクを調製した（インク固形分中の異方性フィラーの割合を変更した）以外は実施例１と同様にして異方性フィラー含有シートを作製した。
（実施例４）
　異方性フィラーとして平均粒径１２μｍの窒化ホウ素一次粒子（トクヤマ製「πＢＮ－Ｓ０３」）を用いた以外は実施例１と同様にして異方性フィラー含有シートを作製した。
（実施例５）
　半硬化シートに対する真空プレス時のプレス圧力を５ＭＰａとした以外は実施例４と同様にして異方性フィラー含有シートを得た。
（実施例６）
　溶剤（メチルエチルケトン）５０質量部中で、前記樹脂組成物３０体積％と、前記カップリング剤を付加した窒化ホウ素一次粒子７０体積％の合計５０質量部とを混合してインクを調製した（インク固形分中の異方性フィラーの割合を変更した）以外は実施例４と同様にして異方性フィラー含有シートを作製した。 (Example 2)
An anisotropic filler-containing sheet was obtained in the same manner as in Example 1 except that the pressing pressure during vacuum pressing on the semi-cured sheet was 5 MPa.
(Example 3)
In 50 parts by mass of a solvent (methyl ethyl ketone), an ink was prepared by mixing 30% by volume of the resin composition and 50 parts by mass in total of 70% by volume of boron nitride primary particles to which the coupling agent was added (ink solids). An anisotropic filler-containing sheet was produced in the same manner as in Example 1 except that the ratio of the anisotropic filler in the minute was changed.
Example 4
An anisotropic filler-containing sheet was prepared in the same manner as in Example 1, except that boron nitride primary particles having an average particle diameter of 12 μm (“πBN-S03” manufactured by Tokuyama) were used as the anisotropic filler.
(Example 5)
An anisotropic filler-containing sheet was obtained in the same manner as in Example 4 except that the pressing pressure during vacuum pressing on the semi-cured sheet was 5 MPa.
(Example 6)
In 50 parts by mass of a solvent (methyl ethyl ketone), an ink was prepared by mixing 30% by volume of the resin composition and 50 parts by mass in total of 70% by volume of boron nitride primary particles to which the coupling agent was added (ink solids). An anisotropic filler-containing sheet was produced in the same manner as in Example 4 except that the proportion of the anisotropic filler in the minute was changed.
（比較例１）
　超音波振動の付与を行わなかった以外は実施例１と同様にして異方性フィラー含有シートを得た。
（比較例２）
　超音波振動の付与を行わなかった以外は実施例３と同様にして異方性フィラー含有シートを得た。
（比較例３）
　超音波振動の付与を行わなかった以外は実施例４と同様にして異方性フィラー含有シートを得た。
（比較例４）
　超音波振動の付与を行わなかった以外は実施例６と同様にして異方性フィラー含有シートを得た。
（比較例５）
　異方性フィラーとして、凝集窒化ホウ素粒子（デンカ製「ＳＧＰＳ」）を用い、かつ超音波振動の付与を行わなかった以外は実施例１と同様にして異方性フィラー含有シートを作製した。
（比較例６）
　異方性フィラーとして、凝集窒化ホウ素粒子（デンカ製「ＳＧＰＳ」）を用い、かつ超音波振動の付与を行わなかった以外は実施例３と同様にして異方性フィラー含有シートを作製した。 (Comparative Example 1)
An anisotropic filler-containing sheet was obtained in the same manner as in Example 1 except that no ultrasonic vibration was applied.
(Comparative Example 2)
An anisotropic filler-containing sheet was obtained in the same manner as in Example 3 except that no ultrasonic vibration was applied.
(Comparative Example 3)
An anisotropic filler-containing sheet was obtained in the same manner as in Example 4 except that no ultrasonic vibration was applied.
(Comparative Example 4)
An anisotropic filler-containing sheet was obtained in the same manner as in Example 6 except that the application of ultrasonic vibration was not performed.
(Comparative Example 5)
An anisotropic filler-containing sheet was prepared in the same manner as in Example 1 except that aggregated boron nitride particles (“SGPS” manufactured by Denka) were used as the anisotropic filler and ultrasonic vibration was not applied.
(Comparative Example 6)
An anisotropic filler-containing sheet was produced in the same manner as in Example 3 except that aggregated boron nitride particles (“SGPS” manufactured by Denka Co., Ltd.) were used as the anisotropic filler and no ultrasonic vibration was applied.
　実施例１～６、及び、比較例１～６で作製した異方性フィラー含有シートの熱伝導率と窒化ホウ素一次粒子の配向強度比（Ｉ（００２）／Ｉ（１００））を表１に示す。
　実施例１と２のシートは、同じインクを用い、高周波振動の付与なしで作製した比較例１と比較して、配向強度比Ｉ（００２）／Ｉ（１００）が小さく（ランダム配向の場合の理論値６．７に近く）、熱伝導率が約２～３倍高くなった。なお、実施例１及び２、比較例１いずれにおいても、Ｘ線回折法で評価されるシート表面付近の粒子の配向強度比が、プレス後（Ｃシート）においてはプレス前（Ｂシート）と比べて大きくなったが、これは、シート表面付近に存在する縦配向した粒子の一部が、プレス板に押されて横配向したためと考えられ、シート内部においてはランダム配向性は維持されていると考えられる。実際、実施例２及び比較例１で得られたシート（Ｃシート）の断面のＳＥＭ画像からは、高周波振動を付与せずに得られたシートの内部では粒子が横配向しているのに対し（比較例１、図２）、高周波振動を付与して得られたシートの内部では粒子がランダムに配向していることが確認できた（実施例２、図１）。
