JPH0737548B2 - Heat dissipation sheet - Google Patents

Description

The present invention relates to a crosslinked product obtained by cross-linking ethylene-based copolymers in a mixture consisting of at least two kinds of ethylene-based copolymers and inorganic fillers with each other. The present invention relates to a heat dissipation sheet. More specifically, (A) at least an ethylene unit and a carboxylic acid unit, a dicarboxylic acid unit,
An ethylene copolymer having at least one unit selected from the group consisting of its anhydride unit and its half ester unit, (B) selected from the group consisting of at least ethylene unit and hydroxyl unit, amino unit and glycidyl unit Ethylene copolymer containing at least one unit and (C) thermal conductivity of 0.2 Kcal / m · hr
A mixture of inorganic fillers having a temperature of ℃ or more and an electric resistance value of 10 ⁸ Ω · cm or more, and the mixing ratio of the inorganic filler in the mixture is 10 to 80% by volume. The present invention relates to a heat-dissipating sheet made of a cross-linked product obtained by cross-linking ethylene-based copolymers by heating, which not only has excellent thermal conductivity, but also has good electrical insulation and chlorine. It is an object of the present invention to provide a heat dissipation sheet which does not contain impurities such as sulfur, amine and has excellent moisture resistance.

2. Description of the Related Art With the development of the electronic industry, high performance and high density of ICs and other electronic components are advancing. In general, heat-generating components such as power transistors and integrated circuits are vulnerable to heat and are often destroyed, causing concern about the life and reliability of electronic devices. In order to quickly remove the heat generated from these heat-generating components, a heat-dissipating sheet having good thermal conductivity is interposed in the heat-generating electronic components, and heat dissipation is promoted by a heat-dissipating fin or the like to suppress heat generation.

Conventionally, as this type of heat dissipation sheet, there are those in which mica or polyester film is coated with grease, and those in which synthetic rubber contains an inorganic filler or the like. The former is cheaper, but not only does it have insufficient thermal conductivity, it also requires a step of applying grease, etc. Moreover, the grease evaporates due to heating during long-term use, which causes cracks, etc. It has the drawback of deterioration over time, and it has not been used much recently.

On the other hand, the latter not only has excellent stability even when used for a long period of time, but also has the advantage of not requiring grease or the like. However, there is a limit to the filling amount of the inorganic filler, and the thermal conductivity is also poor, and further, not only cracks are generated from the tightened portion due to repeated heat generation-cooling, but there are drawbacks such as a marked deterioration in electrical insulation. is there. In addition, sulfur used for vulcanizing synthetic rubber, sulfur, chlorine, amine contained in lubricants, stabilizers, vulcanization accelerators, etc. corrode electronic parts and promote corrosion by moisture absorption etc. There are drawbacks such as

Problems to be Solved by the Invention From the above, the present invention does not have these drawbacks (problems), that is, not only has excellent thermal conductivity, but also does not contain impurities such as sulfur, chlorine, and amine. Further, it is to obtain a heat dissipation sheet having excellent moisture resistance and excellent processing characteristics.

Means and Actions for Solving Problems According to the present invention, these problems include (A) “a group consisting of at least ethylene and a carboxylic acid unit, a dicarboxylic acid unit, an anhydride unit thereof and a half ester unit thereof. It is composed of at least one unit selected from, and the content of ethylene units is 30 to 99.5% by weight.
An ethylene-based copolymer which is "[hereinafter referred to as" ethylene-based copolymer (A) "(B)" at least an ethylene unit and a hydroxyl unit,
An ethylene copolymer having at least one unit selected from the group consisting of an amino unit and a glycidyl unit and having an ethylene unit content of 30 to 99.5% by weight [hereinafter, referred to as "ethylene copolymer (B ) ”] And (C) a mixture of inorganic fillers having a thermal conductivity of 0.2 Kcal / m · hr · ° C or higher and an electric resistance value of 10 ⁸ Ω · cm or higher, in the mixture. The mixing ratio of either ethylene copolymer in the total amount of both ethylene copolymers is 1 to 99% by weight, and the mixing ratio of the inorganic filler in the mixture is 10 to 80% by volume. %, Which can be solved by a heat dissipation sheet made of a cross-linked product obtained by cross-linking the ethylene-based copolymer with each other by heating this mixture. Hereinafter, the present invention will be specifically described.

