WO2016185936A1

WO2016185936A1 - Thermally conductive composition and thermally conductive paste

Info

Publication number: WO2016185936A1
Application number: PCT/JP2016/063789
Authority: WO
Inventors: 一浩並木; 梢菊地
Original assignee: ポリマテック・ジャパン株式会社
Priority date: 2015-05-15
Filing date: 2016-05-09
Publication date: 2016-11-24
Also published as: JP6979686B2; JPWO2016185936A1

Abstract

The purpose of the present invention is to provide a thermally conductive composition which has none of the concerns of low molecular siloxanes, by which a thermally conductive filler can be filled at a high density, which exhibits a good handleability at ordinary temperatures and which softens at a usage temperature. Provided is a thermally conductive composition which contains a thermally conductive filler and a binder constituted from a phase change material having a melting point of 35-120ºC, a non-ionic surfactant and a non-volatile component, wherein the content of the phase change material is 10 parts by mass or higher, the content of the non-ionic surfactant is 60 parts by mass or higher and the content of the non-volatile component is 30 parts by mass or less, each relative to 100 parts by mass of the binder. This thermally conductive composition is a solid and exhibits excellent handleability at ordinary temperatures, softens, melts and binds tightly to an adherend when actually used, and thus can reduce thermal resistance.

Description

Thermally conductive composition and thermally conductive paste

The present invention relates to a thermally conductive composition used by being disposed between a heat generator and a heat radiator. More specifically, the present invention relates to a heat conductive composition containing a phase change product having a predetermined melting point.

In an electronic device, a heat sink such as a heat sink is attached to dissipate heat generated from a heat generator such as a semiconductor element or a machine part. For the purpose of efficiently transferring heat to the heat sink, A heat conductive member is sandwiched between the radiator and the heat sink. There are various types of heat conductive members such as a heat conductive sheet (solid), a heat conductive grease (liquid), and a curable heat conductive grease (from liquid to solid). The technique regarding heat conductive grease is described in, for example, Japanese Patent No. 4713161 (Patent Document 1).

Japanese Patent No. 4713161

However, heat conductive grease is paste-like at room temperature, and it is difficult to apply when the gap between the heat generator and the heat radiator is narrow, and it is easy to accidentally adhere to areas other than the desired application site. Inconvenience may be pointed out. Since it is easy to handle if it is solid at room temperature in the work intervening between the heating element and the heat dissipation body, it is solid at room temperature, but after being incorporated in the heating element, it absorbs heat and softens. Development of a heat conductive member having a property of being in close contact with the adherend and capable of reducing the thermal resistance is in progress.

However, the use of a thermoplastic silicone material as a substance exhibiting such properties has a problem of concern about the generation of low molecular siloxane. In addition, the use of a wax-based material has a problem in that it is difficult to increase the thermal conductivity because a highly conductive material cannot be filled.

Therefore, the present invention has been made to solve these problems. That is, an object is to provide a thermally conductive composition that is free from concerns about low-molecular siloxane, can be highly filled with a thermally conductive filler, is easy to handle at room temperature, and softens at the use temperature.

In order to achieve the above object, the present invention provides the following heat conductive composition and heat conductive paste.

That is, the present invention is a heat conductive composition comprising a phase change product having a melting point of 35 ° C. to 120 ° C., a binder comprising a nonionic surfactant and a non-volatile component, and a heat conductive filler, The phase change product occupying 100 parts by mass of the binder is a thermally conductive composition having 10 parts by mass or more, a nonionic surfactant of 60 parts by mass or more, and a non-volatile component of 30 parts by mass or less.

Since it includes a phase change product having a melting point of 35 ° C. to 120 ° C., it can be made into a heat conductive composition that is solid at normal temperature and takes away heat from the heating element and melts the phase change product. Moreover, since a nonionic surfactant is included, a phase change thing and a heat conductive filler can be disperse | distributed suitably and can be mixed. In addition, since a non-volatile component is included, it can be set as the heat conductive composition arranged to the desired property.

