WO2015016221A1 - Elastomer molded article and method for producing same - Google Patents
Elastomer molded article and method for producing same Download PDFInfo
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- WO2015016221A1 WO2015016221A1 PCT/JP2014/069952 JP2014069952W WO2015016221A1 WO 2015016221 A1 WO2015016221 A1 WO 2015016221A1 JP 2014069952 W JP2014069952 W JP 2014069952W WO 2015016221 A1 WO2015016221 A1 WO 2015016221A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/22—Component parts, details or accessories; Auxiliary operations
- B29C39/24—Feeding the material into the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
- B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
- B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
- B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K9/00—Use of pretreated ingredients
- C08K9/08—Ingredients agglomerated by treatment with a binding agent
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L101/00—Compositions of unspecified macromolecular compounds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
- H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
- H01L23/3737—Organic materials with or without a thermoconductive filler
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
- B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
- B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
- B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
- B29C2035/0811—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using induction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/22—Component parts, details or accessories; Auxiliary operations
- B29C39/42—Casting under special conditions, e.g. vacuum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2021/00—Use of unspecified rubbers as moulding material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
- B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
- B29K2995/0008—Magnetic or paramagnetic
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
- B29K2995/0012—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular thermal properties
- B29K2995/0013—Conductive
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Definitions
- the present invention relates to an elastomer molded body having high thermal conductivity and a method for producing the same.
- a heat sink made of copper or aluminum having a high thermal conductivity is used.
- a heat transfer member is interposed between the electronic component and the heat sink in order to efficiently transfer heat generated in the electronic component to the heat sink. Heat generated in the electronic component is released from the heat dissipation surface of the heat sink via the heat transfer member.
- a molded body in which a thermally conductive filler is blended in a matrix made of a polymer material is used as the heat transfer member.
- particles having high thermal conductivity such as graphite may be blended in order to improve the heat dissipation of the molded body.
- graphite even if graphite is simply blended, it is difficult to form a heat transfer path by bringing graphite into contact with each other.
- the hardness of the molded body is increased and the elongation is decreased, so that flexibility may be impaired.
- Patent Document 2 discloses a urethane foam molded article in which magnetic particles are blended to improve heat dissipation.
- the magnetic particles are oriented in the polyurethane foam in a state of being connected to each other, a heat transfer path is formed in the orientation direction of the magnetic particles.
- the heat dissipation of a urethane foam molded object improves.
- the thermal conductivity of iron or stainless steel blended as magnetic particles is smaller than that of graphite. Therefore, the effect of improving heat dissipation is not sufficient only by orienting the magnetic particles.
- Patent Documents 4 and 5 disclose a molded body in which composite particles in which magnetic particles are bonded to the surface of thermally conductive particles are blended with a base material.
- the heat conductive particles having a large thermal conductivity are oriented by utilizing the magnetic field orientation of the magnetic particles.
- the oriented heat conductive particles composite particles
- a heat transfer path is formed in the substrate.
- the present invention has been made in view of such circumstances, and provides an elastomer molded body having further improved thermal conductivity without impairing the orientation of composite particles blended as a thermally conductive filler. Is an issue. It is another object of the present invention to provide a manufacturing method thereof.
- an elastomer molded article of the present invention has a base material made of an elastomer, and a powder of composite particles that are oriented and contained in the base material. Includes a heat conductive particle made of a non-magnetic material and a magnetic particle bonded to the surface of the heat conductive particle with a binder, and the particle size distribution of the powder of the composite particle has a small particle size side peak and a large particle size distribution. It has two peaks of the particle size side peak.
- the elastomer molded body of the present invention has a powder of oriented composite particles.
- the thermally conductive particles forming the core of the composite particles have a large thermal conductivity.
- the thermally conductive particles themselves are nonmagnetic. However, magnetic particles are adhered to the surface of the heat conductive particles.
- the magnetic particles are oriented along the magnetic field lines in a magnetic field. Therefore, when a magnetic field is applied to the composite particles, the composite particles are oriented along the lines of magnetic force. That is, by compositing the thermally conductive particles and the magnetic particles, the thermally conductive particles made of a non-magnetic material can be oriented using the magnetic field orientation of the magnetic particles.
- the composite particles are linearly connected, so that a heat transfer path is formed in the base material. Therefore, the thermal conductivity of the elastomer molded body of the present invention is high.
- the particle size distribution of the composite particle powder has two peaks, a small particle size side peak and a large particle size side peak. That is, the composite particle powder is a powder in which a small particle size powder and a large particle size powder are mixed.
- the particle size distribution in the present invention a volume-based frequency distribution of particles is employed.
- the particle size distribution of the composite particle powder produced without adjusting the particle size such as classification usually has one peak.
- the composite particles and the base material can be distinguished relatively clearly as shown in Examples described later. Can do. That is, since the composite particles are arranged linearly in the orientation direction, most of the composite particles adjacent to each other in the plane direction intersecting the orientation direction is the base material.
- a large particle size side peak is formed in the elastomer molded body of the present invention in which the powder of composite particles having a particle size distribution having two peaks, a small particle size side peak and a large particle size side peak, is oriented.
- the large particle size particles are aligned and connected linearly, and the small particle size particles constituting the small particle size side peak are also linearly aligned between the large particle particles adjacent to each other in the plane direction intersecting the alignment direction. It is a series. Therefore, as shown in the examples described later, when the surface intersecting the orientation direction is observed, the small particle size particles are formed so as to fill the gap (base material portion) between the large particle size particle and the large particle size particle. It can be confirmed that they are distributed.
- the elastomer molded body of the present invention heat transfer can be performed over the entire surface. For this reason, the thermal conductivity of the elastomer molded body can be improved without increasing the filling rate of the composite particles.
- small particles having a small particle size are interposed between the large particles, even if the filling rate of the composite particles is increased, the composite particles are unlikely to interfere with each other and the orientation is not easily impaired.
- the composite particles in the substrate need only be arranged in a predetermined direction with a certain regularity.
- the elastomer molded body may be arranged in a straight line or a curved line between one end and the other end (the end may not be 180 ° opposite to the one end).
- the method for producing an elastomer molded body of the present invention is a method for producing an elastomer molded body having the above-described configuration (1) in the case where composite particles are produced by the agitation granulation method, using an agitation granulator.
- the powder raw material containing the heat conductive particles, the magnetic particles, and the binder is stirred to produce composite particles, and the composite particles are classified into small particles and large particles.
- a molding step of molding the mixed raw material in a magnetic field is a method for producing an elastomer molded body having the above-described configuration (1) in the case where composite particles are produced by the agitation granulation method, using an agitation granulator.
- the composite particle powder preparation step first, a powder raw material containing a powder of heat conductive particles, a powder of magnetic particles, and a binder for bonding them is stirred at high speed using a stirring granulator.
- the powder of a composite particle can be manufactured easily.
- the heat conductive particles and the magnetic particles can be softly bonded with the binder. Therefore, even when the thermally conductive particles have a shape with a high thermal conductivity (a shape with a large aspect ratio), the magnetic particles can be combined without breaking the shape.
- the adhesion amount of a magnetic particle can be increased by using a binder.
- a desired orientation state of the composite particles can be realized even in a relatively low magnetic field having a magnetic flux density of 350 mT or less.
- an electromagnet is used to form the magnetic field. If the molding can be performed in a low magnetic field, the gap between the electromagnets arranged with the molding die interposed therebetween can be increased. For this reason, the cavity of a shaping
- the above Patent Document 1 describes that the orientation of the graphite powder can be promoted by attaching a ferromagnetic powder to the surface of the graphite powder.
- a mechanochemical method is mentioned as a method for mechanically fixing the particles.
- bonding with a binder is not described.
- the magnetic particles are attached to the surface of the thermally conductive particles without using a binder, it is difficult to increase the amount of magnetic particles attached. That is, in the composite particles without using a binder, the amount of magnetic particles attached is small and the magnetism necessary for orientation is insufficient. For this reason, when the said particle
- graphite since graphite is brittle, there is also a problem that when mechanochemical treatment involving compression and shearing of particles is performed, it is easily pulverized and the shape cannot be maintained.
- the produced composite particle powder is classified to prepare a small particle size powder and a large particle size powder.
- the small particle size particles can be dispersed so as to fill the gaps between the large particle size particles. Thereby, the heat conductivity of the elastomer molded body manufactured can be improved.
- the prepared small particle size powder and large particle size powder are mixed with the elastomer raw material to prepare a mixed raw material.
- the prepared mixed raw material is molded in a magnetic field.
- the large particle size particles are aligned and connected in a linear manner, and the small particle size particles are also filled between the large particle particles and the large particle particles adjacent to each other in the plane direction intersecting the alignment direction. Oriented and linearly connected.
- the uneven distribution of the composite particles due to the difference in magnetic flux density can be suppressed by applying a magnetic field having a substantially uniform magnetic flux density (uniform magnetic field) to the mixed raw material.
- the composite particles can be oriented while being dispersed throughout the substrate.
- a relatively small amount of composite particles can be blended to easily produce the elastomer molded body of the present invention having high thermal conductivity.
- FIG. 2 is a particle size distribution of the mixed powder of Example 1.
- FIG. It is a perspective view of the magnetic induction molding apparatus used for manufacture of an elastomer molded object. It is sectional drawing of the same apparatus.
- 2 is an X-ray CT photograph of the elastomer molded body of Example 1.
- FIG. 3 is an X-ray CT photograph of an elastomer molded body of Comparative Example 2. It is a graph which shows the relationship between the filling rate of composite particle
- the elastomer molded body of the present invention has a base material composed of an elastomer and a powder of composite particles that are oriented and contained in the base material.
- the elastomer may be appropriately selected from a crosslinked rubber and a thermoplastic elastomer.
- the elastomer may be a solid body or a foamed body such as polyurethane foam. However, in view of the filling properties such as composite particles, a solid body having no bubbles (cells) is desirable.
- the crosslinked rubber include urethane rubber, silicone rubber, fluorine rubber, acrylic rubber, acrylonitrile butadiene rubber, and the like.
- the thermoplastic elastomer include various thermoplastic elastomers such as styrene, olefin, vinyl chloride, polyester, polyurethane, and polyamide.
- the curing method of the crosslinked rubber may be appropriately selected according to the type of rubber polymer. For example, heat curing, ultraviolet curing, electron beam curing, moisture curing and the like can be mentioned.
- heat curing ultraviolet curing, electron beam curing, moisture curing and the like can be mentioned.
- the temperature of the elastomer raw material is raised and cured.
- the curing temperature of the elastomer is desirably 150 ° C. or lower.
- the viscosity of the elastomer is desirably 100 Pa ⁇ s or less.
- the viscosity of the elastomer is high, the composite particles may not be easily oriented due to the influence of viscous resistance.
- the elastomer may be diluted with a solvent to lower the viscosity, and the solvent may be volatilized during curing.
- the elastomer is preferably urethane rubber, silicone rubber, or fluororubber.
- the composite particles include heat conductive particles made of a non-magnetic material and magnetic particles bonded to the surface of the heat conductive particles with a binder.
- the heat conductive particles may be non-magnetic and have high thermal conductivity.
- diamagnetic materials and paramagnetic materials other than ferromagnetic materials and antiferromagnetic materials are referred to as nonmagnetic materials.
- the thermal conductivity of the thermally conductive particles is desirably 200 W / m ⁇ K or more.
- a material of the heat conductive particles for example, a carbon material such as graphite or carbon fiber is suitable. Also, aluminum, gold, silver, copper, and alloys based on these may be used.
- the heat conductive particles one kind of particles may be used or two or more kinds of particles may be used in combination.
- the shape of the heat conductive particle is not particularly limited as long as it can be combined with the magnetic particle.
- various shapes such as a flaky shape, a fibrous shape, a columnar shape, a spherical shape, an elliptical sphere shape, and an oval sphere shape (a shape in which a pair of opposing hemispheres are connected by a cylinder) can be employed.
- the thermally conductive particles have a shape other than a sphere, the contact area between the composite particles increases. As a result, a heat transfer path is easily secured and the amount of heat transferred is increased.
- the shape of metal particles such as aluminum, gold, and copper is spherical.
- the graphite particles even if the graphite particles have a shape with a large aspect ratio, they can be obtained at a lower cost than metal particles. For this reason, graphite is suitable as a material for the thermally conductive particles.
- graphite examples include natural graphite such as scaly graphite, scaly graphite, and earthy graphite, and artificial graphite. Artificial graphite is not easily scaled. For this reason, natural graphite is preferred because it is scaly and has a high effect of improving thermal conductivity.
- expanded graphite in which a substance that generates gas by heating is inserted between scaly graphite layers may be used. Expanded graphite is often used as a flame retardant. When heat is applied to expanded graphite, the generated gas expands the layers and forms a stable layer against heat and chemicals. The formed layer becomes a heat-insulating layer and prevents heat transfer, thereby providing a flame retardant effect. Therefore, it is preferable to use at least one of natural graphite particles and expanded graphite particles as the heat conductive particles.
- the composite particles are oriented. For this reason, the heat applied to the elastomer molded body is easily transmitted to the thermally conductive particles. Therefore, when the thermally conductive particles are made of expanded graphite, the expanded graphite reaches the expansion start temperature early. Thereby, the flame-retardant effect by expanded graphite is exhibited rapidly. Thus, flame retardance can be imparted to the elastomer molded body by using expanded graphite as the thermally conductive particles.
- a suitable one may be selected from known expanded graphite powder in consideration of the expansion start temperature, the expansion rate, and the like.
- the expansion start temperature of expanded graphite must be higher than the temperature at the time of molding the elastomer molded body.
- expanded graphite having an expansion start temperature of 150 ° C. or higher is suitable.
- the magnetic particles only need to have excellent magnetization characteristics.
- ferromagnetic materials such as iron, nickel, cobalt, gadolinium, stainless steel, magnetite, maghemite, manganese zinc ferrite, barium ferrite, strontium ferrite, MnO, Cr Antiferromagnetic materials such as 2 O 3 , FeCl 2 , and MnAs, and alloys particles using these are preferable.
- iron, nickel, cobalt, and powders of these iron-based alloys are preferable from the viewpoint of easy availability as fine particles and high saturation magnetization.
- the magnetic particles are bonded to the surface of the thermally conductive particles and play a role in orienting the thermally conductive particles.
- the magnetic particles may be directly bonded to the surface of the thermally conductive particles. As described later, when particles other than the magnetic particles are bonded to the surface of the thermally conductive particles, It may be indirectly bonded. Further, the magnetic particles may be adhered to only a part of the surface of the heat conductive particles or the like, or may be adhered so as to cover the entire surface.
- the size of the magnetic particles may be appropriately determined in consideration of the size of the thermally conductive particles, the orientation of the composite particles, the thermal conductivity between the composite particles, and the like.
- the particle diameter of the magnetic particles is desirably 1/25 or more and 1/2 or less of the particle diameter of the heat conductive particles.
- the particle diameter is the length of the longest part of the particle.
- the average particle size of the magnetic particles to be combined needs to be 100 nm or more. It is more preferable that the thickness is 1 ⁇ m or more, further 5 ⁇ m or more.
- the shape of the magnetic particles is not particularly limited.
- the shape of the magnetic particles is flat, the distance between adjacent heat conductive particles is shorter than when the shape is spherical. Thereby, the thermal conductivity between adjacent composite particles is improved. As a result, the thermal conductivity of the elastomer molded body is improved.
- the shape of the magnetic particles is flat, the magnetic particles and the heat conductive particles are in contact with each other on the surface. That is, the contact area between the two becomes large. Thereby, the adhesive force of a magnetic particle and a heat conductive particle improves. Therefore, the magnetic particles are difficult to peel off.
- the thermal conductivity between the magnetic particles and the thermally conductive particles is also improved. For these reasons, it is desirable to employ flaky particles as the magnetic particles.
- the elastomer molded body of the present invention may be required to have insulating properties.
- conduction between the composite particles can be interrupted by adhering insulating inorganic particles in addition to magnetic particles to the surface of the thermally conductive particles.
- the heat conductive particles and magnetic particles (conducting particles) between adjacent composite particles even if the composite particles are oriented in contact with each other. It becomes difficult to contact each other. Therefore, the electrical resistance between the composite particles increases.
- electrical_connection between composite particles can be interrupted when composite particles contact via an insulating inorganic particle.
- the insulating inorganic particles may be particles of an inorganic material having insulating properties. Among these, those having relatively high thermal conductivity are desirable from the viewpoint of not inhibiting the thermal conductivity between the composite particles. For example, it is preferable that the thermal conductivity of the insulating inorganic particles is 5 W / m ⁇ K or more. Examples of the insulating inorganic material having a thermal conductivity of 5 W / m ⁇ K or more include aluminum hydroxide, aluminum oxide (alumina), magnesium hydroxide, magnesium oxide, and talc. Further, when the insulating inorganic particles have flame retardancy, flame retardancy can be imparted to the elastomer molded body.
- aluminum hydroxide is suitable because of its relatively high thermal conductivity and flame retardancy.
- Aluminum hydroxide is dehydrated and decomposed when heated to a predetermined temperature. Since dehydration decomposition is an endothermic reaction, temperature rise is suppressed and a flame retardant effect is brought about.
- the insulating inorganic particles may be directly bonded to the surface of the heat conductive particles, or may be indirectly bonded via magnetic particles.
- the insulating inorganic particles may be adhered to only a part of the surface of the heat conductive particles or the like, or may be adhered so as to cover the entire surface. From the viewpoint of increasing the electrical resistance between the composite particles and improving the electrical insulation of the elastomer molded body, it is desirable that the insulating inorganic particles are disposed on the outermost layer of the composite particles.
- the size of the insulating inorganic particles may be appropriately determined in consideration of the adhesiveness to the heat conductive particles and the magnetic particles, the electric insulation between the composite particles and the heat conductivity. If the insulating inorganic particles are too large, the adhesiveness and the thermal conductivity between the composite particles are lowered.
- the particle diameter of the insulating inorganic particles is preferably 1/100 or more and 1/10 or less of the particle diameter of the heat conductive particles.
- the particle diameter is the length of the longest part of the particle.
- the shape of the insulating inorganic particles is not particularly limited.
- the distance between adjacent heat conductive particles is shorter than that of a spherical shape.
- the thermal conductivity between adjacent composite particles is improved.
- the thermal conductivity of the elastomer molded body is improved.
- the contact area between the insulating inorganic particles, the magnetic particles, and the heat conductive particles is increased.
- adhesive force improves and it becomes difficult to exfoliate insulating inorganic particles.
- the thermal conductivity between the insulating inorganic particles, the magnetic particles, and the heat conductive particles is also improved. For these reasons, it is desirable to employ flaky particles as the insulating inorganic particles.
- the binder for adhering the thermally conductive particles and the magnetic particles and the like may be appropriately selected in consideration of the type of the thermally conductive particles and the influence on the moldability.
