Curable resin composition and gap filler

Abstract

To provide a curable resin composition that contributes to reducing the abrasiveness of gap fillers, while achieving both low viscosity and high thermal conductivity.SOLUTION: A curable resin composition comprises a polyol, a polyisocyanate, and an inorganic filler, where the inorganic filler includes at least a first inorganic filler, which is an inorganic filler surface-coated with zinc molybdate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable resin composition and a gap filler.

Background Art

[0002] In recent years, with the miniaturization and high performance of electronic devices, heat dissipation measures for electronic devices have become an issue, and the development of various thermally conductive materials has been progressing. The thermally conductive materials to be developed can be roughly divided into a filler to be filled and a resin. As the filler, alumina and magnesium oxide are known, and as the resin, silicone resins and urethane resins are known.

[0003] For example, Patent Document 1 reports an isocyanate-containing composition containing an isocyanate group-containing urethane polymer, an inorganic filler, a plasticizer, and at least one compound selected from the group consisting of a phosphate ester, a sulfate ester, a sulfonic acid, and a carboxylic acid. It is disclosed that the inorganic filler is a metal oxide such as alumina and magnesium oxide, a metal hydroxide such as aluminum hydroxide and magnesium hydroxide, a metal nitride such as aluminum nitride and boron nitride, and the like.

[0004] Further, Patent Document 2 reports a curable composition containing a polyol (A), a polyisocyanate (B), at least one dispersant (C) for an inorganic filler selected from the group consisting of a phosphate ester (C1), a fatty acid having 12 to 24 carbon atoms (C2), a sucrose fatty acid ester (C3), a sorbitan fatty acid ester (C4), and a glycerin fatty acid ester (C5), and an inorganic filler (D). It is disclosed that the inorganic filler (D) is titanium oxide, alumina, magnesium oxide, a metal nitride, a metal hydroxide, and the like.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Thermal conductive materials can be used appropriately according to applications such as sheets, potting, adhesives, greases, and gap fillers. In particular, with the electrification of automobiles, the demand for gap fillers with excellent performance and reliability is increasing.

[0007] Normally, a gap filler is applied through a dispenser. However, since it contains a large amount of abrasive thermal conductive inorganic filler, the equipment wears out severely and regular part replacement is necessary. Therefore, a gap filler with low abrasiveness is required to reduce the running cost.

[0008] However, in any of the patent documents, the inventions mainly relate to the structure and physical properties of dispersants for inorganic fillers and resins. The inorganic fillers used are metal oxides such as general alumina and titanium oxide, and sufficient consideration has not been given to reducing the abrasiveness of gap fillers.

[0009] The present invention has been made to solve the above problems, and an object thereof is to provide a curable resin composition that contributes to reducing the abrasiveness of a gap filler and has both low viscosity and high thermal conductivity. [Means for Solving the Problems]

[0010] As a result of intensive studies, the present inventors have found that a resin composition containing an inorganic filler surface-coated with a specific substance can solve the above problems.

[0011] (1) A curable resin composition containing a polyol, a polyisocyanate, and an inorganic filler, wherein the inorganic filler contains at least an inorganic filler (first inorganic filler) surface-coated with zinc molybdate. (2) The curable resin composition according to (1) above, further containing a plasticizer, wherein the plasticizer contains at least a phosphate ester. (3) The curable resin composition according to (1) or (2) above, wherein the inorganic filler further contains one or more inorganic fillers (second inorganic fillers) selected from the group consisting of metals, metal oxides, metal nitrides, metal hydroxides, and metal carbonates. (4) The curable resin composition according to (3) above, wherein the second inorganic filler is magnesium carbonate. (5) The curable resin composition according to any one of (1) to (4) above, wherein the first inorganic filler is talc. (6) The curable resin composition according to any one of (1) to (5) above, wherein the porosity of the inorganic filler is 15 to 28%. Porosity = total pore volume (Vp) × bulk density × 100 (7) A gap filler comprising the curable resin composition according to any one of (1) to (6) above. (8) The gap filler according to (7) above, having a thermal conductivity of 2 to 5 W / m·K. [Advantages of the Invention]

[0012] According to the present invention, it is possible to provide a curable resin composition and a gap filler having reduced abrasiveness, low viscosity, and high thermal conductivity. [Embodiments for Carrying Out the Invention]

[0013] Hereinafter, embodiments of the present invention will be described in detail.

