Silicone-based dispersant and filler dispersion liquid

Abstract

To provide a dispersant that can give excellent filler dispersibility in a liquid medium.SOLUTION: The inventive silicone dispersant is an organopolysiloxane, which is a compound of formula (1), having an alkoxy silyl at one end, and with a number average molecular weight (Mn) of 13000 or more. In the formula (1), R1 independently represents a C1-12 monovalent saturated hydrocarbon group, or a C6-12 monovalent aromatic hydrocarbon group, R2 independently represents a C1-12 monovalent saturated hydrocarbon group, X is oxygen or a C2-8 divalent hydrocarbon group, and a is an integer of 1-3.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a dispersant capable of imparting excellent filler dispersibility in a liquid medium and a filler dispersion liquid containing the same.

Background Art

[0002] Products using liquid media such as hydrocarbons, alkanols, alkenols, fatty acids, unsaturated fatty acids, esters of fatty acids and hydroxyl group-containing compounds, esters of unsaturated fatty acids and hydroxyl group-containing compounds, silicone oils, acrylic resins, epoxy resins, urethane resins, etc. include cosmetics, liquid toners, oil-based inkjet inks, weak solvent-based paints, lubricating oils, detergents, heat conductive materials, conductive materials, optical materials, etc. Further, by dispersing fillers such as pigments in these liquid media, functions according to the applications are imparted.

[0003] For example, in recent years, with the high-density and high-integration of printed circuit boards and hybrid ICs incorporating electronic components such as transistors, ICs, and memory elements, and the increase in the capacity of secondary batteries (cell type), in order to efficiently dissipate the heat generated from electronic and electrical devices such as electronic components and batteries, as a thermal conductive material, a thermally conductive silicone composition composed of organopolysiloxane and thermal conductive fillers such as aluminum oxide powder and zinc oxide powder has been widely used. And in particular, in order to cope with a high heat dissipation amount, a thermally conductive silicone composition filled with a large amount of thermal conductive fillers has been proposed. However, in order to reduce the thermal resistance or improve the thermal conductivity, even if the filling rate of the thermal conductive fillers filled in heat dissipation greases or heat dissipation sheets is improved, the viscosity of the resin composition used in heat dissipation greases or heat dissipation sheets increases, making it difficult to discharge the resin composition. Therefore, heretofore, various studies have been made on the combination of thermal conductive fillers filled in order to lower the thermal resistance or increase the thermal conductivity of heat dissipation greases or heat dissipation sheets (see Patent Document 1, Patent Document 2, or Patent Document 3). However, in the combinations of thermal conductive fillers that have been conventionally studied, they are not sufficient from the viewpoint of thermal conductivity, or those with high thermal conductivity have high viscosity, and there is nothing that achieves both of these.

[0004] In order to solve that problem, Patent Document 4 describes that in a thermally conductive silicone composition filled with a thermal conductive filler, an organopolysiloxane having trimethoxysilyl at one end has the role of reducing the viscosity of the composition and imparting fluidity. Regarding the influence of the molecular weight of the organopolysiloxane having trimethoxysilyl on viscosity reduction and fluidity imparting, it is described that a larger molecular weight is preferable, but in the examples, no specific example using an organopolysiloxane having trimethoxysilyl at one end with a molecular weight of 5000 or more is described.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The present invention relates to a dispersant capable of imparting excellent filler dispersibility in a liquid medium and a filler dispersion liquid containing the same. The problem of the present invention is to provide a dispersant capable of imparting excellent filler dispersibility in a liquid medium. Another problem of the present invention is to provide a filler dispersion liquid in which the filler is stably dispersed, obtained by using the above dispersant. [Means for Solving the Problems]

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that an organopolysiloxane having an alkoxysilyl at one end and a number average molecular weight (Mn) of 13,000 or more is useful as a dispersant, and have completed the present invention.

[0008] That is, according to the present invention, the following dispersants are provided. Item 1. A silicone-based dispersant comprising an organopolysiloxane represented by the formula (1), having an alkoxysilyl at one end, and having a number average molecular weight (Mn) of 13,000 or more. TIFF0007700440000001.tif2081 In the formula (1), R 1 is independently a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and R 2is independently a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms, X is oxygen or a divalent hydrocarbon group having 2 to 8 carbon atoms, n is an integer of 1 or more, and a is an integer of 1 to 3.