- a water-soluble binder is preferable because it has little influence on moldability and is environmentally friendly.
- methyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol and the like can be mentioned.
- the binder that adheres the magnetic particles and the binder that adheres the insulating inorganic particles may be the same or different.
- the composite particles can be manufactured, for example, by spraying the powder of the heat conductive particles with a paint in which the powder of the magnetic particles is dispersed in the solution in which the binder is dissolved.
- a powder raw material containing heat conductive particle powder, magnetic particle powder, and binder can be produced by stirring at high speed (stir granulation method). In the stirring granulation method, frictional heat is generated by high-speed stirring. For this reason, as a binder, a non-volatile thing is desirable.
- the water-soluble binder described above is suitable.
- the particle size distribution of the composite particle powder has two peaks, a small particle size side peak and a large particle size side peak.
- the particle size distribution of the composite particle powder may be measured using a laser diffraction / scattering particle size distribution measuring apparatus.
- a volume-based frequency distribution of particles is employed as the particle size distribution in the present invention.
- the peak particle size of the small particle size side peak and the large particle size side peak It is desirable that the difference from the peak particle size is relatively large.
- the peak particle size of the large particle size side peak is preferably at least twice the peak particle size of the small particle size side peak. It is more preferable that it is 5 times or more.
- the peak particle size of the large particle size side peak is desirably 20 times or less than the peak particle size of the small particle size side peak. . It is more preferable that it is 15 times or less.
- the ratio of the peak particle size of the small particle size side peak to the peak particle size of the large particle size side peak is preferably 1: 2 to 1:20, and 1: 5 to 1 : 15 is more preferable.
- the large particle size particles included in the large particle size side peak are small in mass ratio and included in the small particle size side peak. It is desirable that they are blended at a ratio equal to or greater than that of the particle size.
- the ratio between the area of the small particle size side peak and the area of the large particle size side peak is preferably 1: 1 to 1:30. A ratio of 1: 5 to 1:20 is more preferable.
- the filling rate of the composite particles in the elastomer molded body may be determined in consideration of the physical properties of the elastomer molded body, the effect of improving thermal conductivity, and the like.
- the filling rate of the composite particles is desirably 50% by volume or less when the volume of the elastomer molded body is 100% by volume.
- the filling rate of the composite particles is 40% by volume or less, there is little interference between the composite particles, and the effect of improving thermal conductivity is large.
- it is desirable that the filling rate of the composite particles is 10% by volume or more. More preferably, the volume is 25% by volume or more.
- the thermal conductivity when the filling rate of the composite particles is 26% by volume or more and 38% by volume or less when the volume of the elastomer molded body is 100% by volume is 2. 4 W / m ⁇ K or more is desirable.
- the thermal conductivity may be measured according to the heat flow meter method of JIS A1412-2 (1999).
- the elastomer molded body of the present invention may further include a non-oriented filler that is dispersed in the base material without being oriented.
- the non-oriented filler may be appropriately selected according to the purpose such as improvement of thermal conductivity, provision of insulation, improvement of flame retardancy, and the like.
- the above-described heat conductive particles, insulating inorganic particles and the like may be dispersed as they are.
- the method for producing an elastomer molded body of the present invention is a production method for producing composite particles by agitation granulation method, and includes a composite particle powder preparation step, a mixed raw material preparation step, and a forming step. Hereinafter, each step will be described.
- Composite particle powder preparation step This step uses a stirring granulator to stir the powder raw material containing thermally conductive particle powder, magnetic particle powder, and binder to produce composite particle powder, It is a step of classifying the composite particle powder to prepare a small particle size powder and a large particle size powder.
- the heat conductive particles, magnetic particles, and binder are as described above. Therefore, the description is omitted here.
- the blending amount of the powder of the heat conductive particles, the powder of the magnetic particles, and the binder considering the magnetic field orientation of the composite particles to be manufactured, the thermal conductivity of the elastomer molded body including the composite particles, What is necessary is just to adjust suitably.
- the blending amount of the magnetic particle powder is 20 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the graphite powder.
- the amount is less than 20 parts by mass, the amount of adhesion of the magnetic particles is small, so that the magnetism necessary for the orientation of the composite particles may be insufficient.
- the adhesion amount of the magnetic particles becomes excessive. Accordingly, an increase in the mass of the elastomer molded body and an increase in cost are incurred accordingly.
- the blending amount of the binder is desirably 2% by mass or more and 4% by mass or less when the total mass of the powder to be bonded is 100% by mass as an amount necessary and sufficient for coating the particles to be bonded.
- the binder does not reach the surface of the heat conductive particles or the magnetic particles, and the adhesiveness decreases.
- it exceeds 4 mass% there exists a possibility that composite particles may aggregate with an excess binder.
- the binder may be solid or liquid. When water-soluble powder is used as the binder, it is preferable to add water after previously stirring the binder and the powder of other raw materials. By doing so, aggregation of particles can be suppressed.
- both powders may be stirred together to adhere to the thermally conductive particles, but first the magnetic particles are adhered to the thermally conductive particles. Then, the insulating inorganic particles may be adhered next.
- the first stage of this step is the first stirring step of stirring the first powder raw material containing the powder of the heat conductive particles, the powder of the magnetic particles, and the binder, and the powder of the insulating inorganic particles and the binder It is good to comprise so that it may have and the 2nd stirring process of stirring further.
- the method for classifying the produced composite particle powder is not particularly limited. For example, it may be performed by sieving, a dry classifier or the like.
- the particle size ranges of the small particle size powder and the large particle size powder after classification may be appropriately determined in consideration of the thickness of the elastomer molded body to be manufactured. From the viewpoint of aligning the small particle size so as to fill the space between the large particle size and not disturb the orientation of the large particle size, there is a difference in each peak particle size when the particle size distribution is measured.
- a relatively large one is desirable.
- the peak particle size of the large particle size powder is preferably at least twice the peak particle size of the small particle size powder. It is more preferable that it is 5 times or more.
- the peak particle size of the large particle size powder is desirably 20 times or less the peak particle size of the small particle size powder. It is more preferable that it is 15 times or less.
- This step is a step of preparing a mixed raw material by mixing the small particle size powder and large particle size powder of the composite particles produced in the previous step and an elastomer raw material.
- the elastomer raw material In addition to the polymer of the elastomer component (in the case where the elastomer is a crosslinked rubber, the elastomer raw material), if necessary, a crosslinking agent, a plasticizer, a catalyst, a foaming agent, a foam stabilizer, a flame retardant, a charge Contains inhibitors, thickeners, stabilizers, fillers, colorants and the like.
- the mixed raw material may be produced by stirring the composite particle powder and the elastomer raw material using a stirring blade or the like.
- a collision stirring method may be employed in which a polyol raw material and a polyisocyanate raw material are mixed by being injected and collided with each other at a high pressure.
- the small particle size powder and the large particle size powder may be blended in advance in at least one of the polyol material and the polyisocyanate material.
- the large particle size side powder should be blended at a mass ratio equal to or greater than the small particle size powder. Is desirable.
- the mass ratio of the small particle size powder to the large particle size powder is desirably 1: 1 to 1:10.
- non-oriented fillers such as heat conductive particles and insulating inorganic particles may be dispersed in the base material in addition to the composite particles.
- the powder of composite particles and the non-oriented filler may be mixed with the elastomer raw material.
- the blending amount of the composite particle powder may be determined in consideration of the physical properties of the elastomer molded body, the effect of improving thermal conductivity, and the like. For example, from the viewpoint of reducing the influence on moldability and physical properties, it is desirable to blend so that the filling rate of the composite particles is 50% by volume or less when the volume of the elastomer molded body is 100% by volume. . It is more suitable when it is 40 volume% or less. On the other hand, in order to obtain the effect of improving thermal conductivity, it is desirable to blend so that the filling rate of the composite particles is 10% by volume or more. More preferably, the volume is 25% by volume or more.
- Molding step This step is a step of placing the mixed raw material prepared in the previous step in a mold and molding the mixed raw material in a magnetic field.
- the mold may be a closed mold or an open mold.
- the magnetic field may be formed in the direction in which the composite particles are oriented. For example, when orienting composite particles in a straight line, it is desirable to apply magnetic lines of force from one end of the mixed raw material to the other end.
- a magnet may be disposed so as to sandwich the mixed raw material.
- a permanent magnet or an electromagnet may be used as the magnet. When an electromagnet is used, magnetic field formation can be switched on and off instantaneously, and the control of the magnetic field strength is easy. Therefore, it is easy to control molding.
- the magnetic field lines constituting the magnetic field form a closed loop. By doing so, leakage of the magnetic field lines is suppressed, and a stable magnetic field can be applied to the mixed raw material.
- the mold may be made of a material having low magnetic permeability, that is, a non-magnetic material.
- a mold made of aluminum or aluminum alloy is suitable.
- the magnetic field and magnetic lines generated from a magnetic source such as an electromagnet are not easily affected, and the magnetic field state is easily controlled.
- a mold made of a magnetic material may be used as appropriate according to the required magnetic field and magnetic field lines.
- the difference in magnetic flux density between the mixed raw materials is preferably within ⁇ 10%. It is more preferable that it is within ⁇ 5%, more preferably within ⁇ 3%.
- the flaky stainless steel powder was produced by flattening a spherical stainless steel powder (“DAP410L” manufactured by Daido Steel Co., Ltd., average particle size: 10 ⁇ m). That is, a spherical stainless steel powder was filled into a planetary ball mill (“Planet-M” manufactured by Gokin Planetaring) together with zirconia balls having a diameter of 5 mm, and processed at a rotational speed of 300 rpm for 1 hour.
- a spherical stainless steel powder (“DAP410L” manufactured by Daido Steel Co., Ltd., average particle size: 10 ⁇ m). That is, a spherical stainless steel powder was filled into a planetary ball mill (“Planet-M” manufactured by Gokin Planetaring) together with zirconia balls having a diameter of 5 mm, and processed at a rotational speed of 300 rpm for 1 hour.
- a powder of composite particles was produced in the same manner as above except that the scaly graphite powder was replaced with “X-100”. After the produced composite particle powder was dried, it was sieved with two types of sieves having openings of 100 ⁇ m and 45 ⁇ m to obtain a small particle size powder having a particle size of 45 ⁇ m or more and 100 ⁇ m or less.
- the mass ratio of the blended flaky graphite powder and the stainless steel powder is 100: 37.5.
- the blending amount of HPMC is 2.2% by mass when the total mass of the scaly graphite powder and the stainless steel powder is 100% by mass.
- Example 1 100 g of the small particle size powder and 400 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 4).
- Example 2 50 g of the small particle size powder and 450 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 9).
- Example 3 200 g of the small particle size powder and 400 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 2).
- Example 4 A mixed powder of Example 1 was prepared by mixing 250 g of the small particle size powder and 250 g of the large particle size powder (the mass ratio of the small particle size powder to the large particle size powder was 1: 1).
- the particle size distribution of the mixed powders of Examples 1 to 4 was measured with a laser diffraction / scattering particle size distribution measuring apparatus (“MT-3300EX” manufactured by Nikkiso Co., Ltd.).
- FIG. 1 the particle size distribution of the mixed powder of Example 1 is shown.
- the particle size distribution of the mixed powder (composite particle powder) was confirmed to have two peaks, a small particle size side peak and a large particle size side peak.
- the peak particle size of the small particle size side peak was 90 ⁇ m
- the peak particle size of the large particle size side peak was 900 ⁇ m
- the ratio of both peak particle sizes was 1:10.
- the area ratio between the small particle size side peak and the large particle size side peak was 1:10.
- the peak areas of the small particle size side and the large particle size side were calculated from the particle size distributions of the mixed powders of Examples 2 to 4.
- the mixed powder of Example 2 was 1:20.
- the mixed powder of 1: 5 was 1:1 of the mixed powder of Example 4.
- a mixed raw material was prepared by mixing the mixed powder with the manufactured silicone compound.
- the mixed powder was blended so that the filling rate of the composite particles was 32.7% by volume when the volume of the produced elastomer molded body was 100% by volume.
- each of the mixed raw materials is poured into an aluminum mold (see FIGS. 2 and 3 to be described later.
- the cavity is a rectangular parallelepiped having a length of 130 mm ⁇ width of 130 mm ⁇ thickness of 5 mm). , Sealed.
- molding die was installed in the magnetic induction molding apparatus, and it shape
- FIG. 2 shows a perspective view of the magnetic induction molding apparatus.
- FIG. 3 shows a sectional view of the apparatus. In FIG. 2, hatching of the yoke part and the core part is omitted for convenience of explanation.
- the magnetic induction molding apparatus 1 includes a gantry 2, an electromagnet unit 3, a molding die 4, a planar heater 50, and a heat insulating member 51.
- the electromagnet unit 3 is placed on the upper surface of the gantry 2.
- the electromagnet unit 3 and the gantry 2 are fixed by screwing a bracket 21 to each.
- the electromagnet portion 3 includes yoke portions 30U and 30D, coil portions 31L and 31R, and pole pieces 32U and 32D.
- the yoke portion 30U is made of iron and has a flat plate shape.
- the yoke part 30D is made of iron and has a flat plate shape.
- the yoke portions 30U and 30D are arranged to face each other in the vertical direction.
- the coil part 31L is interposed between the yoke parts 30U and 30D.
- the coil part 31 ⁇ / b> L is disposed on the left side of the mold 4.
- Two coil portions 31L are arranged in the vertical direction.
- Each of the coil portions 31L includes a core portion 310L and a conductive wire 311L.
- the core portion 310L is made of iron and has a columnar shape extending in the vertical direction.
- the conducting wire 311L is wound around the outer peripheral surface of the core portion 310L.
- the conducting wire 311L is connected to a power source (not shown).
- the coil portion 31R is interposed between the yoke portions 30U and 30D.
- the coil portion 31 ⁇ / b> R is disposed on the right side of the mold 4.
- Two coil portions 31 ⁇ / b> R are arranged in the vertical direction.
- the coil portions 31R each have the same configuration as the coil portion 31L. That is, the coil portion 31R includes a core portion 310R and a conducting wire 311R.
- the conducting wire 311R is wound around the outer peripheral surface of the core portion 310R.
- the conducting wire 311R is connected to a power source (not shown).
- the pole piece 32U is made of iron and has a flat plate shape.
- the pole piece 32U is disposed at the center of the lower surface of the yoke portion 30U.
- the pole piece 32U is interposed between the yoke portion 30U and the mold 4.
- the pole piece 32D is made of iron and has a flat plate shape.
- the pole piece 32D is disposed at the center of the upper surface of the yoke portion 30D.
- the molding die 4 is disposed between the coil part 31L and the coil part 31R.
- the molding die 4 includes an upper die 40U and a lower die 40D.
- the upper mold 40U has a square plate shape.
- the lower mold 40D has a rectangular parallelepiped shape.
- a recess is formed on the upper surface of the lower mold 40D.
- the recess has a rectangular parallelepiped shape that opens upward.
- the planar heater 50 has a square sheet shape.
- the planar heater 50 is disposed so as to cover the lower surface of the lower mold 40D.
- the mold 4 is held at 100 ° C. by the planar heater 50.
- the heat insulating member 51 is made of glass fiber and has a flat plate shape.
- the heat insulating member 51 is interposed between the planar heater 50 and the pole piece 32D. The heat transfer from the planar heater 50 to the electromagnet unit 3 is suppressed by the heat insulating member 51.
- Magnetic field lines L radiated from the upper end of the core portion 310L of the coil portion 31L flow into the cavity 41 of the mold 4 through the yoke portion 30U and the pole piece 32U. Then, it flows into the lower end of the core part 310L through the pole piece 32D and the yoke part 30D.
- the lines of magnetic force L radiated from the upper end of the core portion 310R of the coil portion 31R flow into the cavity 41 of the mold 4 through the yoke portion 30U and the pole piece 32U. Then, it flows into the lower end of the core portion 310R through the pole piece 32D and the yoke portion 30D.
- the magnetic lines L constitute a closed loop, the leakage of the magnetic lines L is suppressed.
- a uniform magnetic field is formed by magnetic lines L that are substantially parallel from the top to the bottom.
- the magnetic flux density in the cavity 41 was about 300 mT. Further, the difference in magnetic flux density in the cavity 41 was within ⁇ 3%.
- Molding was performed at 100 ° C. while applying a magnetic field for 30 minutes. After the molding was completed, the mold was removed to obtain an elastomer molded body. The obtained elastomer moldings were numbered according to the numbers of the mixed powders.
- an elastomer molded body was prepared in the same manner as in Examples 1 to 4, except that the powder of composite particles produced using scaly graphite powder “W + 32” was blended as it was without sieving instead of the mixed powder. Manufactured. There is one peak of the particle size distribution of the mixed composite particle powder. The obtained elastomer molded body was used as the elastomer molded body of Comparative Example 2.
- FIG. 4 shows an X-ray CT photograph of the elastomer molded body of Example 1.
- FIG. 5 the X-ray CT photograph of the elastomer molded object of the comparative example 2 is shown.
- the small particle size particles are dispersed and oriented so as to fill the gap (base material portion) between the large particle size particle and the large particle size particle. I was able to confirm.
- FIG. 5 in the elastomer molded body of Comparative Example 2 in which composite powder without classification was blended, almost no small particle size particles were observed between the large particle size particles. I could't.
- the thermal conductivity of the elastomer molded bodies of Examples 1 to 4 was larger than the thermal conductivity of the elastomer molded bodies of Comparative Examples 1 and 2.
- the thermal conductivity of the elastomer molded bodies of Examples 1 to 3 having a large blending ratio of the large particle size powder was as large as 3.4 W / m ⁇ K or more.
- the elastomer molded body in which the mixed powder of Example 1 was blended had a higher thermal conductivity than the elastomer molded body in which the powder of composite particles without classification was blended. became. Specifically, the thermal conductivity when the filling rate of the composite particles is 26% by volume or more and 38% by volume or less was 2.4 W / m ⁇ K or more.
- the elastomer molded body in which the mixed powder of Example 1 was blended had a higher filling rate at which the thermal conductivity was maximized than the elastomer molded body in which the composite particle powder without classification was blended. From this result, it can be seen that when the mixed powder of Example 1 is used, the powder of the composite particles can be filled more highly in order to increase the thermal conductivity.
- an elastomer molded body in which mixed powder is blended is an elastomer molded body in which only large particle diameter powder is blended (the mass of small particle diameter powder and large particle diameter powder).
- the thermal conductivity was greater than the ratio 0: 1).
- the one where the filling rate was high became large in thermal conductivity.
- thermal conductivity became large. For example, when the filling rate is 32.7% by volume, the thermal conductivity is maximized in the elastomer molded body in which the mass ratio of the small particle size powder to the large particle size powder is 1: 4.
