JP2023150526A - Surface-treated boron nitride, method for manufacturing surface-treated boron nitride, resin composition, and heat-dissipating substrate - Google Patents

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

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.

In recent years, electronic devices have rapidly become more sophisticated and more compact. Along with this, the power density of semiconductor devices has increased, making it difficult to control the heat generated. Therefore, thermally conductive materials are used for mounted components and surrounding components.
Conventionally, high thermal conductivity compounds such as boron nitride have been frequently used as additives (fillers) for resins. Generally, the higher the concentration of the thermally conductive filler, the higher the thermal conductivity of the resulting resin composition. However, the viscosity of the resin composition also increases in direct proportion to filler concentration. Therefore, if the amount of filler blended in the resin composition exceeds a certain value, problems may arise in processing the material.

Therefore, a method is known in which the filler is modified with a surface treatment agent (so-called surface treatment) to improve its affinity with the resin and to suppress the increase in viscosity when the filler is filled into the resin.
Examples of methods for modifying boron nitride particles with a surface treatment agent include 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), and aluminate coupling. A method of surface treatment with an agent, a zirconate coupling agent, etc. (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) etc. are disclosed.

Japanese Patent Application Publication No. 2001-192500 Japanese Patent Application Publication No. 2006-257392 Japanese Patent Application Publication No. 2009-221039 WO2019/013323 Hirohiro Hanagasaki and 2 others “Investigative research on the properties of surface-treated BN filler as a material for heat dissipating resin”, Hiroshima Prefectural Western Industrial Technology Center Research Report, 49, 70-73 (2006)

However, the surface treatment agents described in Patent Documents 1 to 3 and Non-Patent Document 1 react with reactive groups such as -NH-, -NH ₂ , and -OH groups on the particle surface to form bonds, but Since the reactive groups were present only on the end faces of the particles and no reactive groups were present on the flat portions that accounted for most of the specific surface area, the effect of surface modification of the particles was insufficient.
In view of the above circumstances, the present invention aims to provide a surface-treated boron nitride that can suppress an increase in viscosity of a resin composition when used as a filler, a method for producing the boron nitride, and a resin composition containing the boron nitride and a resin. An object of the present invention is to provide a heat dissipating substrate made of the resin composition.

As a result of intensive study, the present inventors completed the following invention.

[1] Surface-treated boron nitride that has been surface-treated with a conjugated diene compound or a compound that produces a conjugated diene upon heating.
[2] The surface-treated boron nitride according to [1], which is used as a filler.
[3] A method for producing surface-treated boron nitride, comprising a step of reacting boron nitride with a conjugated diene compound or a compound that produces a conjugated diene upon heating under heating.
[4] A resin composition comprising the surface-treated boron nitride according to [1] or [2] and a resin.
[5] A heat dissipation board made of the resin composition of [4].

According to the surface-treated boron nitride of the present invention, when used as a resin filler, it is possible to suppress an increase in the viscosity of a resin composition containing the filler. Moreover, it becomes possible to increase the filler content in the resin composition, and it is possible to improve the heat dissipation performance of a heat dissipation board formed from the resin composition.

FIG. 2 is a schematic diagram showing how a planar portion of h-BN and a conjugated diene are bonded through conjugate addition.

Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiment described below.
In the present invention, when "X to Y" (X and Y are arbitrary numbers) means "more than or equal to It also includes the meaning of "less than".
In addition, when it is written as "more than or equal to X" (X is any number), it includes the meaning of "preferably greater than X" unless otherwise specified, and it is written as "less than or equal to Y" (where Y is any number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

<Surface treatment boron nitride>
The surface-treated boron nitride of the present invention is boron nitride surface-treated with a conjugated diene compound or a compound that produces a conjugated diene upon heating.

(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 that it can be used, boron nitride is preferably hexagonal boron nitride (h-BN).
Boron nitride is not particularly limited, and any known boron nitride can be used without restriction. For example, boron nitride manufactured using a known manufacturing method may be used. Moreover, you may use what is generally commercially available as boron nitride for fillers.
The particle shape of boron nitride is not particularly limited, and may be scaly, flat, spherical, cubic, or irregularly shaped, and may be formed by agglomeration of particles (primary particles) of these shapes. The shape of the secondary particles is not particularly limited. Furthermore, boron nitride may be a mixture of primary particles and secondary particles.
The size (median diameter, D ₅₀ ) of the primary particles or secondary particles of boron nitride 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 500 μm. The thickness is 300 μm, more preferably 0.1 to 100 μm.
The size of boron nitride can be determined by measuring with a laser diffraction/scattering type particle size distribution measuring device.

