Thermosetting resin compositions, bulk molding compounds, and molded articles thereof

Abstract

The present invention provides a thermosetting resin composition, a bulk molding compound, and a molded article thereof that can produce molded articles with excellent fluidity, injection moldability, compression moldability, and thermal conductivity. [Solution] A thermosetting resin composition is used, comprising a thermosetting resin (A), a low-shrinkage agent (B), a thickener (C), a thermally conductive filler (D), and a reinforcing material (E), wherein the thermosetting resin (A) contains an unsaturated polyester resin (a1) and a vinyl ester resin (a2), the thickener (C) contains acrylic resin particles (c1) and magnesium oxide (c2), and the thermally conductive filler (D) contains a thermally conductive filler (d1) with an average particle size of 100 μm or more and 500 μm or less and a thermally conductive filler (d2) with an average particle size of 10 μm or more and less than 100 μm.

Description

Technical Field

[0001] The present invention relates to a thermosetting resin composition, a bulk molding compound, and a molded article thereof.

Background Art

[0002] Thermosetting resin compositions obtained by adding a low shrinkage agent, inhibitor, curing agent, filler, mold release agent, reinforcing material, etc. to thermosetting resins such as unsaturated polyester resins and vinyl ester resins and kneading them in a kneader have advantages such as electrical insulation, heat resistance, flame retardancy, high rigidity, and dimensional stability. Therefore, they are widely applied to electronic components related to fields such as home appliances, automobiles, and energy. Among these thermosetting resin compositions, a bulk molding compound (hereinafter sometimes abbreviated as "BMC") in a bulk form can be made into a molded article by a molding method such as compression molding, transfer molding, or injection molding.

[0003] In recent years, as electronic components are advancing in high output (high density) and miniaturization (weight reduction), heat generated inside the electronic components accumulates, causing problems such as a decrease in the output of electronic components and a shortening of their lifespan due to this heat.

[0004] Under such circumstances, excellent thermal conductivity is required for BMC molded articles, and thermosetting resin compositions using a thermal conductivity filler have been proposed (see, for example, Patent Document 1). However, although the molding material obtained from this thermosetting resin composition can achieve both moldability and thermal conductivity, there are cases where the thermal conductivity is insufficient depending on the application.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem that the present invention aims to solve is to provide a thermosetting resin composition, a bulk molding compound, and a molded article thereof that can produce a molded article with excellent fluidity, injection moldability, compression moldability, and thermal conductivity. [Means for solving the problem]

[0007] As a result of diligent research to solve the above problems, the present inventors have found that a thermosetting resin composition containing a specific thermosetting resin, a low-shrinkage agent, a specific thickener, a specific thermally conductive filler, and a reinforcing material solves the above problems, and have completed the present invention.

[0008] In other words, the present invention provides a thermosetting resin composition comprising a thermosetting resin (A), a low-shrinkage agent (B), a thickener (C), a thermally conductive filler (D), and a reinforcing material (E), wherein the thermosetting resin (A) contains an unsaturated polyester resin (a1) and a vinyl ester resin (a2), the thickener (C) contains acrylic resin particles (c1) and magnesium oxide (c2), the thermally conductive filler (D) contains a thermally conductive filler (d1) with an average particle size of 100 μm or more and 500 μm or less, and a thermally conductive filler (d2) with an average particle size of 10 μm or more and less than 100 μm, and wherein the thermally conductive filler (d1) is 150 to 400 parts by mass and the thermally conductive filler (d2) is 20 to 130 parts by mass per 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B). [Effects of the Invention]

[0009] The thermosetting resin composition of the present invention is excellent in fluidity, injection moldability, and compression moldability, and can produce molded products with excellent thermal conductivity. Therefore, it is extremely useful for supports for electrical and electronic components used in home appliances and automobiles, motor encapsulants for electric vehicles, housings for communication devices such as PCs and smartphones, various sensor components, battery holders for electric vehicles, heat sinks for LED lamps, and the like. [Modes for carrying out the invention]

[0010] The thermosetting resin composition of the present invention is a thermosetting resin composition containing a thermosetting resin (A), a low shrinkage agent (B), a thickener (C), a thermally conductive filler (D), and a reinforcing material (E), wherein the thermosetting resin (A) contains an unsaturated polyester resin (a1) and a vinyl ester resin (a2), the thickener (C) contains acrylic resin particles (c1) and magnesium oxide (c2), the thermally conductive filler (D) contains a thermally conductive filler (d1) with an average particle size of 100 μm or more and 500 μm or less and a thermally conductive filler (d2) with an average particle size of 10 μm or more and less than 100 μm, and the amount of the thermally conductive filler (d1) is 150 to 400 parts by mass and the amount of the thermally conductive filler (d2) is 20 to 130 parts by mass per 100 parts by mass of the total amount of the thermosetting resin (A) and the low shrinkage agent (B).