Since the phase change product occupying 100 parts by mass of the binder is 10 parts by mass or more, the nonionic surfactant is 60 parts by mass or more, and the non-volatile component is 30 parts by mass or less, both the phase change product and the thermally conductive filler are suitable. It can be highly filled in the heat conductive composition in a dispersed state. That is, heat resistance can be made extremely low by including 60 mass parts or more of nonionic surfactants. In addition, by including 10 parts by mass or more of a predetermined phase change product in combination with this nonionic surfactant, high thermal conductivity and phase change properties can be expressed.

The phase change product can be one or a combination selected from paraffin wax, ester wax, and polyolefin wax. By making the phase change material one or a combination selected from paraffin wax, ester wax, and polyolefin wax, it is solid at room temperature but melts in actual use and adheres closely to the heating element and heat radiator Can be made. Thereby, it can be set as a heat conductive composition with high heat conductivity.

The nonionic surfactant may be one or a combination selected from aliphatic carboxylic acid esters or aromatic carboxylic acid esters. By making the nonionic surfactant one or a combination selected from an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester, the affinity between the phase change product and the thermally conductive filler can be increased.

A heat conductive composition having a heat conductive filler content of 50 to 90 parts by volume with respect to 100 parts by volume of the heat conductive composition can be obtained. Since the proportion of the heat conductive filler is 50 to 90% by volume, it is possible to obtain a heat conductive composition having a high amount of heat conductive filler and high heat conductivity. Further, a heat conductive composition having a thermal resistance value of 0.080 to 0.150 ° C./W at a thickness of 20 to 40 μm can be obtained. Since the thermal resistance value at a thickness of 20 to 40 μm is 0.080 to 0.150 ° C./W, the thermal conductive composition is excellent in thermal conductivity.

A heat conductive paste containing any one of the above heat conductive compositions and a solvent, which is paste or liquid at room temperature, can be obtained. Since any one of the above heat-conductive compositions and a solvent is used to form a heat-conductive paste that is paste-like or liquid at room temperature, when the heat-conductive composition is interposed between the heat generator and the heat radiator Also, it is possible to deal with a case where it is inconvenient for a solid. That is, it can be used corresponding to a conventionally used coating apparatus, coating equipment, and coating method, such as a device for coating thermally conductive grease.
A paste-like or liquid heat-conductive paste is preferable to the heat-conductive composition in that it can be easily adhered to an adherend. In the case where the heat generating body or the heat radiating body is integrated in advance, for example, when attaching the heat radiating body and the heat conductive composition to the heat generating body, the solid heat conductive composition is in close contact with the room temperature. Since it is weak, it is easy to make it adhere to an adherend as long as it is a heat conductive paste, compared to being easily peeled off or displaced from the adherend.

According to the heat conductive composition of the present invention, there is no concern about low-molecular siloxane, it is a heat conductive composition having high heat conductivity and excellent handleability at room temperature.

It is a schematic cross section of a thermal resistance tester.

Hereinafter, embodiments of the present invention will be described. The thermally conductive composition of the present invention comprises a phase change product having a melting point of 35 ° C. to 120 ° C., a binder composed of a nonionic surfactant and an optional nonvolatile component, and a thermally conductive filler. ing. The components contained in the heat conductive composition will be described below.

Phase change product: A phase change product is a substance having a melting point of 35 ° C to 120 ° C. The properties required for the thermally conductive composition are solid at room temperature and absorb or soften or melt the heat of electronic components that generate heat during actual use. It is the main part.

Therefore, if the melting point is less than 35 ° C., it becomes excessively flexible even at room temperature, and the handleability may be deteriorated. On the other hand, when the temperature exceeds 120 ° C., it can be used only for special applications that operate at high temperatures, and is inferior in versatility. The upper limit of the melting point is more preferably determined according to individual specifications, but it is required to be a temperature that does not hinder the operation of the device, and if it is a general application, it is preferably 80 ° C. or lower. .

