JP2017137410A - Heat-dissipating resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-dissipating resin composition having improved heat dissipation properties and flowability with a smaller content of a heat conductive filler.SOLUTION: A heat-dissipating resin composition contains 30-60 pts.wt. of at least one thermosetting resin (A) selected from an unsaturated polyester resin, an epoxy resin, an urethane resin and a silicone resin, 40-70 pts.wt. of a heat conductive filler (B) containing a secondary aggregate having a particle size of more than 20 μm and single particles having a particle size of 20 μm or less (total amount of component (A) and component (B) is 100 pts.wt.), and 0.05-3.0 pts.wt. of a crosslinking agent (C) capable of reacting the thermosetting resin (A).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat dissipating resin composition.

  In an electronic component, in order to protect the part which generate | occur | produced heat | fever and its peripheral part, it seals with a heat-radiation molded object, or makes them contact with a heat-radiation molded object and is made to heat-transfer to a cooling medium.

  The heat dissipation molded body is obtained by molding a heat dissipation resin composition. As a heat-dissipating resin composition, a composition in which a thermally conductive filler is blended with a matrix resin is known.

  As a heat-dissipating resin composition in which a thermally conductive filler is blended with a matrix resin, Patent Document 1 contains a matrix resin and a filler, and the filler contains nanofiber aluminum nitride. A composition is described.

  Patent Document 2 is obtained by surface-treating zinc oxide particles with at least one metal compound selected from the group consisting of Mg, Co, Ca and Ni, and has a median diameter (D50). The low-conductivity zinc oxide particle characterized by being 1-10000 micrometers is described, and the heat dissipation resin composition containing this low-conductivity zinc oxide particle is also described.

  However, in the conventional heat-dissipating resin composition, it is necessary to add a large amount of filler to the matrix resin in order to increase the heat conductivity of the heat-dissipating molded article and improve the heat-dissipating property. In addition, when the filler to be blended has a spherical shape or a substantially uniform shape, the blending amount of the filler must be increased in order to increase the contact point between the fillers to form a heat transfer path. However, if a large amount of filler is added to the matrix resin, the fluidity of the heat-dissipating resin composition is greatly reduced, and such a composition can be used for materials having no fluidity, such as prepregs. It was difficult to use for casting applications such as transfer molding and injection molding with a large degree of freedom of shape.

JP 2009-302150 A JP 2011-230947 A

  As described above, in a heat dissipating resin composition in which a heat conductive filler is blended with a conventional matrix resin, in order to increase heat conductivity and improve heat dissipation, the inclusion of the heat conductive filler in the composition It is necessary to increase the amount, but this greatly reduces the fluidity. Therefore, an object of the present invention is to provide a heat-dissipating resin composition having improved heat dissipation and fluidity with a less heat conductive filler content.

  As a result of various investigations of means for solving the above problems, the present inventors have used a thermally conductive filler in the form of secondary aggregates and single particles in the heat-dissipating resin composition, thereby containing less filler. It discovered that the heat dissipation of a composition and fluidity | liquidity could be improved by the quantity, and completed this invention.

That is, the gist of the present invention is as follows.
(1) 30-60 parts by weight of a thermosetting resin (A) that is at least one selected from unsaturated polyester resins, epoxy resins, urethane resins, and silicone resins, secondary aggregates having a particle size of more than 20 μm, and 40 to 70 parts by weight of thermally conductive filler (B) containing single particles having a particle size of 20 μm or less (the total amount of components (A) and (B) is 100 parts by weight), and the thermosetting resin A heat-dissipating resin composition comprising 0.05 to 3.0 parts by weight of a crosslinking agent (C) capable of reacting with (A).

  According to the present invention, it is possible to provide a heat-dissipating resin composition with improved heat dissipation and fluidity with less heat conductive filler content.

FIG. 1 is an image view of a cross section in the thickness direction of the heat-radiating molded article of the present invention. FIG. 2 is an SEM observation of the state of boron nitride before and after the rotation treatment. FIG. 2A is an SEM observation view of the boron nitride aggregated particles before the rotation treatment, and FIG. 2B is an SEM observation view of boron nitride after the rotation treatment. 3 is a SEM observation of a cross section of the heat-dissipating molded article of Example 2. FIG. FIG. 4 is a diagram showing the thermal conductivity of the heat dissipating resin compositions of Examples 1 and 2 and Comparative Example 1-5. FIG. 5 is a diagram showing the fluidity of the heat-dissipating resin compositions of Examples 1 and 2 and Comparative Example 1-5.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The heat-radiating resin composition of the present invention includes a thermosetting resin (A), a heat conductive filler (B), and a crosslinking agent (C) that can react with the thermosetting resin (A).