[0014] [Curable Resin Composition] The curable resin composition of the present invention contains a polyol, a polyisocyanate, and an inorganic filler, and is characterized in that the inorganic filler contains at least an inorganic filler (first inorganic filler) surface-coated with zinc molybdate.

[0015] The curable resin composition of the present invention relates to a two-component reaction type polyurethane resin composition substantially using a reaction product of a polyol and a polyisocyanate.

[0016] (Polyol) Examples of the polyol include polyester polyol, polyether polyol, polycarbonate polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, etc. These polyols may be used alone or in combination of two or more.

[0017] As the polyester polyol, one or more low molecular weight compounds having three or more active hydrogen atoms (for example, compounds having a molecular weight of 50 or more and less than 500) are used as initiators, and a reaction product obtained by esterifying a low molecular weight polyol and a polycarboxylic acid; a ring-opening polymer of a cyclic ester compound such as ε-caprolactone; a copolymer of the esterification reaction product or the ring-opening polymer, etc. can be used.

[0018] Examples of the low molecular weight polyols that can form polyester polyols through an esterification reaction with polycarboxylic acids include aliphatic polyols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2 - propanediol, 1,3 - propanediol, dipropylene glycol, tripropylene glycol, 1,2 - butanediol, 1,3 - butanediol, 1,4 - butanediol, 2,3 - butanediol, 1,5 - pentanediol, 1,5 - hexanediol, 1,6 - hexanediol, 2,5 - hexanediol, 1,7 - heptanediol, 1,8 - octanediol, 1,9 - nonanediol, 1,10 - decanediol, 1,11 - undecanediol, 1,12 - dodecanediol, 2 - methyl - 1,3 - propanediol, neopentyl glycol, 2 - butyl - 2 - ethyl - 1,3 - propanediol, 3 - methyl - 1,5 - pentanediol, 2 - ethyl - 1,3 - hexanediol, 2 - methyl - 1,8 - octanediol; alicyclic polyols such as 1,4 - cyclohexanedimethanol; hydroquinone, resorcinol; aromatic polyols such as bisphenol A, bisphenol F, 4,4’ - biphenol, etc.

[0019] Examples of the polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and their anhydrides or esterified products, etc.

[0020] Examples of the polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, polyoxypropylene polyoxytetramethylene glycol, etc.

[0021] Examples of the polycarbonate polyol include reaction products obtained by using one or more low molecular weight compounds having three or more active hydrogen atoms (e.g., compounds having a molecular weight of 50 or more and less than 500) as initiators and reacting a carbonic acid ester and / or phosgene with a low molecular weight polyol. As the carbonic acid ester, one or more can be used. Examples include aliphatic carbonates such as alkyl carbonates (e.g., methyl carbonate, ethyl carbonate, etc.), dialkyl carbonates (e.g., dimethyl carbonate, diethyl carbonate, etc.); carbonates containing an alicyclic structure such as cyclo carbonate (hereinafter, “containing an alicyclic structure” may be simply referred to as “alicyclic”); and aromatic carbonates such as diphenyl carbonate.

[0022] From the viewpoint of excellent heat resistance and high temperature and humidity resistance, polybutadiene polyol, hydrogenated polybutadiene polyol, etc. are preferred. Examples of such commercially available polyols include Hybrin (registered trademark) XLA-8054A-4 (manufactured by Mitsui Chemicals, Inc.), NISSO-PB GI-1000 (manufactured by Nippon Soda Co., Ltd.), NISSO-PB GI-2000 (manufactured by Nippon Soda Co., Ltd.), NISSO-PB GI-3000 (manufactured by Nippon Soda Co., Ltd.), Poly bd R15HT (manufactured by Idemitsu Kosan Co., Ltd.), Poly bd R45HT (manufactured by Idemitsu Kosan Co., Ltd.), Pandex GCB41 (manufactured by DIC Corporation), etc.

[0023] The number average molecular weight of the polyol is not particularly limited, but is preferably in the range of, for example, 700 to 10,000, and more preferably in the range of 1,000 to 10,000. Being within this range provides excellent moldability and stability over time of the resulting resin composition. In this specification, the number average molecular weight can be calculated by the gel permeation chromatography (GPC) method.

