WO2018154832A1

WO2018154832A1 - Thermally conductive resin composition, cured product thereof, and thermally conductive sheet and method for manufacturing same

Info

Publication number: WO2018154832A1
Application number: PCT/JP2017/036103
Authority: WO
Inventors: 浩司中谷
Original assignee: 三菱電機株式会社
Priority date: 2017-02-24
Filing date: 2017-10-04
Publication date: 2018-08-30
Also published as: JP6678809B2; JPWO2018154832A1

Abstract

The purpose of the present invention is to provide: a new curable resin composition which can form a cured product having excellent flexibility without using silicone rubber or a plasticizer and which can be suitably used as a material for a thermally conductive sheet; a cured product of the curable resin composition; and a thermally conductive sheet formed from the curable resin composition. The present invention provides: a thermally conductive resin composition which comprises (A) an epoxy compound having a polyether structure other than a polyethylene glycol structure or a (meth)acrylic structure represented by formula [1], (B) an amine compound, and (C) a thermally conductive filler; a cured product of the thermally conductive resin composition; and a thermally conductive sheet formed from the resin composition.

Description

Thermally conductive resin composition, cured product thereof, and thermally conductive sheet and method for producing the same

The present invention relates to a thermally conductive resin composition, a cured product thereof, a thermally conductive sheet, and a production method thereof.

∙ Electronic and electrical products and components included in them may be deteriorated in characteristics or damaged by heat generated during use. In order to suppress such a problem, it is known that a heat radiating member is interposed between a portion that generates heat and a cooling member such as a heat sinker to promote heat dissipation of the portion that generates heat (for example, Patent Document 1). And 2).

Japanese Patent No. 4296588 JP 2010-116515 A

As the heat radiating member, a heat conductive sheet that promotes heat transfer from the heat generating portion to the cooling member can be cited. As a heat conductive sheet, a sheet made of resin or rubber in which a filler having electrical insulation and heat conductivity is dispersed is known. The heat conductive sheet is required to have electrical insulation, and high adhesion to a contact member (a heat generating component or a cooling member) is required to reduce thermal resistance (contact resistance). In order to improve the adhesion, it is effective to give the heat conductive sheet flexibility, that is, to reduce the hardness of the heat conductive sheet.

As means for reducing the hardness of the heat conductive sheet, it is known to use silicone rubber as the rubber or to contain a large amount of plasticizer in the heat conductive sheet. However, when silicone rubber is used, there is a problem that electric contact failure occurs due to generation of low molecular siloxane gas. When a plasticizer is used, there is a problem that bleed out (exudation of the plasticizer from the heat conductive sheet) occurs.

Patent Documents 1 and 2 disclose a curable resin composition that can form a cured product having excellent flexibility without using silicone rubber and a plasticizer.

In Patent Document 1, although polybutadiene is used for the resin skeleton, since the olefin bond contained in the polybutadiene is a chemical bond that is easily oxidized, there is a problem that sufficient heat resistance cannot be obtained in the cured product due to oxidation. The hydrogenated olefin bond of polybutadiene also disappears due to the reduction reaction by hydrogenation, but it is impossible to completely reduce the olefin bond, and a part of the remaining olefin bond is oxidized. There was a problem that the heat resistance of the cured product was not sufficient. In Patent Document 2, an epoxy resin having a polyether skeleton that does not contain an olefin structure is used. However, when the polyether structure contains a hydrophilic component such as a polyethylene glycol (PEG) skeleton, There was a problem that sufficient moisture resistance and water resistance could not be obtained.

The present invention is capable of forming a cured product having excellent flexibility without using silicone rubber and a plasticizer, and a new curable resin composition that can be suitably used as a heat conductive sheet material and the cured product thereof An object of the present invention is to provide a thermally conductive sheet formed from the curable resin composition. Another object of the present invention is to provide a curable resin composition containing a resin that does not contain an olefin structure and a polyethylene glycol structure as a resin component, and a cured product thereof, and the cured product. It is providing the heat conductive sheet formed from a conductive resin composition.

In the first aspect, the present invention provides a heat conductive resin composition comprising an epoxy compound (A), an amine compound (B), and a heat conductive filler (C). The heat conductive resin composition according to the present invention may be a one-component type, or a two-component type comprising a first agent containing an epoxy compound (A) and a second agent containing an amine compound (B). It may be.

The epoxy compound (A) has an epoxy equivalent of 400 to 2000 and a polyether structure other than the polyethylene glycol structure or the following formula [1]:

(In formula [1], m represents an integer of 1 or more, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group.)
(Meth) acrylic structure represented by. The amine compound (B) has an amine hydrogen equivalent of 80 to 1000.

In the second aspect, the present invention further provides a cured product of the above-described thermally conductive resin composition, a thermally conductive sheet containing the cured product, and a method for producing the thermally conductive sheet.

The method for producing the heat conductive sheet includes a step of forming the heat conductive resin composition into a sheet shape to obtain a sheet-like formed product, and a step of curing the sheet-like formed product by heating.

According to one embodiment of the present invention, it is possible to form a cured product having excellent flexibility without using silicone rubber and a plasticizer, and a new curability that can be suitably used as a heat conductive sheet material. A resin composition, a cured product thereof, and a thermally conductive sheet formed from the curable resin composition can be provided. Moreover, according to another embodiment of this invention, the curable resin composition which hardened | cured material exhibits excellent heat resistance, moisture resistance, and water resistance can be provided.