[0011] The thermosetting resin (A) contains an unsaturated polyester resin (a1) and a vinyl ester resin (a2). However, to further improve fluidity and injection moldability, the mass ratio (a1 / a2) of the unsaturated polyester resin (a1) and vinyl ester resin (a2) is preferably 90 / 10 to 30 / 70, and more preferably 70 / 30 to 50 / 50.

[0012] The thermosetting resin (A) may also contain thermosetting resins other than unsaturated polyester resin (a1) and vinyl ester resin (a2).

[0013] The thermosetting resin composition of the present invention contains a resin component comprising a thermosetting resin (A) and a low-shrinkage agent (B) as essential components. However, considering the balance between molding shrinkage rate and other physical properties, the mass ratio (A / B) of the thermosetting resin (A) and the low-shrinkage agent (B) is preferably 95 / 5 to 50 / 50, and more preferably 90 / 10 to 70 / 30.

[0014] The aforementioned shrinkage-reducing agent (B) is added to suppress the curing shrinkage of the thermosetting resin composition, and examples include polymethyl methacrylate, polystyrene, saturated polyester, styrene-butadiene rubber, and polyvinyl acetate. These shrinkage-reducing agents can be used individually or in combination of two or more.

[0015] The aforementioned thickener (C) contains acrylic resin particles (c1) and magnesium oxide (c2). By using these together, the fluidity of the BMC described later is improved, ensuring injection moldability (measurability) and injection moldability (fillability).

[0016] The acrylic resin particles (c1) are not particularly limited, but an average particle size of 0.1 to 8 μm is preferred, and 0.1 to 3 μm is more preferred, as this improves the fluidity of the BMC and further enhances injection moldability (metering) and injection moldability (filling). In this invention, the "average particle size" is the median diameter (D50) value obtained by laser diffraction scattering.

[0017] The acrylic resin particles (c1) are preferably in amounts of 1 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

[0018] The magnesium oxide (c2) is preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

[0019] Examples of the thermally conductive filler (D) include metallic fillers such as silver, copper, aluminum, iron, and stainless steel; inorganic fillers such as alumina, magnesia, beryllia, silica, boron nitride, aluminum nitride, silicon carbide, boron carbide, and titanium carbide; and carbon-based fillers such as diamond, graphite, and other materials. Among these, carbon-based fillers are preferred from the viewpoint of improving thermal conductivity and reducing weight, and graphite is more preferred. These thermally conductive fillers can be used individually or in combination of two or more types.

[0020] The heat-conductive filler (D) contains a heat-conductive filler (d1) with an average particle diameter of 100 μm or more and 500 μm or less and a heat-conductive filler (d2) with an average particle diameter of 10 μm or more and less than 100 μm. However, with respect to 100 parts by mass of the total amount of the thermosetting resin (A) and the shrinkage-reducing agent (B), the heat-conductive filler (d1) is 150 to 400 parts by mass, and the heat-conductive filler (d2) is 20 to 130 parts by mass, whereby a thermosetting resin composition excellent in the balance between fluidity and injection moldability and heat conductivity can be obtained.

[0021] Since the balance between fluidity and injection moldability and heat conductivity of the heat-conductive filler (d1) is further improved, 200 to 350 parts by mass is preferable with respect to 100 parts by mass of the total amount of the thermosetting resin (A) and the shrinkage-reducing agent (B).

[0022] As the heat-conductive filler (d1), a filler having an average particle diameter of 100 μm or more and 500 μm or less can be used alone or in combination of two or more kinds.

[0023] Since the balance between fluidity and injection moldability and heat conductivity of the heat-conductive filler (d2) is further improved, 30 to 120 parts by mass is preferable with respect to 100 parts by mass of the total amount of the thermosetting resin (A) and the shrinkage-reducing agent (B).

[0024] As the heat-conductive filler (d2), a filler having an average particle diameter of 10 μm or more and less than 100 μm can be used alone or in combination of two or more kinds.

[0025] Further, since the balance between fluidity and injection moldability and heat conductivity is further improved, the average particle diameter of the heat-conductive filler (d2) is more preferably 30 μm or more and less than 60 μm.

