Heat-storing thermally conductive material

Abstract

A heat-storing thermally conductive material characterized by comprising: a heat storage material; a thermally conductive filler; and an oil-gelling agent or a two-component curable base resin.

Description

Heat storage thermal conductive material

[0001] The present invention relates to a heat storage thermal conductive material. This application claims priority based on Japanese Patent Application Nos. 2024-007947, 2024-008194, and 2024-008061, all filed in Japan on January 23, 2024, the contents of which are incorporated herein by reference.

[0002] Heat transfer materials that are provided between a heat generating element and a heat dissipating member and transmit heat are known in various forms, such as grease type, gap filler type, and sheet type. By using these heat transfer materials, for example, heat generated in the heat generating element can be efficiently dissipated from a heat dissipating member such as a metal housing or a heat sink. By providing such a heat transfer material between the heat generating element and the heat dissipating member, the thermal resistance between the heat generating element and the heat dissipating member can be reduced.

[0003] In the field of automotive parts, etc., the market for lithium-ion batteries (LIBs) and the like has expanded in recent years as a power source for automobiles such as electric vehicles (EVs), but battery cases for secondary batteries such as lithium-ion batteries (LIBs) have a problem in that the heat generated by the secondary batteries during charging and discharging tends to accumulate within the case due to compactness and high output, causing the secondary batteries to reach their maximum operating temperature in a short period of time. In particular, automotive parts, etc., are sometimes exposed to thermally severe environments in which the interior temperature of the automobile reaches 40°C or higher, and under such high-temperature conditions, the secondary batteries quickly reach their maximum operating temperature, causing the problem of shortening the continuous operating time of the batteries.

[0004] For this reason, there is an urgent need to develop heat dissipation designs for such secondary batteries. In particular, lithium-ion secondary batteries may be damaged if they are exposed to high temperatures exceeding their operating limit for a long period of time. Therefore, there is an urgent need for thermal countermeasures to suppress and mitigate the temperature rise in the battery.

[0005] The use of a heat storage material is an effective heat dissipation measure for components that are used in such thermally severe ambient conditions and therefore have difficulty in achieving a temperature difference with the ambient environment. In Patent Document 1, a combination of a thermoplastic base polymer, a thermally conductive filler, and a heat storage material ensures a molded body with a predetermined hardness, improves adhesion to the heat dissipation object, and enhances the effect of suppressing and mitigating temperature rise even for a heat dissipation object that is in a condition where it is difficult to achieve a temperature difference with the ambient environment due to the influence of a thermally severe ambient temperature (ambient temperature).

[0006] In particular, when a battery, such as a lithium-ion battery, is used as the heat dissipation target, the use of a heat storage material that utilizes latent heat and has a phase change temperature within the operating temperature range of the battery can mitigate the temperature rise of the battery within the operating temperature range of the battery. In this case, if the heat storage material alone is used, the temperature will rise again once the limit of the heat storage capacity is exceeded, limiting the heat dissipation effect. However, by including a thermally conductive filler, a heat conduction path is secured, improving heat dissipation properties and enabling the operating time to be extended (see, for example, Patent Document 1).

[0007] A known technique for storing heat is to use the latent heat of phase transition that occurs when a substance solidifies or melts. Among these, paraffin compounds have particularly excellent features, such as high heat storage density and no corrosiveness to metals. Furthermore, when a heat-generating part is located inside a housing that houses it, a low-viscosity, fluid heat transfer material may be poured into the housing. With the increasing integration of various electronic devices, there is a demand for heat transfer materials that can be poured into narrower spaces without trapping air bubbles or other gaps.

[0008] For example, Patent Document 2 discloses a latent heat storage material that is highly durable and does not bleed or separate from the supporting material even under heat cycles that involve repeated phase transitions due to solidification and melting.

[0009] Japanese Patent No. 6893741 (B) Japanese Patent Publication No. 2016-196578 (A)

[0010] However, the latent heat storage material disclosed in Patent Document 2 has a structure in which a latent heat storage material made of n-paraffin is supported on a hydrogenated styrene-ethylene / propylene block copolymer. Therefore, there is a problem that the material has almost no fluidity and cannot be injected into narrow gaps. Furthermore, there is a concern about durability, with the heat storage capacity decreasing over time.

[0011] The present invention has been made in view of the above background, and aims to provide a heat storage thermal conductive material that has fluidity that allows it to be filled into narrow spaces without gaps, and that exhibits little deterioration in heat storage capacity over time.