About melting | fusing point, it is preferable that the temperature range from the melting start to the melting end is narrow. This is because the narrower the temperature range, the faster the phase changes and the adhesion to the adherend becomes. Examples of the material having a narrow temperature range include a substance having a narrow molecular weight distribution and a substance having crystallinity.
In the present invention, the melting point is the temperature of the endothermic peak of the DSC curve measured by differential scanning calorimetry (DSC). The temperature range of the melting point is the intersection of the DSC curve baseline and the tangent at the inflection point from the baseline to the endothermic peak and the tangent at the inflection point from the endothermic peak to the baseline. Temperature range.

Such a phase change product is preferably a non-silicone material, and more specifically, various wax-like materials such as paraffin wax, ester wax and polyolefin wax can be exemplified.

The content of the phase change product is 10 parts by mass or more in 100 parts by mass of the binder composed of the phase change product, the nonionic surfactant, and the nonvolatile component. This is because the heat-conductive composition can have a phase change property if it is 10 parts by mass or more. Further, since the content of the nonionic surfactant is 60 parts by mass or more, the content of the phase change product is inevitably 40 parts by mass or less, so that it is included in the range of 10 to 40 parts by mass. . When the content of the phase change product exceeds 40 parts by mass, the content of the nonionic surfactant is relatively decreased and the thermal resistance may be deteriorated.

Nonionic surfactant: Nonionic surfactant is a main component that enhances the filling property of the thermally conductive filler. Examples of such nonionic surfactants include polyoxyethylene type, alkyl ether type, aliphatic carboxylic acid ester type, aromatic carboxylic acid ester type, special phenol type, amide type, and alkyl glucooxide type. Among these, it is preferable to use an aromatic carboxylic acid ester type or a polyoxyethylene type in that heat resistance can be improved. Moreover, it is preferable to use an aliphatic carboxylic acid ester type in that the filling property of the heat conductive filler can be improved. In other words, it is possible to reduce the viscosity by adding the aliphatic carboxylic acid ester type, and the viscosity when the heat conductive composition is softened by heating can be lowered. Therefore, since the thickness can be reduced with a constant load, the thermal resistance can be lowered.

As the aromatic carboxylic acid ester, phthalic acid ester, trimethylitonic acid ester, pyromellitic acid ester and the like are suitable. As the polyoxyethylene type, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine and the like are suitable. Aliphatic carboxylic acid esters include sorbitan laurate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monooleate, polyethylene glycol monolaurate, polyethylene glycol mono Palmitate, polyethylene glycol monostearate, polyethylene glycol monooleate, pentaerythritol monooleate, monoglyceryl oleate, decaglyceryl pentaoleate are preferred.

The content of the nonionic surfactant is 60 parts by mass or more in 100 parts by mass of the binder. On the other hand, since the content of the phase change product is 10 parts by mass or more, the content of the nonionic surfactant is inevitably 90 parts by mass or less, and is included in the range of 60 to 90 parts by mass. A preferred content is 75 to 85 parts by mass. When the content is less than 60 parts by mass, the thermal resistance value may be deteriorated. On the other hand, when the amount exceeds 90 parts by mass, the phase change property is relatively less than 10 parts by mass, and thus the phase change property may not be exhibited. If it is 75-85 mass parts, a phase change can be shown notably and thermal resistance can also be made low.

Nonionic surfactants are generally known to be used as dispersants together with anionic surfactants, cationic surfactants, amphoteric surfactants, fluorine compounds, polymer dispersants, and the like. However, addition of 10% by mass or less is recommended with respect to the total composition so as not to affect the properties of the main component, and it has hardly been used in excess of 30% by mass. However, as a result of intensive studies by the inventors, it has been found that the content of the heat conductive filler can be increased by increasing the content of the nonionic surfactant in relation to a predetermined phase change product.

It is considered that the reason why the amount of the thermally conductive filler can be increased by increasing the content of the nonionic surfactant with respect to 100 parts by mass of the binder to 60 to 90 parts by mass is as follows. In other words, heat conductive fillers such as metal oxide films, oxides, and hydroxides often have a hydrophilic surface, but the hydrophilic group portion of the nonionic surfactant is present on such a hydrophilic surface. Easy to adsorb. The other lipophilic part of the nonionic surfactant has good affinity with the phase change product. For this reason, the heat conductive filler and the phase change material are easily combined with each other through the nonionic surfactant. On the other hand, cationic surfactants and anionic surfactants have many solid salts and few options, and liquids also tend to have a low property of linking thermal conductive fillers as binders. If the heat conductive filler cannot be filled in a high amount or the viscosity becomes high, it is difficult to obtain physical properties required for the heat conductive composition.