(A) Ethylene-based copolymer (A) The ethylene-based copolymer (A) used in the present invention is at least an ethylene unit and a group consisting of "carboxylic acid unit, dicarboxylic acid unit, anhydride unit thereof and half ester unit thereof". And an ethylene-based copolymer containing at least one unit selected from the following [hereinafter referred to as "second component (A)"] and containing 30 to 99.5% by weight of the ethylene unit.

This ethylene-based copolymer (A) is a copolymer that can be obtained by copolymerizing the following monomers in order to constitute at least the second component (A), and multi-component copolymers of these and other monomers. Examples thereof include those obtained by hydrolyzing and / or alcohol-modifying the acid anhydride groups in the polymers and their copolymers.

Typical examples of this monomer include unsaturated monocarboxylic acids having at most 25 carbon atoms such as acrylic acid, methacrylic acid and ethacrylic acid, and maleic anhydride, tetrahydrophthalic anhydride, maleo-pimaric anhydride, 4-methylcyclohexane. Unsaturated dicarboxylic acids having 4 to 50 carbon atoms such as -4-ene-1,2-carboxylic anhydride and bicyclo (2,2,1) -hepta-5-ene-2,3-dicarboxylic anhydride Anhydrous is mentioned.

In addition, as other monomers, unsaturated such as methyl (meth) acrylate, ethyl (meth) acrylate, hydroxymethyl (meth) acrylate and diethyl fumarate having at most 30 (preferably 10 or less) carbon atoms. Examples include carboxylic acid esters and vinyl esters having at most 30 carbon atoms such as vinyl acetate and vinyl propionate.

Of the above ethylene-based copolymers (A), a copolymer of ethylene and an unsaturated dicarboxylic acid anhydride or a multicomponent copolymer of these and an unsaturated dicarboxylic acid ester and / or vinyl ester is hydrolyzed and The dicarboxylic acid anhydride unit of these copolymers can be converted into a dicarboxylic acid unit or a half ester unit by modifying with / or alcohol. In the present invention, the ethylene-based copolymer (A) obtained by replacing a part or all of the unsaturated dicarboxylic acid anhydride units of the copolymer or multicomponent copolymer with a dicarboxylic acid unit or a half ester unit is also used. Can be used as desired.

To carry out hydrolysis, the ethylene-based copolymer (A) is dissolved in an organic solvent (for example, toluene) that dissolves the copolymer in the presence of a catalyst (for example, a tertiary amine).
It can be obtained by reacting with water at a temperature of 80 to 100 ° C. for 0.5 to 10 hours (preferably 2 to 6 hours, preferably 3 to 6 hours) and then neutralizing with an acid.

In order to carry out the alcohol modification, the ethylene copolymer (A) can be obtained by a solution method or a kneading method described later.

The solution method is similar to the case of hydrolysis in the presence or absence of the above catalyst in an organic solvent (the reaction is slow in the absence)
The reflux temperature of the alcohol used in 2 minutes to 5 hours (desirably 2 minutes to 2 hours, preferably 15 minutes to 1)
Time) is a method of reacting.

On the other hand, the kneading method is usually 0.01 to 1.0 parts by weight (preferably 0.05 to 100 parts by weight) per 100 parts by weight of the ethylene copolymer (A).
0.5 part by weight) of the tertiary amine and the dicarboxylic acid unit in the copolymer are generally added in an amount of 0.1 to 3.0 times mol (preferably 1.0 to 2.0 times mol) of the saturated alcohol in the ethylene copolymer (A). ) Above the melting point of the alcohol used but below the boiling point of the alcohol used, using a kneader such as a Banbury mixer or extruder, which is commonly used in the field of rubber and synthetic resins, for several minutes to several tens of minutes (desirably ,
This is a method of reacting while kneading.

The saturated alcohol used in the above modification with alcohol is a linear or branched saturated alcohol having 1 to 12 carbon atoms, and examples thereof include methyl alcohol, ethyl alcohol and primary butyl alcohol.

