JP6678809B2 - Thermal conductive resin composition, cured product thereof, thermal conductive sheet and method for producing the same - Google Patents

Description

  The present invention relates to a thermally conductive resin composition, a cured product thereof, and a thermally conductive sheet and a method for producing the same.

  Electronic and electrical products and components included therein 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 radiation member is interposed between a heat generating portion and a cooling member such as a heat sinker to promote heat radiation of the heat generating portion (for example, Patent Document 1). And 2).

Patent No. 4296588 JP 2010-116515 A

  Examples of the heat dissipating member include a heat conductive sheet for promoting heat transfer from a heat generating portion to a cooling member. As the heat conductive sheet, a sheet in which a filler having electric insulation and heat conductivity is dispersed in a sheet made of resin or rubber is known. The heat conductive sheet is required to have electrical insulation properties and high adhesion to a contact member (heat-generating component or cooling member) in order to reduce thermal resistance (contact resistance). In order to enhance the adhesion, it is effective to make the heat conductive sheet flexible, 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 make the heat conductive sheet contain a large amount of a plasticizer. However, when a silicone rubber is used, there is a problem that an electric contact failure occurs due to generation of a low molecular siloxane gas. When a plasticizer is used, there is a problem that bleed-out (bleeding of the plasticizer from the heat conductive sheet) occurs.

  Patent Documents 1 and 2 disclose curable resin compositions capable of forming a cured product having excellent flexibility without using silicone rubber and a plasticizer.

  In Patent Literature 1, polybutadiene is used for the resin skeleton. However, since the olefin bond contained in 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. For polybutadiene obtained by hydrogenating the olefin bond, the olefin bond disappears due to the hydrogenation by the reduction reaction, but it is impossible to completely reduce the olefin bond. There was a problem that the heat resistance of the cured product was not sufficient. Further, in Patent Document 2, an epoxy resin having a polyether skeleton not containing an olefin structure is used. However, when a hydrophilic component such as a polyethylene glycol (PEG) skeleton is contained in the polyether structure, a cured product is used. 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 a silicone rubber and a plasticizer, and a new curable resin composition and a cured product thereof which can be suitably used as a heat conductive sheet material. And a heat conductive sheet formed from the curable resin composition. Another object of the present invention is to provide a curable resin composition containing, as a resin component, a resin not containing an olefin structure and a polyethylene glycol structure because of its excellent heat resistance, moisture resistance, and water resistance. An object of the present invention is to provide a heat conductive sheet formed from a conductive resin composition.

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

  The epoxy compound (A) has an epoxy equivalent of 400 to 2,000 and a polyether structure other than the polyethylene glycol structure or the following formula [1]:

(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.)
Having a (meth) acrylic structure represented by The amine compound (B) has an amine hydrogen equivalent of 80 to 1,000.

  In a second aspect, the present invention further provides a cured product of the above-mentioned 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 a thermally conductive sheet includes a step of forming the thermally conductive resin composition into a sheet to obtain a sheet-like molded article, and a step of curing the sheet-like molded article by heating.

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

Embodiment 1 FIG. Heat conductive resin composition The heat conductive resin composition according to the present embodiment includes an epoxy compound (A), an amine compound (B), and a heat conductive filler (C). Hereinafter, each component will be described in detail. The compounds exemplified as each component in the present specification can be used alone or in combination of two or more, unless otherwise specified.

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

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

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

  As the epoxy compound (A), those having an epoxy equivalent of 400 to 2,000 are 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 per molecule of the compound. 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 within the above range, it is possible to form a cured product having an appropriate crosslinking density, so that a soft (hardness) (Low) is obtained. The epoxy equivalent of the epoxy compound (A) is more preferably from 400 to 1500, and still more preferably from 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. If the epoxy equivalent is more than 2,000, the crosslinking reaction does not proceed sufficiently, and a sufficiently cured cured product may not be obtained.

  As described above, the fact that the heat conductive sheet is flexible (has a low hardness) suppresses air entrapment when attaching the heat conductive sheet to a member such as a heat-generating component or a cooling member, thereby improving adhesion. And contribute to the reduction of thermal resistance (contact resistance). Thereby, heat conductivity can be improved.