Embodiment 1. FIG. Thermally conductive resin composition The thermally conductive resin composition which concerns on this embodiment contains an epoxy compound (A), an amine compound (B), and a thermally conductive filler (C). Hereinafter, each component will be described in detail. In addition, unless otherwise indicated, the compound illustrated as each component in this specification can be used individually or in combination of multiple types.

[1] Epoxy compound (A)
The epoxy compound (A) is a compound containing an epoxy group. The epoxy compound (A) can react with the amino group of the amine compound (B) described later to form a cured product having a crosslinked structure.

A cured product (and a heat conductive sheet, the same applies hereinafter) obtained by a crosslinking reaction involving an epoxy group can be excellent in electrical insulation, heat resistance, moisture resistance and water resistance. In particular, a cured product having an epoxy-amine crosslinking site formed by a crosslinking reaction involving an epoxy group and an amino group can be excellent in electrical insulation, heat resistance, moisture resistance and water resistance.

The number of epoxy groups of the epoxy compound (A) is preferably 2 or more, more preferably 2 to 6, more preferably 2 to 5, per molecule from the viewpoint of forming a flexible cured product. When the number of epoxy groups is excessively large, the crosslinking density becomes too high and it tends to be difficult to form a flexible cured product. When the number of epoxy groups is less than 2, the crosslinking reaction does not proceed sufficiently and a cured product that is sufficiently cured tends to be not obtained.

As the epoxy compound (A), one having an epoxy equivalent of 400 to 2000 is used. The “epoxy equivalent” means a value obtained by dividing the molecular weight (or number average molecular weight) of the epoxy compound (A) by the number of epoxy groups that the compound has per molecule. The epoxy equivalent can be calculated from the molecular weight calculated from the chemical structure (or the measured value of the number average molecular weight) and the number of epoxy groups calculated from the chemical structure.

By using an epoxy compound (A) containing two or more epoxy groups in one molecule and having an epoxy equivalent weight within the above range, a cured product having an appropriate crosslinking density can be formed. (Low) can be obtained. The epoxy equivalent of the epoxy compound (A) is more preferably 400 to 1500, and still more preferably 420 to 1200. If the epoxy equivalent is less than 400, the crosslink density becomes too high, and it becomes difficult to form a flexible cured product. When the epoxy equivalent is greater than 2000, the crosslinking reaction does not proceed sufficiently, and a cured product that is sufficiently cured may not be obtained.

As described above, the heat conductive sheet is flexible (has low hardness), which suppresses the biting of air when sticking the heat conductive sheet to a member such as a heat generating component or a cooling member, thereby improving adhesion. Increases and contributes to reduction of thermal resistance (contact resistance). Thereby, thermal conductivity can be improved.

The molecular weight (or number average molecular weight) of the epoxy compound (A) is usually from 400 to 4000, preferably from 500 to 3500, more preferably from 800 to 3000, from the viewpoint of enhancing the flexibility of the cured product. When the molecular weight (or number average molecular weight) of the epoxy compound (A) is less than 400, the crosslinking density tends to be too high, and it tends to be difficult to form a flexible cured product. When the molecular weight (or number average molecular weight) of the epoxy compound (A) is greater than 4000, the crosslinking reaction does not proceed sufficiently, and a cured product that is sufficiently cured tends to be difficult to obtain. The number average molecular weight of an epoxy compound (A) can be calculated | required as a standard polystyrene conversion value by a gel permeation chromatography (GPC).

Moreover, the epoxy compound (A) having a molecular weight (or number average molecular weight) of 500 or more tends to be liquid. Therefore, when using a liquid epoxy compound (A), the heat conductive resin composition does not necessarily require a solvent for dissolving or diluting the epoxy compound (A). This facilitates the preparation operation of the heat conductive resin composition. Furthermore, when an epoxy compound (A) having a molecular weight (or number average molecular weight) of 500 or more is used, the flexibility and heat resistance of the cured product tend to be improved.

The epoxy compound (A) is a polyether structure other than the polyethylene glycol structure or the following formula [1]:

(Meth) acrylic structure represented by. In the formula [1], m represents an integer of 1 or more, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group.

The polyethylene glycol structure means a structure having two or more structural units represented by —OCH ₂ CH ₂ — in one molecule, and is typically a structure formed by repeating two or more of the above structures. (Meth) acryl means at least one selected from methacryl and acryl.

Use of the epoxy compound (A) having a polyether structure other than the polyethylene glycol structure contributes to improvement in flexibility and electrical insulation of the obtained cured product. Moreover, the moisture resistance and water resistance of hardened | cured material can be improved by using the epoxy compound (A) which has polyether structures other than a polyethyleneglycol structure. When an epoxy compound having a polyethylene glycol structure is used, since the hydrophilicity of the compound is relatively high, the moisture resistance and water resistance of the resulting cured product can be lowered.

From the viewpoint of increasing the flexibility of the cured product and from the viewpoint of increasing the heat resistance, electrical insulation, moisture resistance and water resistance of the cured product, the epoxy compound (A) preferably does not contain an olefin structure, and does not contain an olefin structure. A chain compound is more preferable. The olefin structure refers to a structure represented by —C═C—. A chain compound is a compound having a molecular structure that is linear or branched, and does not contain any cyclic structure other than an epoxy ring. Examples of the cyclic structure include an alicyclic ring and an aromatic ring.