- Example 1 ⁇ Composition of non-oriented filler>
- an insulating inorganic material magnesium oxide powder (“Starmag PSF-WR” manufactured by Kamishima Chemical Industry Co., Ltd., average particle size 1.0 ⁇ m) is blended as an unoriented filler, and an elastomer A molded body was produced.
- the mixed powder of Example 1 was blended so as to be 32.7% by volume when the volume of the elastomer molded body was 100% by volume, and the magnesium oxide powder was blended so as to be 8% by volume.
- FIG. 8 the measurement result of thermal conductivity is shown with a graph.
- the elastomer molded body of the present invention can be used in a wide range of fields such as electronic equipment, automobiles, and architecture. Specifically, it is suitable for a heat radiating member used for electronic equipment such as a personal computer, a heat radiating member for an in-vehicle ECU (electronic control unit), a heat radiating member for LED (light emitting diode) illumination, and the like.
- a heat radiating member used for electronic equipment such as a personal computer
- a heat radiating member for an in-vehicle ECU (electronic control unit) a heat radiating member for LED (light emitting diode) illumination, and the like.
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Abstract
An elastomer molded article comprises: a base material comprising an elastomer; and a powder of composite particles which is contained in the base material in an oriented state. The composite particles comprise: heat-conductive particles formed from a non-magnetic material; and magnetic particles attached onto the surfaces of the heat-conductive particles by a binder. The particle size distribution of the powder of the composite particles has two peaks, i.e., a peak appearing on a smaller particle diameter side and a peak appearing on a larger particle diameter side. A method for producing an elastomer molded article comprises: a composite particle powder preparation step of producing a powder of composite particles using a stirring granulator, and then sieving the powder of the composite particles to prepare a powder having a smaller particle diameter and a powder having a larger particle diameter; a mixed raw material preparation step of mixing the powder having a smaller particle diameter and the powder having a larger particle diameter of the composite particles with an elastomer raw material to prepare a mixed raw material; and a molding step of placing the mixed raw material in a molding die to mold the mixed raw material under a magnetic field.
Description
本発明は、熱伝導性が高いエラストマー成形体、およびその製造方法に関する。
The present invention relates to an elastomer molded body having high thermal conductivity and a method for producing the same.
電子機器には、CPU(Central Processing Unit)等の発熱を伴う電子部品が使用される。電子部品の発熱が大きくなると、誤作動や製品寿命の低下を招くおそれがある。そこで、電子部品の温度上昇を抑制するために、熱伝導率が大きい銅やアルミニウム製のヒートシンクが使用される。この際、電子部品とヒートシンクとの間には、電子部品において発生した熱をヒートシンクに効率良く伝達するために、熱伝達部材が介装される。電子部品において発生した熱は、熱伝達部材を介して、ヒートシンクの放熱面から放出される。例えば、特許文献1~5に開示されているように、熱伝達部材としては、高分子材料からなるマトリックス中に、熱伝導性フィラーが配合された成形体が用いられる。
For electronic equipment, electronic components with heat generation such as a CPU (Central Processing Unit) are used. If the heat generation of the electronic component is increased, there is a risk of causing malfunction or shortening of the product life. Accordingly, in order to suppress the temperature rise of the electronic component, a heat sink made of copper or aluminum having a high thermal conductivity is used. At this time, a heat transfer member is interposed between the electronic component and the heat sink in order to efficiently transfer heat generated in the electronic component to the heat sink. Heat generated in the electronic component is released from the heat dissipation surface of the heat sink via the heat transfer member. For example, as disclosed in Patent Documents 1 to 5, a molded body in which a thermally conductive filler is blended in a matrix made of a polymer material is used as the heat transfer member.
特許文献1に記載されているように、成形体の放熱性の向上を図るには、黒鉛等の熱伝導率の大きな粒子を配合すればよい。しかし、単に黒鉛を配合しても、黒鉛同士を接触させて熱の伝達経路を形成することは難しい。例えば、熱の伝達経路を形成するため、黒鉛を多量に配合すると、成形体の硬度が高くなり、伸びが低下することで、柔軟性が損なわれるおそれがある。また、成形体の質量が増加する、コストがかさむといった問題も生じる。
As described in Patent Document 1, particles having high thermal conductivity such as graphite may be blended in order to improve the heat dissipation of the molded body. However, even if graphite is simply blended, it is difficult to form a heat transfer path by bringing graphite into contact with each other. For example, when a large amount of graphite is blended to form a heat transfer path, the hardness of the molded body is increased and the elongation is decreased, so that flexibility may be impaired. Moreover, the problem that the mass of a molded object increases and cost increases also arises.
一方、特許文献2には、磁性粒子を配合して放熱性を向上させたウレタン発泡成形体が開示されている。ポリウレタンフォーム中に、磁性粒子を互いに連接した状態で配向させると、磁性粒子の配向方向に熱の伝達経路が形成される。これにより、ウレタン発泡成形体の放熱性は向上する。しかし、磁性粒子として配合される鉄やステンレス鋼の熱伝導率は、黒鉛より小さい。したがって、磁性粒子を配向させただけでは、放熱性の向上効果は充分ではない。
On the other hand, Patent Document 2 discloses a urethane foam molded article in which magnetic particles are blended to improve heat dissipation. When the magnetic particles are oriented in the polyurethane foam in a state of being connected to each other, a heat transfer path is formed in the orientation direction of the magnetic particles. Thereby, the heat dissipation of a urethane foam molded object improves. However, the thermal conductivity of iron or stainless steel blended as magnetic particles is smaller than that of graphite. Therefore, the effect of improving heat dissipation is not sufficient only by orienting the magnetic particles.
これらの問題を解決するため、特許文献4、5には、熱伝導性粒子の表面に磁性粒子が接着された複合粒子を基材に配合した成形体が、開示されている。当該成形体においては、磁性粒子の磁場配向を利用して、熱伝導率の大きな熱伝導性粒子を配向させる。配向した熱伝導性粒子(複合粒子)が線状に連なることにより、基材中に熱の伝達経路が形成される。これにより、成形体の放熱性を向上させることができる。
In order to solve these problems, Patent Documents 4 and 5 disclose a molded body in which composite particles in which magnetic particles are bonded to the surface of thermally conductive particles are blended with a base material. In the molded body, the heat conductive particles having a large thermal conductivity are oriented by utilizing the magnetic field orientation of the magnetic particles. When the oriented heat conductive particles (composite particles) are linearly connected, a heat transfer path is formed in the substrate. Thereby, the heat dissipation of a molded object can be improved.
しかしながら、本発明者がさらに検討を重ねたところ、成形体の熱伝導率を大きくするために、複合粒子の充填率(成形体における複合粒子の体積割合)を高くしていくと、ある充填率を境にして、熱伝導率が小さくなってしまうことがわかった。この理由は、複合粒子の充填率を高くすると、成形時に複合粒子同士が干渉し合い、配向性が損なわれてしまうためと考えられる。
However, when the present inventors have further studied, in order to increase the thermal conductivity of the molded body, when the filling ratio of composite particles (volume ratio of the composite particles in the molded body) is increased, a certain filling ratio is obtained. It was found that the thermal conductivity decreased at the boundary. The reason for this is considered to be that when the filling rate of the composite particles is increased, the composite particles interfere with each other during molding and the orientation is impaired.
本発明は、このような実情に鑑みてなされたものであり、熱伝導性フィラーとして配合される複合粒子の配向性を損なうことなく、熱伝導性をより向上させたエラストマー成形体を提供することを課題とする。また、その製造方法を提供することを課題とする。
The present invention has been made in view of such circumstances, and provides an elastomer molded body having further improved thermal conductivity without impairing the orientation of composite particles blended as a thermally conductive filler. Is an issue. It is another object of the present invention to provide a manufacturing method thereof.
(1)上記課題を解決するため、本発明のエラストマー成形体は、エラストマーからなる基材と、該基材中に配向して含有されている複合粒子の粉末と、を有し、該複合粒子は、非磁性体からなる熱伝導性粒子と、該熱伝導性粒子の表面にバインダーにより接着された磁性粒子と、を含み、該複合粒子の粉末の粒度分布は、小粒径側ピークおよび大粒径側ピークの二つのピークを有することを特徴とする。
(1) In order to solve the above-mentioned problems, an elastomer molded article of the present invention has a base material made of an elastomer, and a powder of composite particles that are oriented and contained in the base material. Includes a heat conductive particle made of a non-magnetic material and a magnetic particle bonded to the surface of the heat conductive particle with a binder, and the particle size distribution of the powder of the composite particle has a small particle size side peak and a large particle size distribution. It has two peaks of the particle size side peak.
本発明のエラストマー成形体は、配向した複合粒子の粉末を有する。複合粒子のコアをなす熱伝導性粒子は、大きな熱伝導率を有する。熱伝導性粒子自身は、非磁性体である。しかし、熱伝導性粒子の表面には、磁性粒子が接着されている。磁性粒子は、磁場中で磁力線に沿って配向する。よって、複合粒子に磁場を作用させると、複合粒子は、磁力線に沿って配向する。つまり、熱伝導性粒子と磁性粒子とを複合化することにより、磁性粒子の磁場配向を利用して、非磁性体からなる熱伝導性粒子を、配向させることができる。基材中に、複合粒子が線状に連なることにより、基材中に熱の伝達経路が形成される。したがって、本発明のエラストマー成形体の熱伝導性は高い。
The elastomer molded body of the present invention has a powder of oriented composite particles. The thermally conductive particles forming the core of the composite particles have a large thermal conductivity. The thermally conductive particles themselves are nonmagnetic. However, magnetic particles are adhered to the surface of the heat conductive particles. The magnetic particles are oriented along the magnetic field lines in a magnetic field. Therefore, when a magnetic field is applied to the composite particles, the composite particles are oriented along the lines of magnetic force. That is, by compositing the thermally conductive particles and the magnetic particles, the thermally conductive particles made of a non-magnetic material can be oriented using the magnetic field orientation of the magnetic particles. In the base material, the composite particles are linearly connected, so that a heat transfer path is formed in the base material. Therefore, the thermal conductivity of the elastomer molded body of the present invention is high.
ここで、複合粒子の粉末の粒度分布は、小粒径側ピークおよび大粒径側ピークの二つのピークを有する。すなわち、複合粒子の粉末は、小粒径粉末と大粒径粉末とが混合された粉末である。本発明における粒度分布としては、粒子の体積基準の頻度分布を採用する。
Here, the particle size distribution of the composite particle powder has two peaks, a small particle size side peak and a large particle size side peak. That is, the composite particle powder is a powder in which a small particle size powder and a large particle size powder are mixed. As the particle size distribution in the present invention, a volume-based frequency distribution of particles is employed.
分級等の粒度調整を行わずに製造された複合粒子の粉末の粒度分布は、通常、一つのピークを有する。このような複合粒子の粉末を配向させた従来の成形体において、配向方向と交差する面を観察すると、後述する実施例において示すように、複合粒子と基材とを比較的明確に区別することができる。つまり、複合粒子は、配向方向に線状に連なり配置されるため、配向方向と交差する面方向に隣り合う複合粒子間の大部分は、基材である。
The particle size distribution of the composite particle powder produced without adjusting the particle size such as classification usually has one peak. In the conventional molded body in which the powder of the composite particles is oriented, when the surface intersecting the orientation direction is observed, the composite particles and the base material can be distinguished relatively clearly as shown in Examples described later. Can do. That is, since the composite particles are arranged linearly in the orientation direction, most of the composite particles adjacent to each other in the plane direction intersecting the orientation direction is the base material.
これに対して、小粒径側ピークおよび大粒径側ピークの二つのピークを持つ粒度分布の複合粒子の粉末を配向させた本発明のエラストマー成形体においては、大粒径側ピークを構成する大粒径粒子が配向して線状に連なると共に、小粒径側ピークを構成する小粒径粒子も、配向方向と交差する面方向に隣り合う大粒径粒子間に配向して線状に連なる。したがって、後述する実施例において示すように、配向方向と交差する面を観察すると、大粒径粒子と大粒径粒子との間の隙間(基材部分)を埋めるように、小粒径粒子が分散されていることが確認できる。よって、本発明のエラストマー成形体によると、面全体で熱伝達を行うことができる。このため、複合粒子の充填率を高くしなくても、エラストマー成形体の熱伝導性を向上させることができる。また、大粒径粒子間に介在されるのは粒子径が小さい小粒径粒子であるため、複合粒子の充填率を高くしても、複合粒子同士が干渉しにくく配向性が損なわれにくい。
In contrast, in the elastomer molded body of the present invention in which the powder of composite particles having a particle size distribution having two peaks, a small particle size side peak and a large particle size side peak, is oriented, a large particle size side peak is formed. The large particle size particles are aligned and connected linearly, and the small particle size particles constituting the small particle size side peak are also linearly aligned between the large particle particles adjacent to each other in the plane direction intersecting the alignment direction. It is a series. Therefore, as shown in the examples described later, when the surface intersecting the orientation direction is observed, the small particle size particles are formed so as to fill the gap (base material portion) between the large particle size particle and the large particle size particle. It can be confirmed that they are distributed. Therefore, according to the elastomer molded body of the present invention, heat transfer can be performed over the entire surface. For this reason, the thermal conductivity of the elastomer molded body can be improved without increasing the filling rate of the composite particles. In addition, since small particles having a small particle size are interposed between the large particles, even if the filling rate of the composite particles is increased, the composite particles are unlikely to interfere with each other and the orientation is not easily impaired.
なお、本発明のエラストマー成形体において、基材中の複合粒子は、ある規則性を持って所定の方向に配置されていればよい。例えば、エラストマー成形体の一端と他端(一端に対して180°対向した端部でなくてもよい)との間に直線状に配置されていても、曲線状に配置されていてもよい。また、中心から外周に向かって放射状に配置されていてもよい。
In the elastomer molded body of the present invention, the composite particles in the substrate need only be arranged in a predetermined direction with a certain regularity. For example, the elastomer molded body may be arranged in a straight line or a curved line between one end and the other end (the end may not be 180 ° opposite to the one end). Moreover, you may arrange | position radially from the center toward the outer periphery.
(2)本発明のエラストマー成形体の製造方法は、複合粒子を撹拌造粒法により製造する場合における上記(1)の構成のエラストマー成形体の製造方法であって、撹拌造粒機を用いて、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーを含む粉末原料を撹拌して複合粒子の粉末を製造し、該複合粒子の粉末を分級して小粒径粉末および大粒径粉末を準備する複合粒子粉末準備工程と、該複合粒子の該小粒径粉末および該大粒径粉末と、エラストマー原料と、を混合して混合原料を調製する混合原料調製工程と、該混合原料を成形型に配置して、磁場中で該混合原料を成形する成形工程と、を有することを特徴とする。
(2) The method for producing an elastomer molded body of the present invention is a method for producing an elastomer molded body having the above-described configuration (1) in the case where composite particles are produced by the agitation granulation method, using an agitation granulator. The powder raw material containing the heat conductive particles, the magnetic particles, and the binder is stirred to produce composite particles, and the composite particles are classified into small particles and large particles. A composite particle powder preparation step to be prepared, a mixed raw material preparation step for preparing a mixed raw material by mixing the small particle size powder and the large particle size powder of the composite particle, and an elastomer raw material, and molding the mixed raw material And a molding step of molding the mixed raw material in a magnetic field.
複合粒子粉末準備工程においては、まず、熱伝導性粒子の粉末、磁性粒子の粉末、およびこれらを接着するためのバインダーを含む粉末原料を、撹拌造粒機を用いて高速撹拌する。これにより、複合粒子の粉末を容易に製造することができる。撹拌造粒法によると、熱伝導性粒子と磁性粒子とを、バインダーによりソフトに接着させることができる。よって、熱伝導性粒子が、熱伝導性が高い形状(アスペクト比が大きな形状)を有する場合でも、その形状を崩すことなく、磁性粒子を複合化することができる。また、バインダーを用いることにより、磁性粒子の接着量を多くすることができる。磁性粒子を多量に接着させることにより、磁束密度が350mT以下の比較的低磁場でも、複合粒子の所望の配向状態を実現することができる。後述するように、磁場の形成には、例えば電磁石が用いられる。低磁場中で成形できると、成形型を挟んで配置される電磁石のギャップを、大きくすることができる。このため、成形型のキャビティを大きくすることができ、製品の形状自由度が高くなる。また、電磁石の設備コスト、ランニングコストも低くすることができる。
In the composite particle powder preparation step, first, a powder raw material containing a powder of heat conductive particles, a powder of magnetic particles, and a binder for bonding them is stirred at high speed using a stirring granulator. Thereby, the powder of a composite particle can be manufactured easily. According to the stirring granulation method, the heat conductive particles and the magnetic particles can be softly bonded with the binder. Therefore, even when the thermally conductive particles have a shape with a high thermal conductivity (a shape with a large aspect ratio), the magnetic particles can be combined without breaking the shape. Moreover, the adhesion amount of a magnetic particle can be increased by using a binder. By adhering a large amount of magnetic particles, a desired orientation state of the composite particles can be realized even in a relatively low magnetic field having a magnetic flux density of 350 mT or less. As will be described later, for example, an electromagnet is used to form the magnetic field. If the molding can be performed in a low magnetic field, the gap between the electromagnets arranged with the molding die interposed therebetween can be increased. For this reason, the cavity of a shaping | molding die can be enlarged and the shape freedom degree of a product becomes high. Moreover, the installation cost and running cost of the electromagnet can be reduced.
ちなみに、上記特許文献1には、強磁性体の粉末を黒鉛粉末の表面に付着させて、黒鉛粉末の配向を促進できることが、記載されている。また、粒子を機械的に固着させる方法として、メカノケミカル法が挙げられている。しかし、バインダーを用いて接着させることは、記載されていない。例えば、バインダーを用いずに、磁性粒子を熱伝導性粒子の表面に付着させた場合、磁性粒子の付着量を多くすることは困難である。すなわち、バインダーを用いずに複合化した粒子においては、磁性粒子の付着量が少なく、配向に必要な磁性が不足する。このため、当該粒子を用いた場合、低磁場で、所望の配向状態を実現することはできない。また、黒鉛は脆いため、粒子の圧縮、剪断を伴うメカノケミカル処理を行うと、容易に粉砕されて、形状を維持できないという問題もある。
Incidentally, the above Patent Document 1 describes that the orientation of the graphite powder can be promoted by attaching a ferromagnetic powder to the surface of the graphite powder. Further, a mechanochemical method is mentioned as a method for mechanically fixing the particles. However, bonding with a binder is not described. For example, when the magnetic particles are attached to the surface of the thermally conductive particles without using a binder, it is difficult to increase the amount of magnetic particles attached. That is, in the composite particles without using a binder, the amount of magnetic particles attached is small and the magnetism necessary for orientation is insufficient. For this reason, when the said particle | grain is used, a desired orientation state cannot be implement | achieved by a low magnetic field. Further, since graphite is brittle, there is also a problem that when mechanochemical treatment involving compression and shearing of particles is performed, it is easily pulverized and the shape cannot be maintained.
