JP2005320484A - Heat-conductive composition and heat-conductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-conductive composition which is flexible, has excellent shape followingness, excellent adhesiveness, excellent recyclability, and high heat conductivity, and to provide a heat-conductive sheet. <P>SOLUTION: This heat-conductive composition is characterized by comprising 50 to 95 pts.wt. of an adhesive polymer, 5 to 50 pts.wt. of a side chain-crystallizable polymer which is incompatible with the adhesive polymer and exhibits flowability at the heat-generating temperature of the a heat generator, and a heat-conductive filler in an amount of 10 to 300 pts.wt. per 100 pts.wt. of the total amount of the polymers. The heat-conductive composition has an adhesive power ratio (adhesive power at 80°C / adhesive power a 23°C) at 80°C and 23°C of ≤0.2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermally conductive composition and a thermally conductive sheet having thermal conductivity.

  2. Description of the Related Art In recent years, in electrical / electronic components that use semiconductors as a representative example, cooling of electrical / electronic components accompanying heat generation has become important in order to prevent malfunctions due to heat. As a cooling method, a method is adopted in which the heat generated by the electric / electronic component is conducted to the heat radiating body to radiate heat. However, the surfaces of the heat generator and the heat radiator are often not smooth. For this reason, the heat dissipation effect is improved by interposing an adhesive sheet using a heat conductive pressure-sensitive adhesive having flexibility between the heating element and the heat dissipation element so that a sufficient contact area is obtained. ing. Such an adhesive sheet is in close contact with the surface of the heating element or the heat radiating body, and a high heat radiating effect is obtained by increasing the contact area. For this reason, the said adhesive sheet is requested | required of a softness | flexibility and shape followability.

  As the adhesive sheet, Patent Document 1 discloses a copolymer containing an alkyl acrylate ester as a main component, a higher aliphatic alcohol having a melting point of 40 to 80 ° C. and a higher aliphatic alcohol which is incompatible with the copolymer. A thermally conductive pressure-sensitive adhesive sheet containing a compound such as a fatty acid and thermally conductive fine particles is described.

  Such a heat conductive pressure-sensitive adhesive sheet receives heat from a heating element and is heated to a temperature equal to or higher than the melting point of the compound. Yes. However, since the compound is a low molecular weight compound as compared with the polymer, the dispersibility with respect to the copolymer as the main component is limited, and for example, the dispersed particle size must be small. For this reason, the flexibility is not sufficient, and depending on the surface shape of the heat generating body and the heat radiating body, it is difficult to achieve complete contact, particularly with a fine uneven shape, and thus there is a problem that a high heat radiating effect cannot be obtained. . Further, since the decrease in the adhesive strength when the compound is melted is small, it cannot be easily removed from the heating element and the heat dissipation element. For this reason, if it is forcibly removed, a part of the compound remains on the surface of the heating element or radiator, so-called adhesive residue is generated, which may hinder recycling of the heating element or radiator.

JP 2003-105299 A

  An object of the present invention is to provide a thermally conductive composition and a thermally conductive sheet which are flexible and excellent in shape followability and adhesiveness, excellent in peelability and recyclability, and have high thermal conductivity.

As a result of intensive studies to solve the above problems, the present inventors have found that the heat conductive composition is incompatible with the adhesive polymer, and the exothermic temperature of the heating element is incompatible with the adhesive polymer. When the side-chain crystallizable polymer is fluid, the side-chain crystallizable polymer is incompatible with the adhesive polymer (sea) that is the base material (is not a continuous island). ) And exhibiting flexibility in a state of forming a so-called sea-island structure, shape followability and adhesion are exhibited, thermal conductivity is improved, and adhesiveness is sufficiently lowered to facilitate removal. The present inventors have found a new fact that the recyclability of electric / electronic parts is improved and completed the present invention.
That is, the thermally conductive composition of the present invention comprises 50 to 95 parts by weight of an adhesive polymer, side chain crystals that are incompatible with the adhesive polymer and exhibit fluidity at the heating temperature of the heating element. It is characterized by containing 5 to 50 parts by weight of the convertible polymer and further containing 10 to 300 parts by weight of a heat conductive filler with respect to 100 parts by weight of the total amount of these polymers.

  The heat conductive composition of the present invention preferably has a ratio of adhesive strength at 80 ° C. to 23 ° C. (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) of 0.2 or less. Thereby, a heat conductive composition can be easily removed from a heat generating body or a heat radiator.