In both cases of hydrolysis and modification with alcohol, the conversion rate to dicarboxylic acid and the half esterification rate are both 0.5 to 100%, preferably 10.0 to 100%.

The ethylene unit in this ethylene copolymer (A) is 30 ~
99.5% by weight, preferably 30 to 99.0% by weight, especially 35
-99.0% by weight is preferred. The proportion of the carboxylic acid unit, the anhydride unit and the half ester unit in the copolymer is 0.1 to 70% by weight as their total amount, preferably 0.5 to 70% by weight, and particularly 0.5 to 60% by weight. % Is preferred. If an ethylene-based copolymer having a proportion of carboxylic acid units, anhydride units and half ester units in the ethylene-based copolymer (A) of less than 0.1% by weight is used, the ethylene-based copolymer described below is used. When it is crosslinked by heating with (B), not only is the crosslinking incomplete, but the adhesion with the metal layer is not good. On the other hand, even if it exceeds 70% by weight, the characteristics of the present invention will be exhibited, but it is not necessary to exceed 70% by weight, which is not preferable in terms of production and economy.

When a multi-component copolymer containing the unsaturated carboxylic acid ester and / or vinyl ester is used, the total amount thereof is usually at most 70% by weight, preferably 60% by weight or less. When an ethylene-based copolymer having a copolymerization ratio of unsaturated dicarboxylic acid ester and / or vinyl ester of more than 70% by weight is used, the softening point of the copolymer becomes high, and the fluidity at a temperature of 150 ° C. or lower becomes low. Not only is it undesirable because it is damaged, but it is also not economically desirable.

(B) Ethylene Copolymer (B) The ethylene copolymer (B) used in the present invention is at least one ethylene unit and at least one selected from the group consisting of a hydroxyl unit, an amino unit and a glycidyl unit. Unit "(hereinafter referred to as" second component (B) "), and its ethylene unit is 30 to 9
It is an ethylene-based copolymer containing 9.5% by weight.

This ethylene-based copolymer (B) is a copolymer that can be obtained by copolymerizing at least ethylene and the following monomer to form the second component (B), and a multi-component of these and other monomers. -Based copolymers and ethylene and vinyl esters (especially vinyl acetate)
Saponified products obtained by saponifying a copolymer with

Examples of this monomer include glycidyl alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates represented by the following general formula (where the carbon number of the alkyl group is usually 1
.About.25), .alpha.-alkenyl alcohols having 3 to 25 carbon atoms, .alpha.-amines having 2 to 25 carbon atoms, and primary or secondary aminoalkyl (meth) acrylates (the alkyl group usually has 1 carbon atom). ~ 25).

(Here, R ₁ is H or a methyl group, and R ₂ has 1 to 1 carbon atoms.
12 straight-chain or branched alkyl groups) Typical examples of this monomer include butenetricarboxylic acid monoglycidyl ester, glycidyl methacrylate, glycidyl acrylate, glycidyl ethacrylate, itaconic acid glycidyl ester, and hydroxymethyl (meth) acrylate. , Hydroxymethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, allyl alcohol, allyl amine and aminoethyl (meth) acrylate. .

Further, examples of the other monomer include the unsaturated dicarboxylic acid ester and vinyl ester.

The ethylene unit in this ethylene copolymer (B) is 30 to
It is 99.5% by weight, preferably 30 to 99.0% by weight, and particularly preferably 35 to 99.0% by weight. The proportion of hydroxyl units, amino units and glycidyl units in the copolymer is 0.1 to 70% by weight for the same reason as in the case of the ethylene copolymer (A), and 0.5 to 70% by weight. Particularly preferred is 0.5 to 60% by weight. Further, when using the multi-component copolymer containing the unsaturated carboxylic acid ester and / or vinyl ester, the total amount thereof is generally at most 70 wt% for the same reason as in the case of the ethylene copolymer (A). %, Especially 60% by weight
The following is desirable.

The melt index (measured under condition 4 according to JIS K-7210, hereinafter referred to as “MI”) of the ethylene copolymer (A) and the ethylene copolymer (B) is generally 0.
001 to 1000 g / 10 minutes, preferably 0.05 to 500 g / 10 minutes,
Particularly preferred is 0.1 to 500 g / 10 minutes. When these ethylene-based copolymers having MI of less than 0.01 g / 10 min are used, it is difficult to mix these copolymers uniformly, and the moldability is not good.