The nonionic surfactant preferably has a viscosity at normal temperature of 10 to 10,000 mPa · s for the purpose of enhancing the filling property. Moreover, since there is much relative content of nonionic surfactant, when the stability of a heat conductive composition is considered, it is preferable that it is non-reactive. If the viscosity is less than 10 mPa · s, the volatility may be high, and the characteristics may change over time from the start of use. In addition, the thermally conductive composition may become brittle due to the low molecular weight. On the other hand, when the viscosity exceeds 10,000 mPa · s, the heat-conductive filler cannot be highly filled, and the heat-conductive composition becomes hard and may not be sufficiently softened even when heated.

The nonionic surfactant is preferably mixed uniformly with the phase change product, and the HLB value corresponding to the phase change product can be used as an index of ease of mixing. For example, a nonionic surfactant having an HLB value of 1.7 to 16.7 can be uniformly mixed with paraffin wax or polyolefin wax, which is preferable.

Nonvolatile component: Nonvolatile components can be included as components other than phase change products and nonionic surfactants as binders. Examples of the non-volatile component include a liquid component such as a plasticizer having a melting point of less than 35 ° C. and a resin component having a melting point of more than 120 ° C. Examples of the liquid component having a melting point of less than 35 ° C. include paraffin oil and ester oil. By adding these oils, the flexibility of the thermally conductive composition at normal temperature and in a heated state can be increased. In addition, even if it is a liquid component whose melting | fusing point is less than 35 degreeC, the solvent which volatilizes at the time of use and does not remain | survive is not contained in a non-volatile component.

Resin components having a melting point exceeding 120 ° C. include ethylene-propylene rubber (EPR, EPDM), ethylene-butylene copolymer, ethylene-butylene-styrene copolymer, ethylene-propylene-styrene copolymer, hydrogenated polyalkyl. Examples include diene monool, hydrogenated polyalkyldiene diol, hydrogenated polyisopre. By adding a resin component, the strength of the thermally conductive composition can be increased. This resin component is preferably compatible with the nonionic surfactant and other components.

The content of the non-volatile component is 30 parts by mass or less, out of 100 parts by mass of the binder, and may not be included. That is, out of 100 parts by mass of the binder, the non-volatile component, which is a component remaining because the phase change product is 10 parts by mass or more and the nonionic surfactant is 60 parts by mass or more, is 30 parts by mass or less. In the case of a resin component having a melting point exceeding 120 ° C., if it is contained in a large amount, the heat conductive composition may become too hard. Therefore, the amount is preferably 5 parts by mass or less in 100 parts by mass of the binder.

Non-volatile components can contain various additives for the purpose of enhancing various properties such as productivity, weather resistance, and heat resistance. Examples of such additives include various functional improvers such as reinforcing materials, colorants, heat resistance improvers, coupling agents, flame retardants, and deterioration inhibitors.

Thermally conductive filler: The thermally conductive filler is a substance that literally imparts thermal conductivity to the thermally conductive composition. Examples of the thermally conductive filler include fine powder made of metal, carbon, metal oxide, metal nitride, metal carbide, metal hydroxide, and the like. Examples of the metal include copper and aluminum. Examples of the carbon include pitch-based carbon fibers, PAN-based carbon fibers, fibers obtained by carbonizing resin fibers, fibers obtained by graphitizing resin fibers, and graphite powder. When voltage resistance is required, it is preferable to use a thermally conductive filler other than metal or carbon.

