Silicone resin composition

Abstract

To provide a silicone resin composition that holds its flowability even when filled with a high proportion of thermally conductive filler, and has excellent handleability.SOLUTION: A silicone resin composition contains (A) an organopolysiloxane represented by the formula (1), with a molecular weight distribution (Mw / Mn) of 1.20 or less, and (B) thermally conductive filler. (In the formula (1), R1 independently represent a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group, and X is a branched alkyl ether or a linear alkyl ether having a hydroxy group at an end).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a silicone resin composition that retains fluidity and has excellent handleability even when highly filled with a thermally conductive filler to impart thermal conductivity. [Background technology]

[0002] Many electronic components generate heat during use, and it is necessary to remove the heat in order to maintain their functionality. In particular, the amount of heat generated by recent electronic components increases with the increasing integration and power output of circuit boards, making heat countermeasures an important issue.

[0003] As a means for removing heat from electronic components, a method has been proposed in which a thermally conductive material such as thermally conductive grease or sheet is interposed between the electronic components and a cooling member such as a heat sink to release heat from the electronic components. One such thermally conductive material is a silicone resin composition made of organopolysiloxane and a thermally conductive filler such as aluminum oxide powder or zinc oxide powder (see Patent Document 1, Patent Document 2, or Patent Document 3).

[0004] In the above thermal conductive materials, the Bruggman model is known as a formula for predicting thermal conductivity. This formula shows that when the filling rate of the thermal conductive filler is low, the thermal conductivity hardly changes regardless of the filling rate, but when the filling rate exceeds a certain level, the thermal conductivity increases rapidly. In other words, in order to increase the thermal conductivity of a thermal conductive material, it is important to fill it with as much thermal conductive filler as possible.

[0005] On the other hand, when the filling rate of the thermally conductive filler is increased, the fluidity of the resin composition used in the thermally conductive material is significantly reduced, making it difficult to discharge or apply the resin composition, and the resin composition is unable to follow the fine irregularities on the surfaces of electronic components and heat sinks, resulting in a problem of increased contact thermal resistance. As a method for solving this problem, a method of using an additive to improve the dispersibility of the thermally conductive filler in the resin composition is known. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-054099 A [Patent Document 2] JP 2004-091743 A [Patent Document 3] JP 2000-063873 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a silicone resin composition which not only retains fluidity and has good workability even when highly filled with a thermally conductive filler, but also conforms to the surface irregularities of electronic components and the like to reduce contact thermal resistance, thereby exhibiting high heat dissipation performance. [Means for solving the problem]

[0008] As a result of intensive research aimed at solving the above problems, the present inventors discovered that a combination of a polyorganosiloxane having a specific structure and a molecular weight distribution (Mw / Mn) of 1.20 or less, and a silicone resin composition containing a thermally conductive filler is useful, and thus completed the present invention.

[0009] That is, according to the present invention, there is provided the following silicone resin composition. Term 1.(A) Formula (1): TIFF0007632143000001.tif2143 (in formula (1), R 1 are independently a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group, X is a group having a hydroxyl group at its terminal and represented by formula (2) or formula (3), and n is an integer of 1 or more. TIFF0007632143000002.tif2052 TIFF0007632143000003.tif653 and an organopolysiloxane having a molecular weight distribution (Mw / Mn) of 1.20 or less. (B) Thermally conductive filler A silicone resin composition comprising: Effect of the Invention

[0010] The silicone resin composition of the present invention has excellent workability because it maintains its fluidity even when highly filled with a thermally conductive filler. In addition, it conforms to the irregularities on the surfaces of electronic components and heat sinks, and therefore has high heat dissipation performance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described, however, the present invention is not limited to the following embodiment.

[0012] [Component (A)] Component (A) is an organopolysiloxane having a hydroxyl group at one end and represented by formula (1).

