JP5536723B2 - Epoxy resin composition, molded body and sheet material - Google Patents

Description

  The present invention relates to an epoxy resin composition, a molded body formed from the resin composition, and a sheet material. More specifically, the present invention relates to an epoxy resin composition, a molded body, and a sheet material that have both thermal conductivity and conductivity, which are used for a heat radiating member of an electronic component, a positive electrode material of a battery, or an electromagnetic wave absorber.

  Conductive epoxy resins are used in various fields such as molded articles such as fuel cell separators, semiconductor sealing applications, and battery component mounting applications (see, for example, Patent Documents 1 and 2). For example, Patent Document 1 proposes a conductive epoxy resin composition containing an epoxy resin, a curing agent, a curing accelerator made of a urea derivative, and a carbon material containing expanded graphite.

  Patent Document 2 discloses a semiconductor encapsulant containing a naphthalene type epoxy resin, a phenyl resin curing agent having at least one substituted or unsubstituted naphthalene ring in one molecule, carbon black, and an inorganic filler. Stopping epoxy resin compositions have been proposed.

  On the other hand, as electronic components such as semiconductor elements become denser, more integrated and have higher output, countermeasures for heat generation from these electronic components have become important. Therefore, conventionally, a resin molded body having both conductivity and thermal conductivity has also been proposed (see Patent Document 3). In the heat radiating member described in Patent Document 3, in a sheet material containing silicone resin or acrylic resin and graphite powder, the thermal conductivity is increased by orienting graphite having anisotropy in the thickness direction of the sheet. Yes.

JP 2006-152170 A JP 2007-31691 A JP 2009-94110 A

  However, the conventional techniques described above have the following problems. That is, the epoxy resin composition described in Patent Document 1 can secure fluidity at the time of kneading and molding by using a curing accelerator having a specific structure. If the structure of a certain epoxy resin and curing agent is not taken into account, there is a problem that the effect of improving fluidity is low.

  In addition, the epoxy resin composition described in Patent Document 2 is used for a semiconductor encapsulant, and since carbon black is added for the purpose of improving laser marking properties, the addition amount is small and high conductivity. And heat dissipation is not obtained. In contrast, the heat dissipating member described in Patent Document 3 can provide excellent thermal conductivity. However, in recent years, the amount of heat generated from electronic components has increased as in power semiconductors such as LEDs (Light Emitting Diodes). Therefore, further improvement in conductivity and heat dissipation is demanded.

  Therefore, the main object of the present invention is to provide an epoxy resin composition, a molded body, and a sheet material excellent in both conductivity and heat dissipation.

The epoxy resin composition according to the present invention is a resin composition containing at least an epoxy resin, a curing agent, and a carbon material, and one or both of the epoxy resin and the curing agent have a naphthalene structure. The carbon material is fibrous carbon having a fiber length of 3 to 30 μm and an aspect ratio of 10 to 500, and the content of the carbon material is 1 to 40% by mass in the whole composition .
This resin composition can make content of the said carbon material into 1-20 mass% with the whole composition .
As examples of the carbon material, for example, can be used-carbon fibers and / or carbon nanotubes.

The molded body according to the present invention is obtained by molding the above-described epoxy resin composition.
The molded body has a thermal conductivity of, for example, 0.5 to 70.0 W / mK, and a surface resistance of, for example, 1.0E + 16 to 0.1Ω / □.

  The sheet material according to the present invention is obtained by thermoforming the above-described epoxy resin composition, and has a thickness of 10 to 500 μm.

According to the present invention, the epoxy resin and / or curing agent has a naphthalene structure, a fiber length of 3~30μm as a carbon material, the aspect ratio is using fiber維状carbons 10 to 500, conductive An epoxy resin composition, a molded body, and a sheet material excellent in both properties and heat dissipation are obtained.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

(First embodiment)
The epoxy resin composition according to the first embodiment of the present invention will be described. The epoxy resin composition of this embodiment contains at least an epoxy resin, a curing agent, and a carbon material. One or both of the epoxy resin and the curing agent have a naphthalene structure, and the carbon material is carbon particles or fibrous carbon having a hexagonal structure or an amorphous structure, and an average particle diameter or fiber length. Is 30 μm or less.