　同様に、実施例３～６のシートは、いずれも、同じインクを用い、高周波振動の付与なしで作製した対応するもの（比較例２～４）と比較して熱伝導率が約２倍高くなった。
　また、実施例４のシートは、異方性フィラーとして凝集窒化ホウ素粒子を用い、高周波振動を付与しなかった以外は同様にして作製した比較例５のシートと比較して、配向強度比は大きいものの、空隙率が低く、その結果熱伝導率は高くなった。
　同様に、実施例６のシートは、異方性フィラーとして凝集窒化ホウ素粒子を用い、高周波振動の付与しなかった以外は同様にして作製した比較例６のシートと比較して、配向強度比は大きいものの、空隙率が低く、その結果熱伝導率は高くなった。 Table 1 shows the thermal conductivity of the anisotropic filler-containing sheets prepared in Examples 1 to 6 and Comparative Examples 1 to 6 and the orientation strength ratio (I (002) / I (100)) of the boron nitride primary particles. Show.
The sheets of Examples 1 and 2 use the same ink, and the orientation strength ratio I (002) / I (100) is small (in the case of random orientation) as compared with Comparative Example 1 prepared without applying high-frequency vibration. Nearly the theoretical value of 6.7), the thermal conductivity was about 2-3 times higher. In both Examples 1 and 2 and Comparative Example 1, the orientation strength ratio of the particles in the vicinity of the sheet surface evaluated by the X-ray diffraction method is compared with that before pressing (B sheet) after pressing (C sheet). This is thought to be due to the fact that some of the longitudinally oriented particles present near the sheet surface were pushed by the press plate and laterally oriented, and random orientation was maintained inside the sheet. Conceivable. Actually, from the SEM images of the cross sections of the sheet (C sheet) obtained in Example 2 and Comparative Example 1, the particles are laterally oriented inside the sheet obtained without applying high-frequency vibration. (Comparative example 1, FIG. 2), it has confirmed that the particle | grains were orientating at random inside the sheet | seat obtained by providing a high frequency vibration (Example 2, FIG. 1).
Similarly, the sheets of Examples 3 to 6 all have about twice the thermal conductivity as compared to the corresponding sheets (Comparative Examples 2 to 4) prepared using the same ink and without applying high frequency vibration. became.
Further, the sheet of Example 4 has a larger orientation strength ratio than the sheet of Comparative Example 5 produced in the same manner except that aggregated boron nitride particles were used as the anisotropic filler and high frequency vibration was not applied. However, the porosity was low, resulting in a high thermal conductivity.
Similarly, the sheet of Example 6 uses aggregated boron nitride particles as an anisotropic filler, and the orientation strength ratio is the same as that of the sheet of Comparative Example 6 prepared in the same manner except that high frequency vibration is not applied. Although large, the porosity was low, resulting in high thermal conductivity.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明の製造方法により製造される異方性フィラー含有シートは、各種用途に使用できる。
　本発明の製造方法により製造される異方性フィラー含有シートは、異方性フィラーとして熱伝導性物質を用いた場合には、熱伝導シートとして利用でき、特に、高い熱伝導性を有すると共に絶縁性も有しているので、熱伝導性と絶縁性を要求される各種用途（例えば、電力機器用回路基板や半導体パワーデバイス等の発熱性電子部品における放熱性絶縁層や接着剤層の材料など）に好適に使用できる。 The anisotropic filler-containing sheet produced by the production method of the present invention can be used for various applications.
The anisotropic filler-containing sheet produced by the production method of the present invention can be used as a thermal conductive sheet when a thermally conductive material is used as the anisotropic filler, and particularly has high thermal conductivity and insulation. In addition, various applications that require thermal conductivity and insulation (for example, materials for heat-dissipating insulating layers and adhesive layers in heat-generating electronic components such as circuit boards for power equipment and semiconductor power devices) ).
　本願は、２０１７年６月９日に日本国特許庁に出願された日本特許出願（特願２０１７－１１４３７７）に基づくものであり、その内容はここに参照として取り込まれる。
 