[0024] (Polyisocyanate) The polyisocyanates include, for example, aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, etc. These may be used alone or in combination of two or more kinds.

[0025] Examples of the aromatic polyisocyanates include phenylenediisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, etc.

[0026] Examples of the aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

[0027] Examples of the alicyclic polyisocyanates include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, etc.

[0028] In addition, carbodiimide-modified polyisocyanates, castor oil-modified polyisocyanates, biuret-modified polyisocyanates, allophanate-modified polyisocyanates, polymethylene polyphenyl polyisocyanates (polymeric MDI), isocyanurate-modified polyisocyanates, etc. of the aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates are included.

[0029] From the viewpoint of viscosity inhibition, hexamethylene diisocyanate is preferable, and from the viewpoint of heat resistance, isophorone diisocyanate is preferable. Examples of commercially available products of such polyisocyanates include Hybrin (registered trademark) XLA-8054A-5 (manufactured by Mitsui Chemicals, Inc.), Pandex GCA11 (manufactured by DIC Corporation), and the like.

[0030] In the resin composition of the present invention, it is preferable that the blending ratio of the polyol and the polyisocyanate is such that the polyisocyanate is in excess. The blending ratio may be determined by the ratio (molar ratio) of the isocyanate group to the hydroxyl group, and it is preferably Isocyanate group:Hydroxyl group = 1.5 to 2.5:1, and more preferably 1.7 to 2.3:1. When within the above range, the reaction can proceed efficiently to form a polyurethane resin.

[0031] In this specification, the isocyanate group content can be measured by the potentiometric titration method in accordance with JIS K1603-1:2007.

[0032] In the resin composition of the present invention, the total mass of the polyol and the polyisocyanate is preferably 5 to 30% by mass, and more preferably 7 to 15% by mass, when the total mass of the resin composition is 100% by mass.

[0033] In addition, in this embodiment, commercially available gel urethane in which a polyol component and a polyisocyanate component are blended in advance can also be used. Examples of gel urethane include Pandex GC (manufactured by DIC Corporation), SU-4500A / B (manufactured by Sun Yurek Co., Ltd.), MU-120A / MU-120B (manufactured by Bernox Co., Ltd.), and the like.

[0034] (First inorganic filler) The first inorganic filler of the present invention is not particularly limited, but is characterized by containing at least an inorganic filler surface-coated with zinc molybdate.

[0035] In this specification, "surface coating" more specifically means that zinc molybdate is supported on the particle surface. Also, the state of support may be either that it is supported without gaps throughout the particles or that it is partially supported.

[0036] Examples of the inorganic filler surface-coated with zinc molybdate include metals such as gold, silver, copper, and their alloys; metal oxides such as alumina, titanium oxide, magnesium oxide, and silica; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; metal carbonates such as calcium carbonate and magnesium carbonate; metal nitrides such as aluminum nitride, boron nitride, and silicon nitride; and silicates such as talc, mica, and glass. From the viewpoints of high thermal conductivity and low Mohs hardness, zinc oxide, aluminum hydroxide, magnesium hydroxide, and talc are preferred, and talc is particularly preferred.

[0037] (Second inorganic filler) In the present invention, as the second inorganic filler, an inorganic filler not surface-coated with zinc molybdate can be further included.

[0038] The second inorganic filler is not particularly limited, and examples thereof include the same ones as the first inorganic filler. From the viewpoints of chemical stability, high thermal conductivity, and low Mohs hardness, alumina and magnesium carbonate are preferred.

[0039] The second inorganic filler may be used alone or in combination of two or more. When used in combination of two or more, different filler types can be used so that characteristics suitable for the application can be obtained. For example, if it is desired to improve the thermal conductivity, aluminum hydroxide or alumina can be blended, and if it is desired to improve the abrasion resistance, it is preferably composed only of magnesium carbonate.

[0040] Also, even when using the same type of filler, it is also preferable to blend and use a plurality of fillers having different average particle diameters (D50) as described later. By blending a plurality of fillers having different average particle diameters (D50), the filler can take a closest-packed structure, and as a result, it is possible to improve the thermal conductivity, which is preferable.