[Epoxy resin]
The epoxy resin blended in the epoxy resin composition of the present embodiment may be an epoxy compound having two or more epoxy groups in one molecule, and in particular, a polycyclic aromatic such as naphthalene structure or anthracene structure in the molecule. Those having a group structure are preferred. Among them, the naphthalene structure is liquid at room temperature and has good wettability with the carbon material. By using an epoxy resin having a naphthalene structure in the molecule, the filling rate of the carbon material is increased and the conductivity is increased. And heat dissipation can be improved.

  The compounding amount of the epoxy resin in the epoxy resin composition is not particularly limited, but is 30 to 90% by mass per total resin composition from the viewpoint of the properties of the obtained cured product, in particular, conductivity and resin strength. It is preferable that it is 40 to 85% by mass.

[Curing agent]
The curing agent blended in the epoxy resin composition of the present embodiment is the epoxy resin curing agent described above, and specifically, phenol novolac resins, acid anhydride resins, amino resins, imidazoles, and the like are used. Can do. Also about this hardening | curing agent, what has a polycyclic aromatic structure is preferable, and what has a naphthalene structure is especially preferable among these. Thereby, the filling rate of a carbon material can be raised and electroconductivity and heat dissipation can be improved.

  Although the compounding quantity of the hardening | curing agent in an epoxy resin composition is not specifically limited, From the viewpoint of the characteristic of the hardening body obtained, especially resin hardness, it is 3.0-70 mass% per resin composition whole quantity. It is preferably 5.0 to 50% by mass. In particular, when the curing agent is a phenol novolac resin, an acid anhydride resin or an amino resin, the equivalent ratio to the epoxy resin is preferably 0.75 to 1.25, more preferably an equivalent ratio of 0.8. ~ 1.2. In addition, about what hardens | cures by ion polymerization like imidazoles etc., an equivalent ratio is not specifically limited.

[Carbon material]
The carbon material blended in the epoxy resin composition of the present embodiment is carbon particles having a hexagonal structure or an amorphous structure, or fibrous carbon. These are easier to form a percolation structure in the resin than other carbon materials, and exhibit low conductivity and thermal conductivity with low filling, so that an epoxy resin composition having excellent conductivity and thermal conductivity is obtained. can get.

  Examples of such a carbon material include carbon black, graphite powder, carbon fiber, and carbon nanotube, and these can be used alone or in combination. Among these carbon materials, carbon nanofibers are preferable from the viewpoint of easy formation of a percolation structure that improves affinity with resin, dispersibility, conductivity, and thermal conductivity.

  However, when carbon particles having an average particle diameter exceeding 30 μm or fibrous carbon having a fiber length exceeding 30 μm are used, it is difficult to form a thin film when the resin composition is formed into a sheet. Therefore, the carbon material blended in the epoxy resin composition of the present embodiment has an average particle diameter or fiber length of 30 μm or less.

  Further, the aspect ratio of the carbon material is preferably 10 to 500, and more preferably 50 to 300. Thereby, high electrical conductivity and high thermal conductivity of the sheet molded product can be realized with a small filling amount.

  Furthermore, it is preferable that the compounding quantity of a carbon material is 1-40 mass% of the whole resin composition from a viewpoint of an electroconductive characteristic, a thermal radiation characteristic, and a moldability, and it is more preferable that it is 1-20 mass%. Thereby, high electrical conductivity and high thermal conductivity of the sheet molded product can be realized.

(Other ingredients)
In addition to the components described above, an organic solvent, a coupling agent, or the like may be blended in the resin composition forming the laterally oriented sheet 3.

[Production method]
Next, the manufacturing method of the epoxy resin composition comprised as mentioned above is demonstrated. The production method of the epoxy resin composition of the present embodiment is not particularly limited, and each of the above-described components is a known method such as a universal mixing stirrer, a planetary mixer, a roll mill, a kneader, a Banbury mixer, What is necessary is just to mix or knead | mix.

  As described above in detail, in the epoxy resin composition of the present embodiment, an epoxy resin having a naphthalene structure and / or a curing agent is used, so that it has a low resistance and high thermal conductivity. The carbon particles or the fibrous carbon having a texture can be highly filled. Thereby, both electroconductivity and heat dissipation can be improved compared with the past.