[0012] In order to solve the above problems, a heat storage thermal conductive material according to one embodiment of the present invention proposes the following means: (1) A heat storage thermal conductive material according to aspect 1 of the present invention is a heat storage thermal conductive material comprising a heat storage material, a thermally conductive filler, and an oil gelling agent or a two-component curing base resin.

[0013] (2) Aspect 2 of the present invention is characterized in that the heat storage thermal conductive material of Aspect 1 contains an antioxidant.

[0014] (3) Aspect 3 of the present invention is characterized in that in the heat storage thermal conductive material of Aspect 1 or 2, the antioxidant is a hindered phenol-based or hindered amine-based radical scavenger.

[0015] (4) A fourth aspect of the present invention is characterized in that, in the heat storage thermal conductive material of any one of the first to third aspects, the antioxidant is contained in an amount of 0.5 parts by mass or more per 100 parts by mass of the heat storage material.

[0016] (5) Aspect 5 of the present invention is characterized in that, in the heat storage thermal conductive material of any one of aspects 1 to 4, the melting point of the heat storage material is 48°C or higher.

[0017] (6) A sixth aspect of the present invention is the heat storage thermal conductive material according to any one of the first to fifth aspects, characterized in that the heat storage material has an average molecular weight of 400 or more.

[0018] (7) Aspect 7 of the present invention is the heat storage thermal conductive material of any one of Aspects 1 to 6, characterized in that the oil gelling agent or two-component curing base resin is an oil gelling agent, and the oil gelling agent contains a fatty acid metal salt or a mixture of a fatty acid metal salt and a fatty acid.

[0019] (8) Aspect 8 of the present invention is the heat storage thermal conductive material of any one of Aspects 1 to 7, characterized in that the oil gelling agent is aluminum 2-ethylhexanoate.

[0020] (9) A ninth aspect of the present invention is the heat storage thermal conductive material according to any one of the first to eighth aspects, characterized in that the thermal conductive filler contains ceramic particles.

[0021] (10) A tenth aspect of the present invention is the heat storage thermal conductive material according to any one of the first to ninth aspects, characterized in that the heat storage material contains a paraffin compound or a fatty acid.

[0022] (11) Aspect 11 of the present invention is the heat storage thermal conductive material according to any one of aspects 1 to 9, characterized in that the heat storage material is a microcrystalline wax.

[0023] According to the present invention, it is possible to provide a heat storage thermally conductive material that has fluidity that allows it to fill narrow spaces without gaps and that exhibits little deterioration in heat storage capacity over time.

[0024] Hereinafter, a heat storage thermal conductive material according to one embodiment of the present invention will be described with reference to the drawings. Note that the following embodiments are specifically described to better understand the gist of the invention, and unless otherwise specified, do not limit the present invention. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0025] First Embodiment The heat storage thermally conductive material of this embodiment includes a heat storage material, a thermally conductive filler, and an oil gelling agent. The heat storage material is intended to effectively suppress and mitigate temperature rises in heat dissipation objects in conditions where it is difficult to achieve a temperature difference with the surrounding environment due to the influence of thermally severe ambient environmental temperatures (ambient temperatures). An example of such a heat storage material is a mixture of alkanes with 16 or more carbon atoms, i.e., paraffin. An example of paraffin is normal paraffin (particularly a mixture of linear alkanes with approximately 16 to 40 carbon atoms). An example of a heat storage material is normal paraffin, which has a melting point of 48°C and a latent heat of fusion of 206 J / g. The carbon number of normal paraffin depends on the temperature range to be stored, but is preferably 16 to 40. In this case, the melting point is approximately 18°C ​​to 81°C, making it suitable for use in the present invention. Note that the heat storage thermally conductive material of this embodiment may also include a two-component curing base resin instead of the oil gelling agent.

[0026] Such paraffin is a solid-liquid phase transition type latent heat storage material, which changes from a solid phase to a liquid phase when absorbing heat from a heat dissipation object, and stores heat using the latent heat of the phase change (melting).

[0027] Among solid-liquid phase transition type latent heat storage materials, paraffin in particular has a relatively large latent heat and a large amount of heat storage per unit volume, and can achieve stable heat release and heat storage even after repeated melting and solidification. Furthermore, it has favorable properties as a heat storage material, such as being resistant to corrosion of the heat release target, being inexpensive, and having an easily adjustable phase change temperature (melting point) depending on the molecular weight, etc.

[0028] The latent heat storage material may contain an alkane having 16 or more carbon atoms or any fatty acid. Examples of fatty acids include dodecanoic acid with a melting point of 44°C, tetradecanoic acid with a melting point of 54°C, hexadecanoic acid with a melting point of 63°C, and docosanoic acid with a melting point of 82°C.