Examples of the metal oxide include aluminum oxide, magnesium oxide, zinc oxide, iron oxide, and quartz, and examples of the metal nitride include boron nitride and aluminum nitride. In addition, examples of the metal carbide include silicon carbide, and examples of the metal hydroxide include aluminum hydroxide. The shape of the thermally conductive filler may be spherical or non-spherical, but spherical particles are preferred because they are more easily filled, and thus are more likely to increase thermal conductivity.

The average particle size of the thermally conductive filler is preferably 0.3 to 10 μm. When the average particle size is less than 0.3 μm, it becomes difficult to highly fill the binder with the heat conductive filler. On the other hand, when the average particle size exceeds 10 μm, the compressibility of the heat conductive composition is deteriorated even in a heated state, and it is difficult to lower the thermal resistance. In addition, the average particle diameter referred to in the present specification, claims and the like is a volume-based average particle diameter measured by a laser diffraction scattering method unless otherwise described.

The heat conductive filler preferably contains a predetermined amount of 0.1 to 1 μm heat conductive filler or 5 to 20 μm heat conductive filler. This is because, when a plurality of thermally conductive fillers having different particle diameters are mixed, high filling can be achieved as a whole, and thermal conductivity can be improved.

The filling amount of the heat conductive filler occupies 50 to 90 parts by volume with respect to 100 parts by volume of the heat conductive composition, and more preferably 60 to 90 parts by volume. If it is less than 50 volume parts, there exists a possibility that thermal conductivity may become low. On the other hand, if the volume exceeds 90 parts by volume, the viscosity is not sufficiently lowered even if the binder undergoes a phase change due to the small amount of the binder component, making it difficult to form a thin film and increasing the thermal resistance.

Other components: Components other than the binder and the heat conductive filler can be added to the heat conductive composition. For example, when the heat conductive composition is assembled in an electronic device as a heat conductive medium, particles serving as a spacer can be blended so that the heat conductive composition maintains a certain thickness even in a heated state. Examples of the particles serving as the spacer include glass beads and ceramic particles. The particles can be contained in an amount of 5 parts by volume or less, preferably about 0.1 to 3 parts by volume with respect to 100 parts by volume of the heat conductive composition. . If it is less than 0.1 part by volume, it may not function as a spacer. If it exceeds 5 parts by volume, thermal conductivity may be deteriorated.

Also, a solvent can be added to the heat conductive composition if necessary. For example, when forming a sheet, a solvent is added to the thermally conductive composition to form a thermally conductive paste, and after applying the thermally conductive paste, the solvent is volatilized to form a sheet-like thermally conductive composition. You can get things.

As the solvent, a solvent which volatilizes at a predetermined temperature and is compatible with the phase change product and the nonionic surfactant can be used. For example, for paraffin waxes and polyolefin waxes, hydrocarbon solvents, aromatic solvents, ketone solvents, and ester solvents can be used. The heat conductive paste preferably has a viscosity of 1.0 to 2,000 Pa · s by adjusting the amount of solvent added.

In order to produce a heat conductive composition, necessary components are added to and mixed with a binder and a heat conductive filler. Since the phase change product is solid at room temperature, in order to mix uniformly, it is preferable to heat and knead, and it is preferable to mix using a kneader or a planetary mixer with a heater. Moreover, when adding a solvent, it can be made easy to mix at normal temperature by dissolving a phase change thing in a solvent.

The heat conductive composition changes its phase at a predetermined temperature due to the nature of the phase change material it contains, so it has an appropriate hardness at room temperature while softening when heated to a predetermined temperature and adheres to the adherend. Can increase the sex. In other words, since it has a hardness that is at least solid or non-fluid clay at room temperature, if it is in the form of a sheet, it is hard enough to maintain its shape, is easy to handle, and is not a sheet However, the adhesiveness is not excessively high, and it is easy to handle because it does not contaminate other members that come into contact. In this respect, it is different from grease that easily adheres when other members come into contact and has difficulty in handling.

The above embodiment can be modified as appropriate without departing from the spirit of the present invention. EXAMPLES Hereinafter, although this invention is further demonstrated based on an Example, this invention is not limited to the range shown by an Example.

The heat conductive compositions or heat conductive pastes of Sample 1 to Sample 26 described below were prepared and subjected to various tests.