Of these ethylene-based copolymers, when they are produced by a copolymerization method, they are usually produced under a high pressure of 500 to 2500 Kg / cm ^2.
Copolymerizing ethylene with the second component (A) or the second component (B) or with these other components in the presence of a fast chain transfer agent (for example, an organic peroxide) at a temperature of 120 to 260 ° C. It can be obtained by the method described above and the manufacturing method thereof is well known. Further, the method of producing the ethylene-based copolymer (A) by hydrolysis and / or modification with an alcohol and the method of producing the ethylene-based copolymer (B) by the saponification method are well known methods. is there.

(C) Inorganic filler Further, the thermal conductivity of the inorganic filler used in the present invention is 0.2 Kcal / m · hr · ° C or higher. The electric resistance value is 10 ⁸ Ω · cm or more. In carrying out the present invention,
Any one is preferable as long as it has these physical properties, but a particle diameter of 0.1 to 100 microns is preferable, and a particle diameter of 0.1 to 50 microns is particularly preferable.
If the particle size is less than 0.1 micron, agglomeration occurs and it is difficult to uniformly disperse the mixture of the present invention during production. On the other hand, if it exceeds 100 microns, not only the flexibility and strength of the sheet described below will decrease, but also the smoothness of the surface will be lost, so the contact area with the heat dissipation fins and heat generating parts when using the heat dissipation sheet. Becomes smaller,
It is not preferable because it lowers the heat dissipation (heat conduction) effect.

Representative examples of the inorganic filler include beryllium oxide, boron nitride, magnesium oxide (magnesia), aluminum oxide (alumina), silicon carbide and glass beads.

(D) Production of Mixture (1) Mixing Ratio In producing the mixture of the present invention, it accounts for the total amount (total) of the ethylene copolymer (A) and the ethylene copolymer (B) in the obtained mixture. The mixing ratio of the ethylene-based copolymer (A) is 1 to 99% by weight [that is, the mixing ratio of the ethylene-based copolymer (B) is 99 to 1% by weight].
95% by weight is desirable and 10 to 90% by weight is especially preferred. A mixture of the ethylene-based copolymer (A) and the ethylene-based copolymer (B) which is contained in the total amount of the ethylene-based copolymer (A) and the ethylene-based copolymer (B) is less than 1% by weight or more than 99% by weight. When the above-mentioned method is used for crosslinking, the crosslinking is insufficient.

The mixing ratio of the inorganic filler in the mixture is 10-80.
%, Preferably 15 to 80% by volume, particularly preferably 20 to 80% by volume. When the mixing ratio of the inorganic filler in the mixture is less than 10% by volume, the thermal conductivity is low. On the other hand, when it exceeds 80% by volume, it is difficult to obtain a mixture having a uniform composition, and even if a mixture having a uniform composition is obtained, the thermal conductivity is improved but the strength of the sheet is reduced. Undesired.

(2) Mixing method To produce this mixture, the ethylene-based copolymer (A),
The ethylene copolymer (B) and the inorganic filler may be uniformly mixed. At this time, each mixed component may be mixed at the same time, or a part of the mixed components may be mixed in advance,
The remaining mixture components may be mixed with the obtained mixture (for example, the ethylene copolymer (A) and the ethylene copolymer (B) are mixed, and the inorganic filler is mixed with the obtained mixture). As a mixing method, dry blending may be performed using a mixer such as a Henschel mixer which is generally performed in the field of olefin polymers, and a method of melt kneading using a mixer such as Banbury, an extruder and a roll mill is used. can give. At this time, a more uniform mixture can be obtained by previously dry blending and melt-kneading the resulting mixture. It is necessary that the ethylene-based copolymer (A) and the ethylene-based copolymer (B) do not substantially undergo a crosslinking reaction during melt-kneading (when the resulting mixture is crosslinked, the resulting mixture is molded and processed as described below. Finally, it is not preferable because it may cause poor moldability). From this fact, the temperature of melt-kneading depends on the type and viscosity of each ethylene copolymer used, but it is preferably room temperature (20 ° C) to 150 ° C, preferably 140 ° C or lower.