  This application is based on a Japanese patent application (Japanese Patent Application No. 2017-114377) filed with the Japan Patent Office on June 9, 2017, the contents of which are incorporated herein by reference.

Claims (9)

  1. 　支持体上に、異方性フィラーと樹脂を含むインクの膜を形成する工程、及び
    　前記膜が流動可能である間に、前記膜に５ｋＨｚ以上の周波数を有する振動を与える工程、
    　を含む、異方性フィラー含有シートの製造方法。     Forming a film of an ink containing an anisotropic filler and a resin on a support; and applying a vibration having a frequency of 5 kHz or more to the film while the film is flowable.
    The manufacturing method of an anisotropic filler containing sheet | seat containing.
  2. 　前記振動の周波数が、１０～１０００ｋＨｚである、請求項１に記載の異方性フィラー含有シートの製造方法。 The method for producing an anisotropic filler-containing sheet according to claim 1, wherein the vibration frequency is 10 to 1000 kHz.
  3. 　前記異方性フィラーの平均最長径が、０．５μｍ～２００μｍである、請求項１又は２に記載の異方性フィラー含有シートの製造方法。 3. The method for producing an anisotropic filler-containing sheet according to claim 1, wherein the average longest diameter of the anisotropic filler is 0.5 μm to 200 μm.
  4. 　前記異方性フィラーのアスペクト比が、２以上である、請求項１～３のいずれか一項に記載の異方性フィラー含有シートの製造方法。 The method for producing an anisotropic filler-containing sheet according to any one of claims 1 to 3, wherein an aspect ratio of the anisotropic filler is 2 or more.
  5. 　前記異方性フィラーが、鱗片状の窒化ホウ素粒子を含む、請求項１～４のいずれか一項に記載の異方性フィラー含有シートの製造方法。 The method for producing an anisotropic filler-containing sheet according to any one of claims 1 to 4, wherein the anisotropic filler contains scaly boron nitride particles.
  6. 　前記異方性フィラーが、六方晶窒化ホウ素粒子を含む、請求項１～５のいずれか一項に記載の異方性フィラー含有シートの製造方法。 The method for producing an anisotropic filler-containing sheet according to any one of claims 1 to 5, wherein the anisotropic filler comprises hexagonal boron nitride particles.
  7. 　前記膜中の前記異方性フィラーの体積率が、１０～９０体積％である、請求項１～６のいずれか一項に記載の異方性フィラー含有シートの製造方法。 The method for producing an anisotropic filler-containing sheet according to any one of claims 1 to 6, wherein the volume fraction of the anisotropic filler in the film is 10 to 90% by volume.
  8. 　前記樹脂が熱硬化性樹脂を含む、請求項１～７のいずれか一項に記載の異方性フィラー含有シートの製造方法。 The method for producing an anisotropic filler-containing sheet according to any one of claims 1 to 7, wherein the resin contains a thermosetting resin.
  9. 　さらに、前記膜をプレスする工程を含む、請求項１～８のいずれか一項に記載の異方性フィラー含有シートの製造方法。
          The method for producing an anisotropic filler-containing sheet according to any one of claims 1 to 8, further comprising a step of pressing the film.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62154410A (en) * 1985-12-25 1987-07-09 信越化学工業株式会社 Heat conductive insulating sheet
JP2001172398A (en) * 1999-12-17 2001-06-26 Polymatech Co Ltd Thermal conduction molded product and its production method
JP2002080617A (en) * 2000-09-06 2002-03-19 Polymatech Co Ltd Thermoconductive sheet
JP2006335957A (en) * 2005-06-03 2006-12-14 Polymatech Co Ltd Method of manufacturing thermally conductive molded article and thermally conductive molded article

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62154410A (en) * 1985-12-25 1987-07-09 信越化学工業株式会社 Heat conductive insulating sheet
JP2001172398A (en) * 1999-12-17 2001-06-26 Polymatech Co Ltd Thermal conduction molded product and its production method
JP2002080617A (en) * 2000-09-06 2002-03-19 Polymatech Co Ltd Thermoconductive sheet
JP2006335957A (en) * 2005-06-03 2006-12-14 Polymatech Co Ltd Method of manufacturing thermally conductive molded article and thermally conductive molded article

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