By using an epoxy compound (A) that does not contain an olefin structure, the heat resistance of the cured product can be improved. On the other hand, in the above-mentioned Patent Document 1, an epoxy resin having a polybutadiene or hydrogenated polybutadiene skeleton is used. However, the olefin structure contained in the polybutadiene is easily oxidized, and the resulting cured product is also easily oxidized and deteriorated and has heat resistance. Can be inadequate. In an epoxy resin having a hydrogenated polybutadiene skeleton, the olefin structure is less than that before hydrogenation, but it is difficult to completely eliminate the olefin structure. Accordingly, even when an epoxy resin having a hydrogenated polybutadiene skeleton is used, the heat resistance of the cured product may be insufficient.

By using the epoxy compound (A) which is a chain compound not containing an olefin structure, the heat resistance of the obtained cured product can be improved and the flexibility of the cured product can be further increased.

A suitable example of the polyether structure of the epoxy compound (A) is the following formula [2]:

It is a structure containing two or more structural units represented by these. In the formula [2], R ³ represents a chain alkylene group. The epoxy compound (A) can include two or more structural units represented by the formula [2] with different R ³ . From the viewpoint of enhancing the flexibility of the cured product, the polyether structure is preferably a structure formed by repeating two or more structural units represented by the formula [2], that is, the following formula [2-1]:

The structure represented by is included. R ³ in formula [2-1] has the same meaning as in formula [2]. Epoxy compound (A) may contain a structural unit wherein R ³ represented by two or more different formula [2-1]. N in the formula [2-1] is an integer of 2 or more, and is a value corresponding to the molecular weight of the epoxy compound (A). The integer n is usually about 2 to 50, preferably 3 to 50, more preferably 5 to 40, and still more preferably 8 to 35.

The chain alkylene group represented by R ³ may be linear or branched. The number of carbon atoms of the chain alkylene group is usually 3 to 12, preferably 3 to 8, and more preferably 3 to 6. Specific examples of the chain alkylene group include propane-1,2-diyl group, propane-1,3-diyl group (trimethylene group), 2-methylpropane-1,3-diyl group, butane-1,4- Diyl group (tetramethylene group), 2-methylbutane-1,4-diyl group, 3-methylbutane-1,4-diyl group, pentane-1,5-diyl group (pentamethylene group), 2,2-dimethylpropane -1,3-diyl group, hexane-1,6-diyl group (hexamethylene group), octane-1,8-diyl group (octamethylene group) and the like.

As a suitable example of the structural unit represented by the formula [2], the following formula [4]:

And the following unit [5]:

The structural unit represented by these is mentioned. That is, the polyether structure that the epoxy compound (A) may have is one or more structural units selected from the group consisting of the structural unit represented by the formula [4] and the structural unit represented by the formula [5]. Is preferably a structure containing 2 or more in total, and two or more structural units selected from the group consisting of the structural unit represented by the formula [4] and the structural unit represented by the formula [5] It is more preferable that the structure which repeats more than is included.

Use of the epoxy compound (A) having a (meth) acrylic structure represented by the above formula [1] also contributes to improvement in flexibility and electrical insulation of the obtained cured product. Moreover, by using the epoxy compound (A) having the (meth) acrylic structure, the moisture resistance, water resistance, weather resistance, and chemical resistance of the cured product can be improved. Since the (meth) acrylic structure does not contain an olefin structure, the use of the epoxy compound (A) having the (meth) acrylic structure improves the heat resistance of the resulting cured product and improves the heat resistance of the cured product. Flexibility can be increased.

For the same reason as the epoxy compound (A) having a polyether structure, the epoxy compound (A) having the (meth) acrylic structure is preferably a chain compound having no cyclic structure.

M in the above formula [1] is a value corresponding to the molecular weight of the epoxy compound (A), and is usually 2 or more. m is, for example, about 2 to 50, preferably 3 to 50, more preferably 5 to 40, and still more preferably 8 to 40.

In the above formula [1], examples of the alkyl group represented by R ² include alkyl groups having 1 to 12 carbon atoms. The number of carbon atoms of the alkyl group is preferably 1 to 6. From the viewpoint of increasing the flexibility of the cured product, the alkyl group preferably has a linear structure such as a linear or branched chain, and more preferably does not include a cyclic structure such as an alicyclic ring. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, n-hexyl group, 2-ethylhexyl group and the like. It is done.

[2] Amine compound (B)
The amine compound (B) is a compound containing amine hydrogen. “Amine hydrogen” means a hydrogen atom constituting a primary or secondary amino group (a hydrogen atom bonded to a nitrogen atom of a primary or secondary amino group). The primary and / or secondary amino group of the amine compound (B) can react with the epoxy group of the epoxy compound (A) to form a crosslinked structure.

A cured product (and a heat conductive sheet, the same applies hereinafter) obtained by a crosslinking reaction involving an amino group can have good electrical insulation, heat resistance, moisture resistance and water resistance. In particular, a cured product having an epoxy-amine crosslinking site formed by a crosslinking reaction involving an epoxy group and an amino group can be excellent in electrical insulation, heat resistance, moisture resistance and water resistance.