  The molecular weight (or number average molecular weight) of the epoxy compound (A) is usually from 400 to 4,000, preferably from 500 to 3,500, and more preferably from 800 to 3,000, from the viewpoint of increasing 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 crosslink density tends to be too high to form a flexible cured product. When the molecular weight (or number average molecular weight) of the epoxy compound (A) is more than 4,000, the crosslinking reaction does not proceed sufficiently, and a sufficiently cured cured product tends to be hardly obtained. The number average molecular weight of the epoxy compound (A) can be determined as a value in terms of standard polystyrene by gel permeation chromatography (GPC).

  The epoxy compound (A) having a molecular weight (or number average molecular weight) of 500 or more tends to be in a liquid state. Therefore, when a liquid epoxy compound (A) is used, a solvent for dissolving or diluting the epoxy compound (A) is not necessarily required in the thermally conductive resin composition. This facilitates the operation of preparing the thermally conductive resin composition. Further, when an epoxy compound (A) having a molecular weight (or a 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) has a polyether structure other than the polyethylene glycol structure or the following formula [1]:

Having a (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, -OCH 2 _CH 2 _- means a structure having a structural unit represented by two or more in one molecule, it is typically a structure formed by repeating the above structure 2 or more. (Meth) acryl means at least one selected from methacryl and acryl.

  The 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. Further, by using an epoxy compound (A) having a polyether structure other than the polyethylene glycol structure, the moisture resistance and water resistance of the cured product can be increased. When an epoxy compound having a polyethylene glycol structure is used, the moisture resistance and water resistance of the obtained cured product may be reduced due to the relatively high hydrophilicity of the compound.

  The epoxy compound (A) preferably does not contain an olefin structure, and does not contain an olefin structure, from the viewpoint of increasing the flexibility of the cured product and enhancing the heat resistance, electrical insulation, moisture resistance, and water resistance of the cured product. More preferably, it is a chain compound. The olefin structure refers to a structure represented by -C = C-. The chain compound refers to a compound having a chain structure such as a straight chain or a branched chain having no molecular structure other than an epoxy ring. The cyclic structure is, for example, an alicyclic ring, an aromatic ring, or the like.

  By using the epoxy compound (A) containing no olefin structure, the heat resistance of the cured product can be increased. On the other hand, in the above-mentioned Patent Document 1, an epoxy resin having a polybutadiene or hydrogenated polybutadiene skeleton is used. May be insufficient. An epoxy resin having a hydrogenated polybutadiene skeleton has a smaller olefin structure than before hydrogenation, but it is difficult to completely eliminate the olefin structure. Therefore, even when an epoxy resin having a hydrogenated polybutadiene skeleton is used, the heat resistance of the cured product may still be insufficient.

  By using the epoxy compound (A) which is a chain compound containing no 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 preferred example of the polyether structure of the epoxy compound (A) is represented by the following formula [2]:

Is a structure including two or more structural units represented by In the formula [2], R ³ represents a chain alkylene group. The epoxy compound (A) may include two or more structural units represented by the formula [2] in which R ³ is different. From the viewpoint of enhancing the flexibility of the cured product, the polyether structure is preferably a structure obtained by repeating two or more structural units represented by the formula [2], that is, the following formula [2-1]:

Including the structure represented by R ³ in the formula [2-1] has the same meaning as in the formula [2]. The epoxy compound (A) can include two or more types of structural units represented by the formula [2-1] in which R ³ is different. N in the formula [2-1] is an integer of 2 or more, and has 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 in the chain alkylene group is usually from 3 to 12, preferably from 3 to 8, and more preferably from 3 to 6. Specific examples of the chain alkylene group include propane-1,2-diyl, propane-1,3-diyl (trimethylene), 2-methylpropane-1,3-diyl, and 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.

  Preferred examples of the structural unit represented by the formula [2] include the following formula [4]:

And a structural unit represented by the following formula [5]:

And a structural unit represented by That is, the polyether structure which the epoxy compound (A) may have is at least one structural unit 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 two or more structural units in total, and one or more structural units selected from the group consisting of a structural unit represented by formula [4] and a structural unit represented by formula [5] It is more preferable to include a structure in which at least two are repeated.