(conjugated diene compound)
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 conjugated diene skeleton. 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, Danishevsky diene (1-methoxy-3-(trimethylsilyloxy)-1,3-butadiene), β-carotene, vitamin A, etc.

(Compound that produces a conjugated diene when heated)
Compounds that can produce conjugated dienes upon heating include dicyclopentadiene, indene, 3-isochromanone, and benzocyclobutene.

(surface treated)
"Surface-treated" means a state in which an organic substance derived from a conjugated diene is bonded to at least a portion 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, but a covalent bond is preferable. The surface treatment may be performed such that the boron nitride surface is bonded to the conjugated diene polymer. Further, the surface treatment may be such that organic substances physically or chemically adsorbed onto the boron nitride surface spontaneously aggregate through intermolecular interactions to form a thin film layer. Note that the surface treatment may be applied to only a part of the boron nitride surface or to the entire surface.

(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 these are called h-BN and c-BN. h-BN has a graphite-type structure of a planar six-membered ring in which B and N are bonded alternately, and the planes overlap in layers.
In the planar part of h-BN, there is no functional group because a π-conjugated plane composed of B and N extends. Since the end face is the end point of the planar structure, there are -OH groups, -NH ₂ groups, and -NH- groups. Since most of the surface is flat, h-BN has few -OH groups, -NH ₂ groups, and -NH- groups, making it difficult to treat with common surface treatment agents.

As described above, when boron nitride is used as a filler, it is required to treat its surface to improve its affinity with the resin. The present inventors have made extensive studies to improve the affinity of boron nitride for resins, and if surface treatment can be applied to the flat portion of boron nitride, most of the surface area of boron nitride can be surface treated. Thinking that it might be possible to greatly improve the affinity for resins, we continued to conduct further studies and completed the present invention.

According to studies by the present inventors, although the detailed principle has not been elucidated, N atoms and B atoms on the surface of boron nitride are conjugated and added to the conjugated diene site, resulting in a bond (hetero-Diels-Alder type). It is presumed that bonding occurs 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 bond through conjugate addition).

This improves the affinity between the surface-treated filler interface and the resin, and reduces the viscosity of the resin composition compared to an untreated one. In the conventional method, bonds are formed by reacting with reactive groups such as -NH-, -NH ₂ , -OH groups, etc., but in this method, the surface treatment agent does not necessarily require these reactive groups, and the surface treatment agent does not necessarily require these reactive groups, and the surface treatment agent is It can also be combined with

(Applications of surface treatment boron nitride)
Since the surface-treated boron nitride of the present invention has been surface-treated on its flat surface as described above, its affinity with resin is improved. Therefore, it can be suitably used as a resin filler.

<Method for manufacturing surface-treated boron nitride>
The method for producing surface-treated boron nitride includes a step of reacting boron nitride with a conjugated diene compound or a compound that produces a conjugated diene upon heating under heating.
The above step 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 when heated). When the mixture is solid, the lack of fluidity makes stirring difficult, and furthermore, the conjugated diene compound (or a compound that generates a conjugated diene when heated) and boron nitride are not uniformly dispersed, reducing reaction efficiency. descend. From the viewpoint of the above-mentioned operability and reaction efficiency, an organic solvent (for example, toluene, xylene, decane, etc.) may be added. Furthermore, when using an expensive conjugated diene compound (or a compound that produces a conjugated diene upon heating), the above-mentioned organic solvent may be added from the viewpoint of economy.
The heating temperature is preferably 80°C to 250°C, more preferably 90°C to 200°C. By setting the temperature to 80°C or higher, the reaction can proceed efficiently, and by setting the temperature to 250°C or lower, decomposition of each component can be prevented and energy efficiency can be improved. In addition, when using a compound that produces a conjugated diene upon heating, the lower limit of the heating temperature is preferably 120°C or higher, more preferably 140°C or higher.

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

After the reaction, it is preferable to leave it to cool, isolate it by filtration (eg, Buchner), and wash the surface-treated boron nitride with an organic solvent (eg, heptane, ethanol, etc.). Further, it is preferable to perform vacuum drying at 80° C. to 120° C. for 0.5 to 3 hours.

<Resin composition>
The resin composition of the present invention contains the above-described surface-treated boron nitride of the present invention and a resin. Since the flat surface of boron nitride is surface-treated to improve its affinity with resin, a resin composition containing a resin and the surface-treated boron nitride of the present invention can be used as a resin filler. In this case, the increase in viscosity of the resin composition can be suppressed. Thereby, even if the resin composition contains a high content of boron nitride, it is possible to maintain the moldability of the resin composition.