From the viewpoint of forming a flexible cured product, the number of amine hydrogens in the amine compound (B) is preferably 4 or more, more preferably 4 to 10, even more preferably 4 to 8, per molecule. Particularly preferred is 4 to 6. If the amine hydrogen number is excessively large, the crosslinking density tends to be too high and it becomes difficult to form a flexible cured product. If the number of amine hydrogens is less than 4, the crosslinking reaction does not proceed sufficiently and a cured product that is sufficiently cured tends not to be obtained.

As the amine compound (B), those having an amine hydrogen equivalent of 80 to 1000 are used. The “amine hydrogen equivalent” means a value obtained by dividing the molecular weight (or number average molecular weight) of the amine compound (B) by the number of amine hydrogens that the compound has per molecule. The epoxy equivalent can be calculated from the molecular weight calculated from the chemical structure (or the measured value of the number average molecular weight) and the amine hydrogen number calculated from the chemical structure.

By using an epoxy compound (A) containing 4 or more amine hydrogens in one molecule and having an amine hydrogen equivalent weight within the above range, a cured product having an appropriate crosslinking density can be formed. A cured product having a low hardness can be obtained. The amine hydrogen equivalent of the amine compound (B) is preferably 80 to 960. When the amine hydrogen equivalent is less than 80, the crosslinking density becomes too high, and it becomes difficult to form a flexible cured product. If the amine hydrogen equivalent is greater than 1000, the crosslinking reaction does not proceed sufficiently, and a sufficiently cured product may not be obtained.

The molecular weight (or number average molecular weight) of the amine compound (B) is usually 300 to 8000, preferably 400 to 7000, more preferably 500 to 6000, from the viewpoint of increasing the flexibility of the cured product. When the molecular weight (or number average molecular weight) of the amine compound (B) is less than 300, the crosslinking density tends to be too high, and it tends to be difficult to form a flexible cured product. If the molecular weight (or number average molecular weight) of the amine compound (B) is greater than 8000, the crosslinking reaction does not proceed sufficiently, and a cured product that is sufficiently cured tends to be difficult to obtain. The number average molecular weight of an amine compound (B) can be calculated | required as a standard polystyrene conversion value by a gel permeation chromatography (GPC).

Also, the amine compound (B) having a molecular weight (or number average molecular weight) of 500 or more tends to be liquid. Therefore, when the liquid amine compound (B) is used, a solvent for dissolving or diluting the amine compound (B) is not necessarily required in the heat conductive resin composition. This facilitates the preparation operation of the heat conductive resin composition. Furthermore, when the amine compound (B) having a molecular weight (or number average molecular weight) of 500 or more is used, the flexibility and heat resistance of the cured product tend to be improved.

The amine compound (B) preferably has a polyether structure other than the polyethylene glycol structure from the viewpoint of increasing the flexibility of the cured product and from the viewpoint of increasing the heat resistance, electrical insulation, moisture resistance and water resistance of the cured product. From the same viewpoint, the amine compound (B) preferably contains no olefin structure, and more preferably is a chain compound containing no olefin structure. By using the amine compound (B) not containing an olefin structure, the heat resistance of the cured product can be improved. By using the amine compound (B) which is a chain compound not containing an olefin structure, the heat resistance of the obtained cured product can be improved and the flexibility of the cured product can be further increased.

A suitable example of the polyether structure possessed by the amine compound (B) is the following formula [3]:

It is a structure containing two or more structural units represented by these. In the formula [3], R ⁴ represents a chain alkylene group. The amine compound (B) can include two or more structural units represented by the formula [3] in which R ⁴ is different. From the viewpoint of enhancing the flexibility of the cured product, the polyether structure is preferably a structure formed by repeating two or more structural units represented by the formula [3], that is, the following formula [3-1]:

The structure represented by is included. R ⁴ in formula [3-1] has the same meaning as in formula [3]. The amine compound (B) can contain two or more structural units represented by the formula [3-1] having different R ⁴ . P in the formula [3-1] is an integer of 2 or more, and is a value corresponding to the molecular weight of the amine compound (B). The integer p is usually about 2 to 50, preferably 3 to 50, more preferably 5 to 40, and still more preferably 8 to 35. Specific examples of the chain alkylene group represented by R ⁴ are the same as the chain alkylene group represented by R ³ .

Preferred examples of the structural unit represented by the formula [3] include a structural unit represented by the above formula [4] and a structural unit represented by the above formula [5]. That is, the polyether structure that the amine compound (B) may have is one or more structural units selected from the group consisting of the structural unit represented by the formula [4] and the structural unit represented by the formula [5]. Is preferably a structure containing 2 or more in total, and two or more structural units selected from the group consisting of the structural unit represented by the formula [4] and the structural unit represented by the formula [5] It is more preferable that the structure which repeats more than is included.

The amine compound (B) preferably has at least a primary amino group, and more preferably has 2 or 3 primary amino groups in one molecule. Thereby, since the hardened | cured material which has moderate crosslinking density can be formed, it becomes easy to obtain a flexible hardened | cured material. Since it becomes easy to obtain a flexible cured product, it is preferable that these two or three primary amino groups are arranged at the molecular ends of the amine compound (B). The amine compound (B) may have a secondary amino group together with the primary amino group.