The thermally conductive sheet of the present invention has a fluidity at the exothermic temperature of the heating element, which is incompatible with 50 to 95 parts by weight of the adhesive polymer between the release-treated films, and the adhesive polymer. It contains 5 to 50 parts by weight of the side chain crystallizable polymer shown, and further contains 10 to 300 parts by weight of a heat conductive filler with respect to 100 parts by weight of the total amount of these polymers. The thickness of the sheet is preferably 20 to 200 μm in order to obtain shape followability and adhesion.
Another form of the heat conductive sheet in the present invention is 50 to 95 parts by weight of an adhesive polymer between the release-treated films, an incompatible with the adhesive polymer, and a heating element. A pressure-sensitive adhesive layer containing 5 to 50 parts by weight of a side-chain crystallizable polymer exhibiting fluidity at an exothermic temperature, and further containing 10 to 300 parts by weight of a heat conductive filler with respect to 100 parts by weight of the total amount of these polymers Is provided on both surfaces of a base film having thermal conductivity.

  The heat conductive composition of the present invention has the effect that the shape followability and adhesion are expressed and the heat conductivity is improved by being dispersed with high dispersibility and exhibiting flexibility at the heat generation temperature of the heating element. is there. In addition, by having a specific side chain crystallizable polymer, it is easy to remove, so that the recyclability of electrical and electronic parts is improved, and there is no so-called adhesive residue on the surface of the heating element and heat dissipation element. There is.

  The thermally conductive composition of the present invention is a composition comprising an adhesive polymer, a side chain crystallizable polymer, and a thermally conductive filler, and the side chain crystallizable polymer has the adhesive property. It must be incompatible with the polymer it has and exhibit fluidity at the exothermic temperature of the heating element.

  The side chain crystallizable polymer in the present invention has a property of reversibly changing between a crystalline state and a fluid state in response to a temperature change. Specifically, the side-chain crystallizable polymer in the present invention is preferably incompatible with the adhesive polymer. The term “incompatible” as used herein means that the adhesive polymer and the side chain crystallizable polymer are not substantially compatible. When both polymers are compatible, the cohesive force of the heat conductive composition is lowered, and there is a possibility that the handling property is lowered or the heat conductive composition flows out between the heat generator and the heat radiator.

  The side chain crystallizable polymer in the present invention is preferably crystallized at a temperature of, for example, a melting point of 30 ° C. or higher, preferably 40 ° C. or higher and lower than the melting point. As a result, the side chain crystallizable polymer exhibits fluidity when it receives heat from the heating element during heat generation, and has high wettability at the interface between the heating element and the heat dissipation element. Since the adhesiveness is sufficiently lowered, the heat radiating member can be easily removed and the recyclability is improved. On the other hand, when the melting point of the side chain crystallizable polymer is less than 30 ° C., the heat conductive composition may be softened or fluidized during storage, and the handling property may be deteriorated or the form may be lost.

  In the present invention, the “melting point” refers to a temperature at which a specific portion of a polymer that is initially aligned in an ordered arrangement becomes disordered by an equilibrium process. The melting point in the present invention is measured by a differential thermal scanning calorimeter (DSC) of the side chain crystallizable polymer under measurement conditions of 10 ° C./min.

  Specific examples of the side-chain crystallizable polymer include acrylic ester or methacrylic acid ester having a linear alkyl group having 16 or more carbon atoms and acrylic acid having an alkyl group having 1 to 12 carbon atoms. It may be a polymer (homopolymer or copolymer) obtained by polymerizing 0 to 70 parts by weight of an acid ester or methacrylic acid ester and 0 to 10 parts by weight of a polar monomer.

Examples of the acrylic acid ester and / or methacrylic acid ester (hereinafter referred to as (meth) acrylate) having a linear alkyl group having 16 or more carbon atoms include stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meta). ) A (meth) acrylate having a linear alkyl group having 18 to 22 carbon atoms such as acrylate is preferably used.
Examples of the (meth) acrylate having an alkyl group having 1 to 12 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate, and lauryl (meth) acrylate. Etc.
Examples of polar monomers include carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl Ethylenically unsaturated monomers having a hydroxyl group such as (meth) acrylate and 2-hydroxyhexyl (meth) acrylate are used, among which acrylic acid is particularly preferable.

