Surface-treated boron nitride, method for producing surface-treated boron nitride, resin composition, heat dissipation substrate

Abstract

To provide: a surface-treated boron nitride that can suppress an increase in the viscosity of a resin composition when used as a filler; a method for manufacturing the boron nitride; a resin composition containing the boron nitride and a resin; and a heat-dissipating substrate comprising the resin composition.SOLUTION: The present invention provides a surface-treated boron nitride that has been surface-treated with a conjugated diene compound or a compound that produces a conjugated diene upon heating.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to surface-treated boron nitride, a method for producing surface-treated boron nitride, a resin composition, and a heat dissipation substrate. Background Art

[0002] In recent years, the performance improvement and size reduction of electronic devices have progressed rapidly. Along with this, the increase in power density of semiconductor devices has made it difficult to control the generated heat. For this reason, thermally conductive materials are used for mounted components and surrounding components. Conventionally, high thermal conductivity compounds such as boron nitride have been often used as resin additives (fillers). Generally, the higher the concentration of the thermally conductive filler, the higher the thermal conductivity of the obtained resin composition. However, the viscosity of the resin composition also increases in direct proportion to the filler concentration. Therefore, when the blending amount of the filler in the resin composition exceeds a certain value, processing problems of the material may occur.

[0003] Therefore, a method is known in which a filler is modified with a surface treatment agent (so-called surface treatment) to improve the affinity with a resin, thereby suppressing an increase in viscosity when the filler is filled into the resin. As methods for modifying boron nitride particles with a surface treatment agent, there are disclosed, for example, a method of surface treatment with phenylene diisocyanate (Patent Document 1), a method of surface treatment with a silane coupling agent (Non-Patent Document 1), a method of surface treatment with an aluminate coupling agent, a zirconate coupling agent or the like (Patent Document 2), a method of surface treatment with an aromatic acid halide (Patent Document 3), a method of surface modification with an aromatic hydrocarbon compound having a condensed ring structure (Patent Document 4), and the like. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2001-192500 Patent Document 2 Japanese Patent Publication No. 2006-257392 [Patent Document 3] Japanese Patent Publication No. 2009-221039 [Patent Document 4] WO2019 / 013323 [Non-Patent Document 1] Hiroshi Hanagasaki, et al., "Investigation and Study on the Properties of Surface-Treated BN Filler as a Heat-Dissipating Resin Material," Research Report of Hiroshima Prefectural Western Industrial Technology Center, 49, 70-73 (2006). [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the surface treatment agents described in Patent Documents 1-3 and Non-Patent Document 1 react with reactive groups such as -NH-, -NH2, and -OH groups on the particle surface to form bonds. However, since reactive groups on the surface of boron nitride particles are only present on the end faces of the particles, and no reactive groups are present on the planar portion which accounts for the majority of the specific surface area, the effect as a surface modification of particles was insufficient. In view of the above circumstances, the object of the present invention is to provide a surface-treated boron nitride that can suppress the increase in viscosity of a resin composition when used as a filler, a method for producing the boron nitride, a resin composition containing the boron nitride and a resin, and a heat dissipation substrate made of the resin composition. [Means for solving the problem]

[0006] As a result of diligent research, the inventors have completed the following invention.

[0007] [1] Surface-treated boron nitride, which is surface-treated with a conjugated diene compound or a compound that produces a conjugated diene upon heating. [2] Surface-treated boron nitride as described in [1], used as a filler. [3] A method for producing surface-treated boron nitride, comprising the step of reacting boron nitride with a conjugated diene compound or a compound that generates a conjugated diene upon heating under heating. [4] A resin composition comprising the surface-treated boron nitride described in [1] or [2] and a resin. A heat dissipation substrate comprising the resin composition of [5] [4]. [Effects of the Invention]

[0008] According to the surface-treated boron nitride of the present invention, when used as a filler in a resin, it is possible to suppress the increase in viscosity of the resin composition containing the filler. Furthermore, it becomes possible to increase the filler content in the resin composition, thereby improving the heat dissipation performance of the heat dissipation substrate formed from the resin composition. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing how the planar portion of h-BN and the conjugated diene bond through conjugate addition. [Modes for carrying out the invention]

[0010] Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiments described below. In this invention, when "X~Y" (where X and Y are any numbers) is written, unless otherwise specified, it means "X or greater and Y or less," and also includes the meaning of "preferably greater than X" or "preferably less than Y." Furthermore, when "X or greater" (where X is any number) is written, unless otherwise specified, it includes the meaning of "preferably greater than X," and when "Y or less" (where Y is any number) is written, unless otherwise specified, it also includes the meaning of "preferably less than Y."