次に、製造した複合粒子の粉末を分級して、小粒径粉末および大粒径粉末を準備する。複合粒子の粉末を、粒径範囲が異なる二種類の粉末に分けることにより、大粒径粒子間の隙間を埋めるように、小粒径粒子を分散させることができる。これにより、製造されるエラストマー成形体の熱伝導性を向上させることができる。
Next, the produced composite particle powder is classified to prepare a small particle size powder and a large particle size powder. By dividing the composite particle powder into two types of powders having different particle size ranges, the small particle size particles can be dispersed so as to fill the gaps between the large particle size particles. Thereby, the heat conductivity of the elastomer molded body manufactured can be improved.
混合原料調製工程においては、準備した小粒径粉末および大粒径粉末と、エラストマー原料と、を混合して混合原料を調製する。そして、成形工程においては、調製した混合原料を磁場中で成形する。これにより、大粒径粒子が配向して線状に連なると共に、小粒径粒子も、配向方向と交差する面方向に隣り合う大粒径粒子と大粒径粒子との間を埋めるように、配向して線状に連なる。また、混合原料に、磁束密度が略均一な磁場(一様な磁場)を作用させることにより、磁束密度の違いによる複合粒子の偏在を抑制することができる。よって、複合粒子の充填率が比較的低くても、複合粒子を基材全体に分散させた状態で配向させることができる。このように、本発明の製造方法によると、比較的少量の複合粒子を配合して、熱伝導性が高い本発明のエラストマー成形体を、容易に製造することができる。
In the mixed raw material preparation step, the prepared small particle size powder and large particle size powder are mixed with the elastomer raw material to prepare a mixed raw material. In the molding step, the prepared mixed raw material is molded in a magnetic field. Thereby, the large particle size particles are aligned and connected in a linear manner, and the small particle size particles are also filled between the large particle particles and the large particle particles adjacent to each other in the plane direction intersecting the alignment direction. Oriented and linearly connected. Moreover, the uneven distribution of the composite particles due to the difference in magnetic flux density can be suppressed by applying a magnetic field having a substantially uniform magnetic flux density (uniform magnetic field) to the mixed raw material. Therefore, even if the filling rate of the composite particles is relatively low, the composite particles can be oriented while being dispersed throughout the substrate. Thus, according to the production method of the present invention, a relatively small amount of composite particles can be blended to easily produce the elastomer molded body of the present invention having high thermal conductivity.
1:磁気誘導成形装置、2:架台、21:ブラケット、3:電磁石部、30D、30U:ヨーク部、31L、31R:コイル部、32D、32U:ポールピース、310L、310R:芯部、311L、311R:導線、4:成形型、40U:上型、40D:下型、41:キャビティ、50:面状ヒーター、51:断熱部材、L:磁力線。
1: Magnetic induction molding device, 2: Stand, 21: Bracket, 3: Electromagnet part, 30D, 30U: Yoke part, 31L, 31R: Coil part, 32D, 32U: Pole piece, 310L, 310R: Core part, 311L, 311R: Conductor, 4: Mold, 40U: Upper mold, 40D: Lower mold, 41: Cavity, 50: Planar heater, 51: Thermal insulation member, L: Magnetic field line.
以下、本発明のエラストマー成形体およびその製造方法の実施形態について説明する。なお、本発明のエラストマー成形体およびその製造方法は、以下の実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲において、当業者が行い得る変更、改良等を施した種々の形態にて実施することができる。
Hereinafter, embodiments of the elastomer molded body and the manufacturing method thereof according to the present invention will be described. The elastomer molded body and the method for producing the same according to the present invention are not limited to the following embodiments, and various modifications and improvements that can be made by those skilled in the art are possible without departing from the spirit of the present invention. It can be implemented in the form.
<エラストマー成形体>
本発明のエラストマー成形体は、エラストマーからなる基材と、該基材中に配向して含有されている複合粒子の粉末と、を有する。 <Elastomer molded body>
The elastomer molded body of the present invention has a base material composed of an elastomer and a powder of composite particles that are oriented and contained in the base material.
本発明のエラストマー成形体は、エラストマーからなる基材と、該基材中に配向して含有されている複合粒子の粉末と、を有する。 <Elastomer molded body>
The elastomer molded body of the present invention has a base material composed of an elastomer and a powder of composite particles that are oriented and contained in the base material.
エラストマーとしては、架橋ゴムおよび熱可塑性エラストマーの中から適宜選択すればよい。エラストマーは、ソリッド体でも、ポリウレタンフォーム等の発泡体でもよい。但し、複合粒子などの充填性を考慮すると、気泡(セル)を有しないソリッド体が望ましい。例えば、架橋ゴムとしては、ウレタンゴム、シリコーンゴム、フッ素ゴム、アクリルゴム、アクリロニトリルブタジエンゴム等が挙げられる。また、熱可塑性エラストマーとしては、スチレン系、オレフィン系、塩化ビニル系、ポリエステル系、ポリウレタン系、ポリアミド系の各種熱可塑性エラストマーが挙げられる。
The elastomer may be appropriately selected from a crosslinked rubber and a thermoplastic elastomer. The elastomer may be a solid body or a foamed body such as polyurethane foam. However, in view of the filling properties such as composite particles, a solid body having no bubbles (cells) is desirable. For example, examples of the crosslinked rubber include urethane rubber, silicone rubber, fluorine rubber, acrylic rubber, acrylonitrile butadiene rubber, and the like. Examples of the thermoplastic elastomer include various thermoplastic elastomers such as styrene, olefin, vinyl chloride, polyester, polyurethane, and polyamide.
架橋ゴムの硬化方法は、ゴムポリマーの種類に応じて適宜選択すればよい。例えば、加熱硬化、紫外線硬化、電子線硬化、湿気硬化等が挙げられる。複合粒子を磁場配向させるためには、エラストマーの硬化を、磁場を作用させながら行う必要がある。例えば、加熱硬化型のエラストマーの場合、エラストマー原料の温度を上げて、硬化させる。しかし、高温になると磁場を形成する磁石の磁性が低下して、磁場が弱くなるおそれがある。このため、エラストマーの硬化温度は、150℃以下であることが望ましい。また、複合粒子を低磁場で配向させるためには、エラストマーの粘度は、100Pa・s以下であることが望ましい。エラストマーの粘度が高いと、粘性抵抗の影響で複合粒子が配向しにくくなるおそれがある。なお、エラストマーの粘度が高い場合には、溶剤で希釈して低粘度化し、硬化時に溶剤を揮発させればよい。溶剤を使用せずに液状化、低粘度化が可能であるという観点から、エラストマーとしては、ウレタンゴム、シリコーンゴム、フッ素ゴムのいずれかが望ましい。
The curing method of the crosslinked rubber may be appropriately selected according to the type of rubber polymer. For example, heat curing, ultraviolet curing, electron beam curing, moisture curing and the like can be mentioned. In order to orient the composite particles in a magnetic field, it is necessary to cure the elastomer while applying a magnetic field. For example, in the case of a thermosetting elastomer, the temperature of the elastomer raw material is raised and cured. However, when the temperature is high, the magnetism of the magnet that forms the magnetic field is reduced, which may weaken the magnetic field. For this reason, the curing temperature of the elastomer is desirably 150 ° C. or lower. In order to orient the composite particles in a low magnetic field, the viscosity of the elastomer is desirably 100 Pa · s or less. When the viscosity of the elastomer is high, the composite particles may not be easily oriented due to the influence of viscous resistance. If the elastomer has a high viscosity, it may be diluted with a solvent to lower the viscosity, and the solvent may be volatilized during curing. From the viewpoint that liquefaction and low viscosity can be achieved without using a solvent, the elastomer is preferably urethane rubber, silicone rubber, or fluororubber.
複合粒子は、非磁性体からなる熱伝導性粒子と、該熱伝導性粒子の表面にバインダーにより接着された磁性粒子と、を含む。
The composite particles include heat conductive particles made of a non-magnetic material and magnetic particles bonded to the surface of the heat conductive particles with a binder.
熱伝導性粒子は、非磁性体であって、熱伝導率が大きいものであればよい。本明細書では、強磁性体および反強磁性体以外の、反磁性体および常磁性体を、非磁性体と称す。例えば、熱伝導性粒子の熱伝導率は、200W/m・K以上であることが望ましい。熱伝導性粒子の材質としては、例えば、黒鉛、炭素繊維等の炭素材料が好適である。また、アルミニウム、金、銀、銅、およびこれらを母材とする合金等であってもよい。熱伝導性粒子としては、一種類の粒子を用いても、二種類以上の粒子を併用してもよい。
The heat conductive particles may be non-magnetic and have high thermal conductivity. In the present specification, diamagnetic materials and paramagnetic materials other than ferromagnetic materials and antiferromagnetic materials are referred to as nonmagnetic materials. For example, the thermal conductivity of the thermally conductive particles is desirably 200 W / m · K or more. As a material of the heat conductive particles, for example, a carbon material such as graphite or carbon fiber is suitable. Also, aluminum, gold, silver, copper, and alloys based on these may be used. As the heat conductive particles, one kind of particles may be used or two or more kinds of particles may be used in combination.
熱伝導性粒子の形状は、磁性粒子と複合化できれば、特に限定されるものではない。例えば、薄片状、繊維状、柱状、球状、楕円球状、長円球状(一対の対向する半球を円柱で連結した形状)等の種々の形状を採用することができる。熱伝導性粒子が球以外の形状をなす場合には、複合粒子同士の接触面積が大きくなる。これにより、熱の伝達経路が確保されやすくなると共に、伝達される熱量も大きくなる。なお、通常、アルミニウム、金、銅等の金属粒子の形状は、球状である。一方、黒鉛粒子は、アスペクト比が大きい形状のものでも、金属粒子と比較して安価に入手できる。このため、熱伝導性粒子の材質としては、黒鉛が好適である。
The shape of the heat conductive particle is not particularly limited as long as it can be combined with the magnetic particle. For example, various shapes such as a flaky shape, a fibrous shape, a columnar shape, a spherical shape, an elliptical sphere shape, and an oval sphere shape (a shape in which a pair of opposing hemispheres are connected by a cylinder) can be employed. When the thermally conductive particles have a shape other than a sphere, the contact area between the composite particles increases. As a result, a heat transfer path is easily secured and the amount of heat transferred is increased. In general, the shape of metal particles such as aluminum, gold, and copper is spherical. On the other hand, even if the graphite particles have a shape with a large aspect ratio, they can be obtained at a lower cost than metal particles. For this reason, graphite is suitable as a material for the thermally conductive particles.
黒鉛としては、鱗片状黒鉛、鱗状黒鉛、土状黒鉛等の天然黒鉛や、人造黒鉛等が挙げられる。人造黒鉛は、鱗片状になりにくい。このため、鱗片状であり、熱伝導性の向上効果が高いという理由から、天然黒鉛が好適である。また、黒鉛として、鱗片状の黒鉛の層間に、加熱によりガスを発生する物質が挿入された膨張黒鉛を用いてもよい。膨張黒鉛は、難燃剤として用いられることが多い。膨張黒鉛に熱が加わると、発生したガスにより、層間が広がると共に、熱や化学品に対して安定した層が形成される。形成された層が断熱層となり、熱の移動を妨げることにより、難燃効果がもたらされる。よって、熱伝導性粒子としては、天然黒鉛粒子および膨張黒鉛粒子の少なくとも一方を用いるとよい。
Examples of graphite include natural graphite such as scaly graphite, scaly graphite, and earthy graphite, and artificial graphite. Artificial graphite is not easily scaled. For this reason, natural graphite is preferred because it is scaly and has a high effect of improving thermal conductivity. Further, as the graphite, expanded graphite in which a substance that generates gas by heating is inserted between scaly graphite layers may be used. Expanded graphite is often used as a flame retardant. When heat is applied to expanded graphite, the generated gas expands the layers and forms a stable layer against heat and chemicals. The formed layer becomes a heat-insulating layer and prevents heat transfer, thereby providing a flame retardant effect. Therefore, it is preferable to use at least one of natural graphite particles and expanded graphite particles as the heat conductive particles.
本発明のエラストマー成形体において、複合粒子は配向している。このため、エラストマー成形体に加わった熱は、熱伝導性粒子に伝達されやすい。よって、熱伝導性粒子が膨張黒鉛からなる場合、膨張黒鉛が、膨張開始温度に早く到達する。これにより、膨張黒鉛による難燃効果が、速やかに発揮される。このように、熱伝導性粒子として膨張黒鉛を用いることにより、エラストマー成形体に難燃性を付与することができる。
In the elastomer molded body of the present invention, the composite particles are oriented. For this reason, the heat applied to the elastomer molded body is easily transmitted to the thermally conductive particles. Therefore, when the thermally conductive particles are made of expanded graphite, the expanded graphite reaches the expansion start temperature early. Thereby, the flame-retardant effect by expanded graphite is exhibited rapidly. Thus, flame retardance can be imparted to the elastomer molded body by using expanded graphite as the thermally conductive particles.
熱伝導性粒子として膨張黒鉛を用いる場合、公知の膨張黒鉛粉末の中から、膨張開始温度や膨張率等を考慮して、好適なものを選択すればよい。例えば、膨張黒鉛の膨張開始温度は、エラストマー成形体の成形時の温度よりも、高くなければならない。具体的には、膨張開始温度が150℃以上の膨張黒鉛が好適である。
In the case of using expanded graphite as the heat conductive particles, a suitable one may be selected from known expanded graphite powder in consideration of the expansion start temperature, the expansion rate, and the like. For example, the expansion start temperature of expanded graphite must be higher than the temperature at the time of molding the elastomer molded body. Specifically, expanded graphite having an expansion start temperature of 150 ° C. or higher is suitable.
磁性粒子は、磁化特性に優れたものであればよく、例えば、鉄、ニッケル、コバルト、ガドリニウム、ステンレス鋼、マグネタイト、マグヘマイト、マンガン亜鉛フェライト、バリウムフェライト、ストロンチウムフェライト等の強磁性体、MnO、Cr2O3、FeCl2、MnAs等の反強磁性体、およびこれらを用いた合金類の粒子が好適である。なかでも、微細な粒子として入手しやすく、飽和磁化が高いという観点から、鉄、ニッケル、コバルト、およびこれらの鉄系合金(ステンレス鋼を含む)の粉末が好適である。
The magnetic particles only need to have excellent magnetization characteristics. For example, ferromagnetic materials such as iron, nickel, cobalt, gadolinium, stainless steel, magnetite, maghemite, manganese zinc ferrite, barium ferrite, strontium ferrite, MnO, Cr Antiferromagnetic materials such as 2 O 3 , FeCl 2 , and MnAs, and alloys particles using these are preferable. Among these, iron, nickel, cobalt, and powders of these iron-based alloys (including stainless steel) are preferable from the viewpoint of easy availability as fine particles and high saturation magnetization.
磁性粒子は、熱伝導性粒子の表面に接着されており、熱伝導性粒子を配向させる役割を果たす。磁性粒子は、熱伝導性粒子の表面に直接接着されていてもよく、後述するように、熱伝導性粒子の表面に磁性粒子以外の粒子も接着されている場合には、当該粒子を介して間接的に接着されていてもよい。また、磁性粒子は、熱伝導性粒子等の表面の一部のみに接着していてもよく、表面全体を被覆するように接着していてもよい。磁性粒子の大きさは、熱伝導性粒子の大きさ、複合粒子の配向性、および複合粒子間の熱伝導性等を考慮して、適宜決定すればよい。例えば、磁性粒子の粒子径は、熱伝導性粒子の粒子径の1/25以上1/2以下であることが望ましい。ここで、粒子径は、粒子の最長部分の長さである。磁性粒子の大きさが小さくなると、磁性粒子の飽和磁化が低下する傾向がある。したがって、より少量の磁性粒子により、複合粒子を配向させるためには、複合化する磁性粒子の粉末の平均粒径を、100nm以上とする必要がある。1μm以上、さらには5μm以上とするとより好適である。
The magnetic particles are bonded to the surface of the thermally conductive particles and play a role in orienting the thermally conductive particles. The magnetic particles may be directly bonded to the surface of the thermally conductive particles. As described later, when particles other than the magnetic particles are bonded to the surface of the thermally conductive particles, It may be indirectly bonded. Further, the magnetic particles may be adhered to only a part of the surface of the heat conductive particles or the like, or may be adhered so as to cover the entire surface. The size of the magnetic particles may be appropriately determined in consideration of the size of the thermally conductive particles, the orientation of the composite particles, the thermal conductivity between the composite particles, and the like. For example, the particle diameter of the magnetic particles is desirably 1/25 or more and 1/2 or less of the particle diameter of the heat conductive particles. Here, the particle diameter is the length of the longest part of the particle. When the size of the magnetic particles is reduced, the saturation magnetization of the magnetic particles tends to decrease. Therefore, in order to orient the composite particles with a smaller amount of magnetic particles, the average particle size of the magnetic particles to be combined needs to be 100 nm or more. It is more preferable that the thickness is 1 μm or more, further 5 μm or more.
磁性粒子の形状は、特に限定されるものではない。例えば、磁性粒子の形状が扁平の場合には、球状の場合と比較して、隣接する熱伝導性粒子間の距離が短くなる。これにより、隣接する複合粒子間における熱伝導性が向上する。その結果、エラストマー成形体の熱伝導性が向上する。また、磁性粒子の形状が扁平の場合には、磁性粒子と熱伝導性粒子とが面で接触する。つまり、両者の接触面積が大きくなる。これにより、磁性粒子と熱伝導性粒子との接着力が向上する。よって、磁性粒子が剥離しにくくなる。加えて、磁性粒子と熱伝導性粒子との間の熱伝導性も向上する。このような理由から、磁性粒子としては、薄片状の粒子を採用することが望ましい。
The shape of the magnetic particles is not particularly limited. For example, when the shape of the magnetic particles is flat, the distance between adjacent heat conductive particles is shorter than when the shape is spherical. Thereby, the thermal conductivity between adjacent composite particles is improved. As a result, the thermal conductivity of the elastomer molded body is improved. When the shape of the magnetic particles is flat, the magnetic particles and the heat conductive particles are in contact with each other on the surface. That is, the contact area between the two becomes large. Thereby, the adhesive force of a magnetic particle and a heat conductive particle improves. Therefore, the magnetic particles are difficult to peel off. In addition, the thermal conductivity between the magnetic particles and the thermally conductive particles is also improved. For these reasons, it is desirable to employ flaky particles as the magnetic particles.