[0009] Further, according to the present invention, there is provided a filler dispersion liquid shown below. Item 2. A filler dispersion liquid containing a filler, a liquid medium, and the silicone-based dispersant described in Item 1. Item 3. The filler dispersion liquid according to Item 2, wherein the content of the liquid medium is 4 to 50 parts by mass and the content of the silicone-based dispersant is 0.1 to 20 parts by mass with respect to 100 parts by mass of the filler.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a dispersant capable of stably dispersing a filler in a liquid medium.

[0011] Furthermore, according to the present invention, it is possible to provide a filler dispersion liquid in which the filler is stably dispersed, obtained by using the above dispersant. The filler dispersion liquid of the present invention is useful, for example, as cosmetics, liquid developers, oil-based inkjet inks, ultraviolet curable inkjet inks, weak solvent-based paints, offset inks, lubricants, cleaning agents, insecticides, release agents, adhesives, heat conductive materials, conductive materials, optical materials, and the like.

Brief Description of the Drawings

[0012]

Figure 1

Modes for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0014] <Silicone-based Dispersant> The dispersant of the present invention is an organopolysiloxane having an alkoxysilyl group at one end and a number average molecular weight (Mn) of 13,000 or more, which is used to disperse a filler in a liquid medium. And the dispersant of the present invention is a silicone-based dispersant which is an organopolysiloxane having an alkoxysilyl group at one end represented by the formula (1) and a number average molecular weight (Mn) of 13,000 or more.

[0015] TIFF0007700440000002.tif2185 In the formula (1), R 1 independently represents a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and R 2 independently represents a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms, X represents oxygen or a divalent hydrocarbon group having 2 to 8 carbon atoms, n is an integer of 1 or more, and a is an integer of 1 to 3.

[0016] Examples of the alkoxysilyl group include trimethoxysilyl, triethoxysilyl, tripropoxysilyl, methyldimethoxysilyl, methyldiethoxysilyl, ethyldimethoxysilyl, ethyldiethoxysilyl, propyldimethoxysilyl, propyldiethoxysilyl, dimethylmethoxysilyl, dimethylethoxysilyl, diethylmethoxysilyl, diethylethoxysilyl, dipropylmethoxysilyl, dipropylethoxysilyl, etc. Among these, from the viewpoints of affinity with the filler and easy availability of production raw materials, trimethoxysilyl is preferred.

[0017] The number average molecular weight (Mn) of the dispersant in terms of polystyrene measured by the gel permeation chromatography (GPC) method is 13,000 or more. If the number average molecular weight is less than 13,000, steric repulsion when dispersing the filler cannot be exerted due to the too small molecular weight, and a stable dispersion liquid cannot be obtained.

[0018] The dispersant of the present invention is used to disperse fillers in a liquid medium. Examples of the liquid medium include hydrocarbons, alkanols, alkenols, fatty acids, unsaturated fatty acids, esters of fatty acids and hydroxyl group-containing compounds, esters of unsaturated fatty acids and hydroxyl group-containing compounds, silicone oils, acrylic resins, epoxy resins, urethane resins, and the like. These liquid media can be used alone or in combination of two or more. A liquid medium suitable as a heat conductive material is silicone oil.

[0019] Examples of the hydrocarbon include hexane, hexene, 2-ethylhexane, heptane, heptene, cyclohexane, cyclohexane heptane, octane, octene, 2-ethylhexane, nonane, decane, isodecane, dodecane, isododecane, tridecane, undecane, octadecane, C8-20 isoparaffin, squalane, petrolatum, microcrystalline wax, hydrogenated polyisobutene, 1-octene, 2-octene, 1-nonene, 2-nonene, 1-decene, 2-decene, 1-undecene, 2-undecene, 1-dodecene, 2-dodecene, 1-tridecene, 2-tridecene, 1-tetradecene, 2-tetradecene, 1-pentadecene, 2-pentadecene, 1-hexadecene, 2-hexadecene, 1-heptadecene, 2-heptadecene, 1-octadecene, 2-octadecene dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane, propylcyclohexane, and the like.