  The thermosetting resin (A) is used for dispersing the heat conductive filler (B). The thermosetting resin used in the present invention is at least one selected from unsaturated polyester resins, epoxy resins, urethane resins, and silicone resins, and unsaturated polyester resins are preferred.

  In the heat radiating resin composition of the present invention, the content of the thermosetting resin is 30 to 60 parts by weight, preferably 35 to 60 parts by weight. When the content of the thermosetting resin is 30 parts by weight or more, the composition has sufficient fluidity, and when the content of the thermosetting resin is 60 parts by weight or less, the composition has good thermal conductivity.

  The thermally conductive filler (B) includes a secondary aggregate (B-1) having a particle size of more than 20 μm and a single particle (B-2) having a particle size of 20 μm or less. In the present invention, the secondary aggregates and single particles of the heat conductive filler are the same heat conductive filler and have different forms. By combining the secondary aggregates and single particles of the thermally conductive filler in the heat-dissipating resin composition, single particles having a smaller particle size are dispersed around the secondary aggregates, and a heat transfer path is formed. Since it becomes easy, compared with the case where the heat conductive filler of a single form is used, heat conductivity can be made high with less filler content, and heat dissipation improves. Furthermore, in the heat dissipating resin composition of the present invention, since the content of the heat conductive filler can be reduced, the fluidity of the composition is increased and the moldability is improved.

  The image figure of the cross section of the thickness direction of the heat dissipation molded object obtained by shape | molding the heat dissipation resin composition of this invention in FIG. 1 is shown. As shown in FIG. 1, in the heat-radiating molded article of the present invention, the secondary aggregates 1 and single particles 2 of the thermally conductive filler are dispersed in the matrix resin 3 which is a thermosetting resin cured by a crosslinking agent. . Although not shown, the secondary aggregate 1 is an aggregated particle in a state where two or more single particles are in close contact. Since a single particle 2 having a small particle size is dispersed around the secondary aggregate 1, a heat transfer path (indicated by an arrow in FIG. 1) is easily formed, so that thermal conductivity is increased and heat dissipation is improved. improves.

  The heat conductive filler is not particularly limited, and for example, boron nitride, alumina, silica, aluminum hydroxide, magnesium oxide, calcium carbonate, talc and mica can be used. From the viewpoint of thermal conductivity, boron nitride, Alumina and magnesium oxide are preferred, and boron nitride is more preferred. Thermally conductive fillers may be used in combination of two or more, but are preferably used alone. When using 2 or more types of heat conductive fillers, it is preferable that 90 weight% or more of a heat conductive filler is the same component. As the thermally conductive filler, an insulating material is preferably selected. The thermal conductivity of the thermally conductive filler is, for example, 1 to 200 W / m · K.

  In the heat dissipating resin composition of the present invention, the content of the heat conductive filler is 40 to 70 parts by weight, preferably 40 to 65 parts by weight. In the present invention, the content of the thermally conductive filler refers to the total content of secondary aggregates and single particles. When the content of the heat conductive filler is within this range, the heat conductivity of the heat dissipating resin composition is increased, the discharge performance is improved, and at the same time, the fluidity of the composition can be secured.

  From the viewpoint of good thermal conductivity, the thermally conductive filler preferably uses secondary aggregates in an amount equal to or more than the weight of single particles, and the weight ratio of secondary aggregates to single particles is, for example, 50: It is 50-80: 20, Preferably it is 50: 50-70: 30.