[0041] The shape of the inorganic filler is not particularly limited, and examples include plate-like, spherical, polyhedral, card house-like (aggregation of a plurality of plate-like particles), etc. From the viewpoint of further improving the thermal conductivity, a polyhedral shape is preferable.

[0042] The average particle diameter (D50) of the inorganic filler is not particularly limited, but for example, it is preferably 0.001 μm to 100 μm, more preferably 0.01 μm to 50 μm, and particularly preferably 0.1 μm to 30 μm. The average particle diameter (D50) can be measured by a laser diffraction scattering particle size distribution measurement method.

[0043] The porosity of the inorganic filler of the present invention may be 15 to 28%, and more preferably 17 to 26%. When within the above range, it is possible to further improve the reduction of the viscosity and the increase in the thermal conductivity of the resulting resin composition, which is preferable.

[0044] The porosity can be calculated by the following formula. Porosity = total pore volume Vp × bulk density × 100

[0045] The total pore volume Vp can be calculated from the bulk density and the true density, and the true density can be obtained by the ratio with the theoretical density of the inorganic filler used. Total pore volume Vp = (1 / bulk density) - (1 / true density)

[0046] The bulk density can be measured using a density analyzer (for example, GeoPyc (registered trademark) Model 1360 density analyzer (Micromeritics, Norcross, GA)). Specifically, a compressive force of 180 N is applied to the sample by a plunger, and the linear distance traveled by the plunger is converted into the volume displacement of the powder sample. Then, the average of the measured values is converted into the calculated bulk density value (g / cm 3 represented) of the sample.

[0047] In the present invention, an inorganic filler (first inorganic filler) surface-coated with zinc molybdate is essential, and an uncoated inorganic filler (second inorganic filler) can be used in combination. When two or more types of inorganic fillers are used in combination, the porosity is calculated in the state of the mixture.

[0048] The content of the inorganic filler may be 50 to 95% by mass, preferably 70 to 95% by mass, and particularly preferably 85 to 95% by mass when the total solid content of the resin composition is 100% by mass. When within the above range, the resulting resin composition has excellent thermal conductivity, which is preferable.

[0049] When the first inorganic filler and the second inorganic filler are used in combination, the blending amount of the first inorganic filler is not particularly limited. For example, when the total amount of the inorganic filler is 100% by mass, it may be more than 0% by mass and 100% by mass or less, preferably 1% by mass or more and 50% by mass or less, and more preferably more than 1% by mass and less than 10% by mass. When within the above range, it is preferable because the resulting resin composition has excellent abrasion resistance. 。

[0050] (Plasticizer) The resin composition of the present invention can further contain a plasticizer, and the plasticizer contains at least a phosphate ester. The phosphate ester is not particularly limited, and examples thereof include Disparon DA-375 (manufactured by Kusumoto Chemicals, Ltd.), Pliserf A208N (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Phosphanol RL-210 (manufactured by Toho Chemical Industry Co., Ltd.), Phosphanol RS-710 (manufactured by Toho Chemical Industry Co., Ltd.), Phosphanol RS-410 (manufactured by Toho Chemical Industry Co., Ltd.), and the like.

[0051] The content of the phosphate ester may be in a range that does not inhibit the effects of the present invention. For example, when the total solid content of the resin composition is 100% by mass, it is preferably 0.5 to 8% by mass, and more preferably 1 to 5% by mass.

[0052] Examples of plasticizers other than phosphate esters include phthalic acid-based ones such as phthalic acid diesters, adipic acid diesters, diisononyl phthalate, and diisodecyl phthalate; fatty acid ester-based ones such as di-(2-ethylhexyl) adipate, di-(2-ethylhexyl) azelate, and dibutyl sebacate; epoxy-based ones; polyester-based ones; and sulfonic acid ester-based ones. From the viewpoint of bleed resistance during heat resistance and durability tests, it is preferably a plasticizer with high compatibility and high heat resistance.

[0053] The content of the plasticizer may be in a range that does not inhibit the effects of the present invention. For example, when the total solid content (excluding the inorganic filler content) of the resin composition is 100% by mass, it is preferably 50 to 90% by mass, and more preferably 55 to 85% by mass.

[0054] (Others) If necessary, a urethanization catalyst, a surfactant, an antioxidant, an ultraviolet absorber, etc. can be blended within a range that does not inhibit the effects of the present invention.