[0020] Examples of the alkanol or alkenol include octanol, 2-ethylhexanol, nonanol, decanol, isodecanol, dodecanol, cetyl alcohol, stearyl alcohol, arachyl alcohol, behenyl alcohol, hexyl decanol, octyldodecanol, isocetyl alcohol, isostearyl alcohol, oleyl alcohol, and the like.

[0021] Examples of saturated fatty acids or unsaturated fatty acids include octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tridecanoic acid, stearic acid, oleic acid, 1,2-hydroxystearic acid, ricinoleic acid, ricinoleic acid, undecylenic acid, isononanoic acid, myristic acid, palmitic acid, myristic acid, 2-ethylhexanoic acid, and the like.

[0022] Examples of esters of saturated fatty acids and hydroxyl group-containing compounds, or esters of unsaturated fatty acids and hydroxyl group-containing compounds include methyl laurate, heptyl undecylenate, isononyl isononanoate, ethyl oleate, isopropyl myristate, isopropyl palmitate, butyl stearate, cetyl palmitate, myristyl myristate, octyldodecyl myristate, isopropyl isostearate, ethyl isostearate, cetyl 2-ethylhexanoate, hexyl isostearate, ethylene glycol di(2-ethylhexanoate), ethylene glycol dioleate, propylene glycol di(caprylic / capric acid), propylene glycol dioleate, trimethylolpropane triisostearate, pentaerythrityl tetra(2-ethylhexanoate), neopentyl glycol diheptanoate, isocetyl isostearate, 2-octyldodecyl dimethyloctanoate, myristyl lactate, trioctyldodecyl citrate, diisostearyl malate, di(2-ethylhexyl) succinate, diisopropyl adipate, diisobutyl adipate, cholesteryl stearate fatty acid, and the like. Further examples include fats and oils such as almond oil, avocado oil, olive oil, shea butter, shea butter oil, evening primrose oil, borage seed oil, camellia oil, babassu oil, peanut oil, rosehip oil, which are triesters with glycerin; waxes such as beeswax, candelilla wax, carnauba wax, jojoba oil, and the like.

[0023] Examples of silicone oils include dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxy-modified silicone oil, carbinol-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, and fluorine-modified silicone oil.

[0024] Examples of acrylic resins include monofunctional (meth)acrylates, difunctional (meth)acrylates, polyfunctional (meth)acrylates with three or more functional groups, epoxy (meth)acrylates, urethane (meth)acrylates, and polyester (meth)acrylates with two or more functional groups.

[0025] Examples of epoxy resins include combinations of main agents such as phenolic glycidyl ethers such as bisphenol A, bisphenol F, and phenol novolac, and alcohol-based glycidyl ethers such as polypropylene glycol, with curing agents. Examples of curing agents include amine compounds such as aliphatic polyamines, modified aliphatic polyamines, polyamide amines, polyamides, alicyclic polyamines, modified alicyclic polyamines, modified aromatic polyamines, and tertiary amines. These curing agents may be used alone or in combination of two or more. A reaction accelerator can also be used to promote the reaction between the main agent and the curing agent. Examples of reaction accelerators include phenol, p-t-butylphenol, di-t-butylphenol, cresol, triphenyl phosphite, salicylic acid, and triethanolamine. These reaction accelerators may be used alone or in combination of two or more.

[0026] Examples of the urethane resin include reaction products of a hydroxyl group-containing compound and a polyisocyanate compound, for example, a polyurethane obtained by reacting a short-chain glycol or short-chain ether with an isocyanate compound as a hard segment, and a linear multi-block copolymer of a polyurethane obtained by reacting a long-chain glycol or long-chain ether with an isocyanate compound as a soft segment. Further, reaction products (cured products) of a urethane prepolymer and a polyisocyanate compound can be mentioned.