[0011] <Surface-treated boron nitride> The surface-treated boron nitride of the present invention is obtained by surface-treating boron nitride with a conjugated diene compound or a compound that generates a conjugated diene upon heating.

[0012] (Boron nitride) In the present invention, boron nitride includes hexagonal boron nitride (h-BN), which is a stable phase at normal pressure, and cubic boron nitride (c-BN), which is a stable phase at high pressure. In order to maximize the effect of enabling surface treatment of planar portions, boron nitride is preferably hexagonal boron nitride (h-BN). Boron nitride is not particularly limited, and known products can be used without limitation. For example, boron nitride produced according to a known production method may be used. Alternatively, products generally commercially available as boron nitride for fillers may be used. The particle shape of boron nitride is not particularly limited, and may be scaly, flat condition , spherical, cubic, or amorphous. It may also be secondary particles formed by aggregation of particles (primary particles) of these shapes, and the shape of the secondary particles is not particularly limited. Further, boron nitride may be a mixture of primary particles and secondary particles. The size of the primary particles or secondary particles of boron nitride (median diameter, D 50 ) is not particularly limited, but from the viewpoint of processability of the resin composition, it is preferably 0.05 to 500 µm, more preferably 0.1 to 300 µm, and still more preferably 0.1 to 100 µm. The size of boron nitride can be measured and determined with a laser diffraction / scattering particle size distribution analyzer.

[0013] (Conjugated Diene Compounds) A conjugated diene is a conjugated diene in which double bonds are separated by one single bond, and a conjugated diene compound is a compound containing at least one such conjugated diene skeleton. Examples of conjugated diene compounds include cyclopentadiene, 1,3-cyclohexadiene, 2,4-hexadiene, isoindene, sorbic acid, ethyl sorbate, α-terpinene, 2,4-hexadienal, 1,3-butadiene, 1,4-diphenyl-1,3-butadiene, isoprene, myrcene, Danishefsky's diene (1-methoxy-3-(trimethylsilyloxy)-1,3-butadiene), β-carotene, vitamin A, and the like.

[0014] (Compounds that Generate Conjugated Dienes Upon Heating) Further, examples of the compound capable of generating a conjugated diene by heating include dicyclopentadiene, indene, 3-isochromanone, benzocyclobutene, and the like.

[0015] (Surface-Treated) The term "surface-treated" means a state where an organic substance derived from a conjugated diene is bound to at least a part of the surface of boron nitride. The bond may be any bond such as a covalent bond, a coordinate bond, an ionic bond, a hydrogen bond, or a van der Waals bond, and a covalent bond is preferred. The surface treatment may be in a state where the surface of boron nitride is bound to a polymer of a conjugated diene. Further, the surface treatment may be performed such that the organic substance physically and chemically adsorbed on the boron nitride surface spontaneously aggregates through intermolecular interaction to form a thin film layer. The surface treatment may be performed on only a part or the whole of the boron nitride surface.

[0016] (Difficulty in Surface Treatment of Boron Nitride) Boron nitride includes hexagonal boron nitride, which is a stable phase at normal pressure, and cubic boron nitride, which is a stable phase at high pressure, and they are respectively referred to as h-BN and c-BN. h-BN has a graphite-type structure of planar six-membered rings in which B and N are alternately bonded, and the planes are stacked in layers. In the planar portion of h-BN, a π-conjugated plane composed of B and N extends, so there are no functional groups. On the end face, which serves as the terminal point of the planar structure, there are -OH groups, -NH2 groups, and -NH- groups. Since most of the surface is the planar portion, h-BN has few -OH groups, -NH2 groups, and -NH- groups, making it difficult to treat with common surface treatment agents.

[0017] As described above, when boron nitride is used as a filler, it is required to treat the surface thereof to improve the affinity with a resin. The inventors of the present invention conducted intensive studies to improve the affinity of boron nitride for resins, and conceived that if surface treatment can be performed on the planar portion of boron nitride, most of the surface area of boron nitride can be surface-treated, thereby greatly improving the affinity for resins. They further continued intensive studies and completed the present invention.

[0018] According to our investigations, although the detailed principle has not been elucidated, it is presumed that the N and B atoms on the surface of boron nitride undergo conjugate addition to the conjugated diene moiety, resulting in a bond (hetero-Deels-Alder type), which then forms a bond between the conjugated diene and the planar portion of boron nitride (Figure 1 shows how the planar portion of h-BN and the conjugated diene undergo conjugate addition and bond).