  Moreover, since the epoxy resin composition of this embodiment also has solvent resistance, it is suitable also as a positive electrode material of a battery. In addition, since it has excellent radio wave absorption performance, it can also be used as an electromagnetic wave absorbing material.

(Second Embodiment)
A molded body according to the second embodiment of the present invention will be described. The molded body of this embodiment is obtained by molding the epoxy resin composition of the first embodiment described above, and is an electronic packaging material, a tray or the like on which a sealing agent such as a potting agent or a chip is mounted.

[Thermal conductivity: 0.5-70.0 W / mK]
It is preferable that the heat conductivity of the molded object of this embodiment is 0.5-70 W / mK, More preferably, it is 5-70 W / mK. Thereby, a heat dissipation characteristic can be improved more.

[Surface resistance: 1.0E + 16 to 0.1Ω / □]
The surface resistance of the molded body of the present embodiment is preferably 1.0E + 16 to 0.1Ω / □, and more preferably 1.0E + 6 to 0.1Ω / □. Thereby, electrical conductivity can be raised more.

[Production method]
Next, the manufacturing method of the molded object of this embodiment is demonstrated. The molding method of this molded body is not particularly limited, and for example, known molding methods such as extrusion molding, injection molding, roll molding, and press molding can be applied.

  Then, for example, a sheet in which the carbon material is oriented in the width direction or the length direction is produced using an extrusion molding machine or a roll press apparatus, and a plurality of the sheets may be laminated to form a molded body. In that case, the sheet before lamination is in the B-stage state, and it is desirable that the sheet is heated after lamination to be in the “C-stage state”.

  Here, the “B stage state” means a state in which the resin composition is dried at room temperature and melts again when heated to a high temperature. More precisely, DSC (Differential Scanning Calorimetry) ), The degree of cure is less than 70% with a value calculated from the amount of heat generated during curing. The “C stage state” refers to a state where the curing of the resin composition is almost completed and does not melt again even when heated to a high temperature, and refers to a state where the curing degree is 70% or more.

  Furthermore, the laminated body (molded body) can be cut in a direction perpendicular to the laminating direction with a broken blade or the like to obtain a molded body in which the carbon material is oriented in the thickness direction. This molded body has a configuration in which a plurality of prismatic alignment bodies are arranged in one direction.

  As described above in detail, the molded body of the present embodiment is highly filled with a carbon material, and therefore has excellent heat dissipation as well as conductivity.

(Third embodiment)
A sheet material according to a third embodiment of the present invention will be described. The sheet material of the present embodiment is a sheet material having a thickness of 10 to 500 μm obtained by thermoforming the epoxy resin composition of the first embodiment described above.

[Thickness: 10 to 500 μm]
When the thickness of the sheet material is less than 10 μm, sufficient sheet strength cannot be obtained, and when it exceeds 500 μm, the flexibility is impaired and various properties are deteriorated due to the inclusion of voids during molding. . Therefore, the thickness of the sheet material of the present embodiment is 10 to 500 μm.

[Production method]
The sheet material of this embodiment is obtained by forming the epoxy resin composition of the first embodiment described above on a resin film such as polyethylene terephthalate and heating it. The film forming method of the sheet material is not particularly limited, and for example, known molding methods such as screen printing, die coater, extrusion molding, injection molding, roll molding, and press molding can be applied.

  Since the sheet material of this embodiment is highly filled with a carbon material, it is excellent not only in conductivity but also in heat dissipation.

  Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention. In this example, a sheet material having the configuration shown in Table 1 below was produced and its characteristics were evaluated.

<Sheet manufacturing method>
First, primary kneading was performed with a rotation and revolution type stirring device, and then secondary kneading was performed with three rolls to prepare epoxy resin compositions having compositions shown in Tables 1 and 2 below. Next, after forming an epoxy resin composition on a PET film using a roll press or a coater, the sheet material of Examples 1 to 8 and Comparative Examples 1 to 5 is obtained by heating at 115 ° C. for 60 minutes. It was.

  At that time, the epoxy resin is a naphthalene type epoxy resin (HP-4032D manufactured by DIC), a cyclic bis A type epoxy resin (EP828 manufactured by Mitsubishi Chemical Corporation), a biphenyl type epoxy resin (YX4000 manufactured by Mitsubishi Chemical Corporation), or a triazine type epoxy. Resin (TEPIC-PAS manufactured by Nissan Chemical Co., Ltd.) was used. Imidazoles (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ-CN) were used as the curing agent.