[0027] Examples of the filler include inorganic pigments, organic pigments, extender pigments, fillers, inorganic fine particles, diamond, graphene, graphite, carbon black, carbon nanotubes, clay, conductive fillers, heat conductors, carbon fibers, glass fibers, cellulose, cellulose nanofibers, and the like. These fillers are particulate, powdery, or fibrous substances added to plastics, rubbers, paints, inks, etc. for improving strength and functionality and reducing costs. There are no particular restrictions on the crystal form, particle size, surface state, presence or absence of surface treatment, etc. of the filler. As the filler (heat conductor) of the heat conduction material, aluminum oxide, zinc oxide, aluminum nitride, or boron nitride is preferable, and aluminum oxide is more preferable.

[0028] <Filler dispersion> The filler dispersion of the present invention contains a filler, a liquid medium, and a dispersant for dispersing the filler in the liquid medium. And the dispersant is the silicone-based dispersant described above. As the liquid medium, the liquid medium described above is used. Among them, it is preferable to use silicone oil. In addition to the liquid medium, for example, various organic solvents, monomers, liquid oligomers, etc. can also be used.

[0029] As the filler, the fillers described above are used. Among them, aluminum oxide, zinc oxide, aluminum nitride, or boron nitride is preferable, and aluminum oxide is more preferable.

[0030] The filler dispersion preferably contains 4 to 50 parts by mass, more preferably 5 to 30 parts by mass of the liquid medium with respect to 100 parts by mass of the filler. Further, the filler dispersion preferably contains 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass of the silicone-based dispersant with respect to 100 parts by mass of the filler. When the content of the silicone-based dispersant with respect to 100 parts by mass of the filler is less than 0.1 part by mass, it may be difficult to stably disperse the filler. On the other hand, when the content of the silicone-based dispersant with respect to 100 parts by mass of the filler exceeds 10 parts by mass, an excessive silicone-based dispersant that does not contribute to the dispersion of the filler will be included.

[0031] In the filler dispersion of the present invention, various additives such as other surfactants, plasticizers, and defoamers can be blended within a range that does not impair the purpose.

[0032] The filler dispersion of the present invention can be produced according to a known method for producing a filler dispersion. For example, a method of adding a filler to a liquid medium to which a silicone-based dispersant has been added and then stirring and mixing, a method of adding a liquid medium and a silicone-based dispersant to a filler and then stirring and mixing, etc. can be mentioned. As the dispersing equipment for stirring, mixing, or dispersing, known dispersers can be used. For example, roll mills, ball mills, bead mills, sand mills, homogenizers, disper, rotating and revolving mixers, etc. can be mentioned. Also, the dispersion treatment can be performed in an ultrasonic generating bath.

Examples

[0033] Hereinafter, the present invention will be described more specifically. In the examples, "parts" and "%" are all based on mass (parts by mass, mass%) unless otherwise specified. Also, the present invention is not limited by these examples in any way.

[0034] <Measurement of molecular weight> 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 defined as the molecular weight distribution index (Mw / Mn). Polystyrene was used as the standard sample, and the polystyrene-equivalent molecular weight was measured. The measurement of the polystyrene-equivalent molecular weight by the GPC method was carried out under the following measurement conditions. a) Measuring instrument: HPLC LC-2000Plus series manufactured by JASCO Corporation b) Column: Two Shodex KF-804L columns c) Oven temperature: 40 °C d) Eluent: Toluene at 0.7 mL / min e) Standard sample: Polystyrene f) Injection volume: 20 μL g) Concentration: 0.05 g / 10 mL h) Sample preparation: Using toluene as the solvent, it was stirred and dissolved at room temperature.