電子部品の放熱用途等においては、本発明のエラストマー成形体に絶縁性が要求される場合がある。例えば、熱伝導性粒子の表面に、磁性粒子に加えて、絶縁性無機粒子を接着することにより、複合粒子間の導通を断つことができる。熱伝導性粒子の表面に、絶縁性無機粒子が接着されると、複合粒子同士が接触した状態で配向しても、隣接する複合粒子間において、熱伝導性粒子や磁性粒子(導電性粒子)同士が接触しにくくなる。よって、複合粒子間の電気抵抗が大きくなる。また、絶縁性無機粒子を介して複合粒子同士が接触することにより、複合粒子間の導通を断つことができる。これにより、本発明のエラストマー成形体において、電気絶縁性を実現することができる。
In the heat dissipation application of electronic parts, etc., the elastomer molded body of the present invention may be required to have insulating properties. For example, conduction between the composite particles can be interrupted by adhering insulating inorganic particles in addition to magnetic particles to the surface of the thermally conductive particles. When insulating inorganic particles are bonded to the surface of the heat conductive particles, the heat conductive particles and magnetic particles (conducting particles) between adjacent composite particles, even if the composite particles are oriented in contact with each other. It becomes difficult to contact each other. Therefore, the electrical resistance between the composite particles increases. Moreover, the conduction | electrical_connection between composite particles can be interrupted when composite particles contact via an insulating inorganic particle. Thereby, in the elastomer molded object of this invention, electrical insulation can be implement | achieved.
絶縁性無機粒子は、絶縁性を有する無機材料の粒子であればよい。なかでも、複合粒子間の熱伝導性を阻害しないという観点から、熱伝導率が比較的大きいものが望ましい。例えば、絶縁性無機粒子の熱伝導率が、5W/m・K以上であると好適である。熱伝導率が、5W/m・K以上の絶縁性無機材料としては、水酸化アルミニウム、酸化アルミニウム(アルミナ)、水酸化マグネシウム、酸化マグネシウム、タルク等が挙げられる。また、絶縁性無機粒子が難燃性を有する場合には、エラストマー成形体に難燃性を付与することができる。例えば、水酸化アルミニウムは、熱伝導率が比較的大きく難燃性を有するため、好適である。水酸化アルミニウムは、所定の温度に加熱されると、脱水分解する。脱水分解は吸熱反応であるため、温度上昇が抑制され、難燃効果がもたらされる。
The insulating inorganic particles may be particles of an inorganic material having insulating properties. Among these, those having relatively high thermal conductivity are desirable from the viewpoint of not inhibiting the thermal conductivity between the composite particles. For example, it is preferable that the thermal conductivity of the insulating inorganic particles is 5 W / m · K or more. Examples of the insulating inorganic material having a thermal conductivity of 5 W / m · K or more include aluminum hydroxide, aluminum oxide (alumina), magnesium hydroxide, magnesium oxide, and talc. Further, when the insulating inorganic particles have flame retardancy, flame retardancy can be imparted to the elastomer molded body. For example, aluminum hydroxide is suitable because of its relatively high thermal conductivity and flame retardancy. Aluminum hydroxide is dehydrated and decomposed when heated to a predetermined temperature. Since dehydration decomposition is an endothermic reaction, temperature rise is suppressed and a flame retardant effect is brought about.
絶縁性無機粒子は、熱伝導性粒子の表面に直接接着されていてもよく、磁性粒子を介して間接的に接着されていてもよい。また、絶縁性無機粒子は、熱伝導性粒子等の表面の一部のみに接着していてもよく、表面全体を被覆するように接着していてもよい。複合粒子間の電気抵抗を大きくして、エラストマー成形体の電気絶縁性を高めるという観点から、絶縁性無機粒子は、複合粒子の最表層に配置されていることが望ましい。
The insulating inorganic particles may be directly bonded to the surface of the heat conductive particles, or may be indirectly bonded via magnetic particles. The insulating inorganic particles may be adhered to only a part of the surface of the heat conductive particles or the like, or may be adhered so as to cover the entire surface. From the viewpoint of increasing the electrical resistance between the composite particles and improving the electrical insulation of the elastomer molded body, it is desirable that the insulating inorganic particles are disposed on the outermost layer of the composite particles.
絶縁性無機粒子の大きさは、熱伝導性粒子および磁性粒子に対する接着性、複合粒子間の電気絶縁性および熱伝導性を考慮して、適宜決定すればよい。絶縁性無機粒子が大きすぎると、接着性や複合粒子間の熱伝導性が低下する。例えば、絶縁性無機粒子の粒子径は、熱伝導性粒子の粒子径の1/100以上1/10以下であることが望ましい。ここで、粒子径は、粒子の最長部分の長さである。
The size of the insulating inorganic particles may be appropriately determined in consideration of the adhesiveness to the heat conductive particles and the magnetic particles, the electric insulation between the composite particles and the heat conductivity. If the insulating inorganic particles are too large, the adhesiveness and the thermal conductivity between the composite particles are lowered. For example, the particle diameter of the insulating inorganic particles is preferably 1/100 or more and 1/10 or less of the particle diameter of the heat conductive particles. Here, the particle diameter is the length of the longest part of the particle.
絶縁性無機粒子の形状は、特に限定されるものではない。例えば、絶縁性無機粒子の形状が扁平の場合には、球状の場合と比較して、隣接する熱伝導性粒子間の距離が短くなる。これにより、隣接する複合粒子間における熱伝導性が向上する。その結果、エラストマー成形体の熱伝導性が向上する。また、絶縁性無機粒子と磁性粒子および熱伝導性粒子との接触面積が、大きくなる。これにより、接着力が向上し、絶縁性無機粒子が剥離しにくくなる。加えて、絶縁性無機粒子と磁性粒子および熱伝導性粒子との間の熱伝導性も、向上する。このような理由から、絶縁性無機粒子としては、薄片状の粒子を採用することが望ましい。
The shape of the insulating inorganic particles is not particularly limited. For example, when the shape of the insulating inorganic particles is flat, the distance between adjacent heat conductive particles is shorter than that of a spherical shape. Thereby, the thermal conductivity between adjacent composite particles is improved. As a result, the thermal conductivity of the elastomer molded body is improved. Further, the contact area between the insulating inorganic particles, the magnetic particles, and the heat conductive particles is increased. Thereby, adhesive force improves and it becomes difficult to exfoliate insulating inorganic particles. In addition, the thermal conductivity between the insulating inorganic particles, the magnetic particles, and the heat conductive particles is also improved. For these reasons, it is desirable to employ flaky particles as the insulating inorganic particles.
熱伝導性粒子と磁性粒子等とを接着するバインダーは、熱伝導性粒子等の種類、成形性への影響等を考慮して、適宜選択すればよい。成形性への影響が少なく、環境にも優しいという理由から、水溶性のバインダーが好適である。例えば、メチルセルロース、カルボキシメチルセルロース、ヒドロキシプロピルメチルセルロース、ポリビニルアルコール等が挙げられる。なお、磁性粒子を接着するバインダーと、絶縁性無機粒子を接着するバインダーと、は同じでも異なっていてもよい。
The binder for adhering the thermally conductive particles and the magnetic particles and the like may be appropriately selected in consideration of the type of the thermally conductive particles and the influence on the moldability. A water-soluble binder is preferable because it has little influence on moldability and is environmentally friendly. For example, methyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol and the like can be mentioned. The binder that adheres the magnetic particles and the binder that adheres the insulating inorganic particles may be the same or different.
複合粒子は、例えば、バインダーを溶解した溶液に磁性粒子の粉末等を分散した塗料を、熱伝導性粒子の粉末にスプレーして、製造することができる。また、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーを含む粉末原料を、高速で撹拌して製造することができる(撹拌造粒法)。撹拌造粒法においては、高速撹拌により摩擦熱が生じる。このため、バインダーとしては、揮発性の無いものが望ましい。例えば、前述した水溶性のバインダーが好適である。
The composite particles can be manufactured, for example, by spraying the powder of the heat conductive particles with a paint in which the powder of the magnetic particles is dispersed in the solution in which the binder is dissolved. Further, a powder raw material containing heat conductive particle powder, magnetic particle powder, and binder can be produced by stirring at high speed (stir granulation method). In the stirring granulation method, frictional heat is generated by high-speed stirring. For this reason, as a binder, a non-volatile thing is desirable. For example, the water-soluble binder described above is suitable.
複合粒子の粉末の粒度分布は、小粒径側ピークおよび大粒径側ピークの二つのピークを有する。複合粒子の粉末の粒度分布は、レーザー回折・散乱式粒度分布測定装置を用いて測定すればよい。本発明における粒度分布としては、粒子の体積基準の頻度分布を採用する。
The particle size distribution of the composite particle powder has two peaks, a small particle size side peak and a large particle size side peak. The particle size distribution of the composite particle powder may be measured using a laser diffraction / scattering particle size distribution measuring apparatus. As the particle size distribution in the present invention, a volume-based frequency distribution of particles is employed.
小粒径粒子を、大粒径粒子間を埋めるように、かつ、大粒径粒子の配向を阻害しないように配向させるという観点から、小粒径側ピークのピーク粒径と大粒径側ピークのピーク粒径との差は、比較的大きい方が望ましい。例えば、大粒径側ピークのピーク粒径は、小粒径側ピークのピーク粒径の2倍以上であることが望ましい。5倍以上であるとより好適である。一方、ピーク粒径差が大きすぎると熱伝導率の向上効果が小さくなるため、大粒径側ピークのピーク粒径は、小粒径側ピークのピーク粒径の20倍以下であることが望ましい。15倍以下であるとより好適である。まとめると、二つのピークにおいて、小粒径側ピークのピーク粒径と大粒径側ピークのピーク粒径との比は、1:2~1:20であることが望ましく、1:5~1:15であるとより好適である。
From the viewpoint of aligning the small particle size so as to fill the space between the large particle size and not disturb the orientation of the large particle size, the peak particle size of the small particle size side peak and the large particle size side peak It is desirable that the difference from the peak particle size is relatively large. For example, the peak particle size of the large particle size side peak is preferably at least twice the peak particle size of the small particle size side peak. It is more preferable that it is 5 times or more. On the other hand, if the difference in peak particle size is too large, the effect of improving the thermal conductivity is reduced, so the peak particle size of the large particle size side peak is desirably 20 times or less than the peak particle size of the small particle size side peak. . It is more preferable that it is 15 times or less. In summary, in the two peaks, the ratio of the peak particle size of the small particle size side peak to the peak particle size of the large particle size side peak is preferably 1: 2 to 1:20, and 1: 5 to 1 : 15 is more preferable.
複合粒子の充填率が比較的低くても熱伝導性の向上効果を高めるためには、大粒径側ピークに含まれる大粒径粒子は、質量比で、小粒径側ピークに含まれる小粒径粒子と同等若しくはそれ以上の割合で、配合されることが望ましい。例えば、複合粒子の粉末の粒度分布において、小粒径側ピークの面積と大粒径側ピークの面積との比は、1:1~1:30であることが望ましい。1:5~1:20であるとより好適である。
In order to enhance the effect of improving thermal conductivity even when the packing rate of the composite particles is relatively low, the large particle size particles included in the large particle size side peak are small in mass ratio and included in the small particle size side peak. It is desirable that they are blended at a ratio equal to or greater than that of the particle size. For example, in the particle size distribution of the composite particle powder, the ratio between the area of the small particle size side peak and the area of the large particle size side peak is preferably 1: 1 to 1:30. A ratio of 1: 5 to 1:20 is more preferable.
エラストマー成形体における複合粒子の充填率は、エラストマー成形体の物性や、熱伝導性の向上効果等を考慮して、決定すればよい。例えば、成形性や物性への影響が少ないという観点から、複合粒子の充填率を、エラストマー成形体の体積を100体積%とした場合の50体積%以下とすることが望ましい。特に、複合粒子の充填率を40体積%以下とすると、複合粒子同士の干渉が少なく、熱伝導性の向上効果が大きい。一方、熱伝導性の向上効果を得るためには、複合粒子の充填率を、10体積%以上とすることが望ましい。25体積%以上とするとより好適である。
The filling rate of the composite particles in the elastomer molded body may be determined in consideration of the physical properties of the elastomer molded body, the effect of improving thermal conductivity, and the like. For example, from the viewpoint of having little influence on moldability and physical properties, the filling rate of the composite particles is desirably 50% by volume or less when the volume of the elastomer molded body is 100% by volume. In particular, when the filling rate of the composite particles is 40% by volume or less, there is little interference between the composite particles, and the effect of improving thermal conductivity is large. On the other hand, in order to obtain an effect of improving thermal conductivity, it is desirable that the filling rate of the composite particles is 10% by volume or more. More preferably, the volume is 25% by volume or more.
高い熱伝導性を実現するという観点から、複合粒子の充填率が、エラストマー成形体の体積を100体積%とした時の26体積%以上38体積%以下である場合の熱伝導率は、2.4W/m・K以上であることが望ましい。熱伝導率は、JIS A1412-2(1999)の熱流計法に準じて測定すればよい。
From the viewpoint of realizing high thermal conductivity, the thermal conductivity when the filling rate of the composite particles is 26% by volume or more and 38% by volume or less when the volume of the elastomer molded body is 100% by volume is 2. 4 W / m · K or more is desirable. The thermal conductivity may be measured according to the heat flow meter method of JIS A1412-2 (1999).
本発明のエラストマー成形体は、複合粒子の粉末に加えて、さらに、配向せずに基材中に分散する非配向フィラーを有していてもよい。非配向フィラーは、熱伝導性の向上、絶縁性の付与、難燃性の向上等、目的に応じて適宜選択すればよい。例えば、前述した熱伝導性粒子、絶縁性無機粒子等をそのまま分散させればよい。
In addition to the composite particle powder, the elastomer molded body of the present invention may further include a non-oriented filler that is dispersed in the base material without being oriented. The non-oriented filler may be appropriately selected according to the purpose such as improvement of thermal conductivity, provision of insulation, improvement of flame retardancy, and the like. For example, the above-described heat conductive particles, insulating inorganic particles and the like may be dispersed as they are.
<エラストマー成形体の製造方法>
本発明のエラストマー成形体の製造方法は、複合粒子を撹拌造粒法により製造する場合の製造方法であって、複合粒子粉末準備工程と、混合原料調製工程と、成形工程と、を有する。以下、各工程について説明する。 <Method for producing elastomer molded article>
The method for producing an elastomer molded body of the present invention is a production method for producing composite particles by agitation granulation method, and includes a composite particle powder preparation step, a mixed raw material preparation step, and a forming step. Hereinafter, each step will be described.
本発明のエラストマー成形体の製造方法は、複合粒子を撹拌造粒法により製造する場合の製造方法であって、複合粒子粉末準備工程と、混合原料調製工程と、成形工程と、を有する。以下、各工程について説明する。 <Method for producing elastomer molded article>
The method for producing an elastomer molded body of the present invention is a production method for producing composite particles by agitation granulation method, and includes a composite particle powder preparation step, a mixed raw material preparation step, and a forming step. Hereinafter, each step will be described.
(1)複合粒子粉末準備工程
本工程は、撹拌造粒機を用いて、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーを含む粉末原料を撹拌して複合粒子の粉末を製造し、該複合粒子の粉末を分級して小粒径粉末および大粒径粉末を準備する工程である。 (1) Composite particle powder preparation step This step uses a stirring granulator to stir the powder raw material containing thermally conductive particle powder, magnetic particle powder, and binder to produce composite particle powder, It is a step of classifying the composite particle powder to prepare a small particle size powder and a large particle size powder.
本工程は、撹拌造粒機を用いて、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーを含む粉末原料を撹拌して複合粒子の粉末を製造し、該複合粒子の粉末を分級して小粒径粉末および大粒径粉末を準備する工程である。 (1) Composite particle powder preparation step This step uses a stirring granulator to stir the powder raw material containing thermally conductive particle powder, magnetic particle powder, and binder to produce composite particle powder, It is a step of classifying the composite particle powder to prepare a small particle size powder and a large particle size powder.
熱伝導性粒子、磁性粒子、およびバインダーについては、前述した通りである。よって、ここでは説明を省略する。また、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーの配合量についても、製造される複合粒子の磁場配向性や、複合粒子を含むエラストマー成形体の熱伝導性等を考慮して、適宜調整すればよい。
The heat conductive particles, magnetic particles, and binder are as described above. Therefore, the description is omitted here. In addition, regarding the blending amount of the powder of the heat conductive particles, the powder of the magnetic particles, and the binder, considering the magnetic field orientation of the composite particles to be manufactured, the thermal conductivity of the elastomer molded body including the composite particles, What is necessary is just to adjust suitably.
例えば、熱伝導性粒子として黒鉛を採用した場合には、磁性粒子の粉末の配合量を、黒鉛粉末100質量部に対して20質量部以上150質量部以下とすることが望ましい。20質量部未満の場合、磁性粒子の接着量が少ないため、複合粒子の配向に必要な磁性が不足するおそれがある。一方、150質量部を超えて配合すると、磁性粒子の接着量が過剰になる。よって、その分だけ、エラストマー成形体の質量の増加や、コスト高を招く。
For example, when graphite is employed as the thermally conductive particles, it is desirable that the blending amount of the magnetic particle powder is 20 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the graphite powder. When the amount is less than 20 parts by mass, the amount of adhesion of the magnetic particles is small, so that the magnetism necessary for the orientation of the composite particles may be insufficient. On the other hand, if it exceeds 150 parts by mass, the adhesion amount of the magnetic particles becomes excessive. Accordingly, an increase in the mass of the elastomer molded body and an increase in cost are incurred accordingly.
バインダーの配合量は、接着させる粒子を被覆するのに必要十分な量として、接着対象の粉末の合計質量を100質量%とした場合の、2質量%以上4質量%以下であることが望ましい。バインダーの配合量が2質量%未満の場合には、熱伝導性粒子や磁性粒子の表面にバインダーが行き渡らず、接着性が低下する。一方、4質量%を超えると、過剰のバインダーにより、複合粒子同士が凝集するおそれがある。バインダーは固体でも液体でもよい。バインダーとして水溶性の粉末を用いる場合、予め、バインダーと他の原料の粉末とを撹拌した後に、水を添加するとよい。こうすることにより、粒子の凝集を抑制することができる。
The blending amount of the binder is desirably 2% by mass or more and 4% by mass or less when the total mass of the powder to be bonded is 100% by mass as an amount necessary and sufficient for coating the particles to be bonded. When the blending amount of the binder is less than 2% by mass, the binder does not reach the surface of the heat conductive particles or the magnetic particles, and the adhesiveness decreases. On the other hand, when it exceeds 4 mass%, there exists a possibility that composite particles may aggregate with an excess binder. The binder may be solid or liquid. When water-soluble powder is used as the binder, it is preferable to add water after previously stirring the binder and the powder of other raw materials. By doing so, aggregation of particles can be suppressed.