  The secondary aggregate (also referred to as secondary aggregated particles) (B-1) of the thermally conductive filler has a particle size of more than 20 μm, preferably more than 25 μm. The particle size of the secondary aggregate can be measured by a laser diffraction / scattering particle size meter. In the present invention, the particle size of the secondary aggregate means the maximum particle size of the aggregate when the secondary aggregate is not spherical. In the present invention, the secondary aggregate refers to aggregated particles in a state where two or more single particles are in close contact and cannot be easily dispersed into single particles. The secondary aggregate can be judged by observing with an electron microscope such as a scanning electron microscope (SEM). The shape of the single particle constituting the secondary aggregate is, for example, a flat plate shape, a needle shape, a spherical shape, a fiber shape, or a scale shape, and a scale shape is preferable.

  The single particle (B-2) of the thermally conductive filler has a particle size of 20 μm or less, preferably 15 μm or less. The particle size of a single particle can be measured by a laser diffraction / scattering particle size meter. In the present invention, the particle size of a single particle means the maximum particle size of the particle when the single particle is not spherical. In the present invention, the shape of the single particle of the thermally conductive filler is, for example, a flat plate shape, a needle shape, a spherical shape, a fiber shape, or a scale shape, and a scale shape is preferable.

  The secondary aggregate and single particles of the thermally conductive filler can be obtained, for example, by rotating the aggregate of the thermally conductive filler. The aggregate of the thermally conductive filler before the rotation treatment usually has a particle size of up to about 200 μm, and single particles are loosely aggregated. When the heat-conductive filler aggregates are rotationally processed, the aggregates collide at high speed to generate secondary aggregates in which the particles are re-aggregated and single particles in which the aggregates are crushed. In the secondary aggregate, the particles are aggregated more strongly than the aggregate before the rotation treatment, and the particle size is smaller than that of the aggregate before the rotation treatment. In the heat-dissipating resin composition of the present invention, the aggregate of the heat conductive filler is used as a form of secondary aggregate and single particle by rotating the aggregate rather than using the aggregate without rotating. However, since the heat transfer path is easily formed, the thermal conductivity of the composition is increased, the heat dissipation is improved, and the fluidity of the composition can be secured at the same time.

  The rotation treatment of the aggregate of the heat conductive filler can be performed using, for example, a continuous or batch mixer, an airflow mixer, and a rotary stirring mixer, and it is particularly preferable to use a rotary stirring mixer. . In the present invention, the rotation treatment is usually performed at 10 to 10,000 rpm, preferably 1000 to 9000 rpm, more preferably 2000 to 8000 rpm, and particularly preferably 4000 to 6000 rpm. By rotating and mixing at a rotation speed in this range, secondary aggregates and single particles can be obtained in a balanced manner. The rotation processing time is appropriately selected according to the number of rotations, and is, for example, 10 seconds to 900 seconds, preferably 30 seconds to 300 seconds. The rotation treatment is usually performed at 0 to 85 ° C, preferably at room temperature (about 25 ° C). Secondary aggregates and single particles are used after being classified by dry classification after the rotation treatment, but can also be used without sorting.

  The cross-linking agent (C) is used for cross-linking and curing the thermosetting resin (A). The crosslinking agent can be used without any particular limitation as long as it can react with the thermosetting resin to be used and can cure the thermosetting resin.

  In the heat-dissipating resin composition of the present invention, the content of the crosslinking agent is 0.05 to 3.0 weight with respect to 100 parts by weight of the total amount of the thermosetting resin (A) and the heat conductive filler (B). Part, preferably 0.1 to 1.0 part by weight. When the content of the crosslinking agent is in the above range, the thermosetting resin can be sufficiently cured.

  In addition to the thermosetting resin (A), the heat conductive filler (B), and the cross-linking agent (C), the heat radiating resin composition of the present invention includes, for example, an antioxidant and an ultraviolet absorber as necessary. Other additives such as flame retardants, crosslinking aids, colorants, lubricants, adhesion-imparting agents, mold release agents, antistatic agents, silane coupling agents, carbon, etc. are included within the range that does not impair the effects of the present invention. can do.

  The total amount of the other additives is usually 10 parts by weight or less, preferably 5 parts by weight or less, with respect to 100 parts by weight of the total amount of the thermosetting resin (A) and the heat conductive filler (B). The amount is preferably 1 part by weight or less.

  The heat-dissipating resin composition of the present invention can be obtained, for example, by mixing the components (A) to (C).