[0035] <Synthesis Example 1: Synthesis of an organopolysiloxane having an alkoxysilyl group at one end with a number average molecular weight of 17,000> In a 1000 ml four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, 697 g of polydimethylsiloxane having a hydrosilyl group at one end (number average molecular weight (Mn) = 17,100) and 14 g of vinyltrimethoxysilane (S210 manufactured by JNC Corporation, molecular weight = 148.2) were weighed respectively, and the temperature was raised to 70 °C with stirring under a nitrogen atmosphere. After reaching 70 °C, 81 μL of Pt-VTSC-3.0X manufactured by Umicore Japan was added as a Karstedt catalyst, and the mixture was stirred at 70 °C for 1 hour. After cooling to room temperature, the reflux condenser was replaced with a distillation head having a collection flask. Next, under a reduced pressure condition of 0.3 kPaA using a vacuum pump, it was heated at 120 °C for 1 hour to distill off the volatile substances remaining in the product, thereby obtaining 703 g of polydimethylsiloxane having a trimethoxysilyl group at one end (number average molecular weight (Mn) = 16,900, weight average molecular weight (Mw) = 17,600, molecular weight distribution index (Mw / Mn) = 1.04).

[0036] <Synthesis Example 2: Synthesis of Organopolysiloxane Having Alkoxysilyl at One End with a Number-Average Molecular Weight of 1500> Into a 500 ml four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, 300 g of polydimethylsiloxane having hydrosilyl at one end (number-average molecular weight (Mn) = 1300) and 55 g of vinyltrimethoxysilane (S210 manufactured by JNC Corporation, molecular weight = 148.2) were weighed respectively. Under a nitrogen atmosphere, the temperature was raised to 70 °C while stirring. After reaching 70 °C, 4 μL of Pt-VTSC-3.0X manufactured by Umicore Japan was added as a Karstedt catalyst, and the mixture was stirred at 70 °C for 1 hour. It was cooled to room temperature, and the reflux condenser was replaced with a distillation head having a collection flask. Next, under a reduced pressure condition of 5 kPaA using a vacuum pump, after heating at 150 °C for 1 hour, and further under a reduced pressure condition of 0.1 kPaA, heating at 150 °C for 2 hours to distill off the volatile substances remaining in the product, 338 g of polydimethylsiloxane having trimethoxysilyl at one end (number-average molecular weight (Mn) = 1500, weight-average molecular weight (Mw) = 1700, molecular weight distribution index (Mw / Mn) = 1.14) was obtained.

[0037] <Synthesis Example 3: Synthesis of Organopolysiloxane Having Alkoxysilyl at One End with a Number-Average Molecular Weight of 6500> In a 2000 ml four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, 1000 g of polydimethylsiloxane having a hydrosilyl group at one end (number average molecular weight (Mn) = 5000) and 45 g of vinyltrimethoxysilane (S210 manufactured by JNC, molecular weight = 148.2) were weighed respectively, and the temperature was raised to 70 °C with stirring under a nitrogen atmosphere. After reaching 70 °C, 12 μL of Pt-VTSC-3.0X manufactured by Umicore Japan was added as a Karstedt catalyst, and the mixture was stirred at 70 °C for 1 hour. After cooling to room temperature, the reflux condenser was replaced with a distillation head having a collection flask. Next, under a reduced pressure condition of 5 kPaA using a vacuum pump, it was heated at 150 °C for 1 hour, and then under a reduced pressure condition of 0.1 kPaA, it was heated at 150 °C for 2 hours to distill off the volatile substances remaining in the product, thereby obtaining 1010 g of polydimethylsiloxane having a trimethoxysilyl group at one end (number average molecular weight (Mn) = 6500, weight average molecular weight (Mw) = 6900, molecular weight distribution index (Mw / Mn) = 1.05).

[0038] <Synthesis Example 4: Synthesis of organopolysiloxane having an alkoxysilyl group at one end with a number average molecular weight of 12000> In a 1000 ml four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, 659 g of polydimethylsiloxane having a hydrosilyl group at one end (number average molecular weight (Mn) = 11100) and 20 g of vinyltrimethoxysilane (S210 manufactured by JNC, molecular weight = 148.2) were weighed respectively, and the temperature was raised to 70 °C with stirring under a nitrogen atmosphere. After reaching 70 °C, 76 μL of Pt-VTSC-3.0X manufactured by Umicore Japan was added as a Karstedt catalyst, and the mixture was stirred at 70 °C for 1 hour. After cooling to room temperature, the reflux condenser was replaced with a distillation head having a collection flask. Next, under a reduced pressure condition of 0.3 kPaA using a vacuum pump, it was heated at 120 °C for 1 hour to distill off the volatile substances remaining in the product, thereby obtaining 663 g of polydimethylsiloxane having a trimethoxysilyl group at one end (number average molecular weight (Mn) = 11600, weight average molecular weight (Mw) = 17600, molecular weight distribution index (Mw / Mn) = 1.04).