  The use of the epoxy compound (A) having the (meth) acrylic structure represented by the above formula [1] also contributes to improvement in flexibility and electrical insulation of the obtained cured product. Further, by using the epoxy compound (A) having the (meth) acrylic structure, the cured product can have improved moisture resistance, water resistance, weather resistance, and chemical resistance. 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 obtained 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 a (meth) acrylic structure is preferably a chain compound containing 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 an alkyl group having 1 to 12 carbon atoms. The alkyl group preferably has 1 to 6 carbon atoms. From the viewpoint of enhancing the flexibility of the cured product, the alkyl group preferably has a linear or branched chain structure, and more preferably does not contain a cyclic structure such as an alicyclic ring. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, and a 2-ethylhexyl group. Can be

[2] Amine compound (B)
The amine compound (B) is a compound containing an 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 groups of the amine compound (B) can react with the epoxy groups 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 cross-linking site formed by a cross-linking reaction involving an epoxy group and an amino group can have excellent electrical insulation, heat resistance, moisture resistance, and water resistance.

  The amine hydrogen number of the amine compound (B) is preferably 4 or more, more preferably 4 to 10, and still more preferably 4 to 8, per molecule, from the viewpoint of forming a flexible cured product. And particularly preferably 4 to 6. If the number of amine hydrogens is too large, the crosslinking density tends to be too high, and it tends to be 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 which is sufficiently cured tends not to be obtained.

  As the amine compound (B), those having an amine hydrogen equivalent of 80 to 1,000 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 per molecule of the compound. The epoxy equivalent can be calculated from the molecular weight (or the measured value of the number average molecular weight) calculated from the chemical structure and the amine hydrogen number calculated from the chemical structure.

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

  The molecular weight (or number average molecular weight) of the amine compound (B) is usually from 300 to 8,000, preferably from 400 to 7000, more preferably from 500 to 6,000, from the viewpoint of enhancing 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 crosslink 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 amine compound (B) is larger than 8,000, the crosslinking reaction does not proceed sufficiently, and a cured product which is sufficiently cured tends to be hardly obtained. The number average molecular weight of the amine compound (B) can be determined as a value in terms of standard polystyrene by gel permeation chromatography (GPC).

  Further, the amine compound (B) having a molecular weight (or a 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 thermally conductive resin composition. This facilitates the operation of preparing the thermally conductive resin composition. Furthermore, when an 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 enhancing the flexibility of the cured product and enhancing 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) containing no olefin structure, the heat resistance of the cured product can be increased. By using the amine compound (B) which is a chain compound containing no 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 preferred example of the polyether structure of the amine compound (B) is represented by the following formula [3]:

Is a structure including two or more structural units represented by In the formula [3], R ⁴ represents a chain alkylene group. The amine compound (B) may include two or more types of 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 in which two or more structural units represented by the formula [3] are repeated, that is, the following formula [3-1]:

Including the structure represented by R ⁴ in Formula [3-1] has the same meaning as in Formula [3]. The amine compound (B) may include two or more types of structural units represented by Formula [3-1] in which R ⁴ is different. P in the formula [3-1] is an integer of 2 or more, and has 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 .

  Preferable 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 which the amine compound (B) can have is at least one structural unit 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 two or more structural units in total, and one or more structural units selected from the group consisting of a structural unit represented by formula [4] and a structural unit represented by formula [5] It is more preferable to include a structure in which at least two are repeated.

  The amine compound (B) preferably has at least a primary amino group, and more preferably has two or three primary amino groups in one molecule. As a result, a cured product having an appropriate crosslink density can be formed, so that a flexible cured product can be easily obtained. These two or three primary amino groups are preferably arranged at the molecular terminals of the amine compound (B) because a flexible cured product can be easily obtained. The amine compound (B) may have a secondary amino group together with a primary amino group.

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

  It is also effective to set the value of the number of amine hydrogens / the number of epoxy groups to a value shifted from 1. For example, setting the number of amine hydrogens / the 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 number of amine hydrogens / the number of epoxy groups is more preferably 0.2 to 0.4 or 2.5 to 5, and even more preferably 0.2 to 0.25 or 3 to 5.

[4] Thermal conductive filler (C)
The heat conductive resin composition contains a heat conductive filler (C). This makes it possible to impart thermal conductivity (heat dissipation performance) to the cured product of the thermally conductive resin composition. The thermally conductive filler (C) is preferably electrically insulating and preferably has high thermal conductivity.