As a measure of this "substantially no cross-linking", "the residue whose diameter is 0.1 micron or more after the extraction treatment of the ethylene copolymer in the mixture in boiling toluene for 3 hours"
(Hereinafter referred to as "extraction residue", the same applies hereinafter) is generally preferably 15% by weight or less, preferably 10% by weight or less, and most preferably 5% by weight or less.

(E) Production of heat dissipation sheet (1) Production of uncrosslinked sheet Ethylene copolymer (A) obtained as described above,
A roll method, a T-die extrusion molding method, a calendar roll method, a press molding method (a stamping molding method), which is generally performed in the processing field of thermoplastic resins and rubbers, is performed on a mixture of an ethylene-based copolymer (B) and an inorganic filler. The sheet may be manufactured by applying (including the above). In these processing (molding) methods, the ethylene-based copolymer (A) and the ethylene-based copolymer (B) in the mixture are used.
It is important to mold at a temperature at which does not essentially crosslink. From the above, the molding temperature is preferably 250 ° C or lower, and particularly preferably 160 ° C or lower. However, if the temperature is 80 ° C. or lower, the ethylene-based copolymers in the mixture do not melt, which is not preferable. The extraction residue in the uncrosslinked sheet thus obtained is preferably 15% by weight or less, and 10% by weight or less.
The following is preferable, and 5% by weight or less is most preferable.

(2) Manufacture of heat dissipation sheet The uncrosslinked sheet obtained as described above was made to have a predetermined thickness and size and heated and pressed for a certain period of time so that the ethylene copolymer was crosslinked with each other. The heat dissipation sheet of the present invention can be manufactured. The heating temperature is usually in the temperature range of 100 to 350 ° C. The heating time varies depending on the heating temperature, but in the heating temperature range of 100 to 160 ° C,
2 to 20 minutes, 160 to 240 ℃, 1 to 10 minutes, 240
At ~ 350 ° C, 0.1 to 5 minutes is common. Also, 0.1
It is desirable to pressurize at ~ 40 Kg / cm ₂ . This heating
Before pressurizing, the system may be depressurized and degassed in advance.

The extraction residue in the heat dissipation sheet obtained as above is 70
It is preferably at least wt%, and particularly preferably at least 75 wt%.

In the present invention, it is important to heat the sheet thus obtained in the above temperature range in order to impart heat resistance, and in this temperature range, the ethylene-based copolymer in the mixture cross-links with each other. Reaction occurs and heat resistance is significantly improved.

Further, as shown in FIG. 2, a glass cloth or the like is set in advance in a mold, the mixture is poured into a predetermined mold in a molten state, and the glass cloth is heated under the above heating / pressurizing conditions. It is also possible to obtain a cross-linked heat dissipation sheet while adhering (laminating) with.

(3) Heat Dissipation Sheet The thickness of the heat dissipation sheet obtained as described above is usually 5 μm to 2 mm, preferably 20 μm to 1.5 mm, and particularly preferably 50 μm to 1 mm. Not only is it difficult to manufacture a heat-dissipating sheet having a thickness of less than 5 microns so as to have a uniform thickness, but also the insulation performance becomes unsatisfactory due to the reduced electric resistance. On the other hand, if it exceeds 2 mm, it is not preferable because a sheet having a desired heat dissipation property cannot be obtained.

A typical heat dissipation sheet of the present invention will be briefly described with reference to the drawings.

FIG. 1 is a partially enlarged sectional view of a heat dissipation sheet of the present invention.
Further, FIG. 2 is a partially enlarged cross-sectional view of the heat dissipation sheet when laminated with a glass cloth or the like in order to improve dimensional stability and tensile strength. In FIGS. 1 and 2, 1
Is a heat radiating sheet (essentially consisting of cross-linked products of ethylene-based copolymer and inorganic filler), and 2 is a glass cloth or the like. Further, FIG. 3 is a partially enlarged cross-sectional view of a typical example when the heat dissipation sheet of the present invention is used. This third
In the figure, 1 is a heat dissipation sheet, 3 is a heat generating component, and 4 is a heat dissipation fin.