<Sample 1>: 15 parts by mass of crystalline polyolefin (melting point 42 ° C., melting point temperature range 39 to 45 ° C.) as phase change product 1, 85 parts by mass of sorbitan trioleate as nonionic surfactant A, heat conduction The heat conductive paste of Sample 1 was obtained by mixing 244 parts by mass of aluminum oxide (spherical, 1 μm) as a conductive filler, 400 parts by mass of aluminum oxide (spherical, 12 μm) and 40 parts by mass of isoparaffin as a solvent. The viscosity of this heat conductive paste at room temperature was 417 Pa · s and was a liquid. The heat conductive composition of Sample 1 was obtained by applying this heat conductive paste to an aluminum heat sink as a heat radiator by screen printing and then drying. This heat conductive composition was laminated | stacked on the heat radiator, and thickness was 90 micrometers.

<Samples 2 to 10> Samples 2 to 10 were obtained by changing the blending amounts of the phase change product A and the nonionic surfactant A using the same material as that of the sample 1. Others were the same as Sample 1, and the thermal conductive pastes and thermal conductive compositions of Samples 2 to 10 were produced.
Table 1 shows the composition of Sample 1 to Sample 10.

<Samples 11 to 13>: Samples 11 to 13 are samples in which the type of the phase change object is changed compared to Sample 1. More specifically, sample 11 used phase change product 2, sample 12 used phase change product 3, and sample 13 used a mixture of phase change product 1 and phase change product 2. Others were made in the same manner as Sample 1, and a heat conductive paste and a heat conductive composition of each sample were prepared.

Here, the phase change items 1 to 3 are as follows.
Phase change product 1: crystalline polyolefin (melting point 42 ° C, melting point temperature range 39-45 ° C)
Phase change product 2: paraffin wax (melting point 46 ° C, melting point temperature range 40-50 ° C)
Phase change product 3: Ester wax (melting point 46 ° C, melting point temperature range 40-50 ° C)

<Samples 14 to 19>: Samples 14 to 19 are samples obtained by changing the type of nonionic surfactant as compared with Sample 1. More specifically, sample 14 is nonionic surfactant 2, sample 15 is nonionic surfactant 3, sample 16 is nonionic surfactant 4, sample 17 is nonionic surfactant 5, and sample 18 is nonionic. As the surfactant 6, Sample 19 in which equal amounts of nonionic surfactant 1 and nonionic surfactant 2 were mixed was used. Others were made in the same manner as Sample 1, and a heat conductive paste and a heat conductive composition of each sample were prepared.

Here, the nonionic surfactants 1 to 6 are as follows.
Nonionic surfactant 1: sorbitan trioleate (HLB: 1.7, viscosity: 200 mPa · s)
Nonionic surfactant 2: Decaglyceryl pentaoleate (HLB: 3.5, viscosity: 5,000mPa · s)
Nonionic surfactant 3: Triisodecyl trimellitic acid (HLB: 12, viscosity: 300 mPa · s)
Nonionic surfactant 4: Polyoxyethylene sorbitan monolaurate (HLB: 16.7, viscosity: 500 mPa · s)
Nonionic surfactant 5: Polyoxyethylene oleyl ether (HLB: 13.3, viscosity: 100 mPa · s)
Nonionic surfactant 6: Polyoxyethylene alkylamine (HLB: 15, viscosity: 450 mPa · s)
Table 2 shows the composition of Sample 11 to Sample 19.

<Samples 21 to 26> Samples 21 to 26 are samples obtained by changing the nonionic surfactants to plasticizers 1 to 6, respectively, as compared with sample 1. That is, plasticizer 1 in sample 21, plasticizer 2 in sample 22, plasticizer 3 in sample 23, plasticizer 4 in sample 24, plasticizer 5 in sample 25, plasticizer 6 in sample 26, respectively. Using. Others were made in the same manner as Sample 1, and a heat conductive paste and a heat conductive composition of each sample were prepared.