  As a method for mixing the above components (A) to (C), physical blending such as melt kneading, solvent cast blending, latex blending or polymer complex can be used, but melt kneading method is particularly preferable. As an apparatus for mixing, a tumbler, a Henschel mixer, a rotary mixer, a spar mixer, a ribbon tumbler, a V blender, or the like can be used.

  The present invention also includes a heat dissipating molded article obtained by molding the heat dissipating resin composition. The heat-radiating molded article of the present invention can be produced by molding the above heat-dissipating resin composition by a known molding method such as injection molding, extrusion molding or injection compression molding. In general, a single-screw or multi-screw extruder is used for molding the heat-dissipating resin composition. In addition to the above-described extruder, a Banbury mixer, a roller, a co-kneader, a plast mill, or a Prabender brow graph is used. You can also. These are operated batchwise or continuously.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the technical scope of the present invention is not limited to these examples.

[Preparation of secondary aggregate and single particles of thermally conductive filler]
Boron nitride was used as the thermally conductive filler. A predetermined amount of boron nitride aggregated particles (manufactured by Mizushima Alloy Iron Co., Ltd .: HP-40MF100 (particle size: 45 μm, specific gravity: 1.9)) were weighed and premixed using a sachet. The premixed boron nitride agglomerated particles were put into a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. (200 g / batch), and subjected to high-speed rotation treatment at a rotation speed of 4800 rpm for 1 minute. Thereafter, the rotation speed was increased, and the boron nitride subjected to the rotation treatment was discharged from the apparatus. The boron nitride after the rotation treatment contained secondary aggregates in which the boron nitride scaly single particles were strongly aggregated and boron nitride scaly single particles. FIG. 2 shows the result of observing the state of boron nitride before and after the rotation treatment by SEM. FIG. 2A shows boron nitride aggregated particles (particle size: 45 μm) before the rotation treatment, and FIG. 2B shows boron nitride after the rotation treatment. From FIG. 2A and FIG. 2B, when the boron nitride aggregated particles are rotated under predetermined conditions, the boron nitride aggregated particles collide with each other at high speed in the rotating tank, and the aggregates are crushed. A scaly single particle formed as a result. The secondary aggregate after the rotation treatment was aggregated more firmly than the boron nitride aggregated particles before the rotation treatment. The obtained secondary aggregates and single particles of boron nitride were selected by dry classification. The selected secondary aggregate of boron nitride (B-1) is an aggregated particle in which two or more scaly single particles are in close contact with each other, and the secondary aggregate has a particle size of more than 20 μm and not more than 40 μm. there were. The selected boron nitride single particles (B-2) had a particle size of 15 μm or less.

[Preparation of heat-dissipating resin composition]
Example 1
30 parts by weight of a secondary aggregate of boron nitride (B-1) prepared as described above, 15.5 parts by weight of single particles of boron nitride (B-2), and thermosetting resin (A) 54.5 parts by weight of unsaturated polyester resin (manufactured by Hitachi Chemical Co., Ltd .: WP2008 (specific gravity 1.14)) and 0.8 cross-linking agent (manufactured by Hitachi Chemical Co., Ltd .: resin curing agent: CT-50) 0.8 The heat-dissipating resin composition was prepared by melt-kneading the parts by weight.

(Example 2)
A heat-dissipating resin composition of Example 2 was prepared in the same manner as in Example 1 except that the amount of each component of Example 1 was changed as described in Table 1.

  The heat-radiating composition of Example 2 was melt-kneaded in the same manner as in Example 1, and then fired at 150 ° C. for 1 hour. Further, in order to perform SEM observation, the cured product of Example 2 was embedded in a resin, and then subjected to cross-sectional processing by mirror polishing to obtain a measurement sample. The sample was coated in order to have conductivity necessary for SEM observation. The cross section of the obtained heat-radiation molded object was observed with SEM, and the secondary aggregate of boron nitride in the thermosetting resin cured by the crosslinking agent and the dispersion state of single particles were examined. In SEM observation, a field emission scanning electron microscope was used to take a secondary electron image. The SEM observation figure of the cross section of the heat dissipation molded object of Example 2 is shown in FIG. From FIG. 3, fine single particles are dispersed around the secondary aggregate of boron nitride (a part of the secondary aggregate is shown by being surrounded by a dotted line in FIG. 3), and it becomes easy to form a heat conduction path. ing.