[0029] In this way, when using a phase change material such as a solid-liquid phase transition material as a heat storage material, a material according to the required phase change temperature (equivalent to the melting point in the case of a solid-liquid phase change material) can be selected, i.e., a material having a phase change temperature (melting point) within the desired temperature range.

[0030] Specifically, from the viewpoint of performance, durability, etc., a latent heat temperature range of 18°C ​​or more and 81°C or less is preferable. If the latent heat temperature range is less than 18°C, the heat storage capacity will quickly exceed its limit at high temperatures, and there is a concern that it will be difficult to effectively suppress the temperature rise of the battery. If the latent heat temperature range is greater than 81°C, the battery will become too hot even at temperatures below the melting point of the heat storage material, and this may result in a deterioration of its characteristics.

[0031] The thermally conductive filler transmits heat from the heat dissipation object or heat stored in the heat storage material toward the low-temperature side. The thermally conductive filler may be in a powder or particulate form that can be uniformly mixed with the base resin. Furthermore, when the heat storage thermally conductive material of this embodiment is applied to a heat dissipation medium such as an electrical component or a semiconductor element, it is preferable to use an insulating material as the thermally conductive filler. By using an insulating thermally conductive filler, the heat storage thermally conductive material can also be made insulating.

[0032] The thermally conductive filler may be, for example, ceramic particles having insulating properties. Specific examples include metal oxides such as aluminum oxide, magnesium oxide, titanium oxide, zinc oxide, silicon oxide, beryllium oxide, copper oxide, zirconium oxide, and calcium oxide, and metal nitrides such as boron nitride, aluminum nitride, and silicon nitride. Of these, aluminum oxide and boron nitride are preferred as thermally conductive fillers. Aluminum oxide is particularly preferred as a component of thermally conductive fillers because it is inexpensive and easily available. In this embodiment, aluminum oxide (alumina) is used as the thermally conductive filler. In this embodiment, the thermally conductive filler refers to a filler having a higher thermal conductivity than the base resin.

[0033] The thermally conductive filler has a specific surface area of ​​0.5 m ２It is preferable to use a particulate material having a specific surface area of ​​0.5 m / g or more and an average particle diameter (d50) of 40 μm or less. ２ If the specific surface area of ​​the thermally conductive filler is less than 400 m / g, there is a risk that the thermally conductive material will become fluid and flow out of the location where it is placed in a temperature range where the thermal storage material is at or above its melting point. Also, there is a risk that the thermally conductive filler will precipitate, making the thermally conductive material non-uniform. Although there is no particular upper limit on the specific surface area of ​​the thermally conductive filler, the specific surface area of ​​the thermally conductive filler should be 400 m / g or less. ２ / g or less is desirable.

[0034] On the other hand, if the average particle diameter (d50) of the thermally conductive filler measured using a laser diffraction / scattering particle size distribution analyzer (MT3300EXII: manufactured by Microtrac Bell Co., Ltd.) exceeds 40 μm, there is a concern that the thermal storage material will separate from the thermally conductive material in a temperature range above the melting point of the thermal storage material. There is also a concern that the thermally conductive filler will precipitate, resulting in a non-uniform thermal storage thermally conductive material. While there is no particular lower limit for the average particle diameter of the thermally conductive filler, it is desirable that the average particle diameter of the thermally conductive filler be 0.005 μm or more.

[0035] The blending ratio of the thermally conductive filler is set so that the thermally conductive filler is 20 parts by mass or more when the thermal storage material is 90 parts by mass. If the thermally conductive filler is less than 20 parts by mass when the thermal storage material is 90 parts by mass, there is a concern that the thermal storage material will separate from the thermally conductive material in a temperature range above the melting point of the thermal storage material. Note that it is desirable to set the thermally conductive filler to 3,000 parts by mass or less when the thermal storage material is 90 parts by mass.

[0036] The oil gelling agent is a shape-retaining component that prevents the heat storage material from melting and flowing when the heat storage thermal conductive material reaches or exceeds its melting point, thereby maintaining its shape. Specific examples of oil gelling agents include fatty acid metal salts, and mixtures of fatty acid metal salts and fatty acids. Examples of fatty acid metal salts include 2-ethylhexanoate. Examples of 2-ethylhexanoate include aluminum 2-ethylhexanoate, zinc 2-ethylhexanoate, iron 2-ethylhexanoate, cobalt 2-ethylhexanoate, and manganese 2-ethylhexanoate. Of these, in this embodiment, aluminum 2-ethylhexanoate (Al(—OH)[—OCOCH(C ２ H ５ ) C ４ H ９ ] ２ The fatty acid to be mixed with the fatty acid metal salt may be a monocarboxylic acid having a carboxy group on the hydrocarbon chain, such as 2-ethylhexanoic acid.