Here, the plasticizers 1 to 6 are as follows.
Plasticizer 1: Polybutene oil (viscosity: 400 mPa · s)
Plasticizer 2: Polybutene oil (viscosity: 1,200 mPa · s)
Plasticizer 3: Polybutene oil (viscosity: 50,000 mPa · s)
Plasticizer 4: Paraffin oil (viscosity: 10 mPa · s)
Plasticizer 5: Paraffin oil (viscosity: 3,000 mPa · s)
Plasticizer 6: Paraffin oil (viscosity: 12,000 mPa · s)
Table 3 shows the composition of Sample 21 to Sample 26.

The heat conductive compositions of Samples 1 to 19 and 21 to 26 were subjected to various evaluations by performing the tests described below.

(1) Thermal resistance The thermal resistance was measured with a thermal resistance tester 10 as shown in FIG. First, the heat conductive composition 1 of each sample was installed on the copper block 3 whose surface placed on the heat insulating material 2 was 10 mm × 21 mm. And the heat conductive composition 1 was pinched | interposed with the heat sink 4 made from aluminum which is a heat radiator, and the copper block 3, and the fan 5 was installed on the heat sink 4. FIG. Further, a load F of 7 kg was applied to the heat sink with a weight. A heater 7 (heat generation amount 42 W) is built in the copper block 3. Heating the heater 7 while applying a load of 7 kg, measuring the temperature of the copper block 3 and the heat sink 4 when the temperature reached a steady state, and calculating the thermal resistance of the thermally conductive composition from the following equation (1) Asked.

Thermal resistance = (θj1-θj0) / Heat generation amount Q ··· Equation (1)
In equation (1), θj1 is the temperature of the copper block 5, θj0 is the temperature of the heat sink 4, and the heat generation amount Q is 42W. In this test, the sample thickness (μm) at the time when the steady state was reached was recorded in addition to the thermal resistance value. With respect to the measurement result, a sample having a thermal resistance value of less than 0.150 ° C./W was designated as “◯”, and a sample thickness at the time of measurement was designated as “◯”.

(2) Handling property When a stainless steel weight (20 mm diameter cylinder, 200 g) is placed on the thermally conductive composition of each sample for 10 seconds in an atmosphere at 23 ° C., whether or not a trace of the weight remains on the surface. evaluated. “◯” indicates that no trace was left, “Δ” indicates that a trace was slightly left, and “x” indicates that a trace was clearly left.

(3) Phase change Regarding whether or not the thermally conductive composition has undergone a phase change, the two indicators “(1) thermal resistance” and “(2) handleability” are given, and “(1) heat “○: Something is causing a phase change” when both indicators are compatible, such as “○” for “resistance” and “○” for “(2) Handling”. In either case, the case where “x” was present was judged as “×: the case where no phase change occurred”. If the handleability is good in the handling test, the phase change product is considered to be solid at room temperature. On the other hand, if the sample thickness is 40 μm or less in the thermal resistance test, the phase change product is melted by heating the heater. It is possible.

(4) Heat resistance After leaving the heat conductive composition of each sample at 150 degreeC for 24 hours, the test similar to the test shown by said "(1) thermal resistance" was done, and sample thickness was measured. A sample thickness exceeding 40 μm is “x”, and the sample thickness is 40 μm or less, but a sample thickness of 20% or more compared to a sample that has not been subjected to a heat resistance test is “Δ”, The sample thickness was 40 μm or less and the sample thickness was thicker than that of the sample not subjected to the heat resistance test, but the thickness was less than 20%.

(5) Viscosity The viscosity of the heat conductive paste of each sample was measured with a viscometer (rotary viscometer DV-E manufactured by BROOK FIELD) using a spindle no. The measurement was performed at a rotation speed of 10 rpm and a measurement temperature of 23 ° C. using 14 rotors.

<Evaluation of Samples 1 to 10>:
The sample 2 and the sample 3 in which the amount of the phase change product 1 was 0 to 5 parts by mass were evaluated as “×”. This is thought to be because the physical properties could not be sufficiently enhanced because the content of the phase change product was small. On the other hand, in the sample 3 in which the blending amount of the phase change product 1 is 10 parts by mass, “Δ” is indicated, and the handleability is improved. In Sample 1 and Samples 4 to 10 in which the blending amount of Phase Change Product 1 was 15 parts by mass or more, “◯” was obtained. It turned out to be particularly good at more than part.