  The side chain crystallizable polymer may have a weight average molecular weight of 1000 to 20000. As a result, the side chain crystallizable polymer is dispersed as a non-continuous island having a predetermined dispersed particle size with respect to the adhesive polymer (sea), so that the side chain crystallizable polymer is fluidized. In this case, it can be dispersed with high dispersibility with respect to the adhesive polymer. Here, if the weight average molecular weight of the side-chain crystallizable polymer is less than 1000, the dispersibility of the polymer having adhesiveness decreases. Moreover, since fluidity | liquidity will fall when the said weight average molecular weight is larger than 20000, there exists a possibility that the adhesiveness of a heat generating body and a heat radiator may be inferior. The weight average molecular weight is a value obtained by measuring the side chain crystallizable polymer by gel permeation chromatography (GPC) and converting the obtained measurement value into polystyrene.

The adhesive polymer in the present invention is a copolymer having an acrylic acid ester and / or methacrylic acid ester (hereinafter referred to as (meth) acrylate) having a C 1-12 alkyl group as a main component. Good. Examples of such (meth) acrylates include 2-ethylhexyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and the like.
Moreover, you may use the (meth) acrylate which has a hydroxyalkyl group as another copolymerization component. Examples of such (meth) acrylates include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, and the like.

  The copolymer may have a weight average molecular weight of 50,000 to 500,000, preferably 100,000 to 300,000. When the weight average molecular weight of the polymer is less than 50,000, the workability is deteriorated due to insufficient cohesive force of the heat conductive composition, and there is a possibility that an adhesive residue may be generated when the polymer is removed. On the other hand, if the weight average molecular weight of the polymer is larger than 500,000, the cohesive force is high and the flexibility is inferior.

  The thermally conductive composition in the present invention preferably contains 50 to 95 parts by weight of the adhesive polymer and 5 to 50 parts by weight of the side chain crystallizable polymer. When the blending amount of the side chain crystallizable polymer is less than 5 parts by weight, flexibility is hardly improved even when heated to a temperature equal to or higher than the melting point. On the other hand, if the blending amount is higher than 50 parts by weight, there is a possibility that the adhesive residue will increase when removing.

  A heat conductive filler is added to the heat conductive composition of the present invention in order to increase the heat conductivity. The heat conductive filler is not particularly limited, and examples thereof include boron nitride, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and graphite. Further, the shape is not particularly limited, but fine particles having an average particle diameter of 1 to 50 μm are preferable.

  The thermally conductive filler is preferably blended in an amount of 10 to 300 parts by weight with respect to 100 parts by weight of the total amount of the adhesive polymer and the side chain crystallizable polymer. Thereby, when the side chain crystallizable polymer exhibits fluidity, heat is efficiently transferred from the heating element to the heat dissipation element. When the blending amount of the thermally conductive filler is less than 10 parts by weight, the flexibility of the thermally conductive composition can be maintained, but the thermal conductivity is insufficient. Moreover, when the said compounding quantity is higher than 300 weight part, there exists a possibility that the viscosity of this composition may become high and a softness | flexibility may fall.

  The heat conductive composition of the present invention preferably has a ratio of adhesive strength at 80 ° C. to 23 ° C. (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) of 0.2 or less. When the ratio is larger than 0.2, the adhesive force is not sufficiently lowered, so that it is difficult to remove and adhesive residue is likely to occur. The ratio of adhesive strength is determined from the measured values obtained by a 180 ° peel test (vs. stainless steel) at 80 ° C. and 23 ° C. in each ambient temperature by the method according to JIS Z0237. In addition, as for the heat conductive composition of this invention, it is preferable that 80 degreeC adhesive strength is 0.1-0.5 N / 25mm, and 23 degreeC adhesive strength is 1-5 N / 25mm.

  Moreover, in order to raise heat resistance and cohesion force, in the heat conductive composition of this invention, you may add a crosslinking agent in the range which does not inhibit a softness | flexibility. In addition, it is preferable that the usage form of the heat conductive composition of this invention is a film form or a sheet form form on handling property.

  The thermally conductive sheet according to the present invention is applied to a film (release film) having been subjected to an appropriate release treatment with a coating solution obtained by adding the above-described thermally conductive composition to a solvent, and dried. It is formed by sandwiching both sides with a release film. The heat conductive sheet may be formed into a sheet shape by extrusion molding or calendering. As the release film, for example, a film surface such as polyethylene terephthalate coated with a release agent such as silicone can be used. It can also be impregnated into a metal mesh or metal fiber woven fabric.