[0037] In this embodiment, the oil gelling agent may be added in an amount of, for example, 1% by mass or more and 20% by mass or less when the heat storage material is taken as 100 parts by mass. The addition of such an oil gelling agent prevents the heat storage material from melting and flowing when the temperature reaches or exceeds the melting point, suppressing deterioration of the heat storage thermal conductive material and, for example, making it possible to suppress a decrease in the heat storage capacity over time.

[0038] The heat storage thermal conductive material of this embodiment preferably further contains a dispersant. The dispersant prevents the thermally conductive filler (e.g., ceramic particles) constituting the heat storage thermal conductive material from agglomerating, allowing the ceramic particles to be properly dispersed in the heat storage thermal conductive material. Such a dispersant can stably disperse the ceramic particles in the heat storage thermal conductive material by using the effects of particle-to-particle repulsion due to electric charge and physical separation between particles due to the adhesion of dispersant components to the outer surfaces of the ceramic particles to prevent reagglomeration of the dispersed ceramic particles.

[0039] Examples of such dispersants include sodium polycarboxylate, ammonium polycarboxylate, alkylamine polycarboxylate, amino alcohol polyphosphate, nonionic surfactants, etc. In this embodiment, a nonionic surfactant is used as the dispersant.

[0040] Nonionic surfactants are surfactants with hydrophilic groups that do not ionize when dispersed in water. Examples of nonionic surfactants include ester-type surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters, in which a polyhydric alcohol such as glycerin, sorbitol, or sucrose (cane sugar) is ester-bonded to a fatty acid. Ether-type surfactants include alkylphenol-based polyoxyethylene alkylphenyl ethers. Ester-ether-type surfactants include fatty acid-based polyoxyethylene sorbitan fatty acid esters.

[0041] The heat storage thermal conductive material of this embodiment preferably further contains an anti-settling agent. The anti-settling agent prevents the thermal conductive filler constituting the heat storage thermal conductive material from settling and allows it to be uniformly dispersed. For example, fumed silica can be used as the anti-settling agent.

[0042] The heat storage thermal conductive material having the above-described configuration preferably has a viscosity of 500 Pa s or less before curing. If the viscosity before curing exceeds 500 Pa s, the fluidity of the heat storage thermal conductive material may be too low, which may make it impossible to fill minute gaps with the heat storage thermal conductive material.

[0043] According to the heat storage thermal conductive material having the above-described configuration, by adding an oil gelling agent, it is possible to obtain a heat storage thermal conductive material that has a viscosity that can be filled into narrow gaps without creating cavities, and that can suppress the decrease in heat storage capacity over time.

[0044] (Second Embodiment) The second embodiment will be described below. The difference between the first and second embodiments is that the heat storage thermal conductive material of the second embodiment contains an antioxidant. Description of content common to the first and second embodiments will be omitted. The heat storage thermal conductive material of this embodiment contains a heat storage material, a thermally conductive filler, an oil gelling agent or a two-component curing base resin, and an antioxidant. The heat storage material is intended to enhance the effect of suppressing and mitigating temperature rise even in a heat dissipation object that is in a condition where it is difficult to obtain a temperature difference from the surrounding environment due to the influence of a thermally severe ambient environmental temperature (ambient temperature).

[0045] Microcrystalline wax can also be used as the heat storage material. Microcrystalline wax is a wax that is solid at room temperature and has a higher carbon number, molecular weight, and melting point than general paraffin wax. For example, microcrystalline wax typically has a carbon number distribution of about 30 to 60, a molecular weight of about 500 to 800, and a melting point of about 70°C to 110°C.

[0046] According to the JIS, such microcrystalline waxes are defined as waxes that are solid at room temperature and are separated and refined from the residue of vacuum distillation of crude oil or heavy distillate oil, and are classified into several categories based on factors such as melting point. Microcrystalline waxes are primarily composed of hydrocarbons (isoparaffins) with side chains on the main chain, with small amounts of straight-chain hydrocarbons (normal paraffins) and cyclic hydrocarbons (naphthenes). The composition contains a large amount of isoparaffins and cycloparaffins with small crystal particle sizes, resulting in microcrystalline waxes. Such microcrystalline waxes have high viscosity, excellent extensibility, and excellent brittle resistance at temperatures below room temperature.

[0047] Such normal paraffin and microcrystalline wax are solid-liquid phase transition type latent heat storage materials, which undergo a phase change from solid to liquid when absorbing heat from a heat dissipation object, and store heat using the latent heat of the phase change (melting).