磁性粒子に加えて絶縁性無機粒子も複合化する場合には、両粉末を一緒に撹拌して、熱伝導性粒子に接着させてもよいが、まず磁性粒子を熱伝導性粒子に接着させてから、次に絶縁性無機粒子を接着させてもよい。この場合、本工程の前段を、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーを含む第一粉末原料を撹拌する第一撹拌工程と、撹拌物に、絶縁性無機粒子の粉末およびバインダーを添加して、さらに撹拌する第二撹拌工程と、を有するように構成するとよい。
When combining insulating particles in addition to magnetic particles, both powders may be stirred together to adhere to the thermally conductive particles, but first the magnetic particles are adhered to the thermally conductive particles. Then, the insulating inorganic particles may be adhered next. In this case, the first stage of this step is the first stirring step of stirring the first powder raw material containing the powder of the heat conductive particles, the powder of the magnetic particles, and the binder, and the powder of the insulating inorganic particles and the binder It is good to comprise so that it may have and the 2nd stirring process of stirring further.
製造した複合粒子の粉末の分級方法は、特に限定されない。例えば、篩い分け、乾式分級機等により行えばよい。分級後の小粒径粉末および大粒径粉末の粒子径範囲については、製造するエラストマー成形体の厚さ等を考慮して、適宜決定すればよい。小粒径粒子を、大粒径粒子間を埋めるように、かつ、大粒径粒子の配向を阻害しないように配向させるという観点から、粒度分布を測定した場合における各々のピーク粒径の差が、比較的大きい方が望ましい。例えば、大粒径粉末のピーク粒径は、小粒径粉末のピーク粒径の2倍以上であることが望ましい。5倍以上であるとより好適である。一方、ピーク粒径差が大きすぎると熱伝導率の向上効果が小さくなるため、大粒径粉末のピーク粒径は、小粒径粉末のピーク粒径の20倍以下であることが望ましい。15倍以下であるとより好適である。
The method for classifying the produced composite particle powder is not particularly limited. For example, it may be performed by sieving, a dry classifier or the like. The particle size ranges of the small particle size powder and the large particle size powder after classification may be appropriately determined in consideration of the thickness of the elastomer molded body to be manufactured. From the viewpoint of aligning the small particle size so as to fill the space between the large particle size and not disturb the orientation of the large particle size, there is a difference in each peak particle size when the particle size distribution is measured. A relatively large one is desirable. For example, the peak particle size of the large particle size powder is preferably at least twice the peak particle size of the small particle size powder. It is more preferable that it is 5 times or more. On the other hand, if the difference in the peak particle size is too large, the effect of improving the thermal conductivity is reduced, so that the peak particle size of the large particle size powder is desirably 20 times or less the peak particle size of the small particle size powder. It is more preferable that it is 15 times or less.
(2)混合原料調製工程
本工程は、先の工程において製造された複合粒子の小粒径粉末および大粒径粉末と、エラストマー原料と、を混合して混合原料を調製する工程である。 (2) Mixed Raw Material Preparation Step This step is a step of preparing a mixed raw material by mixing the small particle size powder and large particle size powder of the composite particles produced in the previous step and an elastomer raw material.
本工程は、先の工程において製造された複合粒子の小粒径粉末および大粒径粉末と、エラストマー原料と、を混合して混合原料を調製する工程である。 (2) Mixed Raw Material Preparation Step This step is a step of preparing a mixed raw material by mixing the small particle size powder and large particle size powder of the composite particles produced in the previous step and an elastomer raw material.
エラストマー原料は、エラストマー成分のポリマー(エラストマーが架橋ゴムの場合には、架橋前のポリマー)の他、必要に応じて、架橋剤、可塑剤、触媒、発泡剤、整泡剤、難燃剤、帯電防止剤、減粘剤、安定剤、充填剤、着色剤等を含む。混合原料は、複合粒子の粉末とエラストマー原料とを、撹拌羽根等を用いて撹拌して、製造すればよい。また、エラストマー原料が発泡ウレタン原料の場合には、ポリオール原料とポリイソシアネート原料とを、各々高圧で噴射して衝突させることにより混合する衝突攪拌法を採用してもよい。この場合、小粒径粉末および大粒径粉末は、ポリオール原料およびポリイソシアネート原料の少なくとも一方に、予め配合しておけばよい。
In addition to the polymer of the elastomer component (in the case where the elastomer is a crosslinked rubber, the elastomer raw material), if necessary, a crosslinking agent, a plasticizer, a catalyst, a foaming agent, a foam stabilizer, a flame retardant, a charge Contains inhibitors, thickeners, stabilizers, fillers, colorants and the like. The mixed raw material may be produced by stirring the composite particle powder and the elastomer raw material using a stirring blade or the like. When the elastomer raw material is a foamed urethane raw material, a collision stirring method may be employed in which a polyol raw material and a polyisocyanate raw material are mixed by being injected and collided with each other at a high pressure. In this case, the small particle size powder and the large particle size powder may be blended in advance in at least one of the polyol material and the polyisocyanate material.
複合粒子の充填率が比較的低くても熱伝導性の向上効果を高めるためには、大粒径側粉末は、質量比で小粒径粉末と同等若しくはそれ以上の割合で、配合されることが望ましい。例えば、小粒径粉末と大粒径粉末との質量比は、1:1~1:10であることが望ましい。
In order to enhance the effect of improving the thermal conductivity even if the packing rate of the composite particles is relatively low, the large particle size side powder should be blended at a mass ratio equal to or greater than the small particle size powder. Is desirable. For example, the mass ratio of the small particle size powder to the large particle size powder is desirably 1: 1 to 1:10.
前述したように、本発明のエラストマー成形体においては、基材中に、複合粒子とは別に、熱伝導性粒子、絶縁性無機粒子等の非配向フィラーが分散されていてもよい。この形態のエラストマー成形体を製造する場合には、エラストマー原料に、複合粒子の粉末と非配向フィラーとを混合すればよい。
As described above, in the elastomer molded body of the present invention, non-oriented fillers such as heat conductive particles and insulating inorganic particles may be dispersed in the base material in addition to the composite particles. When an elastomer molded body of this form is manufactured, the powder of composite particles and the non-oriented filler may be mixed with the elastomer raw material.
複合粒子の粉末(小粒径粉末および大粒径粉末)の配合量は、エラストマー成形体の物性や、熱伝導性の向上効果等を考慮して、決定すればよい。例えば、成形性や物性への影響を少なくするという観点から、複合粒子の充填率が、エラストマー成形体の体積を100体積%とした場合の50体積%以下になるように、配合することが望ましい。40体積%以下とするとより好適である。一方、熱伝導性の向上効果を得るためには、複合粒子の充填率が10体積%以上になるように、配合することが望ましい。25体積%以上とするとより好適である。
The blending amount of the composite particle powder (small particle size powder and large particle size powder) may be determined in consideration of the physical properties of the elastomer molded body, the effect of improving thermal conductivity, and the like. For example, from the viewpoint of reducing the influence on moldability and physical properties, it is desirable to blend so that the filling rate of the composite particles is 50% by volume or less when the volume of the elastomer molded body is 100% by volume. . It is more suitable when it is 40 volume% or less. On the other hand, in order to obtain the effect of improving thermal conductivity, it is desirable to blend so that the filling rate of the composite particles is 10% by volume or more. More preferably, the volume is 25% by volume or more.
(3)成形工程
本工程は、先の工程において調製した混合原料を成形型に配置して、磁場中で該混合原料を成形する工程である。 (3) Molding step This step is a step of placing the mixed raw material prepared in the previous step in a mold and molding the mixed raw material in a magnetic field.
本工程は、先の工程において調製した混合原料を成形型に配置して、磁場中で該混合原料を成形する工程である。 (3) Molding step This step is a step of placing the mixed raw material prepared in the previous step in a mold and molding the mixed raw material in a magnetic field.
成形型は、密閉型でも開放型でもよい。磁場は、複合粒子を配向させる方向に形成すればよい。例えば、複合粒子を直線状に配向させる場合、混合原料の一端から他端に向かって、磁力線を作用させることが望ましい。このような磁場を形成するためには、混合原料を挟むように磁石を配置すればよい。磁石には、永久磁石または電磁石を用いればよい。電磁石を用いると、磁場形成のオン、オフを瞬時に切り替えることができ、磁場の強さの制御が容易である。よって、成形を制御しやすい。
¡The mold may be a closed mold or an open mold. The magnetic field may be formed in the direction in which the composite particles are oriented. For example, when orienting composite particles in a straight line, it is desirable to apply magnetic lines of force from one end of the mixed raw material to the other end. In order to form such a magnetic field, a magnet may be disposed so as to sandwich the mixed raw material. A permanent magnet or an electromagnet may be used as the magnet. When an electromagnet is used, magnetic field formation can be switched on and off instantaneously, and the control of the magnetic field strength is easy. Therefore, it is easy to control molding.
また、磁場を構成する磁力線は閉ループを形成していることが望ましい。こうすることで、磁力線の漏洩が抑制され、混合原料に安定した磁場を作用させることができる。なお、成形型の外部に配置した磁石により、成形型の内部に磁場を形成させるには、成形型としては透磁率の低い材質、つまり非磁性の材質のものを使用するとよい。例えば、アルミニウムやアルミニウム合金製の成形型が好適である。この場合、電磁石等の磁力源から発生する磁場、磁力線が影響を受けにくく、磁場状態のコントロールがしやすい。ただし、必要とする磁場、磁力線の状態に応じて適宜、磁性材料からなる成形型を使用してもよい。
Also, it is desirable that the magnetic field lines constituting the magnetic field form a closed loop. By doing so, leakage of the magnetic field lines is suppressed, and a stable magnetic field can be applied to the mixed raw material. In order to form a magnetic field inside the mold by using a magnet arranged outside the mold, the mold may be made of a material having low magnetic permeability, that is, a non-magnetic material. For example, a mold made of aluminum or aluminum alloy is suitable. In this case, the magnetic field and magnetic lines generated from a magnetic source such as an electromagnet are not easily affected, and the magnetic field state is easily controlled. However, a mold made of a magnetic material may be used as appropriate according to the required magnetic field and magnetic field lines.
本工程においては、磁束密度が略均一な磁場を、混合原料に作用させることが望ましい。具体的には、混合原料における磁束密度の差が、±10%以内であるとよい。±5%以内、さらには±3%以内であるとより好適である。混合原料に一様な磁場を作用させることにより、複合粒子の偏在を抑制することができ、所望の配向状態を得ることができる。また、成形は、150mT以上350mT以下の磁束密度で行うとよい。こうすることで、混合原料中の複合粒子を、確実に配向させることができる。本工程にて成形が終了した後、脱型して、本発明のエラストマー成形体を得る。
In this step, it is desirable to apply a magnetic field having a substantially uniform magnetic flux density to the mixed raw material. Specifically, the difference in magnetic flux density between the mixed raw materials is preferably within ± 10%. It is more preferable that it is within ± 5%, more preferably within ± 3%. By applying a uniform magnetic field to the mixed raw material, uneven distribution of the composite particles can be suppressed, and a desired orientation state can be obtained. Moreover, it is good to perform shaping | molding with the magnetic flux density of 150 mT or more and 350 mT or less. By carrying out like this, the composite particle in a mixed raw material can be orientated reliably. After molding is completed in this step, the mold is removed to obtain the elastomer molded body of the present invention.
次に、実施例を挙げて本発明をより具体的に説明する。
Next, the present invention will be described more specifically with reference to examples.
<複合粒子の大粒径粉末および小粒径粉末の製造>
まず、熱伝導性粒子としての二種類の鱗片状黒鉛粉末(伊藤黒鉛工業(株)製「W+32」(+32mesh 80%以上)および「X‐100」(平均粒径60μm))と、磁性粒子としてのステンレス鋼粉末(SUS410L、薄片状、平均粒径20μm)と、バインダーとしてのヒドロキシプロピルメチルセルロース(HPMC、信越化学工業(株)製「TC-5」)と、を準備した。薄片状のステンレス鋼粉末は、球状のステンレス鋼粉末(大同特殊鋼(株)製「DAP410L」、平均粒径10μm)を、扁平化処理して製造した。すなわち、球状のステンレス鋼粉末を、遊星ボールミル(Gokin Planetaring社製「Planet-M」)に、直径5mmのジルコニア製ボールと共に充填し、回転速度300rpmで、一時間処理した。 <Production of large particle size powder and small particle size powder of composite particles>
First, two types of scaly graphite powders (“W + 32” (+32 mesh 80% or more) and “X-100” (average particle size 60 μm) manufactured by Ito Graphite Industries Co., Ltd.) as thermal conductive particles, and magnetic particles Stainless steel powder (SUS410L, flakes,average particle size 20 μm) and hydroxypropylmethylcellulose (HPMC, “TC-5” manufactured by Shin-Etsu Chemical Co., Ltd.) as a binder were prepared. The flaky stainless steel powder was produced by flattening a spherical stainless steel powder (“DAP410L” manufactured by Daido Steel Co., Ltd., average particle size: 10 μm). That is, a spherical stainless steel powder was filled into a planetary ball mill (“Planet-M” manufactured by Gokin Planetaring) together with zirconia balls having a diameter of 5 mm, and processed at a rotational speed of 300 rpm for 1 hour.
まず、熱伝導性粒子としての二種類の鱗片状黒鉛粉末(伊藤黒鉛工業(株)製「W+32」(+32mesh 80%以上)および「X‐100」(平均粒径60μm))と、磁性粒子としてのステンレス鋼粉末(SUS410L、薄片状、平均粒径20μm)と、バインダーとしてのヒドロキシプロピルメチルセルロース(HPMC、信越化学工業(株)製「TC-5」)と、を準備した。薄片状のステンレス鋼粉末は、球状のステンレス鋼粉末(大同特殊鋼(株)製「DAP410L」、平均粒径10μm)を、扁平化処理して製造した。すなわち、球状のステンレス鋼粉末を、遊星ボールミル(Gokin Planetaring社製「Planet-M」)に、直径5mmのジルコニア製ボールと共に充填し、回転速度300rpmで、一時間処理した。 <Production of large particle size powder and small particle size powder of composite particles>
First, two types of scaly graphite powders (“W + 32” (+32 mesh 80% or more) and “X-100” (average particle size 60 μm) manufactured by Ito Graphite Industries Co., Ltd.) as thermal conductive particles, and magnetic particles Stainless steel powder (SUS410L, flakes,
次に、鱗片状黒鉛粉末「W+32」1418g、ステンレス鋼粉末532g、およびHPMC43gを、FMミキサ(日本コークス工業(株)製)の容器内へ投入し、1分間混合した。その後、水を135g添加して、さらに6分間混合して、複合粒子の粉末を製造した。製造した複合粒子の粉末を乾燥した後、目開き1100μm、700μmの二種類の篩いにより篩い分けして、粒子径が700μm以上1100μm以下の大粒径粉末を得た。
Next, 1418 g of scaly graphite powder “W + 32”, 532 g of stainless steel powder, and 43 g of HPMC were put into a container of FM mixer (manufactured by Nippon Coke Industries Co., Ltd.) and mixed for 1 minute. Thereafter, 135 g of water was added and further mixed for 6 minutes to produce composite particle powder. After the produced composite particle powder was dried, it was sieved with two types of sieves having an opening of 1100 μm and 700 μm to obtain a large particle size powder having a particle size of 700 μm to 1100 μm.
また、鱗片状黒鉛粉末を「X‐100」に代えた以外は、上記同様にして、複合粒子の粉末を製造した。製造した複合粒子の粉末を乾燥した後、目開き100μm、45μmの二種類の篩いにより篩い分けして、粒子径が45μm以上100μm以下の小粒径粉末を得た。
Further, a powder of composite particles was produced in the same manner as above except that the scaly graphite powder was replaced with “X-100”. After the produced composite particle powder was dried, it was sieved with two types of sieves having openings of 100 μm and 45 μm to obtain a small particle size powder having a particle size of 45 μm or more and 100 μm or less.
配合した鱗片状黒鉛粉末とステンレス鋼粉末との質量比は、100:37.5である。HPMCの配合量は、鱗片状黒鉛粉末とステンレス鋼粉末との合計質量を100質量%とした場合の、2.2質量%である。
The mass ratio of the blended flaky graphite powder and the stainless steel powder is 100: 37.5. The blending amount of HPMC is 2.2% by mass when the total mass of the scaly graphite powder and the stainless steel powder is 100% by mass.
<混合粉末の調製>
[実施例1]
小粒径粉末100gと大粒径粉末400gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:4)。 <Preparation of mixed powder>
[Example 1]
100 g of the small particle size powder and 400 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 4).
[実施例1]
小粒径粉末100gと大粒径粉末400gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:4)。 <Preparation of mixed powder>
[Example 1]
100 g of the small particle size powder and 400 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 4).
[実施例2]
小粒径粉末50gと大粒径粉末450gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:9)。 [Example 2]
50 g of the small particle size powder and 450 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 9).
小粒径粉末50gと大粒径粉末450gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:9)。 [Example 2]
50 g of the small particle size powder and 450 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 9).
[実施例3]
小粒径粉末200gと大粒径粉末400gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:2)。 [Example 3]
200 g of the small particle size powder and 400 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 2).
小粒径粉末200gと大粒径粉末400gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:2)。 [Example 3]
200 g of the small particle size powder and 400 g of the large particle size powder were mixed to prepare a mixed powder of Example 1 (the mass ratio of the small particle size powder to the large particle size powder was 1: 2).
[実施例4]
小粒径粉末250gと大粒径粉末250gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:1)。 [Example 4]
A mixed powder of Example 1 was prepared by mixing 250 g of the small particle size powder and 250 g of the large particle size powder (the mass ratio of the small particle size powder to the large particle size powder was 1: 1).
小粒径粉末250gと大粒径粉末250gとを混合して、実施例1の混合粉末を調製した(小粒径粉末と大粒径粉末との質量比は1:1)。 [Example 4]
A mixed powder of Example 1 was prepared by mixing 250 g of the small particle size powder and 250 g of the large particle size powder (the mass ratio of the small particle size powder to the large particle size powder was 1: 1).
[粒度分布]
実施例1~4の混合粉末の粒度分布を、レーザー回折・散乱式粒度分布測定装置(日機装(株)製「MT-3300EX」)により測定した。図1に、実施例1の混合粉末の粒度分布を示す。図1に示すように、混合粉末(複合粒子の粉末)の粒度分布は、小粒径側ピークおよび大粒径側ピークの二つのピークを有することが確認された。ここで、小粒径側ピークのピーク粒径は90μm、大粒径側ピークのピーク粒径は900μmであり、両者のピーク粒径の比は、1:10であった。また、粒度分布を、粒子径270μmにて二分して、小粒径側と大粒径側の各々のピーク面積を算出したところ、小粒径側ピークと大粒径側ピークとの面積比は1:10であった。 [Particle size distribution]
The particle size distribution of the mixed powders of Examples 1 to 4 was measured with a laser diffraction / scattering particle size distribution measuring apparatus (“MT-3300EX” manufactured by Nikkiso Co., Ltd.). In FIG. 1, the particle size distribution of the mixed powder of Example 1 is shown. As shown in FIG. 1, the particle size distribution of the mixed powder (composite particle powder) was confirmed to have two peaks, a small particle size side peak and a large particle size side peak. Here, the peak particle size of the small particle size side peak was 90 μm, the peak particle size of the large particle size side peak was 900 μm, and the ratio of both peak particle sizes was 1:10. Further, when the particle size distribution was divided into two at 270 μm and the respective peak areas on the small particle size side and the large particle size side were calculated, the area ratio between the small particle size side peak and the large particle size side peak was 1:10.