  The content of the thermally conductive filler (C) in the thermally conductive resin composition is preferably from 100 parts by mass to 1,000 parts by mass based on 100 parts by mass of the total amount of the epoxy compound (A) and the amine compound (B). Yes, more preferably 230 parts by mass to 650 parts by mass, still more preferably 230 parts by mass to 450 parts by mass. When the content of the thermally conductive filler (C) is less than 50 parts by mass, a cured product and a thermally conductive sheet having sufficient thermal conductivity (heat dissipation performance) cannot be obtained. When the content of the thermally conductive filler (C) is more than 1000 parts by mass, the flexibility of the cured product is impaired even if the thermally conductive filler (C) is not sufficiently uniformly dispersed or even if it can be uniformly dispersed. It is.

  From the viewpoints of thermal conductivity and electrical insulation, the thermally conductive filler (C) is selected from the group consisting of a metal hydroxide filler, a metal oxide filler, a metal nitride filler, a metal carbonate filler and a silicon compound filler. Preferably contains one or more fillers, and one or more fillers selected from the group consisting of metal hydroxide fillers, metal oxide fillers, metal nitride fillers and silicon compound fillers. More preferably, it is included.

  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, silica and the like.

  The thermally conductive filler (C) may include a surface-treated filler. As a result, the dispersibility of the thermally conductive filler (C) in the cured product can be increased, and thus the mechanical properties such as tensile strength and tear strength and the electrical conductivity such as thermal conductivity of the cured product and the thermally conductive sheet can be improved. Can improve physical properties. In addition, when the surface-treated filler is used, the filler can be highly filled, thereby increasing the thermal conductivity and the like of the cured product and the heat conductive sheet. Examples of the surface treatment include a treatment (modification treatment) with a silane coupling agent; a surfactant; an organic acid such as oleic acid and stearic acid.

[5] Other components The heat conductive resin composition may contain one or more components other than the epoxy compound (A), the amine compound (B) and the heat conductive filler (C). Other components include a plasticizer, a flame retardant, a flame retardant auxiliary, a colorant, an antioxidant, an ultraviolet absorber, a heat stabilizer, a crystallization accelerator, a dispersant, a surface conditioner, a defoaming agent, and adhesion imparting. Agents, solvents (for example, organic solvents) and the like.

[6] Preparation of heat conductive resin composition The heat conductive resin composition comprises an epoxy compound (A), an amine compound (B), a heat conductive filler (C), and other components used as necessary. Can be prepared by mixing The mixing method is not particularly limited, and a kneader such as a roll, a kneader, a Banbury mixer, a planetary mixer, or a vacuum defoaming stirrer can be used. If bubbles are mixed during mixing, the cured product and the heat conductive sheet may adversely affect mechanical properties such as tensile strength and tear strength and electrical properties such as thermal conductivity. Therefore, a mixing device capable of suppressing the incorporation 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 aspect of the present invention, in the heat conductive resin composition, the epoxy compound (A) includes two or more epoxy groups in one molecule, has an epoxy equivalent of 400 to 2,000, and has a structure other than the polyethylene glycol structure. Or the following formula [1]:

(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.)
Wherein the amine compound (B) has four or more amine hydrogens in one molecule, and has an amine hydrogen equivalent of 80 to 1,000, and the amine compound (B) The ratio of the number of amine hydrogens contained in the epoxy compound to the number of epoxy groups contained in the epoxy compound (A) (the number of amine hydrogens / the number of epoxy groups) is 0.2 to 5, and the epoxy compound (A) and the amine compound The heat conductive filler (C) is contained in an amount of 100 parts by mass to 1,000 parts by mass based on 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 thermally conductive resin composition are chain compounds containing no olefin structure.

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

  According to the cured product obtained by curing the heat conductive resin composition according to the first embodiment, the cured product can have a hardness value of 95 or less, more preferably 80 or less, and still more preferably 65 or less. The hardness value here is Asker C hardness measured using an Asker C hardness meter in accordance with JIS K 7312. Whether the hardness of the cured molded product is measured by the Asker C, type D durometer, or type A durometer is appropriately selected in consideration of the application and properties of the object to be measured. The hardness of the molded product is measured according to Asker C standard. If the hardness is less than Asker C95, the molded product follows irregularities, the adhesion is improved, and the heat dissipation is improved. A material whose Asker C hardness of the cured product is less than Asker C95 is a soft material, and the followability to the uneven surface is improved, and the heat dissipation is improved. 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.

  In addition, the cured product according to the present embodiment has excellent electrical insulation, heat resistance, moisture resistance, and water resistance because the cross-linking site is composed of an epoxy-amine cross-linking site.