[0048] Among solid-liquid phase transition type latent heat storage materials, normal paraffin and microcrystalline wax in particular have relatively large latent heat and a large amount of heat storage per unit volume, and can achieve stable heat dissipation and heat storage even after repeated melting and solidification. In addition, they are less likely to corrode the heat dissipation target, are inexpensive, and furthermore, have favorable properties as heat storage materials, such as the ability to easily adjust the phase change temperature (melting point) depending on the molecular weight, etc.

[0049] The thermally conductive filler may be, for example, ceramic particles having insulating properties. Specific examples include metal oxides such as aluminum oxide, magnesium oxide, titanium oxide, zinc oxide, silicon oxide, beryllium oxide, copper oxide, zirconium oxide, and calcium oxide, and metal nitrides such as boron nitride, aluminum nitride, and silicon nitride. Among these, boron nitride and aluminum oxide are preferred as thermally conductive fillers. Boron nitride, in particular, is particularly preferred as a component of thermally conductive fillers because it has a high thermal conductivity as an insulating material (theoretical thermal conductivity in the a- and b-axis directions: 410 W / mK). In this embodiment, boron nitride is used as the thermally conductive filler. In this embodiment, the thermally conductive filler refers to a filler having a higher thermal conductivity than the base resin.

[0050] The blending ratio of the thermally conductive filler is preferably 20 parts by mass or more when the thermal storage material is taken as 100 parts by mass. If the thermally conductive filler is less than 20 parts by mass when the thermal storage material is taken as 100 parts by mass, there is a concern that the thermal storage material will become fluid and separate from the thermally conductive material in a temperature range above the melting point of the thermal storage material. Note that it is desirable to set the amount of the thermally conductive filler to 3,000 parts by mass or less when the thermal storage material is taken as 100 parts by mass.

[0051] The oil gelling agent and the two-component curing base resin are shape-retaining components that prevent the heat storage material from melting and flowing when the heat storage thermal conductive material reaches or exceeds its melting point, thereby maintaining its shape. Specific examples of oil gelling agents include fatty acid metal salts, and mixtures of fatty acid metal salts and fatty acids. Examples of fatty acid metal salts include 2-ethylhexanoate. Examples of 2-ethylhexanoate include aluminum 2-ethylhexanoate, zinc 2-ethylhexanoate, iron 2-ethylhexanoate, cobalt 2-ethylhexanoate, and manganese 2-ethylhexanoate. Of these, in this embodiment, aluminum 2-ethylhexanoate (Al(—OH)[—OCOCH(C ２ H ５ ) C ４ H ９ ] ２ The fatty acid to be mixed with the fatty acid metal salt may be a monocarboxylic acid having a carboxy group on the hydrocarbon chain, such as 2-ethylhexanoic acid.

[0052] Two-component curing base resins are resins that solidify by mixing two liquid resin components, primarily through polymerization. One component of the two-component curing base resin is a hydroxyl group-containing compound, such as a polybutadiene polyol composition or a polyester polyol composition. The other component is an isocyanate compound. By mixing these two resin components, a shape-retaining resin is produced through a polymerization reaction.

[0053] The antioxidant is a degradation prevention component that prevents deterioration of the thermal storage thermal conductive material due to oxidation. Examples of antioxidants that can be used include hindered phenol-based or hindered amine-based radical scavengers. Radical scavengers are chemical substances added to stop chain reactions and decomposition. By capturing peroxy radicals and alkyl radicals that cause deterioration of the thermal storage thermal conductive material, they prevent deterioration such as oxidation of resin components caused by these radicals.

[0054] Specific examples of hindered phenol-based or hindered amine-based radical scavengers include 2,2-methylenebis(4-methyl-6-t-butylphenol) (KEMINOX9425, manufactured by Chemipro Chemical Co., Ltd.), a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)decanedioate and methyl(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate (KEMISTAB29, manufactured by Chemipro Chemical Co., Ltd.), and hexadecyl-3,5-ditertiarybutyl-4-hydroxybenzoate (KEMISORB114, manufactured by Chemipro Chemical Co., Ltd.).

[0055] According to the heat storage thermal conductive material having the above-described configuration, by combining a heat storage material having a large molecular weight and a melting point of 48°C or higher, such as microcrystalline wax, with an oil gelling agent or a two-component curing base resin, it is possible to obtain a heat storage thermal conductive material that has a viscosity that can be filled without creating cavities and that can suppress the decrease in heat storage capacity over time.