  As the carbon material, carbon nanotubes (VGCF manufactured by Showa Denko KK) and diamond were used. In addition, a silane coupling agent (manufactured by Toray Dow Corning, Z-0640N) was used as the coupling agent, and ethyl cellosolve was used as the organic solvent.

  Next, the sheet materials of Examples and Comparative Examples produced by the method described above were evaluated by the following methods.

<Volume resistance>
The volume resistance was determined by a measuring method based on JIS K6911. Specifically, the electrical resistance was measured with an insulation resistance meter (R503 and P616, manufactured by Kawaguchi Electric Co., Ltd.) between the circular electrodes (φ70), and the volume resistivity was determined from the electrode shape. At that time, 500 V was applied between the electrodes, and the resistance after 1 minute was measured.

<Surface resistance>
The surface resistance was determined by a measuring method based on JIS K6911. Specifically, the electrical resistance was measured with an insulation resistance meter (R503 and P616, manufactured by Kawaguchi Electric Co., Ltd.) between the double circular electrodes (φ70, φ50), and the surface resistivity was determined from the electrode shape. At that time, 500 V was applied between the electrodes, and the resistance after 1 minute was measured.

<Thermal conductivity>
The thermal conductivity was determined from the thermal diffusivity and the heat capacity (product of specific gravity and specific heat). At that time, the thermal diffusivity was measured by the xenon flash method (LFA447 manufactured by Netzch), and the specific gravity was measured by the Archimedes method (submersion method in water). The specific heat was measured by the DSC method (DSC8230, manufactured by Rigaku).

<Strength>
The strength was evaluated by flexibility. Specifically, a sheet molded product was wound around a paper tube having a diameter of 10 cm, and the case in which the molded product was not cracked before and after the winding was evaluated as ◯, and the cracked or generated was evaluated as x.

<Appearance>
The appearance was evaluated by the presence or absence of foreign matter such as filler aggregates. Specifically, it was indicated as “O” if no foreign matter was found, and “X” if a foreign matter was found.

  The above results are summarized in Tables 1 and 2 below. In addition, the size of the carbon nanotube (CNT) and diamond (Diamond) shown in the following Tables 1 and 2 is a value measured by an electron microscope (SEM, TEM).

  As shown in Table 2 above, the sheet materials of Comparative Examples 1 and 2 using an epoxy resin having no naphthalene structure also had high resistance values and poor flexibility and appearance. Moreover, although the epoxy resin which has a naphthalene structure is used, the sheet material of the comparative examples 3 and 4 which mix | blended the carbon nanotube whose fiber length exceeds 30 micrometers had high resistance value, and its external appearance was also inferior. Further, the sheet material of Comparative Example 5 containing dice diamond had no problem in flexibility and appearance, but had a high resistance value.

  On the other hand, the sheet materials of Examples 1 to 8 produced within the scope of the present invention were excellent in conductivity and heat dissipation, and also had good strength and appearance. Thereby, according to this invention, it was confirmed that the epoxy resin composition, the molded object, and sheet material which were excellent in both electroconductivity and heat dissipation are realizable.

Claims (7)

At least a resin composition containing an epoxy resin, a curing agent, and a carbon material,
One or both of the epoxy resin and the curing agent have a naphthalene structure,
The carbon material is fibrous carbon having a fiber length of 3 to 30 μm and an aspect ratio of 10 to 500 ,
The epoxy resin composition whose content of the said carbon material is 1-40 mass% in the whole composition. Content of the said carbon material is 1-20 mass% in the whole composition, The epoxy resin composition of Claim 1 characterized by the above-mentioned. The carbon material is an epoxy resin composition according to claim 1 or 2, characterized in that a carbon-containing fibers and / or carbon nanotubes. Compact molded epoxy resin composition according to any one of claims 1-3. The molded article according to claim 4 , wherein the thermal conductivity is 0.5 to 70 W / mK. The molded product according to claim 4 or 5 , wherein the surface resistance is 1.0E + 16 to 0.1Ω / □. Sheet having a thickness of 10~500μm obtained by heat-molding the epoxy resin composition according to any one of claims 1-3.