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

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

  When the heat conductive sheet has a low Asker C hardness (excellent in flexibility), it can suppress air entrapment at the time of sticking to a member (a heat-generating component or a cooling member), thereby improving the adhesion. Accordingly, the contact resistance at the interface between the member and the heat conductive sheet is reduced, so that the total thermal resistance of the entire product is reduced, and excellent heat dissipation can be realized.

  In addition, when the surface of the member to which the heat conductive sheet is attached has irregularities, air entrapment is likely to occur when the heat conductive sheet is attached, but the heat conductive sheet according to the present embodiment has According to this, since it is possible to exhibit high flexibility, it is possible to follow the irregularities, and it is possible to make the heat conductive sheet adhere to the member without intervening air which causes a reduction in heat radiation. Become.

  In addition, the heat conductive sheet according to the present embodiment can have excellent electrical insulation, heat resistance, moisture resistance, and water resistance because the cross-linking site is an epoxy-amine cross-linking site.

  The heat conductive 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. It is more preferably at least 3 W / (m · K), particularly preferably at least 1.5 W / (m · K). In addition to increasing the flexibility of the heat conductive sheet to reduce the total thermal resistance with the member to be affixed, the heat conductive sheet itself has excellent heat conduction performance, which is a characteristic of the whole product, , Better heat radiation can be realized. Even when the thermal conductivity is smaller than 1.0 W / (m · K), according to the thermal conductive sheet according to the present embodiment, the total thermal resistance is reduced by utilizing its flexibility, and It is possible to secure the required heat dissipation, but in order to obtain better heat dissipation of the product, the thermal conductivity of the heat conductive sheet must be 1.0 W / (m · K) or more. Is preferred.

  According to the heat conductive sheet according to the present embodiment, it is possible to exhibit sufficient flexibility even when a relatively large amount of the heat conductive filler (C) is contained in order to increase the heat 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. When the thickness of the heat conductive sheet is less than 0.1 mm, the handleability of the heat conductive sheet may be reduced. If the thickness of the heat conductive sheet exceeds 5 mm, the heat resistance may increase and the heat dissipation may decrease.

Embodiment 4. FIG. Method for Manufacturing Heat Conductive Sheet The method for manufacturing a heat conductive sheet according to the present embodiment can be suitably used as a method for manufacturing the heat conductive sheet according to Embodiment 3, and includes the following steps.

  A step of forming the thermally conductive resin composition according to the first embodiment into a sheet to obtain a sheet-shaped molded article, and a step of curing the sheet-shaped molded article by heating.

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

  In the step of obtaining a sheet-shaped molded product, the method of forming the thermally conductive resin composition into a sheet is not particularly limited, and the method can be performed using a press, a roll, a bar coater, or the like. Among them, roll forming is preferred from the viewpoint of production efficiency.

  Examples of a method of curing the sheet-like 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. Among them, a heating method is preferably used.

  The heating temperature at the time of curing by heating is, for example, 80 to 150 ° C, and preferably 120 to 140 ° C. The heating time is, for example, 0.5 to 72 hours, preferably 2 to 48 hours. After the curing step, 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 of an air atmosphere, a nitrogen atmosphere, an argon atmosphere, and 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 heat conductive resin composition Epoxy compound (A), amine compound (B) and heat conductive filler (C) shown in Tables 1 to 3 were blended in the amounts shown in the 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 amount of the amine compound (B) shown in the same 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 parts by mass with respect to 100 parts by mass of the total amount of the epoxy compound (A) and the amine compound (B).

  The kind of the epoxy compound (A) used, the number of epoxy groups and the epoxy equivalent in one molecule, the kind of the amine compound (B), the number of amine hydrogens and the equivalent of amine hydrogen in one molecule, the amine hydrogen of the amine compound (B) The ratio of the number to the number of epoxy groups of the epoxy compound (A) (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 also show the types and amounts of the compounds.

Details of the components shown in Tables 1 to 3 are as follows.
[1] A-1: polytetramethylene glycol diglycidyl ether (“Epogoose 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 (“Epogoose 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 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 heat conductive sheet The obtained heat conductive resin composition was poured into a 100 mL fluorocarbon resin beaker so that the thickness after curing became 10 mm, and the conditions shown in Tables 1 to 3 were used. To obtain a cured product for hardness measurement.