[3] Content of epoxy compound (A) and amine compound (B) The content of epoxy compound (A) and amine compound (B) in the thermally conductive resin composition is the amount of amine hydrogen contained in amine compound (B). The ratio (number of amine hydrogens / number of epoxy groups) between the number and the number of epoxy groups of the epoxy compound (A) is preferably adjusted to be 0.2 to 5. When the amine hydrogen number / epoxy group number is within the above range, it is possible to form a cured product having excellent flexibility even when a large amount of the heat conductive filler (C) is contained. If the amine hydrogen number / epoxy group number is outside the above range, it becomes difficult to form a cured product having excellent flexibility.

It is also effective to set the value of amine hydrogen number / epoxy group number to a value shifted from 1. For example, setting the number of amine hydrogens / number of epoxy groups to 0.2 to 0.5 or 2 to 5 is preferable for forming a cured product having excellent flexibility. The amine hydrogen number / epoxy group number is more preferably 0.2 to 0.4 or 2.5 to 5, and further preferably 0.2 to 0.25 or 3 to 5.

[4] Thermally conductive filler (C)
A heat conductive resin composition contains a heat conductive filler (C). Thereby, heat conductivity (heat dissipation performance) can be provided to the hardened | cured material of a heat conductive resin composition. The heat conductive filler (C) is preferably electrically insulating and preferably has high heat conductivity.

The content of the thermally conductive filler (C) in the thermally conductive resin composition is preferably 100 parts by mass to 1000 parts by mass with respect to 100 parts by mass of the total amount of the epoxy compound (A) and the amine compound (B). Yes, more preferably from 230 to 650 parts by mass, and even more preferably from 230 to 450 parts by mass. When content of a heat conductive filler (C) is smaller than 50 mass parts, the hardened | cured material and heat conductive sheet which have sufficient heat conductivity (heat dissipation performance) cannot be obtained. When the content of the thermally conductive filler (C) is larger than 1000 parts by mass, the flexibility of the cured product is impaired even when the thermally conductive filler (C) is not sufficiently uniformly dispersed or evenly dispersed. It is.

From the viewpoint of thermal conductivity and electrical insulation, the thermal conductive filler (C) is selected from the group consisting of metal hydroxide filler, metal oxide filler, metal nitride filler, metal carbonate filler and silicon compound filler. 1 type, or 2 or more types of fillers are preferably included, and one or more types of fillers selected from the group consisting of metal hydroxide fillers, metal oxide fillers, metal nitride fillers, and silicon compound fillers. More preferably.

Examples of the metal hydroxide constituting the metal hydroxide filler include aluminum hydroxide and magnesium hydroxide. Examples of the metal oxide constituting the metal oxide filler include alumina, hydrated alumina, magnesium oxide, zinc oxide, beryllium oxide, and titanium oxide. Examples of the metal nitride constituting the metal nitride filler include boron nitride and aluminum nitride. Examples of the metal carbonate constituting the metal carbonate filler include magnesium carbonate. Examples of the silicon compound constituting the silicon compound filler include silicon carbide, silicon nitride, silicon oxide, and silica.

The heat conductive filler (C) may contain a surface-treated filler. As a result, the dispersibility of the thermally conductive filler (C) in the cured product can be enhanced, so that mechanical properties such as tensile strength and tear strength and electrical properties such as thermal conductivity in the cured product and the thermally conductive sheet can be obtained. Physical properties can be improved. Moreover, when the surface-treated filler is used, the filler can be highly filled, thereby increasing the thermal conductivity of the cured product and the heat conductive sheet. Examples of the surface treatment include a silane coupling agent; a surfactant; a treatment (modification treatment) with an organic acid such as oleic acid or stearic acid.

[5] Other components The thermally conductive resin composition may contain one or more components other than the epoxy compound (A), the amine compound (B) and the thermally conductive filler (C). Other components include plasticizers, flame retardants, flame retardant aids, colorants, antioxidants, UV absorbers, heat stabilizers, crystallization accelerators, dispersants, surface conditioners, antifoaming agents, and adhesion imparting. Agents, solvents (for example, organic solvents), and the like.

[6] Preparation of thermally conductive resin composition The thermally conductive resin composition comprises an epoxy compound (A), an amine compound (B), a thermally conductive filler (C), and other components used as necessary. Can be prepared by mixing. A mixing method is not particularly limited, and a kneader such as a roll, a kneader, a Banbury mixer, or a planetary mixer, a vacuum defoaming stirrer, or the like can be used. When air bubbles are mixed during mixing, there is a risk of adversely affecting mechanical properties such as tensile strength and tear strength and electrical properties such as thermal conductivity in the cured product and the heat conductive sheet. Therefore, a mixing device capable of suppressing the mixing of bubbles, for example, a vacuum defoaming stirrer or a planetary mixer is preferably used. Among them, it is more preferable to use a rotation and revolution type vacuum defoaming mixer or to use a planetary mixer under vacuum conditions.