  The thermal conductive sheet may have a thickness of 20 to 200 μm. If the thickness of the heat conductive sheet is less than 20 μm, it may be difficult to accurately follow the surface shape of the heating element or the heat dissipation body when the flexibility of the sheet is improved. Moreover, when the thickness of the sheet is more than 200 μm, the thermal conductivity may be deteriorated.

  As a heat generating body in this invention, a semiconductor, a power module, an electronic component etc. are mentioned, for example. Moreover, as a heat radiator, what is attached to the heat generating surface of the said heat generating body and has the performance which can suppress the raise of heat_generation | fever temperature at least by air cooling, water cooling, etc., for example, the heat sink etc. which have a cooling fin are mentioned.

  Next, the usage method of the heat conductive sheet of this invention is demonstrated. First, the release sheets on both sides of the heat conductive sheet are peeled off, and the heat conductive sheet is attached to a predetermined position on the surface of the heating element. Next, the heat radiating body is stuck on the surface of the heating element through the sheet, and the heat radiating body is fixed to the surface of the heating element.

  In this state, the heating element generates heat, and when the surface of the heating element is heated to a temperature substantially equal to the melting point of the side chain crystallizable polymer, the polymer flows from the crystalline state to the non-crystalline state and flows. The wettability is improved at the interface with the heat sink. As a result, the heat conductive sheet follows the fine irregularities present on the surfaces of the heat generator and the heat radiator, and adheres to these surfaces without gaps, so the contact area is increased and high heat conductivity is achieved. Can be shown.

  In the said state, since the adhesive force of a heat conductive sheet has fully reduced, it can remove easily from a heat radiator and a heat generating body. In addition, after the removal, a part of the sheet remains on the surface of the heat generating body or the heat radiating body, so-called adhesive residue does not occur. Further, the sheet can be used repeatedly many times by performing the same operation as described above.

  As other embodiment of this invention, the adhesive layer containing an above described heat conductive composition can be provided in both surfaces of the base film which has heat conductivity. Thereby, the intensity | strength of a heat conductive sheet improves. Although it does not restrict | limit especially as a base film which has the said electroconductivity, For example, metal films, such as copper and aluminum, a metal mesh, a metal fiber woven fabric, and a graphite sheet are mentioned.

  This heat conductive sheet is formed by applying a coating solution obtained by adding the above-described heat conductive composition to a solvent on one side of a base film, drying, and then forming an adhesive layer on the other side in the same manner, It forms by sticking a release film on the surface of this adhesive layer. Alternatively, it can be formed by first applying to a release film, drying, and laminating it on a substrate film to transfer it. In addition, it is preferable when the thickness of the said adhesive layer of one side is 20-100 micrometers to express shape followability.

  In addition, the usage form of the heat conductive composition of this invention is not limited to a film form or a sheet form, For example, an appropriate solvent is added to the said heat conductive composition, and the surface of a heat generating body or a heat radiator is added. It may be applied and dried. Thus, the formed coating film can also show the effect similar to the said heat conductive sheet.

  Hereinafter, although the synthesis example and an Example are given and the heat conductive composition and heat conductive sheet of this invention are demonstrated in detail, this invention is not limited only to a following example. In the following description, “part” means part by weight.

(Synthesis Example 1)
92 parts of 2-ethylhexyl acrylate, 8 parts of 2-hydroxyethyl acrylate, and 1 part of a polymerization initiator (trade name “Perbutyl ND” manufactured by NOF Corporation) are each ethyl acetate / n-heptane (= In addition to 230 parts of 7/3), the mixture was stirred at 60 ° C. for 5 hours to polymerize these monomers to obtain an adhesive polymer (copolymer). The obtained polymer had a weight average molecular weight of 150,000.

(Synthesis Example 2)
Add 95 parts of stearyl acrylate, 5 parts of acrylic acid, 5 parts of dodecyl mercaptan and 1 part of polymerization initiator (trade name “Perbutyl PV” manufactured by NOF Corporation) to 100 parts of toluene, respectively, at 80 ° C. The mixture was stirred for 5 hours to polymerize these monomers to obtain a side chain crystallizable polymer (copolymer). The obtained polymer had a weight average molecular weight of 7000 and a melting point of 50 ° C.

(Synthesis Example 3)
A monomer was polymerized in the same manner as in Synthesis Example 2 except that 95 parts of behenyl acrylate was used instead of 95 parts of stearyl acrylate to obtain a side chain crystallizable polymer (copolymer). The obtained polymer had a weight average molecular weight of 8000 and a melting point of 70 ° C.