[0026] Examples of the reinforcing material (E) include fibrous materials such as glass fibers, vinylon fibers, phenolic fibers, carbon fibers, and polyester fibers. Among these, glass fibers are preferred from the viewpoint of availability, low BMC fluidity, and improvement of the strength and physical properties of BMC molded products. Any type of glass fiber can be used, such as glass chopped strands or milled glass. Fibers with a length of 1.5 to 12 mm are preferred, and those with a length of 1.5 to 9 mm are more preferred, as this improves the fluidity of the BMC and further improves injection moldability (metering), injection moldability (filling), and the physical properties of the BMC molded product.

[0027] The amount of the reinforcing material is preferably 10 to 80 parts by mass, and more preferably 15 to 60 parts by mass, based on 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

[0028] In addition to the above components (A) to (E), the thermosetting resin composition of the present invention may also contain thermoplastic resins, polymerization inhibitors, curing agents, curing accelerators, dispersants, mold release agents, pigments, colorants, defoaming agents, etc., to the extent that they do not impair the effects of the present invention.

[0029] Examples of polymerization inhibitors include toluhydroquinone, hydroquinone, hydroquinone monomethyl ether, 1,4-naphthoquinone, parabenzoquinone, pt-butylcatechol, and 2,6-t-butyl-4-methylphenol. When a polymerization inhibitor is incorporated into the thermosetting resin composition of the present invention, the amount incorporated is preferably 10 to 1500 ppm in the thermosetting resin composition of the present invention.

[0030] The curing agent is preferably an organic peroxide, such as diacyl peroxide, peroxyester, hydroperoxide, dialkyl peroxide, ketone peroxide, peroxyketal, alkyl perester, or parkerborne. These curing agents can be used individually or in combination of two or more.

[0031] The amount of the curing agent is preferably 0.5 to 5 parts by mass, and more preferably 1 to 3 parts by mass, based on 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

[0032] The mold release agent is intended to facilitate the removal of the molded product from the mold after the thermosetting resin composition of the present invention has been molded using a mold. Examples of the mold release agent include unsaturated fatty acid amide mold release agents, polyethylene wax mold release agents, metal soap mold release agents, silicone mold release agents, and fluorine mold release agents. Examples of the metal soap mold release agent include zinc lauryl stearate, calcium laurate, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zinc myristate, calcium montanoate, zinc montanoate, aluminum montanoate, calcium behenate, magnesium behenate, and zinc behenate. These mold release agents can be used individually or in combination of two or more.

[0033] The amount of the mold release agent is preferably 1 to 10 parts by mass, and more preferably 3 to 8 parts by mass, based on 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

[0034] The thermosetting resin composition of the present invention can be produced by kneading the above components using a kneader or other mixing machine. Furthermore, by adjusting the blending composition so that the resulting resin composition becomes bulk, a bulk molding compound (BMC) can be obtained.

[0035] By using the thermosetting resin composition of the present invention as BMC, molded products can be easily obtained by molding methods such as compression molding, transfer molding, and injection molding. [Examples]

[0036] The present invention will be described in more detail below with reference to examples. The acid value of the resin was measured in accordance with JIS K6901.

[0037] (Manufacturing Example 1: Synthesis of unsaturated polyester resin (a1-1)) In a 2L glass flask equipped with a nitrogen gas inlet tube, thermometer, reflux condenser, and stirrer, 206 parts by mass of neopentyl glycol, 53 parts by mass of propylene glycol, 266 parts by mass of hydrogenated bisphenol A, and 288 parts by mass of isophthalic acid were charged, and heating was started under a nitrogen stream. At an internal temperature of 215°C, a dehydration condensation reaction was carried out by a conventional method, and when the solid content acid value reached 6 (mgKOH / g), it was cooled to 190°C. Next, 198 parts by mass of maleic acid was added and the dehydration condensation reaction was continued, and when the solid content acid value reached 28 (mgKOH / g), 0.4 parts by mass of toluhydroquinone was added. The mixture was dissolved in styrene monomer to obtain an unsaturated polyester resin (a1-1) with an unsaturated polyester concentration of 65% by mass.