  Further, the obtained heat conductive resin composition was coated on a fluororesin sheet by a bar coater so as to have a thickness of 1.0 mm after curing, and heated under the conditions shown in Tables 1 to 3. After curing, a heat conductive sheet for measuring heat conductivity was obtained.

(3) Evaluation Test (3-1) Hardness Asker C hardness was measured for the cured product for hardness measurement 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 A disk-shaped sheet having a diameter of 10 mm was cut out from the thermal conductive sheet for measuring the thermal conductivity, and this was used as a measurement sample. The thermal conductivity [W / (m · K)] of the obtained measurement sample was measured by a laser flash method (unsteady method). The results are shown in Tables 1 to 3.

  In Examples 1 to 34, it was possible to reduce the hardness of the cured product while maintaining good electrical insulation. For example, comparing Example 1 to Example 27 and Comparative Example 1 to Comparative Example 8, they have the same content of the thermally conductive filler (C). However, in Comparative Example 1 to Comparative Example 8, the amine compound is used. The ASKER C hardness did not become 95 or less because the amine hydrogen equivalent of (B) was not in the predetermined range. In Comparative Example 9 as well, although the content of the thermally conductive filler (C) was smaller than that of Comparative Examples 1 to 8, the amine hydrogen equivalent of the amine compound (B) was not in the predetermined range. C hardness did not become 95 or less. When Examples 1 to 27 and Comparative Example 10 are compared, they have the same content of the thermally conductive filler (C). However, in Comparative Example 10, the epoxy compound (A) has a predetermined epoxy equivalent. , The ASKER C hardness did not become 95 or less. Since the cured products obtained in Examples 1 to 34 were obtained from a curable resin composition containing a resin having no olefin structure and no polyethylene glycol structure as a resin component, heat resistance and moisture resistance were obtained. It is understood that they have excellent properties and water resistance.

  When the AH / EP ratio is largely 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 becomes lower. 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 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 lower 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 (11)

Thermal conductivity including an epoxy compound (A) containing two or more epoxy groups in one molecule, an amine compound (B) containing four or more amine hydrogens in one molecule, and a thermally conductive filler (C) A resin composition,
The epoxy compound (A) has a polyether structure other than the polyethylene glycol structure or the following formula [1]:

(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.)
Having a (meth) acrylic structure represented by the formula, having an epoxy equivalent of 400 to 2,000,
The amine compound (B), polypropylene glycol structure or a poly (tetramethylene ether glycol), / polypropylene glycol having one polyether structure of the copolymer structure, Ri 1000 der amine hydrogen equivalent weight is 80,
A thermally conductive resin composition wherein the ratio of the number of amine hydrogens in the amine compound (B) to the epoxy group in the epoxy compound (A) (the number of amine hydrogens / the number of epoxy groups) is 0.22 to 5; . The polyether structure of the epoxy compound (A) has the following formula [2]:

(In the formula [2], R ³ represents a chain alkylene group.)
The heat conductive resin composition according to claim 1, which has a structure containing two or more structural units represented by the formula: The total amount 100 parts by weight of the pre-Symbol epoxy compound (A) and the amine compound (B), containing 1000 parts by weight of the thermally conductive filler (C) from 100 parts by weight, according to claim 1 or claim 2 Heat conductive resin composition.   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 terminal. The epoxy compound (A) and the amine compound (B) have a polyether structure other than the polyethylene glycol structure,
The polyether structure has the following formula [4]:

And a structural unit represented by the following formula [5]:

The heat conductive resin composition according to any one of claims 1 to 4 , wherein the composition comprises a total of two or more structural units selected from the group consisting of structural units represented by: Stuff. 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, The Claims 1-3 characterized by the above-mentioned. 6. The heat conductive resin composition according to any one of items 5 to 5 . Relative to the total amount 100 parts by weight of the epoxy compound (A) and the amine compound (B), the thermally conductive filler (C) comprises 450 parts by mass 230 parts by mass, any of claims 1 to 6 2. The heat conductive resin composition according to claim 1. A cured product of the heat conductive resin composition according to any one of claims 1 to 7 . The cured product according to claim 8 , having an ASKER C hardness of 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 7 . A method for producing a thermally conductive sheet,
A step of forming the thermally conductive resin composition according to any one of claims 1 to 7 into a sheet to obtain a sheet-like molded product,
A step of curing the sheet-like molded product by heating,
And a manufacturing method.