In a preferred embodiment of the present invention, in the thermally conductive resin composition, the epoxy compound (A) contains two or more epoxy groups in one molecule, has an epoxy equivalent of 400 to 2000, and has a structure other than a polyethylene glycol structure. Or the following formula [1]:

(In formula [1], m represents an integer of 1 or more, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group.)
The amine compound (B) has a (meth) acrylic structure represented by the formula: 4 amine hydrogens per molecule, the amine hydrogen equivalent is 80 to 1000, and the amine compound (B) The ratio of the number of amine hydrogens in the epoxy compound to the number of epoxy groups in the epoxy compound (A) (number of amine hydrogens / number of epoxy groups) is 0.2 to 5, and the epoxy compound (A) and the amine compound 100 parts by mass to 1000 parts by mass of the thermally conductive filler (C) is included with respect to 100 parts by mass of the total amount of (B).

In another preferred embodiment of the present invention, the epoxy compound (A) and the amine compound (B) in the heat conductive resin composition are chain compounds that do not contain an olefin structure.

Embodiment 2. FIG. Cured Product The cured product according to the present embodiment is obtained by curing the thermally conductive resin composition according to the first embodiment. The cured product according to this embodiment can be obtained by curing the thermally conductive resin composition by heating or irradiation with active energy rays.

The cured product obtained by curing the thermally conductive resin composition according to Embodiment 1 can have a hardness value of 95 or less, further 80 or less, and even 65 or less. The hardness value referred to here is Asker C hardness measured according to JIS K 7312 using an Asker C hardness meter. Whether to measure the hardness of the cured molded product according to the standard of Asker C, Type D durometer, or Type A durometer is appropriately selected in consideration of the use and properties of the object to be measured. If the hardness of the molded product is measured according to Asker C standard and the hardness Asker C95 or less, it follows the unevenness, improves adhesion, and improves heat dissipation. A material whose Asker C hardness of the cured product is Asker C95 or less is a soft material, which improves followability to uneven surfaces and improves heat dissipation. The Asker C hardness of the cured product is preferably 2 or more, more preferably 5 or more, from the viewpoint of handleability of the cured product.

Further, the cured product according to the present embodiment can be excellent in electrical insulation, heat resistance, moisture resistance and water resistance since the cross-linked site is an epoxy-amine cross-linked site.

The shape of the cured product according to the present embodiment is not particularly limited, and may be a sheet shape (also a film shape) like a heat conductive sheet described later, or may be a shape other than that, or It may be indefinite.

Embodiment 3. FIG. Thermally Conductive Sheet The thermally conductive sheet according to the present embodiment includes a cured product of the thermally conductive resin composition according to Embodiment 1, and typically includes the cured product. As will be described later, the thermally conductive sheet can be obtained by curing a thermally conductive resin composition formed in a sheet shape by heating or irradiation with active energy rays.

Asker C hardness is a low thermal conductivity sheet (excellent flexibility), it is possible to suppress the biting of air when sticking to a member (a heat generating component or a cooling member) and to improve the adhesion. Thereby, since the contact resistance in the interface of the said member and a heat conductive sheet is reduced, the total heat resistance as the whole product is reduced, and it becomes possible to implement | achieve the outstanding heat dissipation.

In addition, if the surface of the member to which the heat conductive sheet is affixed has irregularities, when the heat conductive sheet is affixed, air is likely to be caught, but the heat conductive sheet according to the present embodiment According to the present invention, since the high flexibility can be shown, it is possible to follow the unevenness, and it is possible to adhere the heat conductive sheet to the member without interposing air that causes a decrease in heat dissipation. Become.

Also, the thermally conductive sheet according to the present embodiment can be excellent in electrical insulation, heat resistance, moisture resistance and water resistance since the crosslinking site is an epoxy-amine crosslinking site.

The thermal conductivity sheet according to the present embodiment preferably has a thermal conductivity of 1.0 W / (m · K) or more, more preferably 1.2 W / (m · K) or more. More preferably, it is 3 W / (m · K) or more, and particularly preferably 1.5 W / (m · K) or more. In addition to reducing the total heat resistance of the heat-conductive sheet and increasing the flexibility of the member to be applied, it also improves the overall heat-resistance performance of the heat-conductive sheet itself. Better heat dissipation can be realized. Even when the thermal conductivity is smaller than 1.0 W / (m · K), the thermal conductive sheet according to the present embodiment uses the flexibility to lower the total thermal resistance and It is possible to ensure the necessary heat dissipation, but in order to obtain better heat dissipation of the product, the thermal conductivity of the thermal conductive sheet should be 1.0 W / (m · K) or more. Is preferred.

The thermal conductive sheet according to the present embodiment can exhibit sufficient flexibility even if a relatively large amount of the thermal conductive filler (C) is contained in order to increase the thermal conductivity.

The thickness of the heat conductive sheet is not particularly limited, but is preferably 0.1 to 5 mm, more preferably 0.3 to 3 mm. The handleability of a heat conductive sheet may fall that the thickness of a heat conductive sheet is less than 0.1 mm. When the thickness of the heat conductive sheet exceeds 5 mm, the heat resistance may be increased and the heat dissipation may be reduced.

Embodiment 4 FIG. Manufacturing method of heat conductive sheet The manufacturing method of the heat conductive sheet which concerns on this embodiment can be used suitably as a method for manufacturing the heat conductive sheet which concerns on Embodiment 3, and includes the following process.

The process of shape | molding the heat conductive resin composition which concerns on Embodiment 1 in a sheet form, and obtaining a sheet-like molded article, and the process of hardening a sheet-like molded article by heating.