[0056] (Third Embodiment) The third embodiment will be described below. The difference between the first and second embodiments and the third embodiment is that the heat storage thermally conductive material of the third embodiment does not contain an antioxidant and has a melting point of 48°C or higher. Details common to the first or second embodiment and the third embodiment will be omitted. The heat storage thermally conductive material of this embodiment contains a heat storage material, a thermally conductive filler, and an oil gelling agent or a two-component curing base resin, and the melting point of the heat storage material is 48°C or higher. The heat storage material is intended to enhance the effect of suppressing and mitigating temperature rise in a heat dissipation object in conditions where it is difficult to achieve a temperature difference with the surrounding environment due to the influence of thermally severe ambient environmental temperatures (ambient temperatures). An example of such a heat storage material is a mixture of alkanes with 16 or more carbon atoms, i.e., paraffin. An example of paraffin is normal paraffin (particularly a mixture of linear alkanes with approximately 16 to 40 carbon atoms). An example of a heat storage material is normal paraffin, which has a melting point of 48° C. and a latent heat of fusion of 206 J / g. The melting point of normal paraffin depends on the temperature range in which heat storage is desired, but a melting point of approximately 48° C. to 81° C. is suitable for use in the present invention.

[0057] Specifically, from the viewpoint of performance, durability, etc., the heat storage material preferably has a latent heat temperature range of 48°C or higher and 81°C or lower. If the latent heat temperature range is lower than 48°C, the heat storage material will volatilize and oxidize and deteriorate at high temperatures, reducing durability, and there is a concern that the thermal conductivity and heat storage capacity of the heat storage thermal transfer material will decrease when kept at high temperatures for a long period of time. If the latent heat temperature range is higher than 81°C, the battery will become too hot even at temperatures below the melting point of the heat storage material, which may result in a decrease in characteristics. From these points of view, normal paraffin and microcrystalline wax are suitable as latent heat storage materials.

[0058] These latent heat storage materials may contain any fatty acid, such as tetradecanoic acid with a melting point of 54°C, hexadecanoic acid with a melting point of 63°C, or docosanoic acid with a melting point of 82°C.

[0059] Two-component curing base resins are resins that solidify by mixing two liquid resin components, primarily through polymerization. One component of the two-component curing base resin is a hydroxyl group-containing compound, such as a polybutadiene polyol composition or a polyester polyol composition. The other component is an isocyanate compound. By mixing these two resin components, a shape-retaining resin is produced through a polymerization reaction.

[0060] According to the heat storage thermal conductive material having the above-described configuration, by combining a heat storage material having a melting point of 48°C or higher, such as microcrystalline wax, with an oil gelling agent or a two-component curing base resin, it is possible to obtain a heat storage thermal conductive material that has a viscosity that can be filled without creating cavities and that can suppress the decrease in heat storage capacity over time.

[0061] The third embodiment has been described above. However, as a modification of the third embodiment, the heat storage thermally conductive material may contain an antioxidant.

[0062] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims.

[0063] (First Example) The effect of the heat storage thermal conductive material of the present invention was verified. The constituent components are as follows. (Invention Example A1) Heat storage material: n-paraffin (Wax 145, manufactured by Nippon Seiro Co., Ltd.) melting point 63°C Thermally conductive filler: alumina (AL43A, manufactured by Sumitomo Chemical Co., Ltd.) Shape-retaining component: aluminum 2-ethylhexanoate (Octope Aluminum T, manufactured by Hope Pharmaceutical Co., Ltd.) Anti-settling agent: fumed silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) Dispersant: non-ionic surfactant (SN Dispersant 9228, manufactured by San Nopco Ltd.)

[0064] (Comparative Example A1) Heat storage material: Wax 145 (n-paraffin: manufactured by Nippon Seiro Co., Ltd.) melting point 63°C Thermally conductive filler: alumina (AL43A: manufactured by Sumitomo Chemical Co., Ltd.) Shape retention component: two-component curing urethane resin (R15HT: manufactured by Idemitsu Kosan Co., Ltd., MR200: manufactured by Tosoh Corporation) Anti-settling agent: fumed silica (Aerosil R972: manufactured by Nippon Aerosil Co., Ltd.) Dispersant: non-ionic surfactant (SN Dispersant 9228: manufactured by San Nopco Ltd.)

[0065] The heat storage thermal conductive materials (samples) of Example A1 and Comparative Example A1 were prepared by blending the above-described components in the proportions (parts by mass) shown in Table 1A below. For each heat storage thermal conductive material, the initial thermal conductivity immediately after preparation, the initial heat storage amount, the thermal conductivity after 24 hours at 120°C, and the thermal conductivity after 240 hours at 120°C were measured, as well as the presence or absence of yellowing. Based on these results, the initial heat storage amount retention rate after 24 hours at 120°C and the initial heat storage amount retention rate after 240 hours at 120°C were calculated. These results are shown in Table 1.