Next, looking at the thermal resistance values, the thermal resistance values of Samples 1 to 5 are extremely low. The reason is that the compressibility was high and the thickness was reduced by softening with heating. It is done. Further, from the measurement result of the compressibility, it is considered that the greater the proportion of the nonionic surfactant, the more flexible and the thinner the thickness. On the other hand, Sample 6 and Sample 7 had a low thermal resistance, but Sample 8 had a considerably high thermal resistance. From this result, it was found that the heat resistance value was drastically reduced when the blend amount of the nonionic surfactant was 60 parts by mass or more, and extremely low when the compounding amount was 70 parts by mass or more.

<Evaluation of Samples 11 to 13>:
Samples 11 to 13 are samples in which the type of the phase change object is changed with respect to the sample 1. Even when the polyolefin wax was changed to paraffin wax or ester wax, the heat resistance value was less than 0.150 ° C./W, and the heat conductive composition had good handleability and good phase change. Comparing sample 11 and sample 12 with sample 1, the thickness of the thermally conductive composition at the time of measurement was slightly thicker, but phase change product 2 and phase change product 3 have a slightly wider melting point, and are softened by heating. It is thought that the degree to do was a little small.

<Evaluation of Samples 14 to 19>:
Samples 14 to 19 were obtained by changing the type of nonionic surfactant as compared with sample 1. However, the thermal resistance values of all samples 14 to 19 were less than 0.150 ° C./W. Among these nonionic surfactants, the samples 14 to 16 and 19 using the ester type have a relatively low thermal resistance value together with the sample 1, and among them, the sample 15 using the aromatic carboxylic acid ester type and the poly Samples 16 to 18 using the oxyethylene type were particularly excellent in heat resistance.

<Evaluation of Samples 21 to 26>:
Samples 21 to 23 using polybutene oil as a plasticizer having no surface-active action in place of the nonionic surfactant have a thickness of the heat conductive composition at the time of measurement other than that of sample 21 is larger than that of sample 1. The thermal resistance was also high. The reason is considered that when polybutene oil is used, the filling property of the heat conductive filler is poor and the hardness when heated is slightly hard.

In addition, samples 24 to 26 using paraffin oil as a plasticizer also had a thicker thermal conductive composition and higher heat resistance than those of sample 1. The reason for this is considered to be that the heat-conductive filler is poorly filled as in the case of polybutene oil, and the hardness when heated is somewhat hard.

DESCRIPTION OF SYMBOLS 1 Thermal conductive composition 2 Heat insulating material 3 Copper block 4 Heat sink 5 Fan 7 Heater 10 Thermal resistance tester F Load

Claims

A heat conductive composition comprising a phase change product having a melting point of 35 ° C. to 120 ° C., a binder comprising a nonionic surfactant and a nonvolatile component, and a heat conductive filler,
A thermally conductive composition in which a phase-change product occupying 100 parts by mass of the binder is 10 parts by mass or more, a nonionic surfactant is 60 parts by mass or more, and a non-volatile component is 30 parts by mass or less.
The thermally conductive composition according to claim 1, wherein the phase change product is one or a combination selected from paraffin wax, ester wax, and polyolefin wax.
The thermally conductive composition according to claim 1 or 2, wherein the nonionic surfactant is one or a combination selected from aliphatic carboxylic acid esters and aromatic carboxylic acid esters.
The heat conductive composition according to any one of claims 1 to 3, wherein a content of the heat conductive filler is 50 to 90 parts by volume with respect to 100 parts by volume of the heat conductive composition.
The heat conductive composition according to any one of claims 1 to 4, wherein the heat resistance value at a thickness of 20 to 40 µm is 0.080 to 0.150 ° C / W.
A heat conductive paste comprising the heat conductive composition according to any one of claims 1 to 5 and a solvent, which is paste-like or liquid at room temperature.