[0013] TIFF0007632143000004.tif2143 (in formula (1), R 1 are independently a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group, X is a group represented by formula (2) having two terminal hydroxyl groups or a group represented by formula (3) having one terminal hydroxyl group, and n is an integer of 1 or more. TIFF0007632143000005.tif2052 TIFF0007632143000006.tif653

[0014] Examples of the monovalent saturated hydrocarbon group include linear alkyl, branched alkyl, and cyclic alkyl. Examples of the linear alkyl include methyl, ethyl, propyl, and n-butyl. Examples of the branched alkyl include isopropyl, isobutyl, tert-butyl, and 2-ethylhexyl. Examples of the cyclic alkyl include cyclopentyl and cyclohexyl. Examples of the monovalent aromatic hydrocarbon group include phenyl and tolyl.

[0015] Specific examples of the component (A) include FM-DA11, FM-DA21, FM-DA25, FM-DA26, FM-0411, FM-0421, FM-0425, and FM-0426 (each of which is a trade name) manufactured by JNC Corporation.

[0016] When the ratio of the weight average molecular weight (Mw) and number average molecular weight (Mn) of the component (A) in terms of polystyrene, measured by gel permeation chromatography (GPC), is taken as the molecular weight distribution (Mw / Mn), the Mw / Mn must be 1.20 or less. If the molecular weight distribution (Mw / Mn) is within this range, the content of high molecular weight components and low molecular weight components that inhibit dispersion becomes small, and a silicone resin composition with excellent flowability can be obtained.

[0017] [(B) Component] The component (B) functions as a thermally conductive filler in the silicone resin composition of the present invention. The component (B) may be used alone or in combination of two or more types.

[0018] Specific examples of component (B) include aluminum oxide, aluminum nitride, boron nitride, zinc oxide, diamond, graphene, graphite, carbon nanotubes, carbon fibers, glass fibers, and combinations of two or more of these. There are no particular limitations on the crystal form, particle size, surface condition, or surface treatment of component (B).

[0019] [(C) component] The composition of the present invention may further contain an organopolysiloxane other than (A) as component (C). Component (C) is used appropriately for the purpose of adjusting the viscosity of the thermally conductive silicone resin composition of the present invention, imparting curability, etc., but is not limited thereto. Component (C) may be used alone or in combination of two or more, and may be non-curable or curable by heat, moisture, or exposure to active energy rays.

[0020] Specific examples of component (C) include dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxy-modified polysiloxane, carbinol-modified polysiloxane, polyether-modified polysiloxane, alkyl-modified polysiloxane, fluorine-modified polysiloxane, or a combination of two or more of these.

[0021] In the silicone resin composition of the present invention, the content of the (A) component is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 30 parts by mass, relative to 100 parts by mass of the (B) component. When the content of the (A) component is within this range relative to 100 parts by mass of the (B) component, a dispersion in which the (B) component is stably dispersed can be obtained, and the filling rate of the (B) component can be sufficiently ensured, resulting in sufficient heat dissipation. The total content of the (A) component and the (C) component is preferably 0.1 to 50 parts by mass, more preferably 1.0 to 30 parts by mass, relative to 100 parts by mass of the (B) component.

[0022] The silicone resin composition of the present invention preferably has a viscosity of 1000 Pa·s or less at 25° C. When the viscosity is within this range, the composition has good fluidity and is easy to handle during dispensing, application, and the like.

[0023] The silicone resin composition of the present invention may contain various additives such as other surfactants, plasticizers, antifoaming agents, and curing agents, provided the intended purpose of the composition is not impaired. EXAMPLES

[0024] The present invention will be described in more detail below. In the examples, "parts" and "%" are all based on mass (parts by mass, % by mass) unless otherwise specified. The present invention is not limited to these examples.