[0038] (Manufacturing Example 2: Synthesis of vinyl ester resin (a2-1)) In a 2L flask equipped with a nitrogen inlet tube, thermometer, and stirrer, 246 parts by mass of epoxy resin (DIC Corporation's "Epiclon 860-C," bisphenol A type epoxy resin, epoxy equivalent 240), 730 parts by mass of epoxy resin (DIC Corporation's "Epiclon 1050," bisphenol A type epoxy resin, epoxy equivalent 470), 215 parts by mass of methacrylic acid, and 0.45 parts by mass of dibutylhydroxytoluene were added. The mixture was then heated to 100°C under a gas flow of nitrogen and air in a 1:1 ratio. 0.96 parts by mass of 2-methylimidazole was then added, and the mixture was heated to 110°C to carry out the reaction. When the solid content acid value fell below 6 (mgKOH / g), 0.46 parts by mass of toluhydroquinone was added and dissolved in styrene monomer to obtain vinyl ester resin (a2-1) at a vinyl ester concentration of 70% by mass.

[0039] (Manufacturing Example 3: Manufacturing of a low-shrinkage agent (B-1)) In a 2L flask equipped with a nitrogen inlet tube, thermometer, and stirrer, 900 parts by mass of styrene monomer, 600 parts by mass of polystyrene (DIC Corporation's "DIC Styrene CR-3500"), and 0.25 parts by mass of toluhydroquinone were added, and the mixture was heated to 50°C under a flow of nitrogen gas. The mixture was stirred until the thermoplastic polystyrene was completely melted, and then the temperature was lowered to below 40°C to obtain a low-shrinkage agent (B-1) with a polystyrene concentration of 40% by mass.

[0040] (Example 1: Preparation of thermosetting resin composition (1)) 50 parts by mass of unsaturated polyester resin (a1-1) obtained in Production Example 1, 30 parts by mass of vinyl ester resin (a2-1) obtained in Production Example 2, 20 parts by mass of low shrinkage agent (B-1) obtained in Production Example 3, 4 parts by mass of acrylic resin particles (c1) (Zephyr F303 manufactured by Aica Kogyo Co., Ltd.; average particle size 2 μm), 0.15 parts by mass of magnesium oxide (c2-1) (Kyowa Chemical Industry Co., Ltd. "Kyowa Mag 40"), 0.6 parts by mass of curing agent (1) (Perbutyl O manufactured by NOF Corporation; peroxyester-based organic peroxide), 1.2 parts by mass of curing agent (2) (Perbutyl Z manufactured by NOF Corporation; peroxyester-based organic peroxide), mold release agent (1) (Zinc stearate SZ-200 manufactured by Sakai Chemical Industry Co., Ltd.) 4 parts by mass of (0), 1.2 parts by mass of release agent (2) ("Calcium Stearate" manufactured by NOF Corporation), 50 parts by mass of graphite powder (d1-1) ("AGB-32" manufactured by Ito Graphite Industry Co., Ltd.; average particle size 200-300 μm), 200 parts by mass of graphite powder (d1-2) ("AGB-100" manufactured by Ito Graphite Industry Co., Ltd.; average particle size 110 μm), and 100 parts by mass of graphite powder (d2-1) ("AGB-604" manufactured by Ito Graphite Industry Co., Ltd.; average particle size 55 μm) were kneaded for 9 minutes using a planetary mixer, and then 33 parts by mass of reinforcing material (E-1) (glass fiber / chopped strand; "ECS404-6" manufactured by Chongqing International Composite Materials Co., Ltd.; fiber length 6 mm) were added and kneaded for a further 6 minutes to obtain a bulk material. The obtained bulk material was packaged in an aluminum vapor-deposited film and left in a 40°C constant temperature bath for 12 hours to obtain a thermosetting resin composition (1) as BMC.

[0041] (Examples 2-5) Thermosetting resin compositions (2) to (5) were obtained as BMC in the same manner as in Example 1, except that the compounding composition was changed as shown in Table 1.

[0042] (Comparative Examples 1-2) Thermosetting resin compositions (R1) to (R2) were obtained as BMC in the same manner as in Example 1, except that the compounding composition was changed as shown in Table 2.

[0043] The thermosetting resin compositions (1) to (5) and (R1) to (R2) obtained in Examples 1 to 5 and Comparative Examples 1 to 2 were evaluated as follows.

[0044] [Assessment of liquidity] The initial viscosity of the thermosetting resin composition obtained above was measured. Viscosity measurement was performed using a capillary viscometer (capillary rheometer) under the following conditions: Amount of resin composition (sample amount): 75 g, Measurement temperature: 50°C, Extrusion speed: 50 mm / min, Nozzle diameter: 6 mm, Nozzle length: 10 mm Furthermore, substances that could not be measured due to their high viscosity were marked as "unmeasurable."