After the step of curing, a step of adjusting the shape and size of the heat conductive sheet, such as punching the sheet, may be provided as necessary.

In the step of obtaining the sheet-like molded product, the method for molding the heat conductive resin composition into a sheet shape is not particularly limited, and can be performed using a press machine, a roll, a bar coater or the like. Among these, roll forming is preferable from the viewpoint of production efficiency.

Examples of the method of curing the sheet-shaped molded product by heating include a method of heating the sheet-shaped molded product and a method of irradiating the sheet-shaped molded product with active energy rays such as ultraviolet rays. Of these, the heating method is preferably used.

The heating temperature for curing by heating is, for example, 80 to 150 ° C, preferably 120 to 140 ° C. The heating time is, for example, 0.5 to 72 hours, preferably 2 to 48 hours. After the step of curing, a step of curing the heat conductive sheet may be provided as necessary. The curing temperature is, for example, 60 to 120 ° C., and the curing time is, for example, 0.5 to 72 hours. The curing step and the curing step may be performed in any atmosphere such as an air atmosphere, a nitrogen atmosphere, an argon atmosphere, or a vacuum.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Examples 1 to 34, Comparative Examples 1 to 10>
(1) Preparation of thermally conductive resin composition Epoxy compound (A), amine compound (B) and thermally conductive filler (C) shown in Tables 1 to 3 were blended in the blending amounts shown in the same table. Thereafter, kneading was performed using a self-revolving vacuum stirring mixer (“V-mini300” manufactured by EME Co., Ltd.) to obtain a heat conductive resin composition. The unit of the compounding amount of the amine compound (B) shown in the table is a part by mass with respect to 100 parts by mass of the epoxy compound (A). The unit of the blending amount of the thermally conductive filler (C) shown in the table is a part by mass with respect to 100 parts by mass of the total amount of the epoxy compound (A) and the amine compound (B).

Kind of epoxy compound (A) used, number of epoxy groups and epoxy equivalent in one molecule, kind of amine compound (B), number of amine hydrogen and amine hydrogen equivalent in molecule, amine hydrogen of amine compound (B) The ratio of the number of the epoxy group (A) to the number of epoxy groups (the number of amine hydrogens / the number of epoxy groups, referred to as “AH / EP ratio” in Table 1), and the thermally conductive filler (C) used Tables 1 to 3 show the types and blending amounts.

The details of the ingredients shown in Tables 1 to 3 are as follows.
[1] A-1: Polytetramethylene glycol diglycidyl ether (“Epogosei PT (polymer grade)” manufactured by Yokkaichi Gosei Co., Ltd., number average molecular weight Mn: 2144). A-1 has the following chemical structure:

[2] A-2: Polytetramethylene glycol diglycidyl ether (“Epogosei PT (general grade)” manufactured by Yokkaichi Gosei Co., Ltd., number average molecular weight Mn: 870). The chemical structure of A-2 is the same as A-1 except that the value of the integer x is different.
[3] A-3: An epoxy group-containing (meth) acrylic polymer having a (meth) acrylic structure represented by the above formula [1] as a main chain skeleton (“ARUFON UG-4010 manufactured by Toagosei Co., Ltd.) “Number average molecular weight Mn: 2900).
[4] A-4: Bisphenol A type epoxy resin (“JER828” manufactured by Mitsubishi Chemical Corporation, number average molecular weight Mn: 370).
[5] B-1: Polyetheramine (“JEFFAMINE T5000” manufactured by Huntsman, number average molecular weight Mn: 5712). B-1 has the following chemical structure. a + b + c is about 85.

[6] B-2: Polyetheramine (“JEFFAMINE T403” manufactured by Huntsman, number average molecular weight Mn: 486). B-2 has the following chemical structure. a + b + c is 5 to 6.

[7] B-3: Polyetheramine (“ELASTAMINE RT1000” manufactured by Huntsman, number average molecular weight Mn: 1040). B-3 is a poly (tetramethylene ether glycol) / polypropylene glycol copolymer having two primary amino groups in one molecule.
[8] B-4: Diethylenetriamine (DTA) manufactured by Tokyo Chemical Industry Co., Ltd., number average molecular weight Mn: 103.
[9] C-1: Aluminum hydroxide filler (“SBX73” manufactured by Nippon Light Metal Co., Ltd.).
[10] C-2: Aluminum nitride filler (“HF-01” manufactured by Tokuyama Corporation).
[11] C-3: Alumina filler (“AA-18” manufactured by Sumitomo Chemical Co., Ltd.).

(2) Preparation of cured product and thermally conductive sheet The obtained thermally conductive resin composition was poured into a 100 mL fluororesin beaker so that the thickness after curing was 10 mm, and the conditions shown in Tables 1 to 3 And cured by heating to obtain a cured product for hardness measurement.

Moreover, the obtained heat conductive resin composition was apply | coated to the sheet form so that the thickness after hardening on a fluororesin sheet | seat might be set to 1.0 mm with a bar coater, and it heated on the conditions shown in Table 1 to Table 3 Curing was performed to obtain a thermal conductive sheet for measuring thermal conductivity.

(3) Evaluation Test (3-1) Hardness The Asker C hardness of the cured product for measuring the hardness was measured according to JIS K 7312 using an Asker C hardness meter (manufactured by Kobunshi Keiki Co., Ltd.). The results are shown in Tables 1 to 3.