(Synthesis Example 4)
A monomer was polymerized in the same manner as in Synthesis Example 2 except that 75 parts of stearyl acrylate, 20 parts of methyl acrylate, and 5 parts of acrylic acid were used to obtain a side chain crystallizable polymer (copolymer). . The obtained polymer had a weight average molecular weight of 10,000 and a melting point of 40 ° C.

(Synthesis Example 5)
A monomer was polymerized in the same manner as in Synthesis Example 2 except that the proportion of dodecyl mercaptan was changed to 2 parts to obtain a side chain crystallizable polymer (copolymer). The obtained polymer had a weight average molecular weight of 30,000 and a melting point of 50 ° C.

(Synthesis Example 6)
99.5 parts of 2-ethylhexyl acrylate, 0.5 part of 2-hydroxyethyl acrylate and 0.5 parts of polymerization initiator (trade name “Perbutyl ND” manufactured by NOF Corporation) were each added in ethyl acetate. In addition to 230 parts of / n-heptane (= 7/3), the mixture was stirred at 55 ° C. for 5 hours to polymerize these monomers to obtain an adhesive polymer (copolymer). The obtained polymer had a weight average molecular weight of 220,000.
Table 1 shows the copolymers of Synthesis Examples 1 to 6.

(Preparation of thermal conductive sheet)
The polymer solution obtained in Synthesis Example 1 so as to be 10 parts of the polymer of Synthesis Example 2 with respect to 100 parts of the polymer of Synthesis Example 1 in terms of solid content without isolating the solid content from the reaction solution. The polymer solution obtained in Synthesis Example 2 was mixed to prepare a mixed polymer solution. Next, 50 parts of boron nitride powder (average particle size 18 μm, trade name “SGP” manufactured by Denki Kagaku Kogyo Co., Ltd.) is added to 100 parts of the solid content of the mixed polymer solution and dispersed uniformly. A thermally conductive solution was obtained. This thermally conductive solution was applied to a 50 μm thick polyethylene terephthalate film having a thickness of 50 μm, and dried to prepare a thermally conductive sheet. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.05.

(Thermal resistance and thermal conductivity)
The thermal conductive sheet was sandwiched between the heater part and the cooling part (heat radiator), and the temperature difference (ΔT) between the heater part and the cooling part was measured after 5 W of power was applied to the heater part for 1 minute. . The thermal resistance (° C./W) is obtained from the formula: ΔT / 5W. The thermal conductivity (W / m · K) is obtained from the formula: 5W × T × S × ΔT. Here, T represents a value obtained by converting the thickness 50 μm of the thermally conductive sheet into 50 × 10 ⁻⁶ m, and S represents the area (m ² ) of the thermally conductive sheet.

(Removability)
The removability was evaluated from the ratio of the adhesive strength of the heat conductive sheet at 80 ° C. and 23 ° C. (adhesive strength at 80 ° C./adhesive strength at 23 ° C.). The evaluation criteria were set as follows.
○: 0.2 or less Δ: Greater than 0.2, 0.5 or less ×: Greater than 0.5

(Adhesive residue)
The heat conductive sheet is sandwiched between a heater part and a cooling part at an ambient temperature of 23 ° C. and heated to 80 ° C. Subsequently, the presence or absence of adhesive residue when the sheet was manually peeled off from the heater part or the cooling part at the atmospheric temperature was visually evaluated. The evaluation criteria were set as follows.
○: There is no adhesive residue on appearance
X: From the appearance, the adhesive residue is clearly present. The above results are shown in Table 2.

  A heat conductive sheet was produced in the same manner as in Example 1 except that the polymer obtained in Synthesis Example 3 was used in place of the polymer obtained in Synthesis Example 2. The ratio of the adhesive strength of the obtained sheet (80 ° C. adhesive strength / 23 ° C. adhesive strength) was 0.10. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

  A heat conductive sheet was produced in the same manner as in Example 1 except that the polymer obtained in Synthesis Example 4 was used instead of the polymer obtained in Synthesis Example 2. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.15. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

  Heating was conducted in the same manner as in Example 1 except that the solid content of the polymer obtained in Synthesis Example 2 was mixed with 100 parts by weight of the polymer obtained in Synthesis Example 1 so that the solid content of the polymer was 30 parts. A conductive sheet was prepared. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.05. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

[Comparative Example 1]
A thermally conductive sheet was produced in the same manner as in Example 1 except that the polymer solution was changed to only the adhesive polymer obtained in Synthesis Example 1. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.70. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