[0066]

[0067] According to the results shown in Table 1, in Example A1 of the present invention, which used an oil gelling agent (aluminum 2-ethylhexanoate) as the shape-retaining component, the thermal conductivity increased slightly after 240 hours at 120°C, and the decrease in heat storage capacity was only 70%. On the other hand, in Comparative Example A1, which used a urethane resin as the shape-retaining component, the thermal conductivity decreased to about 60% after 240 hours at 120°C, and the decrease in heat storage capacity reached 57%, indicating significant deterioration over time in high-temperature environments. Furthermore, the appearance also showed signs of yellowing. Therefore, the deterioration resistance characteristics of Example A1 of the present invention, which used an oil gelling agent as the shape-retaining component, were confirmed.

[0068] (Example 2) The effect of the heat storage thermal conductive material of the present invention was verified. The constituent components are as follows. (Invention Example B1) Heat storage material: microcrystalline wax (Hi-mic-2045, manufactured by Nippon Seiro Co., Ltd.) molecular weight 500 to 800, melting point 70°C Thermally conductive filler: hexagonal boron nitride (HFL, manufactured by Air Brown Co., Ltd.) Shape-retaining component: aluminum 2-ethylhexanoate (Octope Aluminum T, manufactured by Hope Pharmaceutical Co., Ltd.) Antioxidant: hindered phenol radical scavenger (KEMINOX 9425, manufactured by Chemipro Chemical Co., Ltd.) Anti-settling agent: fumed silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) Dispersant: nonionic surfactant (SN Dispersant 9228, manufactured by San Nopco Ltd.)

[0069] (Invention Example B2) This example was the same as Invention Example B1, except that the antioxidant was changed to a hindered amine radical scavenger (KEMISTAB29, manufactured by Chemipro Chemical Co., Ltd.).

[0070] (Invention Examples B3, 4, and 5) The invention examples were the same as invention example B1, except that the antioxidant was changed to a hindered phenol radical scavenger (KEMISORB114, manufactured by Chemipro Kasei Co., Ltd.).

[0071] Comparative Example B1 This comparative example is the same as Inventive Example B1 except that it does not contain an antioxidant as a component.

[0072] The heat storage thermal conductive materials (samples) of Invention Examples B1 to B5 and Comparative Example B1 were prepared by blending the above-described components in the proportions (parts by mass) shown in Table 2 below. Then, for each heat storage thermal conductive material, the initial heat storage amount immediately after preparation, the heat storage amount after maintaining at 120°C for 24 hours, and the heat storage amount after maintaining at 120°C for 240 hours were confirmed. Based on these results, the initial heat storage amount retention rate after 24 hours at 120°C and the initial heat storage amount retention rate after 240 hours at 120°C were calculated. These results are shown in Table 2.

[0073]

[0074] According to the results shown in Table 2, in Invention Examples B1, 3-5, which contained an antioxidant, there was no decrease in heat storage capacity after 24 hours at 120°C, and even in Invention Example B2, the decrease rate was only 5%. Furthermore, in Invention Examples B1, 4, and 5, there was no decrease in heat storage capacity even after 240 hours at 120°C, with the decrease rate being only 7% in Invention Example B2 and 2% in Invention Example B3. On the other hand, in Comparative Example B1, which did not contain an antioxidant, the decrease rate in heat storage capacity after 24 hours at 120°C reached 10%, and after 240 hours at 120°C, the decrease rate reached 30%. Therefore, the deterioration resistance properties of the heat storage thermal conductive materials of Invention Examples B1-5, which contained an antioxidant, were confirmed.

[0075] (Example 3) The effect of the heat storage thermal conductive material of the present invention was verified. The constituent components are as follows. (Invention Examples C1 and C3) Heat storage material: n-paraffin (Wax 145, manufactured by Nippon Seiro Co., Ltd.) molecular weight 350 to 550, melting point 63°C Thermally conductive filler: alumina (AL43A, manufactured by Sumitomo Chemical Co., Ltd.) Shape retention component: two-component curing urethane resin (R15HT, manufactured by Idemitsu Kosan Co., Ltd. and MR200, manufactured by Tosoh Corporation) Anti-settling agent: fumed silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) Dispersant: non-ionic surfactant (SN Dispersant 9228, manufactured by San Nopco Ltd.)