Examples and Comparative Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

A mixture of the ethylene copolymer (A) and the ethylene copolymer (B) used in Examples and Comparative Examples is shown below.

Ethylene-based copolymer (A) and ethylene-based copolymer (B)
As a mixture with ethylene-acrylic acid copolymer having a MI of 300 g / 10 min (density 0.954 g / cm ³ , acrylic acid copolymerization ratio 20% by weight, hereinafter referred to as “EAA”) and vinyl acetate copolymerization ratio Saponification product obtained by saponifying 28% by weight of ethylene-vinyl acetate copolymer (saponification degree 97.5%, MI 75g / 10 minutes, density 0.951g / c
m ^3, hereinafter referred to as "saponified") mixture consisting a [mixing ratio of 50:50 (weight ratio), hereinafter referred to as "mixture (I)"], ethylene MI is 200 g / 10 min - methacrylic acid copolymer Mixture of polymer (density 0.950 g / cm ³ , methacrylic acid copolymerization ratio 25% by weight) and the saponification degree [mixing ratio
50:50 (weight ratio), hereinafter referred to as "mixture (II)"], M.
Ethylene-ethyl acrylate-I. Is 212 g / 10 min.
Maleic anhydride terpolymer (ethyl acrylate copolymerization ratio 30.7% by weight, maleic anhydride copolymerization ratio 1.
7% by weight, hereinafter referred to as "EAM") and a terpolymer of ethylene-methylmethacrylate-hydroxymethacrylate of MI of 123 g / 10 minutes (copolymerization ratio of methylmethacrylate 20.7% by weight, copolymer of hydroxymethacrylate) Polymerization ratio 11.7% by weight) (mixing ratio 50:50
(Weight ratio), hereinafter referred to as "mixture (III)"] and
Ethylene-methylmethacrylate-maleic anhydride terpolymer with MI of 105 g / 10 min (copolymerization ratio of methylmethacrylate 20.5% by weight, copolymerization ratio of maleic anhydride 3.1% by weight) and ethylene-methylmethacrylate- Glycidyl methacrylate terpolymer (copolymerization ratio of methyl methacrylate 18.6% by weight, copolymerization ratio of glycidyl methacrylate 12.7% by weight, hereinafter "GMA")
(Mixing ratio 30:70 (weight ratio), hereinafter referred to as “mixture (IV)”.) These mixtures were obtained by converting each copolymer or ternary copolymer into a Henschel mixer. Manufactured by dry blending for 5 minutes.

The mixture (I) to (IV), EAA and saponified product obtained as described above were each equipped with an T-die extruder (diameter 40 mm, die width 30 cm, rotation speed 85 rotation /
Min) was used to form a sheet having a thickness of 500 μm under the conditions where the cylinder temperature and the die temperature are shown in Table 1. The extraction residue of each of the obtained sheets was measured. In all cases, it was 0%.

In the examples and comparative examples, alumina (soda content 0.1% by weight, Al ₂ O ₃ 99.39% by weight, true specific gravity
3.95, average particle size 4.0 to 4.5 microns, and boron nitrogen (true specific gravity 2.27, BN content 99.5% by weight, average particle size 3.
0 micron, hereinafter referred to as "BN") was used.

In addition, the glass cloth used in Example 3 is a plain weave in which a filamentous material in which glass fibers having a diameter of 8 microns are converged to a diameter of 200 to 220 microns is woven with a yarn interval of 400 to 500 microns.

Examples 1 to 9 and Comparative Examples 1 to 4 The sheets obtained as described above were melt-mixed with alumina and BN in the proportions shown in Table 2 and heated at the crosslinking temperatures shown in Table 2 for 10 minutes each. 20Kg / cm using a press machine
^Under pressure of ² (gauge pressure), thin material (length 10 cm, width 20 c
m, thickness 400 micron).

Table 2 shows the extraction residue of each thin product (heat dissipation sheet) obtained. In addition, a quick heat flow meter (Showa Denko KK, model QT-2
Was used to measure thermal conductivity and tensile strength (measured according to JIS K9301). The results are shown in Table 2.

It should be noted that, although the mixture was melt mixed in Comparative Example 2, a uniform mixture was not obtained.