[Comparative Example 2]
Except that the solid content of the polymer obtained in Synthesis Example 1 was mixed with the solid content of the polymer obtained in Synthesis Example 1 so that the solid content of the polymer obtained in Synthesis Example 2 was 1 part, heat was applied in the same manner as in Example 1. A conductive sheet was prepared. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.40. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

[Comparative Example 3]
Except for mixing so that the solid content of the polymer obtained in Synthesis Example 2 was 60 parts with respect to 100 parts of the solid content of the polymer obtained in Synthesis Example 1, heat was applied in the same manner as in Example 1. A conductive sheet was prepared. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.30. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

[Comparative Example 4]
A heat conductive sheet was produced in the same manner as in Example 1 except that the polymer obtained in Synthesis Example 5 was used in place of the polymer obtained in Synthesis Example 2. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.60. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

[Comparative Example 5]
A thermally conductive sheet was produced in the same manner as in Example 1 except that the mixture was mixed so that it was 10 parts of n-octadecyl alcohol with respect to 100 parts of the polymer of Synthesis Example 6. The ratio of the adhesive strength of the obtained sheet (adhesive strength at 80 ° C./adhesive strength at 23 ° C.) was 0.50. Subsequently, the obtained thermal conductive sheet was evaluated in the same manner as in Example 1 for thermal resistance, thermal conductivity, removability, and adhesive residue. The results are shown in Table 2.

  As apparent from Table 2, in Examples 1 to 4, it can be seen that by using the thermally conductive composition of the present invention, the thermal conductivity is high, the removability is good, and there is no adhesive residue. On the other hand, in Comparative Examples 1-5, the heat conductivity was low, and the re-peelability and the adhesive residue were inferior.

Claims (9)

  50 to 95 parts by weight of an adhesive polymer, and 5 to 50 parts by weight of a side-chain crystallizable polymer that is incompatible with the adhesive polymer and exhibits fluidity at the exothermic temperature of the heating element, Furthermore, the heat conductive composition characterized by containing 10-300 weight part of heat conductive fillers with respect to 100 weight part of these polymers total amount.   The thermally conductive composition according to claim 1, wherein the side chain crystallizable polymer has a melting point of 30 ° C or higher and crystallizes at a temperature lower than the melting point.   The side chain crystallizable polymer is an acrylic ester or methacrylic acid having 30 to 100 parts by weight of an acrylic ester or methacrylic ester having a linear alkyl group having 16 or more carbon atoms and an alkyl group having 1 to 12 carbon atoms. The heat conductive composition according to claim 1 or 2, which is a polymer having a weight average molecular weight of 1,000 to 20,000 obtained by polymerizing 0 to 70 parts by weight of an acid ester and 0 to 10 parts by weight of a polar monomer.   The polymer having an adhesive property is a copolymer having a weight average molecular weight of 50,000 to 500,000, the main component of which is an acrylic ester or methacrylic ester having an alkyl group having 1 to 12 carbon atoms. The heat conductive composition in any one of 3.   The heat conductive composition according to any one of claims 1 to 4, wherein a ratio of adhesive strength at 80 ° C and 23 ° C (adhesive strength at 80 ° C / adhesive strength at 23 ° C) is 0.2 or less.   50 to 95 parts by weight of an adhesive polymer, and 5 to 50 parts by weight of a side-chain crystallizable polymer that is incompatible with the adhesive polymer and exhibits fluidity at the exothermic temperature of the heating element, Furthermore, the heat conductive sheet characterized by containing 10-300 weight part of heat conductive fillers with respect to 100 weight part of these polymer total amounts.   The heat conductive sheet according to claim 6, wherein the heat conductive sheet has a thickness of 20 to 200 μm.   The heat conductive sheet of Claim 6 or 7 which provided the film which carried out the mold release process on both surfaces.   50 to 95 parts by weight of an adhesive polymer, and 5 to 50 parts by weight of a side-chain crystallizable polymer that is incompatible with the adhesive polymer and exhibits fluidity at the exothermic temperature of the heating element, Furthermore, with respect to 100 parts by weight of the total amount of these polymers, a pressure-sensitive adhesive layer containing 10 to 300 parts by weight of a heat conductive filler is provided on both surfaces of a base film having heat conductivity, and further the surface of this pressure-sensitive adhesive layer. A thermally conductive sheet characterized in that a release-treated film is provided.