[0076] (Invention Example C2) Heat storage material: n-paraffin (Wax 115, manufactured by Nippon Seiro Co., Ltd.) molecular weight 350 to 550, melting point 48°C Thermally conductive filler: alumina (AL43A, manufactured by Sumitomo Chemical Co., Ltd.) Shape retention component: two-component curing urethane resin (R15HT, manufactured by Idemitsu Kosan Co., Ltd. and MR200, manufactured by Tosoh Corporation) Anti-settling agent: fumed silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) Dispersant: non-ionic surfactant (SN Dispersant 9228, manufactured by San Nopco Ltd.)

[0077] (Invention Example C4) Heat storage material: microcrystalline wax (Hi-mic-2045, manufactured by Nippon Seiro Co., Ltd.) molecular weight 500 to 800, melting point 70°C Thermally conductive filler: hexagonal boron nitride (HFL, manufactured by Air Brown Co., Ltd.) Shape retention component: aluminum 2-ethylhexanoate (Octope Aluminum T, manufactured by Hope Pharmaceutical Co., Ltd.) Anti-settling agent: fumed silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) Dispersant: non-ionic surfactant (SN Dispersant 9228, manufactured by San Nopco Ltd.)

[0078] (Comparative Example C1) Heat storage material: Docosane (manufactured by Sasol Chemicals Japan Co., Ltd.) molecular weight 311, melting point 44°C Thermally conductive filler: Alumina (AL43A: manufactured by Sumitomo Chemical Co., Ltd.) Shape retention component: Two-component curing urethane resin (RT15HT: manufactured by Idemitsu Kosan Co., Ltd. and MR200: manufactured by Tosoh Corporation) Anti-settling agent: Fumed silica (Aerosil R972: manufactured by Nippon Aerosil Co., Ltd.) Dispersant: Non-ionic surfactant (SN Dispersant 9228: manufactured by San Nopco Ltd.)

[0079] The heat storage thermal conductive materials (samples) of Invention Examples C1 to C4 and Comparative Example C1 were prepared by blending the above-mentioned components in the proportions (parts by mass) shown in Table 3 below. The initial thermal conductivity and initial heat storage capacity immediately after preparation, the thermal conductivity and heat storage capacity after maintaining at 120°C for 24 hours, and the thermal conductivity and heat storage capacity after maintaining at 120°C for 240 hours were then measured for each heat storage thermal conductive material. These results are shown in Table 3.

[0080]

[0081] According to the results shown in Table 3, in invention examples C1 to C4, which used a heat storage material with a melting point of 48°C or higher, the loss after 24 hours at 120°C was kept to 20% or less. On the other hand, in comparison example C1, which used docosane, which has a melting point of 44°C, as the heat storage material, the loss of heat storage amount reached 75% after 24 hours at 120°C, indicating significant deterioration over time in high-temperature environments. Therefore, the deterioration resistance characteristics of invention examples C1 to C4, which used a heat storage material with a melting point of 48°C or higher, were confirmed.

[0082] According to the present invention, it is possible to provide a heat storage thermally conductive material that has fluidity that allows it to fill narrow spaces without gaps and that exhibits little deterioration in heat storage capacity over time.

Claims

1. A heat storage thermal conductive material comprising a heat storage material, a thermally conductive filler, and an oil gelling agent or a two-component curing base resin.

2. The heat storage and thermal conductive material according to claim 1, further comprising an antioxidant.

3. The heat storage thermal conductive material according to claim 2, wherein the antioxidant is a hindered phenol or hindered amine radical scavenger.

4. The heat storage thermal conductive material according to claim 2, characterized in that the antioxidant is contained in an amount of 0.5 parts by mass or more per 100 parts by mass of the heat storage material.

5. The heat storage thermal conductive material according to claim 1, characterized in that the melting point of the heat storage material is 48°C or higher.

6. The heat storage and thermally conductive material according to claim 5, characterized in that the heat storage material has an average molecular weight of 400 or more.

7. The heat storage thermal conductive material according to claim 1, characterized in that the oil gelling agent or two-component curing base resin is an oil gelling agent, and the oil gelling agent contains a fatty acid metal salt or a mixture of a fatty acid metal salt and a fatty acid.

8. The heat storage thermal conductive material according to claim 7, wherein the oil gelling agent is aluminum 2-ethylhexanoate.

9. The heat storage and thermal conductive material according to claim 1, wherein the thermally conductive filler contains ceramic particles.

10. The heat storage and thermally conductive material according to any one of claims 1 to 9, characterized in that the heat storage material contains a paraffin compound or a fatty acid.

11. The heat storage and thermally conductive material according to any one of claims 1 to 9, characterized in that the heat storage material is a microcrystalline wax.

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