(3-2) Thermal conductivity The thermal conductive sheet for measuring thermal conductivity was cut into a disk-shaped sheet having a diameter of 10 mm and used as a measurement sample. About the obtained measurement sample, heat conductivity [W / (m * K)] was measured by the laser flash method (unsteady method). The results are shown in Tables 1 to 3.

In Examples 1 to 34, it was possible to achieve low hardness of the cured product while maintaining good electrical insulation. For example, when Example 1 to Example 27 is compared with Comparative Example 1 to Comparative Example 8, they have the same content of the heat conductive filler (C), but in Comparative Examples 1 to 8, the amine compound is used. Since the amine hydrogen equivalent of (B) is not within the predetermined range, the ASKER C hardness did not become 95 or less. Even in Comparative Example 9, although the content of the heat conductive filler (C) is smaller than those of Comparative Example 1 to Comparative Example 8, the amine hydrogen equivalent of the amine compound (B) is not within the predetermined range. C hardness did not become 95 or less. Moreover, when Example 1 to Example 27 and Comparative Example 10 are compared, they have the same heat conductive filler (C) content, but in Comparative Example 10, the epoxy equivalent of the epoxy compound (A) is predetermined. As a result, the ASKER C hardness did not become 95 or less. The cured products obtained in Examples 1 to 34 were obtained from a curable resin composition containing a resin that does not contain an olefin structure and a polyethylene glycol structure as a resin component. It is understood that it has excellent properties and water resistance.

When the AH / EP ratio is greatly shifted from 1, for example, 2.5 to 5 (or 3 to 5), or 0.2 to 0.5 (or 0.2 to 0.25), the hardness is further reduced. A cured product tends to be easily obtained (for example, Example 1, Example 4, Example 5, Example 8, Example 9, Example 10, Example 13, Example 14, Example 16, Example 16, Example) (17, Example 18, Example 21, Example 22, Example 23, Example 24, Example 27, Example 28, Example 30, Example 31, Example 32, Example 33, Example 34) .

In order to reduce the hardness of the cured product, it is preferable to use an amine compound (B) having a number average molecular weight of 500 or more such as B-1 and B-3.

Claims

A thermally conductive resin composition comprising an epoxy compound (A), an amine compound (B), and a thermally conductive filler (C),
The epoxy compound (A) is a polyether structure other than the polyethylene glycol structure or the following formula [1]:

(In formula [1], m represents an integer of 1 or more, R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group.)
A thermally conductive resin composition having an (meth) acrylic structure represented by: an epoxy equivalent of 400 to 2000, and the amine compound (B) having an amine hydrogen equivalent of 80 to 1000.
The polyether structure has the following formula [2]:

(In the formula [2], R 3 represents a chain alkylene group.)
The heat conductive resin composition of Claim 1 which is a structure containing two or more structural units represented by these.
The epoxy compound (A) contains two or more epoxy groups in one molecule, the amine compound (B) contains four or more amine hydrogens in one molecule, and the amine hydrogen that the amine compound (B) has The ratio of the number of the epoxy groups to the epoxy groups of the epoxy compound (A) (number of amine hydrogens / number of epoxy groups) is 0.2 to 5, and the thermally conductive resin composition comprises the epoxy compound (A) And the heat conductive resin composition of Claim 1 or Claim 2 which contains the said heat conductive filler (C) with respect to 100 mass parts of total amounts of the said amine compound (B) from 100 mass parts to 1000 mass parts. .
The heat conductive resin composition according to any one of claims 1 to 3, wherein the amine compound (B) has two or three primary amino groups at a molecular end.
The heat conductive resin composition according to any one of claims 1 to 4, wherein the amine compound (B) has a polyether structure other than a polyethylene glycol structure.
The polyether structure has the following formula [3]:

(In Formula [3], R 4 represents a chain alkylene group.)
The heat conductive resin composition of Claim 5 which is a structure containing two or more structural units represented by these.
The epoxy compound (A) and the amine compound (B) have a polyether structure other than a polyethylene glycol structure,
The polyether structure has the following formula [4]:

And the following unit [5]:

The thermally conductive resin composition according to any one of claims 1 to 6, which has a structure including at least two structural units selected from the group consisting of structural units represented by: object.
The said heat conductive filler (C) contains 1 or more types of fillers selected from the group which consists of a metal hydroxide filler, a metal oxide filler, a metal nitride filler, and a silicon compound filler. 8. The thermally conductive resin composition according to any one of 7 above.
Any of Claims 1-8 which contain the said heat conductive filler (C) from 230 mass parts to 450 mass parts with respect to 100 mass parts of total amounts of the said epoxy compound (A) and the said amine compound (B). The heat conductive resin composition of Claim 1.
A cured product of the thermally conductive resin composition according to any one of claims 1 to 9.
The hardened | cured material of Claim 10 whose ASKER C hardness is 95 or less.
A heat conductive sheet comprising a cured product of the heat conductive resin composition according to any one of claims 1 to 9.
A method for producing a thermally conductive sheet, comprising:
A step of molding the thermally conductive resin composition according to any one of claims 1 to 9 into a sheet to obtain a sheet-like molded product;
Curing the sheet-shaped molding by heating;
Manufacturing method.