実施例1~4の混合粉末の粒度分布を、レーザー回折・散乱式粒度分布測定装置(日機装(株)製「MT-3300EX」)により測定した。図1に、実施例1の混合粉末の粒度分布を示す。図1に示すように、混合粉末(複合粒子の粉末)の粒度分布は、小粒径側ピークおよび大粒径側ピークの二つのピークを有することが確認された。ここで、小粒径側ピークのピーク粒径は90μm、大粒径側ピークのピーク粒径は900μmであり、両者のピーク粒径の比は、1:10であった。また、粒度分布を、粒子径270μmにて二分して、小粒径側と大粒径側の各々のピーク面積を算出したところ、小粒径側ピークと大粒径側ピークとの面積比は1:10であった。 [Particle size distribution]
The particle size distribution of the mixed powders of Examples 1 to 4 was measured with a laser diffraction / scattering particle size distribution measuring apparatus (“MT-3300EX” manufactured by Nikkiso Co., Ltd.). In FIG. 1, the particle size distribution of the mixed powder of Example 1 is shown. As shown in FIG. 1, the particle size distribution of the mixed powder (composite particle powder) was confirmed to have two peaks, a small particle size side peak and a large particle size side peak. Here, the peak particle size of the small particle size side peak was 90 μm, the peak particle size of the large particle size side peak was 900 μm, and the ratio of both peak particle sizes was 1:10. Further, when the particle size distribution was divided into two at 270 μm and the respective peak areas on the small particle size side and the large particle size side were calculated, the area ratio between the small particle size side peak and the large particle size side peak was 1:10.
同様に、実施例2~4の混合粉末の粒度分布から、小粒径側と大粒径側の各々のピーク面積を算出したところ、実施例2の混合粉末においては1:20、実施例3の混合粉末においては1:5、実施例4の混合粉末においては1:1であった。
Similarly, the peak areas of the small particle size side and the large particle size side were calculated from the particle size distributions of the mixed powders of Examples 2 to 4. As a result, the mixed powder of Example 2 was 1:20. Of the mixed powder of 1: 5, and 1: 1 of the mixed powder of Example 4.
<エラストマー成形体の製造>
[実施例1~4のエラストマー成形体]
調製した実施例1~4の混合粉末を用いて、エラストマー成形体を製造した。まず、液状シリコーンゴムのビニル基含有ジメチルポリシロキサン(Gelest社製「DMS-V41」)100質量部と、架橋剤のヒドロシリル基含有ジメチルポリシロキサン(Gelest社製「HMS-082」)3質量部と、遅延剤の1-エチニル-1-シクロヘキサノール0.3質量部と、白金触媒(Gelest社製「SIP6830.3」)0.05質量部と、を撹拌羽根を用いて15分間撹拌し、シリコーンコンパウンドを作成した。 <Manufacture of elastomer moldings>
[Elastomer molded bodies of Examples 1 to 4]
An elastomer molded body was produced using the prepared mixed powders of Examples 1 to 4. First, 100 parts by mass of vinyl group-containing dimethylpolysiloxane (“DMS-V41” manufactured by Gelest) of liquid silicone rubber and 3 parts by mass of hydrosilyl group-containing dimethylpolysiloxane (“HMS-082” manufactured by Gelest) of a crosslinking agent Stirring agent 1-ethynyl-1-cyclohexanol 0.3 parts by mass and platinum catalyst (“SIP6830.3” manufactured by Gelest Co., Ltd.) 0.05 parts by mass using a stirring blade for 15 minutes, Created a compound.
[実施例1~4のエラストマー成形体]
調製した実施例1~4の混合粉末を用いて、エラストマー成形体を製造した。まず、液状シリコーンゴムのビニル基含有ジメチルポリシロキサン(Gelest社製「DMS-V41」)100質量部と、架橋剤のヒドロシリル基含有ジメチルポリシロキサン(Gelest社製「HMS-082」)3質量部と、遅延剤の1-エチニル-1-シクロヘキサノール0.3質量部と、白金触媒(Gelest社製「SIP6830.3」)0.05質量部と、を撹拌羽根を用いて15分間撹拌し、シリコーンコンパウンドを作成した。 <Manufacture of elastomer moldings>
[Elastomer molded bodies of Examples 1 to 4]
An elastomer molded body was produced using the prepared mixed powders of Examples 1 to 4. First, 100 parts by mass of vinyl group-containing dimethylpolysiloxane (“DMS-V41” manufactured by Gelest) of liquid silicone rubber and 3 parts by mass of hydrosilyl group-containing dimethylpolysiloxane (“HMS-082” manufactured by Gelest) of a crosslinking agent Stirring agent 1-ethynyl-1-cyclohexanol 0.3 parts by mass and platinum catalyst (“SIP6830.3” manufactured by Gelest Co., Ltd.) 0.05 parts by mass using a stirring blade for 15 minutes, Created a compound.
次に、製造したシリコーンコンパウンドに混合粉末を混合して、混合原料を調製した。混合粉末は、複合粒子の充填率が、製造されるエラストマー成形体の体積を100体積%とした場合の32.7体積%となるように配合した。
Next, a mixed raw material was prepared by mixing the mixed powder with the manufactured silicone compound. The mixed powder was blended so that the filling rate of the composite particles was 32.7% by volume when the volume of the produced elastomer molded body was 100% by volume.
続いて、各混合原料を、予めオーブンにて130℃に加熱したアルミニウム製の成形型(後述する図2、図3参照。キャビティは縦130mm×横130mm×厚さ5mmの直方体。)に注入し、密閉した。そして、成形型を磁気誘導成形装置に設置して、成形を行った。図2に、磁気誘導成形装置の斜視図を示す。図3に、同装置の断面図を示す。図2においては、説明の便宜上、ヨーク部および芯部のハッチングを省略して示す。図2、図3に示すように、磁気誘導成形装置1は、架台2と、電磁石部3と、成形型4と、面状ヒーター50と、断熱部材51と、を備えている。
Subsequently, each of the mixed raw materials is poured into an aluminum mold (see FIGS. 2 and 3 to be described later. The cavity is a rectangular parallelepiped having a length of 130 mm × width of 130 mm × thickness of 5 mm). , Sealed. And the shaping | molding die was installed in the magnetic induction molding apparatus, and it shape | molded. FIG. 2 shows a perspective view of the magnetic induction molding apparatus. FIG. 3 shows a sectional view of the apparatus. In FIG. 2, hatching of the yoke part and the core part is omitted for convenience of explanation. As shown in FIGS. 2 and 3, the magnetic induction molding apparatus 1 includes a gantry 2, an electromagnet unit 3, a molding die 4, a planar heater 50, and a heat insulating member 51.
電磁石部3は、架台2の上面に載置されている。電磁石部3と架台2とは、各々にブラケット21をねじ止めすることにより、固定されている。電磁石部3は、ヨーク部30U、30Dと、コイル部31L、31Rと、ポールピース32U、32Dと、を備えている。
The electromagnet unit 3 is placed on the upper surface of the gantry 2. The electromagnet unit 3 and the gantry 2 are fixed by screwing a bracket 21 to each. The electromagnet portion 3 includes yoke portions 30U and 30D, coil portions 31L and 31R, and pole pieces 32U and 32D.
ヨーク部30Uは、鉄製であり、平板状を呈している。ヨーク部30Dも同様に、鉄製であり、平板状を呈している。ヨーク部30U、30Dは、上下方向に対向して配置されている。
The yoke portion 30U is made of iron and has a flat plate shape. Similarly, the yoke part 30D is made of iron and has a flat plate shape. The yoke portions 30U and 30D are arranged to face each other in the vertical direction.
コイル部31Lは、ヨーク部30U、30Dの間に介装されている。コイル部31Lは、成形型4の左側に配置されている。コイル部31Lは、上下方向に二つ重ねて配置されている。コイル部31Lは、各々、芯部310Lと導線311Lとを備えている。芯部310Lは、鉄製であって、上下方向に延びる柱状を呈している。導線311Lは、芯部310Lの外周面に巻装されている。導線311Lは、電源(図略)に接続されている。
The coil part 31L is interposed between the yoke parts 30U and 30D. The coil part 31 </ b> L is disposed on the left side of the mold 4. Two coil portions 31L are arranged in the vertical direction. Each of the coil portions 31L includes a core portion 310L and a conductive wire 311L. The core portion 310L is made of iron and has a columnar shape extending in the vertical direction. The conducting wire 311L is wound around the outer peripheral surface of the core portion 310L. The conducting wire 311L is connected to a power source (not shown).
コイル部31Rは、ヨーク部30U、30Dの間に介装されている。コイル部31Rは、成形型4の右側に配置されている。コイル部31Rは、上下方向に二つ重ねて配置されている。コイル部31Rは、各々、コイル部31Lと同様の構成を備えている。すなわち、コイル部31Rは、芯部310Rと導線311Rとを備えている。導線311Rは、芯部310Rの外周面に巻装されている。導線311Rは、電源(図略)に接続されている。
The coil portion 31R is interposed between the yoke portions 30U and 30D. The coil portion 31 </ b> R is disposed on the right side of the mold 4. Two coil portions 31 </ b> R are arranged in the vertical direction. The coil portions 31R each have the same configuration as the coil portion 31L. That is, the coil portion 31R includes a core portion 310R and a conducting wire 311R. The conducting wire 311R is wound around the outer peripheral surface of the core portion 310R. The conducting wire 311R is connected to a power source (not shown).
ポールピース32Uは、鉄製であり、平板状を呈している。ポールピース32Uは、ヨーク部30Uの下面中央に配置されている。ポールピース32Uは、ヨーク部30Uと成形型4との間に介装されている。ポールピース32Dは、鉄製であり、平板状を呈している。ポールピース32Dは、ヨーク部30Dの上面中央に配置されている。
The pole piece 32U is made of iron and has a flat plate shape. The pole piece 32U is disposed at the center of the lower surface of the yoke portion 30U. The pole piece 32U is interposed between the yoke portion 30U and the mold 4. The pole piece 32D is made of iron and has a flat plate shape. The pole piece 32D is disposed at the center of the upper surface of the yoke portion 30D.
成形型4は、コイル部31Lとコイル部31Rとの間に、配置されている。成形型4は、上型40Uと下型40Dとを備えている。上型40Uは、正方形板状を呈している。下型40Dは、直方体状を呈している。下型40Dの上面には、凹部が形成されている。凹部は、上方に開口する直方体状を呈している。上型40Uと下型40Dとが合体することにより、直方体状のキャビティ41が区画されている。キャビティ41には、前述したように、混合原料が充填されている。
The molding die 4 is disposed between the coil part 31L and the coil part 31R. The molding die 4 includes an upper die 40U and a lower die 40D. The upper mold 40U has a square plate shape. The lower mold 40D has a rectangular parallelepiped shape. A recess is formed on the upper surface of the lower mold 40D. The recess has a rectangular parallelepiped shape that opens upward. By combining the upper mold 40U and the lower mold 40D, a rectangular parallelepiped cavity 41 is defined. As described above, the cavity 41 is filled with the mixed raw material.
面状ヒーター50は、正方形シート状を呈している。面状ヒーター50は、下型40Dの下面を覆うように配置されている。面状ヒーター50により、成形型4は100℃に保持されている。
The planar heater 50 has a square sheet shape. The planar heater 50 is disposed so as to cover the lower surface of the lower mold 40D. The mold 4 is held at 100 ° C. by the planar heater 50.
断熱部材51は、ガラス繊維製であり、平板状を呈している。断熱部材51は、面状ヒーター50とポールピース32Dとの間に介装されている。断熱部材51により、面状ヒーター50から電磁石部3への熱の移動が、抑制されている。
The heat insulating member 51 is made of glass fiber and has a flat plate shape. The heat insulating member 51 is interposed between the planar heater 50 and the pole piece 32D. The heat transfer from the planar heater 50 to the electromagnet unit 3 is suppressed by the heat insulating member 51.
導線311Lに接続された電源および導線311Rに接続された電源を、共にオンにすると、コイル部31Lの芯部310Lの上端がN極に、下端がS極に磁化される。このため、芯部310Lに、下方から上方に向かって磁力線L(図3に点線で示す)が発生する。同様に、コイル部31Rの芯部310Rの上端がN極に、下端がS極に磁化される。このため、芯部310Rに、下方から上方に向かって磁力線Lが発生する。
When both the power source connected to the conducting wire 311L and the power source connected to the conducting wire 311R are turned on, the upper end of the core portion 310L of the coil portion 31L is magnetized to the N pole and the lower end is magnetized to the S pole. For this reason, a magnetic force line L (indicated by a dotted line in FIG. 3) is generated in the core portion 310L from the bottom to the top. Similarly, the upper end of the core portion 310R of the coil portion 31R is magnetized to the N pole and the lower end is magnetized to the S pole. For this reason, lines of magnetic force L are generated in the core portion 310R from the bottom to the top.
コイル部31Lの芯部310L上端から放射された磁力線Lは、ヨーク部30U、ポールピース32Uを通って、成形型4のキャビティ41内に流入する。その後、ポールピース32D、ヨーク部30Dを通って、芯部310L下端に流入する。同様に、コイル部31Rの芯部310R上端から放射された磁力線Lは、ヨーク部30U、ポールピース32Uを通って、成形型4のキャビティ41内に流入する。その後、ポールピース32D、ヨーク部30Dを通って、芯部310R下端に流入する。このように、磁力線Lは閉ループを構成するため、磁力線Lの漏洩は抑制される。また、成形型4のキャビティ41内には、上方から下方に向かって略平行な磁力線Lにより一様な磁場が形成される。具体的には、キャビティ41内の磁束密度は、約300mTであった。また、キャビティ41内における磁束密度の差は、±3%以内であった。
Magnetic field lines L radiated from the upper end of the core portion 310L of the coil portion 31L flow into the cavity 41 of the mold 4 through the yoke portion 30U and the pole piece 32U. Then, it flows into the lower end of the core part 310L through the pole piece 32D and the yoke part 30D. Similarly, the lines of magnetic force L radiated from the upper end of the core portion 310R of the coil portion 31R flow into the cavity 41 of the mold 4 through the yoke portion 30U and the pole piece 32U. Then, it flows into the lower end of the core portion 310R through the pole piece 32D and the yoke portion 30D. Thus, since the magnetic lines L constitute a closed loop, the leakage of the magnetic lines L is suppressed. In the cavity 41 of the mold 4, a uniform magnetic field is formed by magnetic lines L that are substantially parallel from the top to the bottom. Specifically, the magnetic flux density in the cavity 41 was about 300 mT. Further, the difference in magnetic flux density in the cavity 41 was within ± 3%.
成形は、100℃下で、30分間磁場をかけながら行った。成形が終了した後、脱型して、エラストマー成形体を得た。得られたエラストマー成形体を、混合粉末の番号と対応させて番号付けした。
Molding was performed at 100 ° C. while applying a magnetic field for 30 minutes. After the molding was completed, the mold was removed to obtain an elastomer molded body. The obtained elastomer moldings were numbered according to the numbers of the mixed powders.
[比較例1、2のエラストマー成形体]
比較のため、混合粉末に代えて、粒子径が700μm以上1100μm以下の大粒径粉末のみを配合した以外は、実施例1~4と同様にして、エラストマー成形体を製造した。配合された複合粒子の粉末の粒度分布のピークは、一つである。得られたエラストマー成形体を、比較例1のエラストマー成形体とした。 [Elastomer molded bodies of Comparative Examples 1 and 2]
For comparison, elastomer molded bodies were produced in the same manner as in Examples 1 to 4, except that only a large particle size powder having a particle size of 700 μm or more and 1100 μm or less was blended instead of the mixed powder. There is one peak of the particle size distribution of the mixed composite particle powder. The obtained elastomer molded body was used as the elastomer molded body of Comparative Example 1.
比較のため、混合粉末に代えて、粒子径が700μm以上1100μm以下の大粒径粉末のみを配合した以外は、実施例1~4と同様にして、エラストマー成形体を製造した。配合された複合粒子の粉末の粒度分布のピークは、一つである。得られたエラストマー成形体を、比較例1のエラストマー成形体とした。 [Elastomer molded bodies of Comparative Examples 1 and 2]
For comparison, elastomer molded bodies were produced in the same manner as in Examples 1 to 4, except that only a large particle size powder having a particle size of 700 μm or more and 1100 μm or less was blended instead of the mixed powder. There is one peak of the particle size distribution of the mixed composite particle powder. The obtained elastomer molded body was used as the elastomer molded body of Comparative Example 1.
また、混合粉末に代えて、鱗片状黒鉛粉末「W+32」を用いて製造した複合粒子の粉末を篩い分けせずにそのまま配合した以外は、実施例1~4と同様にして、エラストマー成形体を製造した。配合された複合粒子の粉末の粒度分布のピークは、一つである。得られたエラストマー成形体を、比較例2のエラストマー成形体とした。
Further, an elastomer molded body was prepared in the same manner as in Examples 1 to 4, except that the powder of composite particles produced using scaly graphite powder “W + 32” was blended as it was without sieving instead of the mixed powder. Manufactured. There is one peak of the particle size distribution of the mixed composite particle powder. The obtained elastomer molded body was used as the elastomer molded body of Comparative Example 2.
<エラストマー成形体のX線CT測定>
製造したエラストマー成形体の上面から面垂直方向の配向状態を、X線CT装置((株)島津製作所製「SMX-160LT」)を用いて観察した。図4に、実施例1のエラストマー成形体のX線CT写真を示す。図5に、比較例2のエラストマー成形体のX線CT写真を示す。図4に示すように、実施例1のエラストマー成形体においては、大粒径粒子と大粒径粒子との間の隙間(基材部分)を埋めるように、小粒径粒子が分散して配向していることが確認できた。一方、図5に示すように、分級無しの複合粒子の粉末を配合した比較例2のエラストマー成形体においては、大粒径粒子と大粒径粒子との間に、ほとんど小粒径粒子は見られなかった。 <X-ray CT measurement of elastomer molded body>
The alignment state in the direction perpendicular to the surface from the upper surface of the produced elastomer molded body was observed using an X-ray CT apparatus (“SMX-160LT” manufactured by Shimadzu Corporation). FIG. 4 shows an X-ray CT photograph of the elastomer molded body of Example 1. In FIG. 5, the X-ray CT photograph of the elastomer molded object of the comparative example 2 is shown. As shown in FIG. 4, in the elastomer molded body of Example 1, the small particle size particles are dispersed and oriented so as to fill the gap (base material portion) between the large particle size particle and the large particle size particle. I was able to confirm. On the other hand, as shown in FIG. 5, in the elastomer molded body of Comparative Example 2 in which composite powder without classification was blended, almost no small particle size particles were observed between the large particle size particles. I couldn't.