[0045] [Evaluation of injection moldability (measurability)] A predetermined amount (75 cm³) of the thermosetting resin composition obtained above 3 For each of these, the amount that could be moved from the material storage (push hopper) to the cylinder by the screw within a predetermined time (30 seconds) was measured, and the injection moldability (measurability) was evaluated according to the following criteria. Measurement conditions: Push pressure 5 MPa, screw rotation speed 20 rpm, push hopper and cylinder temperature 35°C ○: 75cm in less than 30 seconds 3 △: 40-75cm in 30 seconds 3 ×: 40cm in 30 seconds 3 less than

[0046] [Evaluation of injection moldability (fillability)] For the thermosetting resin compositions that received a "○" in the above quantitative evaluation results, injection molding was performed using a mold for fluidity evaluation, and the appearance of the molded product was visually observed to evaluate the injection moldability (fillability) according to the following criteria. Molding conditions: Mold temperature 160°C, clamping force 750kN, injection speed 70mm / sec, curing time 55 seconds ○: No shorts, no voids on the molded product surface. △: No shorts, voids present on the surface of the molded product. ×: Shortened parts present, voids present on the surface of the molded product.

[0047] [Evaluation of compression moldability] The thermosetting resin compositions obtained above were subjected to compression molding, and their compressibility was evaluated according to the following criteria. Molding conditions: Molding temperature 145℃, pressure 10MPa, pressurization time 300 seconds, mold 220mm x 220mm ○: No shorting in any of the molded parts with thicknesses of 3mm, 4mm, and 10mm. △: Shortness present in 3mm thick molded parts, but not present in 4mm and 10mm thick molded parts. ×: Shorting occurs in molded parts with a thickness of 3mm and 4mm, but not in molded parts with a thickness of 10mm.

[0048] [Evaluation of thermal conductivity] A flat plate measuring 220 mm x 220 mm x 10 mm thick was fabricated by compression molding under the conditions of a molding temperature of 145°C, a molding pressure of 10 MPa, and a molding holding pressure time of 300 seconds. The thermal conductivity was then measured using a thermophysical property measuring device (TPS500S) from Kyoto Electronics Manufacturing Co., Ltd., in accordance with the hot disk method (ISO 22007-2), and the thermal conductivity was evaluated.

[0049] The composition and evaluation results of the thermosetting resin compositions obtained above are shown in Tables 1 and 2.

[0050] [Table 1]

[0051] [Table 2]

[0052] The thermosetting resin compositions of the present invention in Examples 1 to 5 were confirmed to produce molded articles with excellent fluidity, injection moldability, compression moldability, and thermal conductivity.

[0053] On the other hand, Comparative Example 1 is an example in which the amount of thermally conductive filler (d2) relative to 100 parts by mass of the total amount of thermosetting resin (A) and low shrinkage agent (B) is greater than the upper limit of 130 parts by mass of the present invention, but it was confirmed that the fluidity and injection moldability were insufficient.

[0054] Comparative Example 2 is an example in which the amount of thermally conductive filler (d2) relative to 100 parts by mass of the total amount of thermosetting resin (A) and low-shrinkage agent (B) is less than the lower limit of 20 parts by mass of the present invention, but it was confirmed that the thermal conductivity was insufficient.

Claims

1. A thermosetting resin composition comprising a thermosetting resin (A), a low-shrinkage agent (B), a thickener (C), a thermally conductive filler (D), and a reinforcing material (E), wherein the thermosetting resin (A) contains an unsaturated polyester resin (a1) and a vinyl ester resin (a2), the thickener (C) contains acrylic resin particles (c1) and magnesium oxide (c2), the thermally conductive filler (D) contains a thermally conductive filler (d1) with an average particle size of 100 μm or more and 500 μm or less and a thermally conductive filler (d2) with an average particle size of 10 μm or more and less than 100 μm, and the amount of the thermally conductive filler (d1) is 150 to 400 parts by mass and the amount of the thermally conductive filler (d2) is 20 to 130 parts by mass per 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

2. The thermosetting resin composition according to claim 1, wherein the amount of acrylic resin particles (c1) is 1 to 20 parts by mass and the amount of magnesium oxide (c2) is 0.05 to 5 parts by mass, based on 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

3. The thermosetting resin composition according to claim 1, wherein the reinforcing material (E) is 10 to 80 parts by mass per 100 parts by mass of the total amount of the thermosetting resin (A) and the low-shrinkage agent (B).

4. A bulk molding compound characterized by comprising the thermosetting resin composition described in any one of claims 1 to 3.

5. A molded article obtained using the bulk molding compound described in claim 4.

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