[0025] <Molecular weight measurement> The molecular weight of the organopolysiloxane was measured by gel permeation chromatography (GPC), and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) was taken as the molecular weight distribution (Mw / Mn). Polystyrene was used as a standard sample to measure the molecular weight in terms of polystyrene. The measurement of the molecular weight in terms of polystyrene by the GPC method was carried out under the following measurement conditions. a) Measuring equipment: JASCO HPLC LC-2000Plus series b) Column: Shodex KF-804L x 2 c) Oven temperature: 40℃ d) Eluent: toluene 0.7 mL / min e) Standard sample: polystyrene f) Injection volume: 20μL g) Concentration: 0.05g / 10mL h) Sample preparation: Toluene was used as a solvent and the sample was dissolved by stirring at room temperature.

[0026] <Preparation of samples for fluidity evaluation> As the component (A), polydimethylsiloxanes (A-1) to (A-4) represented by formula (4) and polydimethylsiloxanes (A-5) to (A-8) represented by formula (5) were used.

[0027] TIFF0007632143000007.tif2082 (In formula (4), n is an integer arbitrarily selected so as to obtain the number average molecular weight shown in Table 1.) Table 1 TIFF0007632143000008.tif40150

[0028] TIFF0007632143000009.tif2082 (In formula (5), n is an integer arbitrarily selected so as to obtain the number average molecular weight shown in Table 2.) Table 2 TIFF0007632143000010.tif40150

[0029] The compositions of Examples 1 and 2 and Comparative Examples 1 to 6 were obtained by mixing components (A) to (C) in the composition ratios shown in Tables 3 and 4. That is, components (A) to (C) were weighed out into an ointment jar container, stirred with a spatula, and then kneaded at 2000 rpm for 1 minute under normal pressure conditions and at 2000 rpm for 1 minute under reduced pressure conditions using a Thinky Corporation Awatori Rentaro Vacuum Type (Model: ARV-310) to prepare a composition for evaluating fluidity.

[0030] <Liquidity evaluation> The fluidity of the composition prepared as described above was evaluated visually. The shear viscosity was measured under the following conditions using a rheometer (MCR302, manufactured by Anton Paar). a) Plate shape: circular flat plate 25mmφ b) Sample thickness: 1 mm c) Temperature: 25±1℃ d) Shear rate: 0.01 s -1

[0031] Table 3 TIFF0007632143000011.tif66150Table 4 TIFF0007632143000012.tif66150*1 Spherical alumina with an average diameter of 13 μm (DAW-10 manufactured by Denka Co., Ltd.) *2 Polydimethylsiloxane (KF-96-300CS manufactured by Shin-Etsu Chemical Co., Ltd.)

[0032] The composition (Example 1) to which the component (A) having a molecular weight distribution (Mw / Mn) of 1.20 or less is added has a lower composition viscosity than the compositions (Comparative Examples 1 to 3) to which the component (A) having a molecular weight distribution (Mw / Mn) of more than 1.20 is added. Also, the composition (Example 2) to which the component (A) having a molecular weight distribution (Mw / Mn) of 1.20 or less is added has a lower composition viscosity than the compositions (Comparative Examples 4 to 6) to which the component (A) having a molecular weight distribution (Mw / Mn) of more than 1.20 is added. By comparing the compositions, the composition to which the component (A) having a molecular weight distribution (Mw / Mn) of 1.20 or less is added has a good result in terms of fluidity. From the above, it can be concluded that the silicone resin composition of the present invention has excellent properties. [Industrial Applicability]

[0033] The silicone resin composition of the present invention can be used as a thermally conductive material to be interposed between heat-generating electronic parts such as transistors, IC chips, and memory elements and cooling members such as heat sinks.

Claims

[Claim 1] (A) Formula (1): (In formula (1), R １ are independently a monovalent saturated hydrocarbon group or a monovalent aromatic hydrocarbon group, X is a group having a hydroxyl group at its terminal and represented by formula (2) or formula (3), and n is an integer of 1 or more. and an organopolysiloxane having a molecular weight distribution (Mw / Mn) of 1.20 or less, (B) Thermally conductive filler A silicone resin composition comprising:

Images