製造したエラストマー成形体の上面から面垂直方向の配向状態を、X線CT装置((株)島津製作所製「SMX-160LT」)を用いて観察した。図4に、実施例1のエラストマー成形体のX線CT写真を示す。図5に、比較例2のエラストマー成形体のX線CT写真を示す。図4に示すように、実施例1のエラストマー成形体においては、大粒径粒子と大粒径粒子との間の隙間(基材部分)を埋めるように、小粒径粒子が分散して配向していることが確認できた。一方、図5に示すように、分級無しの複合粒子の粉末を配合した比較例2のエラストマー成形体においては、大粒径粒子と大粒径粒子との間に、ほとんど小粒径粒子は見られなかった。 <X-ray CT measurement of elastomer molded body>
The alignment state in the direction perpendicular to the surface from the upper surface of the produced elastomer molded body was observed using an X-ray CT apparatus (“SMX-160LT” manufactured by Shimadzu Corporation). FIG. 4 shows an X-ray CT photograph of the elastomer molded body of Example 1. In FIG. 5, the X-ray CT photograph of the elastomer molded object of the comparative example 2 is shown. As shown in FIG. 4, in the elastomer molded body of Example 1, the small particle size particles are dispersed and oriented so as to fill the gap (base material portion) between the large particle size particle and the large particle size particle. I was able to confirm. On the other hand, as shown in FIG. 5, in the elastomer molded body of Comparative Example 2 in which composite powder without classification was blended, almost no small particle size particles were observed between the large particle size particles. I couldn't.
<エラストマー成形体の評価>
製造したエラストマー成形体の熱伝導率を、JIS A1412-2(1999)の熱流計法に準拠した、英弘精機(株)製「HC-110」を用いて測定した。表1に、評価結果を、使用した複合粒子の粉末の組成と共に示す。
<Evaluation of elastomer molding>
The thermal conductivity of the produced elastomer molded body was measured using “HC-110” manufactured by Eihiro Seiki Co., Ltd. in accordance with the heat flow meter method of JIS A1412-2 (1999). Table 1 shows the evaluation results together with the composition of the powder of the composite particles used.
製造したエラストマー成形体の熱伝導率を、JIS A1412-2(1999)の熱流計法に準拠した、英弘精機(株)製「HC-110」を用いて測定した。表1に、評価結果を、使用した複合粒子の粉末の組成と共に示す。
The thermal conductivity of the produced elastomer molded body was measured using “HC-110” manufactured by Eihiro Seiki Co., Ltd. in accordance with the heat flow meter method of JIS A1412-2 (1999). Table 1 shows the evaluation results together with the composition of the powder of the composite particles used.
表1に示すように、実施例1~4のエラストマー成形体の熱伝導率は、比較例1、2のエラストマー成形体の熱伝導率よりも、大きくなった。なかでも、大粒径粉末の配合比率が大きい実施例1~3のエラストマー成形体の熱伝導率は、3.4W/m・K以上と大きくなった。
As shown in Table 1, the thermal conductivity of the elastomer molded bodies of Examples 1 to 4 was larger than the thermal conductivity of the elastomer molded bodies of Comparative Examples 1 and 2. Among them, the thermal conductivity of the elastomer molded bodies of Examples 1 to 3 having a large blending ratio of the large particle size powder was as large as 3.4 W / m · K or more.
<複合粒子の充填率と熱伝導率との関係>
実施例1の混合粉末を配合したエラストマー成形体において、複合粒子の充填率に対する熱伝導率の変化を調べた。比較のため、鱗片状黒鉛粉末「W+32」を用いて製造した複合粒子の粉末を篩い分けせずにそのまま配合したエラストマー成形体においても、複合粒子の充填率に対する熱伝導率の変化を調べた。図6に、二つのエラストマー成形体における複合粒子の充填率と熱伝導率との関係をグラフで示す。 <Relationship between packing rate of composite particles and thermal conductivity>
In the elastomer molded body in which the mixed powder of Example 1 was blended, the change in thermal conductivity with respect to the filling rate of the composite particles was examined. For comparison, the change in the thermal conductivity with respect to the filling rate of the composite particles was also examined in an elastomer molded body in which the powder of composite particles produced using the flaky graphite powder “W + 32” was blended as it was without sieving. In FIG. 6, the relationship between the filling rate of the composite particle in two elastomer molded objects and thermal conductivity is shown with a graph.
実施例1の混合粉末を配合したエラストマー成形体において、複合粒子の充填率に対する熱伝導率の変化を調べた。比較のため、鱗片状黒鉛粉末「W+32」を用いて製造した複合粒子の粉末を篩い分けせずにそのまま配合したエラストマー成形体においても、複合粒子の充填率に対する熱伝導率の変化を調べた。図6に、二つのエラストマー成形体における複合粒子の充填率と熱伝導率との関係をグラフで示す。 <Relationship between packing rate of composite particles and thermal conductivity>
In the elastomer molded body in which the mixed powder of Example 1 was blended, the change in thermal conductivity with respect to the filling rate of the composite particles was examined. For comparison, the change in the thermal conductivity with respect to the filling rate of the composite particles was also examined in an elastomer molded body in which the powder of composite particles produced using the flaky graphite powder “W + 32” was blended as it was without sieving. In FIG. 6, the relationship between the filling rate of the composite particle in two elastomer molded objects and thermal conductivity is shown with a graph.
図6に示すように、充填率に関わらず、実施例1の混合粉末を配合したエラストマー成形体の方が、分級無しの複合粒子の粉末を配合したエラストマー成形体よりも、熱伝導率が大きくなった。具体的には、複合粒子の充填率が26体積%以上38体積%以下の場合の熱伝導率は、2.4W/m・K以上であった。また、実施例1の混合粉末を配合したエラストマー成形体の方が、分級無しの複合粒子の粉末を配合したエラストマー成形体よりも、熱伝導率が最大になる充填率が高くなった。この結果から、実施例1の混合粉末を用いると、熱伝導率を大きくするために、複合粒子の粉末をより高充填できることがわかる。
As shown in FIG. 6, regardless of the filling rate, the elastomer molded body in which the mixed powder of Example 1 was blended had a higher thermal conductivity than the elastomer molded body in which the powder of composite particles without classification was blended. became. Specifically, the thermal conductivity when the filling rate of the composite particles is 26% by volume or more and 38% by volume or less was 2.4 W / m · K or more. In addition, the elastomer molded body in which the mixed powder of Example 1 was blended had a higher filling rate at which the thermal conductivity was maximized than the elastomer molded body in which the composite particle powder without classification was blended. From this result, it can be seen that when the mixed powder of Example 1 is used, the powder of the composite particles can be filled more highly in order to increase the thermal conductivity.
<小粒径粉末と大粒径粉末との配合比率と熱伝導率との関係>
実施例1~4の混合粉末を用いて、複合粒子の充填率が26.4体積%、32.7体積%である二種類のエラストマー成形体を製造し、各々の熱伝導率を測定した。また、比較のため、粒子径が700μm以上1100μm以下の大粒径粉末のみを用いて、複合粒子の充填率が26.4体積%、32.7体積%である二種類のエラストマー成形体を製造し、各々の熱伝導率を測定した。なお、各エラストマー成形体の製造方法は、上記実施例1~4のエラストマー成形体の製造方法と、同じである。図7に、小粒径粉末と大粒径粉末との質量比と熱伝導率との関係をグラフで示す。 <Relationship between blending ratio of small particle size powder and large particle size powder and thermal conductivity>
Using the mixed powders of Examples 1 to 4, two types of elastomer molded bodies having a composite particle filling rate of 26.4% by volume and 32.7% by volume were produced, and the thermal conductivity of each was measured. Further, for comparison, two types of elastomer molded bodies having a composite particle filling rate of 26.4% by volume and 32.7% by volume are manufactured using only a powder having a particle size of 700 μm or more and 1100 μm or less. The thermal conductivity of each was measured. The method for producing each elastomer molded body is the same as the method for producing the elastomer molded bodies in Examples 1 to 4 described above. FIG. 7 is a graph showing the relationship between the mass ratio between the small particle size powder and the large particle size powder and the thermal conductivity.
実施例1~4の混合粉末を用いて、複合粒子の充填率が26.4体積%、32.7体積%である二種類のエラストマー成形体を製造し、各々の熱伝導率を測定した。また、比較のため、粒子径が700μm以上1100μm以下の大粒径粉末のみを用いて、複合粒子の充填率が26.4体積%、32.7体積%である二種類のエラストマー成形体を製造し、各々の熱伝導率を測定した。なお、各エラストマー成形体の製造方法は、上記実施例1~4のエラストマー成形体の製造方法と、同じである。図7に、小粒径粉末と大粒径粉末との質量比と熱伝導率との関係をグラフで示す。 <Relationship between blending ratio of small particle size powder and large particle size powder and thermal conductivity>
Using the mixed powders of Examples 1 to 4, two types of elastomer molded bodies having a composite particle filling rate of 26.4% by volume and 32.7% by volume were produced, and the thermal conductivity of each was measured. Further, for comparison, two types of elastomer molded bodies having a composite particle filling rate of 26.4% by volume and 32.7% by volume are manufactured using only a powder having a particle size of 700 μm or more and 1100 μm or less. The thermal conductivity of each was measured. The method for producing each elastomer molded body is the same as the method for producing the elastomer molded bodies in Examples 1 to 4 described above. FIG. 7 is a graph showing the relationship between the mass ratio between the small particle size powder and the large particle size powder and the thermal conductivity.
図7に示すように、いずれの充填率においても、混合粉末を配合したエラストマー成形体の方が、大粒径粉末のみを配合したエラストマー成形体(小粒径粉末と大粒径粉末との質量比は0:1)よりも、熱伝導率が大きくなった。また、混合粉末を配合したエラストマー成形体においては、充填率が高い方が、熱伝導率が大きくなった。また、混合粉末を配合したエラストマー成形体においては、大粒径粉末の配合比率を大きくすると熱伝導率が大きくなった。例えば、充填率が32.7体積%の場合、小粒径粉末と大粒径粉末との質量比が1:4のエラストマー成形体において、熱伝導率が最大になった。
As shown in FIG. 7, at any filling rate, an elastomer molded body in which mixed powder is blended is an elastomer molded body in which only large particle diameter powder is blended (the mass of small particle diameter powder and large particle diameter powder). The thermal conductivity was greater than the ratio 0: 1). Moreover, in the elastomer molded body which mix | blended mixed powder, the one where the filling rate was high became large in thermal conductivity. Moreover, in the elastomer molded body which mix | blended mixed powder, when the mixture ratio of the large particle size powder was enlarged, thermal conductivity became large. For example, when the filling rate is 32.7% by volume, the thermal conductivity is maximized in the elastomer molded body in which the mass ratio of the small particle size powder to the large particle size powder is 1: 4.
<非配向フィラーの配合>
実施例1の混合粉末に加えて、非配向フィラーとして絶縁性無機材料の酸化マグネシウム粉末(神島化学工業(株)製「スターマグPSF-WR」、平均粒径1.0μm)を配合して、エラストマー成形体を製造した。実施例1の混合粉末は、エラストマー成形体の体積を100体積%とした場合の32.7体積%となるように配合し、酸化マグネシウム粉末は、8体積%となるように配合した。図8に、熱伝導率の測定結果をグラフで示す。 <Composition of non-oriented filler>
In addition to the mixed powder of Example 1, an insulating inorganic material magnesium oxide powder (“Starmag PSF-WR” manufactured by Kamishima Chemical Industry Co., Ltd., average particle size 1.0 μm) is blended as an unoriented filler, and an elastomer A molded body was produced. The mixed powder of Example 1 was blended so as to be 32.7% by volume when the volume of the elastomer molded body was 100% by volume, and the magnesium oxide powder was blended so as to be 8% by volume. In FIG. 8, the measurement result of thermal conductivity is shown with a graph.
実施例1の混合粉末に加えて、非配向フィラーとして絶縁性無機材料の酸化マグネシウム粉末(神島化学工業(株)製「スターマグPSF-WR」、平均粒径1.0μm)を配合して、エラストマー成形体を製造した。実施例1の混合粉末は、エラストマー成形体の体積を100体積%とした場合の32.7体積%となるように配合し、酸化マグネシウム粉末は、8体積%となるように配合した。図8に、熱伝導率の測定結果をグラフで示す。 <Composition of non-oriented filler>
In addition to the mixed powder of Example 1, an insulating inorganic material magnesium oxide powder (“Starmag PSF-WR” manufactured by Kamishima Chemical Industry Co., Ltd., average particle size 1.0 μm) is blended as an unoriented filler, and an elastomer A molded body was produced. The mixed powder of Example 1 was blended so as to be 32.7% by volume when the volume of the elastomer molded body was 100% by volume, and the magnesium oxide powder was blended so as to be 8% by volume. In FIG. 8, the measurement result of thermal conductivity is shown with a graph.
図8に示すように、非配向フィラーを配合しても、混合粉末の配合による熱伝導性向上効果は維持された。酸化マグネシウムの熱伝導率は比較的大きい。このため、非配向フィラーとして酸化マグネシウム粉末を配合した場合、熱伝導率がより大きくなった。
As shown in FIG. 8, even when the non-oriented filler was blended, the effect of improving the thermal conductivity by blending the mixed powder was maintained. Magnesium oxide has a relatively high thermal conductivity. For this reason, when the magnesium oxide powder was blended as the non-oriented filler, the thermal conductivity was increased.
本発明のエラストマー成形体は、電子機器、自動車、建築等の幅広い分野において用いることができる。具体的には、パソコン等の電子機器に用いられる放熱部材、車載用ECU(電子制御ユニット)の放熱部材、LED(発光ダイオード)照明用の放熱部材等に好適である。
The elastomer molded body of the present invention can be used in a wide range of fields such as electronic equipment, automobiles, and architecture. Specifically, it is suitable for a heat radiating member used for electronic equipment such as a personal computer, a heat radiating member for an in-vehicle ECU (electronic control unit), a heat radiating member for LED (light emitting diode) illumination, and the like.
Claims (9)
- エラストマーからなる基材と、該基材中に配向して含有されている複合粒子の粉末と、を有し、
該複合粒子は、非磁性体からなる熱伝導性粒子と、該熱伝導性粒子の表面にバインダーにより接着された磁性粒子と、を含み、
該複合粒子の粉末の粒度分布は、小粒径側ピークおよび大粒径側ピークの二つのピークを有することを特徴とするエラストマー成形体。 A base material made of an elastomer, and a powder of composite particles that are oriented and contained in the base material,
The composite particles include thermally conductive particles made of a nonmagnetic material, and magnetic particles bonded to the surface of the thermally conductive particles with a binder,
An elastomer molded article, wherein the particle size distribution of the composite particle powder has two peaks, a small particle size side peak and a large particle size side peak. - 前記複合粒子の粉末の粒度分布において、前記小粒径側ピークのピーク粒径と前記大粒径側ピークのピーク粒径との比は、1:2~1:20である請求項1に記載のエラストマー成形体。 The ratio of the peak particle size of the small particle size side peak to the peak particle size of the large particle size side peak in the particle size distribution of the composite particle powder is 1: 2 to 1:20. Elastomer molded body.
- 前記複合粒子の粉末の粒度分布において、前記小粒径側ピークの面積と前記大粒径側ピークの面積との比は、1:1~1:30である請求項1または請求項2に記載のエラストマー成形体。 The ratio of the area of the small particle size side peak to the area of the large particle size side peak in the particle size distribution of the powder of the composite particles is 1: 1 to 1:30. Elastomer molded body.
- さらに、前記基材中に分散される非配向フィラーを有する請求項1ないし請求項3のいずれか1項に記載のエラストマー成形体。 Furthermore, the elastomer molded object of any one of Claim 1 thru | or 3 which has a non-orientation filler disperse | distributed in the said base material.
- 前記エラストマーは、ウレタンゴム、シリコーンゴム、フッ素ゴム、およびこれらの発泡体のいずれかである請求項1ないし請求項4のいずれか1項に記載のエラストマー成形体。 The elastomer molded body according to any one of claims 1 to 4, wherein the elastomer is any one of urethane rubber, silicone rubber, fluororubber, and foams thereof.
- 前記熱伝導性粒子は、黒鉛からなる請求項1ないし請求項5のいずれか1項に記載のエラストマー成形体。 The elastomer molded body according to any one of claims 1 to 5, wherein the thermally conductive particles are made of graphite.
- 前記複合粒子の充填率が、エラストマー成形体の体積を100体積%とした時の26体積%以上38体積%以下である場合の熱伝導率は、2.4W/m・K以上である請求項1ないし請求項6のいずれか1項に記載のエラストマー成形体。 The thermal conductivity when the filling rate of the composite particles is 26 vol% or more and 38 vol% or less when the volume of the elastomer molded body is 100 vol% is 2.4 W / m · K or more. The elastomer molded body according to any one of claims 1 to 6.
- 請求項1に記載のエラストマー成形体の製造方法であって、
撹拌造粒機を用いて、熱伝導性粒子の粉末、磁性粒子の粉末、およびバインダーを含む粉末原料を撹拌して複合粒子の粉末を製造し、該複合粒子の粉末を分級して小粒径粉末および大粒径粉末を準備する複合粒子粉末準備工程と、
該複合粒子の該小粒径粉末および該大粒径粉末と、エラストマー原料と、を混合して混合原料を調製する混合原料調製工程と、
該混合原料を成形型に配置して、磁場中で該混合原料を成形する成形工程と、
を有することを特徴とするエラストマー成形体の製造方法。 It is a manufacturing method of the elastomer fabrication object according to claim 1,
Using an agitation granulator, a powder material containing heat conductive particles, magnetic particle powder, and a binder is stirred to produce composite particle powder, and the composite particle powder is classified to obtain a small particle size. A composite particle powder preparation step of preparing a powder and a large particle size powder;
A mixed raw material preparation step of preparing a mixed raw material by mixing the small particle size powder and the large particle size powder of the composite particles and an elastomer raw material;
A molding step of placing the mixed raw material in a mold and molding the mixed raw material in a magnetic field;
A method for producing an elastomer molded article, comprising: - 前記混合原料調製工程において、配合する前記小粒径粉末と前記大粒径粉末との質量比は、1:1~1:10である請求項8に記載のエラストマー成形体の製造方法。 The method for producing an elastomer molded body according to claim 8, wherein a mass ratio of the small particle size powder and the large particle size powder to be blended in the mixed raw material preparation step is 1: 1 to 1:10.
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