(resin)
Examples of resins to which the surface treatment boron nitride of the present invention is added include epoxy resins, silicone resins, polyimide resins, acrylic resins (methacrylic resins), phenolic resins, fluororesins, and liquid crystal polymers (LCP). Among them, it is preferable to use epoxy resin. Examples of the epoxy resin include biphenyl type epoxy resin, stilbene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, and dicyclopentadiene-modified phenol. Examples include a type epoxy resin, a naphthol type epoxy resin, and a triazine core-containing epoxy resin. One of these may be used alone or a plurality of them may be used in combination. As the curing agent, amine compounds, acid anhydrides, imidazole or its derivatives, phenols, etc. can be used.

(Filler content)
The content of the filler 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 heat dissipation, which is the effect of the filler. Moreover, in order to prevent the moldability of the resin composition from being excessively impaired, the upper limit is preferably 90 Vol% or less, more preferably 80 Vol% or less, and even more preferably 70 Vol% or less.

<Heat dissipation board>
The heat dissipation substrate of the present invention is made of the above resin composition. As described above, even if the surface-treated boron nitride of the present invention is contained as a filler at a high content, the moldability of the resin composition can be ensured, so that molding defects may occur in the manufacturing process of the heat dissipation board. can be prevented. Furthermore, since the filler content can be increased compared to conventional heat dissipation substrates, it is possible to provide a heat dissipation substrate with higher heat dissipation performance than conventional ones.

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

<Surface treatment process>
(Example 1)
In a reaction vessel (300 mL) equipped with a Dimroth, 30 g of boron nitride (hexagonal boron nitride S03 manufactured by Tokuyama Corporation, median diameter (D ₅₀ ): 7 μm) and dicyclopentadiene (70 g) were added, and the mixture was heated at an oil bath temperature of 150° C. The mixture was heated and stirred for 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.
Note that dicyclopentadiene used in Example 1 produces cyclopentadiene when heated as described below.

(Examples 2 and 3)
Surface-treated boron nitride particles B (Example 2) and surface-treated boron nitride particles C (Example 3) was obtained.

Note that indene was used as the treatment agent in Example 2. Indene produces isoindene by heating as described below.

Furthermore, as the treatment agent in Example 3, the following ethyl sorbate was used.

(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 the container was 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.

The structure of 3-glycidoxypropyltrimethoxysilane, which is a processing agent, is shown below. 3-Glycidoxypropyltrimethoxysilane is commonly used as a surface treatment agent when mixing inorganic powder with resin (see Non-Patent Document 1).

(Comparative example 3)
80 g of boron nitride, 100 g of isopropyl alcohol, and 0.06 g of 1-pyrenecarboxaldehyde (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were placed in an eggplant-shaped flask (100 mL) and stirred for 5 minutes. After filtering the obtained slurry solution, it was washed with isopropyl alcohol and dried under reduced pressure at 100° C. for 12 hours to obtain surface-treated boron nitride E.

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

As Comparative Example 1, a resin composition was similarly prepared using unsurfaced boron nitride instead of surface-treated boron nitride, and its viscosity was measured.

The viscosity measurement of the resin composition was performed at a shear rate of 0.2 s ⁻¹ .
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, diameter 35mm, angle 1°, material titanium)

Table 2 shows that when using the surface-treated boron nitride of the present invention that has been surface-treated with a conjugated diene or a compound that produces a conjugated diene upon heating, the viscosity of the resulting resin composition is lower than that of the surface-untreated boron nitride (Comparative Example 1). ) and cases where conventional processing agents were used (Comparative Examples 2 and 3).

Note that 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. In addition, paragraph [0015] describes the estimated effect of the surface treatment agent, and it is said that the surface treatment agent can be adsorbed to the inorganic nitride even without interaction with the functional groups on the end surface. 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, and this is considered to be more effective in reducing the viscosity of the resin composition.

Claims (5)

Surface-treated boron nitride that has been surface-treated with a conjugated diene compound or a compound that produces a conjugated diene upon heating. Surface-treated boron nitride according to claim 1, used as a filler. A method for producing surface-treated boron nitride, comprising a step of reacting boron nitride with a conjugated diene compound or a compound that produces a conjugated diene by heating under heating. A resin composition comprising the surface-treated boron nitride according to claim 1 or 2 and a resin. A heat dissipation board made of the resin composition according to claim 4.