[0019] This improves the affinity between the surface-treated filler interface and the resin, resulting in a decrease in the viscosity of the resin composition compared to the untreated version. Conventional methods involve the surface treatment agent reacting with reactive groups such as -NH-, -NH2, and -OH groups to form bonds, but this method does not necessarily require these reactive groups, and the surface treatment agent can bond with the planar portion of boron nitride.

[0020] (Applications of boron nitride surface treatment) As described above, the surface-treated boron nitride of the present invention has improved affinity with resins because its planar portion is surface-treated. Therefore, it can be suitably used as a resin filler.

[0021] <Method for producing surface-treated boron nitride> A method for producing surface-treated boron nitride comprises a step of reacting boron nitride with a conjugated diene compound or a compound that generates a conjugated diene upon heating under heating conditions. The above process is carried out by stirring a slurry-like mixture consisting of boron nitride and a conjugated diene compound (or a compound that produces a conjugated diene upon heating). However, if the conjugated diene compound (or a compound that produces a conjugated diene upon heating) is solid, the mixture lacks fluidity, making stirring difficult. Furthermore, the conjugated diene compound (or a compound that produces a conjugated diene upon heating) and boron nitride are not uniformly dispersed, reducing the reaction efficiency. From the viewpoint of ease of operation and reaction efficiency, an organic solvent (e.g., toluene, xylene, decane, etc.) may be added. Also, when using an expensive conjugated diene compound (or a compound that produces a conjugated diene upon heating), the above organic solvent may be added from an economic standpoint. The heating temperature is preferably 80°C to 250°C, and more preferably 90°C to 200°C. A temperature of 80°C or higher allows the reaction to proceed efficiently, while a temperature of 250°C or lower prevents the decomposition of each component and improves energy efficiency. When using compounds that produce conjugated dienes upon heating, the lower limit of the heating temperature is preferably 120°C or higher, and more preferably 140°C or higher.

[0022] The reaction time under heating is not particularly limited, but is preferably 30 minutes to 10 hours, more preferably 1 hour to 7 hours, and even more preferably 2 hours to 5 hours. The reaction is preferably carried out under stirring.

[0023] After the reaction, it is preferable to allow it to cool, isolate it by filtration (e.g., Buchner filter), and wash the surface-treated boron nitride with an organic solvent (e.g., heptane, ethanol, etc.). It is also preferable to dry it under reduced pressure at 80°C to 120°C for 0.5 to 3 hours.

[0024] <Resin composition> The resin composition of the present invention comprises the surface-treated boron nitride of the present invention described above and a resin. Since the surface treatment of the planar portion of the boron nitride improves its affinity with the resin, when a resin composition containing the resin and the surface-treated boron nitride of the present invention is used as a filler for a resin, the increase in viscosity of the resin composition is suppressed. do This makes it possible to maintain the moldability of the resin composition even when it contains a high amount of boron nitride.

[0025] (resin) Examples of resins to which the surface-treated boron nitride of the present invention can be added include epoxy resins, silicone resins, polyimide resins, acrylic resins (methacrylic resins), phenolic resins, fluororesins, and liquid crystal polymers (LCPs). Among these, epoxy resins are preferred. Examples of epoxy resins include biphenyl-type epoxy resins, stilbene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, triphenolmethane-type epoxy resins, alkyl-modified triphenolmethane-type epoxy resins, dicyclopentadiene-modified phenolic-type epoxy resins, naphthol-type epoxy resins, and triazine nucleus-containing epoxy resins. One of these may be used alone or in combination with others. As a curing agent, amine compounds, acid anhydrides, imidazoles or their derivatives, phenols, etc., can be used.

[0026] (Filler content) The filler content in the resin composition is preferably 5 Vol% or more, more preferably 10 Vol% or more, and even more preferably 15 Vol% or more, in order to effectively impart the heat dissipation effect of the filler. Furthermore, the upper limit is preferably 90 Vol% or less, more preferably 80 Vol% or less, and even more preferably 70 Vol% or less, in order to prevent excessive impairment of the moldability of the resin composition.

[0027] <Heat dissipation substrate> The heat dissipation substrate of the present invention is made of the above-described resin composition. As described above, even if the surface-treated boron nitride of the present invention is included in a high concentration as a filler, the moldability of the resin composition can be ensured, thus preventing molding defects from occurring in the manufacturing process of the heat dissipation substrate. Furthermore, since the filler content can be increased compared to conventional heat dissipation substrates, a heat dissipation substrate with higher heat dissipation performance than conventional substrates can be obtained. [Examples]

[0028] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0029] <Surface treatment process> (Example 1) In a reaction vessel (300 mL) equipped with a Liebig casing, boron nitride (Tokuyama Corporation hexagonal boron nitride S03, median diameter (D)) was added. 50 30 g of (7 μm) and dicyclopentadiene (70 g) were added and heated and stirred in an oil bath at 150°C for 3 hours. The slurry after the reaction was filtered and washed with heptane (100 mL x 3 times), and the resulting cake was dried under reduced pressure at 100°C for 1 hour to obtain surface-treated boron nitride particles A. Furthermore, the dicyclopentadiene used in Example 1 generates cyclopentadiene upon heating, as described below.