[0055] The resin composition in this embodiment preferably has a viscosity at 25°C in the range of 50 Pa·s or more and 2,000 Pa·s or less, more preferably 100 Pa·s or more and 1,000 Pa·s or less, and particularly preferably 100 Pa·s or more and 350 Pa·s or less. When the viscosity of the non-flowing reactant formed after being applied to the substrate is within the above range, it is suitable for application to the substrate by a dispenser or the like.

[0056] 〔Use〕 Since the resin composition of the present invention is excellent in thermal conductivity, it can be widely applied to electric and electronic components, semiconductor elements, etc. as a heat dissipation material. However, due to its low wear property and low viscosity, it can be particularly preferably used as a gap filler.

Examples

[0057] Hereinafter, the present invention will be described in more detail based on examples, but this description does not limit the present invention.

[0058] 〔Examples 1 to 10, Comparative Examples 1 and 2〕 A polyol, an isocyanate, a first inorganic filler, and a second inorganic filler were mixed at the blending ratios shown in Tables 1 and 2 to obtain a resin composition.

[0059] 〔Evaluation method〕 The obtained resin composition was evaluated according to the following method.

[0060] (Thermal conductivity) Each of the obtained resin compositions was injected into a frame mold and cured at 70°C for 3 hours to obtain a sheet cured product with a thickness of 1 mm. The thermal diffusivity and specific heat of the produced sheet cured product at 25°C were measured using a thermal conductivity measuring device (LFA467 HyperFlash, manufactured by NETZSCH). Next, the density of this heat dissipation member was measured by the Archimedes method. The thermal conductivity of this heat dissipation member was estimated from the product of the obtained thermal diffusivity, specific heat, and density.

[0061] (Wear property) Each resin composition was cured to a thickness of 1.6 mm, and the wear rate of the drill bit after drilling 2000 holes at 150000 revolutions / min with a drill (drill diameter 0.3 mm) was evaluated by the ratio (percentage) of the area of the drill bit worn by the drilling to the area of the drill bit before the drilling with respect to the area of the drill bit before the drilling. The wear resistance was evaluated according to the following criteria. 〇: Less than 10% △: 10% or more and less than 20% ×: 20% or more

[0062] (Viscosity measurement) The viscosity of the obtained resin composition was measured at a viscosity (25 °C) using an E-type viscometer TVE-20H (manufactured by Toki Sangyo Co., Ltd.).

[0063] (Compressed bulk density) The inorganic filler obtained by the formulation in Table 1 was measured using a density analyzer (for example, GeoPyc (registered trademark) Model 1360 density analyzer (Micromeritics, Norcross, GA)). Specifically, a compressive force of 180 N was applied to the inorganic filler by a plunger, and the linear distance traveled by the plunger was converted into the volume displacement of the inorganic filler. Then, the average of the measured values was converted into the calculated bulk density value (g / cm 3 represented) and calculated.

[0064] (Porosity) Using the calculated compressed bulk density, it can be calculated by the following formula. Porosity = Total pore volume Vp × Compressed bulk density × 100

[0065]

Table 1

[0066]

Table 2

Claims

1. Contains a polyol, a polyisocyanate, and an inorganic filler, The curable resin composition, wherein the inorganic filler comprises at least an inorganic filler (first inorganic filler) whose surface is coated with zinc molybdate.

2. The curable resin composition according to claim 1 , further comprising a plasticizer, the plasticizer including at least a phosphoric acid ester.

3. The curable resin composition according to claim 1, wherein the inorganic filler further comprises one or more inorganic fillers (second inorganic fillers) selected from the group consisting of metals, metal oxides, metal nitrides, metal hydroxides, and metal carbonates.

4. The curable resin composition according to claim 3 , wherein the second inorganic filler is magnesium carbonate.

5. The curable resin composition according to claim 1 , wherein the first inorganic filler is talc.

6. The curable resin composition according to any one of claims 1 to 5, wherein the inorganic filler has a porosity of 15 to 28%. Porosity = total pore volume (Vp) x compressed bulk density x 100

7. A gap filler comprising the curable resin composition according to claim 6.

8. 8. The gap filler of claim 7, having a thermal conductivity of 2 to 5 W / m·K.

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