[0039] For Example 1 and Comparative Examples 1 to 3, as shown in Tables 1 to 4, the organopolysiloxane having an alkoxysilyl group at one end synthesized in Synthesis Examples 1 to 4 was used for evaluation by the following method. The results are shown in Tables 1 to 4 and Figure 1.

[0040] <Preparation of Sample for Dispersibility Evaluation> In an ointment pot container, 2.6 g of polydimethylsiloxane (KF-96-1000CS manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silicone oil, as a liquid medium, and 0.1 g of an organopolysiloxane having trimethoxysilyl at one end synthesized in Synthesis Examples 1 to 4 as a silicone-based dispersant were weighed. Further, 10 g of alumina (DAW-10 manufactured by Denka Co., Ltd.) having an average diameter of 13 μm was weighed as a dispersoid and stirred using a spatula. Next, using a Sinky Awatori Renjiro vacuum type (model: ARV-310), it was kneaded at 2000 rpm for 1 minute under normal pressure conditions and at 2000 rpm for 1 minute under reduced pressure conditions to prepare a sample for dispersibility evaluation.

[0041] <Dispersibility Evaluation> The sample for dispersibility evaluation prepared as described above was evaluated for dispersibility by measuring the shear viscosity at different shear rates under the following conditions using a rheometer (MCR302 manufactured by Anton Paar). a) Plate shape: Circular flat plate 25 mm φ b) Sample thickness: 1 mm c) Temperature: 25 ± 1 °C d) Shear rate: 0.001 to 1 S -1

[0042] Table 1. Dispersibility Evaluation Results 1 TIFF0007700440000003.tif36123

[0043] Table 2. Dispersibility Evaluation Results 2 TIFF0007700440000004.tif41140

[0044] Table 3. Dispersibility Evaluation Results 3 TIFF0007700440000005.tif41140

[0045] Table 4. Dispersibility Evaluation Results 4 TIFF0007700440000006.tif41140

[0046] The organopolysiloxane having trimethoxysilyl at one end with a number average molecular weight (Mn) of 13,000 or more of the present invention has a lower shear viscosity at each shear rate in the evaluation of dispersibility compared to the organopolysiloxane having alkoxysilyl at one end with a number average molecular weight (Mn) of less than 13,000, and it was confirmed that it is good as a dispersant.

Industrial Applicability

[0047] The silicone-based dispersant of the present invention can be used as a dispersant for stably dispersing fillers in a liquid medium in fields such as cosmetics, liquid developers, oil-based inkjet inks, ultraviolet curable inkjet inks, weak solvent-based paints, offset inks, lubricants, detergents, insecticides, mold release agents, adhesives, heat conductive materials, conductive materials, and optical materials.

Claims

A filler dispersion for use as a liquid developer, lubricant, cleaning agent, insecticide, mold release agent, adhesive, heat conductive material, conductive material, or optical material, comprising: a filler, a liquid medium, and a silicone-based dispersant; wherein the liquid medium is polydimethylsiloxane; the silicone-based dispersant is an organopolysiloxane represented by the formula (1) and having a number average molecular weight (Mn) of 13,000 or more. A filler dispersion. In formula (1), R 1 is independently a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and R 2 is independently a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms, X is oxygen, or a divalent hydrocarbon group having 2 to 8 carbon atoms, n is an integer of 1 or more, and a is an integer of 1 to 3.

2. The filler dispersion according to claim 1, wherein the content of the liquid medium is 4 to 50 parts by mass and the content of the silicone-based dispersant is 0.1 to 20 parts by mass with respect to 100 parts by mass of the filler.

3. The filler dispersion according to claim 1 or 2, wherein the filler is aluminum oxide.

4. The filler dispersion according to any one of claims 1 to 3 for use as a heat conductive material.

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