[0030] [ka]

[0031] (Examples 2 and 3) Except for the amounts of ingredients and reaction temperature shown in Table 1, surface-treated boron nitride particles B (Example 2) and surface-treated boron nitride particles C (Example 3) were obtained in the same manner as described in Example 1.

[0032] In Example 2, indene was used as the treatment agent. Indene generates isoindene upon heating, as described below.

[0033] [ka]

[0034] Furthermore, ethyl sorbate was used as the treatment agent in Example 3.

[0035] [ka]

[0036] [Table 1]

[0037] (Comparative Example 2) 80 g of boron nitride and 0.19 g of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) were placed in a sealed container and sealed. The sealed container was shaken well at room temperature to mix the contents. After standing at room temperature for 14 days, it was dried under reduced pressure at 50°C for 12 hours to obtain surface-treated boron nitride particles D.

[0038] The structure of the treatment agent, 3-glycidoxypropyltrimethoxysilane, is shown below. 3-glycidoxypropyltrimethoxysilane is commonly used as a surface treatment agent when mixing inorganic powders with resins (see Non-Patent Document 1).

[0039] [ka]

[0040] (Comparative Example 3) 80 g of boron nitride, 100 g of isopropyl alcohol, and 0.06 g of 1-pyrenecarboxaldehyde (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 100 mL round-bottom flask and stirred for 5 minutes. The resulting slurry solution was filtered, washed with isopropyl alcohol, and dried under reduced pressure at 100°C for 12 hours to obtain surface-treated boron nitride E.

[0041] <Resin viscosity measurement> 1 g each of the surface-treated boron nitrides A to E obtained above, 1.45 g of epoxy resin (YDF8170D), and 0.58 g of amine curing agent (KAYAHARD AA) were placed in a mortar and mixed with a pestle. The viscosity of the resulting composition was measured.

[0042] As Comparative Example 1, a resin composition was prepared in the same manner using untreated boron nitride instead of surface-treated boron nitride, and its viscosity was measured.

[0043] Viscosity measurement of resin compositions is performed at a shear rate of 0.2 s.-1 I went there. The measurement conditions are as follows: • Equipment used: Rheometer (HAAKE MARS40, manufactured by Thermo Fisher Scientific) ·Measurement temperature: 25℃, • Sensor used: C35 / 1 (cone plate type, 35mm diameter, 1° angle, titanium material)

[0044] [Table 2]

[0045] Table 2 shows that when the surface-treated boron nitride of the present invention, which has been surface-treated with a conjugated diene or a compound that produces a conjugated diene upon heating, is used, the viscosity of the resulting resin composition is lower compared to untreated boron nitride (Comparative Example 1) or when conventional treatment agents are used (Comparative Examples 2 and 3).

[0046] Furthermore, the 1-pyrenecarboxaldehyde in Comparative Example 3 is the surface modifier (C-36) described in Table 1 of Patent Document 4 and used in Example 44. Paragraph

[0015] describes the estimated action of the surface treatment agent, stating that the surface treatment agent can be adsorbed onto the inorganic nitride even without interaction with the functional groups on the end face, but as mentioned above, the effect was low. In contrast, in the surface-treated boron nitride of the present invention, it is thought that the surface treatment agent and the boron nitride surface are bonded by a strong covalent bond, which is believed to have resulted in a higher viscosity reduction effect on the resin composition.

Claims

1. Surface-treated hexagonal boron nitride, which is surface-treated with a conjugated diene compound or a compound that produces a conjugated diene upon heating, The surface treatment is characterized by bonding resulting from conjugation addition. Surface-treated hexagonal boron nitride.

2. A surface-treated hexagonal boron nitride according to claim 1, used as a filler.

3. A method for producing surface-treated hexagonal boron nitride, comprising the step of reacting hexagonal boron nitride with a conjugated diene compound or a compound that generates a conjugated diene upon heating under heating.

4. A resin composition comprising the surface-treated hexagonal boron nitride according to claim 1 or 2 and a resin.

5. A heat dissipation substrate comprising the resin composition of claim 4.

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