Examples 10 to 13 EAA and saponified products (the mixing ratio of each is 1: 1 by weight).
Alumina whose volume ratio (%) in the total amount of EAA, saponified product and alumina is shown in 1) and Table 3 was dry blended for 5 minutes using a Henschel mixer. A sheet having a thickness of 500 μm was produced from each of the obtained mixtures by using the above-mentioned extruder under the conditions where the cylinder temperature is shown in Table 1. When the extraction residue of each of the obtained sheets was measured, it was 0% in all cases.

Each sheet thus obtained was hot-pressed under the same conditions as above at a crosslinking temperature of 260 ° C. to produce a thin product (heat dissipation sheet) having the same size and thickness as above. The thermal conductivity and tensile strength of each heat dissipation sheet thus obtained were measured. The results are shown in Table 3.

From the results of the above Examples and Comparative Examples, the ethylene-based copolymer (A), the ethylene-based copolymer (B), and the mixture of the inorganic filler, which are used for producing the heat dissipation sheet of the present invention, are heated to heat the ethylene-based mixture It is clear that the thin product containing the cross-linked product of the copolymer has not only excellent thermal conductivity but also good tensile strength and is an improvement over the conventional defects.

Effects of the Invention The heat dissipation sheet of the present invention exhibits the following effects (features) including the manufacturing process thereof.

(1) Not only has excellent thermal conductivity, but also has an insulating property, so that it can be used as a heat dissipation sheet between a heat generating component and a heat dissipation fin.

(2) Since it does not contain impurities such as chlorine, amine, and sulfur, and has no hygroscopicity, it can be used in a stable state for a long time without any impurities being mixed into the heat-generating component.

(3) Even if the temperature of the heat-generating component rises temporarily due to its excellent heat resistance, the amount of deformation does not occur and the tensile strength is good, so cracks etc. occur when mounting the heat-generating component. There is no.

(4) Since it has rubber elasticity, it has excellent adhesion to the surfaces of the heat-generating components and the heat radiation fins, not only improving the efficiency of heat radiation characteristics, but also acting as a buffer against vibration and the like.

(5) Since it can be manufactured using a conventional rubber processing machine and a device used for processing a thermoplastic resin, a large area can be achieved and the manufacturing cost is low.

Since the heat dissipation sheet of the present invention has the above effects, it can be used in various fields. Typical uses are shown below.

(1) Heat dissipation spacers for power transistors and thyristors (for example, stereos, television sets, computers, automotive electrical components) (2) Heat dissipation spacers for cersistors, PTCs, etc. (3) Heat dissipation spacers for coils, etc. (4) Easy heat generation For heat dissipation of other electric appliances

[Brief description of drawings]

1 and 2 are partially enlarged sectional views of the heat dissipation sheet of the present invention. FIG. 3 is a partially enlarged cross-sectional view when the heat dissipation sheet of the present invention is used as a heat generating component. 1 ...... Heat dissipation sheet 2 ...... Glass non-woven fabric etc. 3 ...... Heat generating parts 4 ...... Heat dissipation fin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C08L 33/02 LHR 33/06 35/00 LJD 87/00 LSD H01L 23/36

Claims (1)

[Claims] 1. A method comprising: (A) at least ethylene and at least one unit selected from the group consisting of carboxylic acid units, dicarboxylic acid units, anhydride units thereof and half ester units, and having an ethylene unit content of 30. ~ 99.5
(B) at least one ethylene unit and at least one unit selected from the group consisting of hydroxyl units, amino units and glycidyl units, and having an ethylene unit content of 30 to 99.5% by weight. It is a mixture consisting of an ethylene-based copolymer (wt%) and an inorganic filler (C) having a thermal conductivity of 0.2 Kcal / m · hr · ° C or higher and an electric resistance value of 10 ⁸ Ω · cm or higher. The mixing ratio of any ethylene-based copolymer in the total amount of both ethylene-based copolymers in the mixture is 1 to 99% by weight, and the mixing ratio of the inorganic filler in the mixture is 10-80% by volume, and a heat-dissipating sheet comprising a crosslinked product obtained by cross-linking the ethylene-based copolymer with each other by heating this mixture.