(Comparative Example 1)
A heat-dissipating resin composition of Comparative Example 1 was prepared in the same manner as in Example 1 except that the amount of each component of Example 1 was changed as described in Table 1.

(Comparative Example 2)
35 parts by weight of the secondary aggregate (B-1) of boron nitride prepared as described above and an unsaturated polyester resin (manufactured by Hitachi Chemical Co., Ltd .: WP2008 (specific gravity 1. 14)) 65 parts by weight and 1.1 parts by weight of a crosslinking agent (C) (manufactured by Hitachi Chemical Co., Ltd .: resin curing agent: CT-50) were melt-kneaded to prepare a heat-dissipating resin composition.

(Comparative Examples 3 and 4)
The heat-radiating resin compositions of Comparative Examples 3 and 4 were prepared in the same manner as Comparative Example 2 except that the amount of each component of Comparative Example 2 was changed as described in Table 1.

(Comparative Example 5)
Alumina (Showa Denko KK: Alumina A-12) was used as the thermally conductive filler (D). 80 parts by weight of alumina, 20 parts by weight of an unsaturated polyester resin (manufactured by Hitachi Chemical Co., Ltd .: WP2008 (specific gravity 1.14)) as a thermosetting resin (A), and a crosslinking agent (C) (Hitachi Chemical Industry) Co., Ltd .: Resin curing agent: CT-50) 0.3 parts by weight was melt-kneaded to prepare a heat-dissipating resin composition.

  About the heat dissipation resin composition of Examples 1, 2 and Comparative Example 1-5, the thermal conductivity and the fluidity of the heat dissipation resin composition (the fluidity of the heat dissipation resin composition of Comparative Example 1 was set to 100). It was measured.

The fluidity of the heat dissipating resin composition was measured as follows:
Using a Koka flow tester having a capillary with a diameter of 1 mm, the flowing-down viscosity was measured and compared at a predetermined temperature to obtain an index of fluidity. If the viscosity was severe (high viscosity and difficult to flow down), a spiral flow length was compared using a transfer molding machine to obtain an index of fluidity.

  The thermal conductivity and fluidity of the heat-dissipating resin compositions of Examples 1 and 2 and Comparative Example 1-5 are shown in Table 1, the thermal conductivity is shown in FIG. 4, and the fluidity is shown in FIG.

  From Table 1, FIG. 4 and FIG. 5, when Example 1 and Comparative Example 3 are compared, the heat-dissipating resin composition of Example 1 containing both secondary aggregates and single particles of the thermally conductive filler is compared. Despite containing the same amount of filler as in Example 3, the thermal conductivity of the composition of Comparative Example 3 was increased while maintaining fluidity. Moreover, when Example 2 and Comparative Example 4 are compared, the heat-dissipating resin composition of Example 2 containing both the secondary aggregates and single particles of the thermally conductive filler has a filler comparable to that of Comparative Example 4. Despite being contained, both the thermal conductivity and fluidity were improved with respect to the composition of Comparative Example 4. From this, by using secondary aggregates and single particles of heat conductive filler in the heat radiating resin composition, it becomes easier to form a heat transfer path, the heat conductivity is increased, and the heat dissipation is improved, At the same time, it was shown that fluidity was secured. Moreover, in Comparative Example 1, although it contains both secondary aggregates and single particles of the thermally conductive filler, the thermal conductivity equivalent to that of Comparative Example 2 having the same content of the thermally conductive filler. It was rate. From this, like Example 1 and 2, by making the total content of the secondary aggregate and single particle of a heat conductive filler into a specific range, heat conductivity becomes high and heat dissipation improves. At the same time, it was shown that fluidity was secured.

1 Secondary aggregate 2 Single particle 3 Matrix resin

Claims (1)

30-60 parts by weight of thermosetting resin (A) that is at least one selected from unsaturated polyester resin, epoxy resin, urethane resin and silicone resin;
40 to 70 parts by weight of heat conductive filler (B) including secondary aggregates having a particle size of more than 20 μm and single particles having a particle size of 20 μm or less (the total amount of components (A) and (B) is 100 Parts by weight)
A heat dissipating resin composition comprising 0.05 to 3.0 parts by weight of a crosslinking agent (C) capable of reacting with the thermosetting resin (A).

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