CN110746732A

CN110746732A - Resin composition and sheet containing resin composition

Info

Publication number: CN110746732A
Application number: CN201810810725.5A
Authority: CN
Inventors: 植田致知; 中村秀树
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp; Asahi Chemical Industry Co Ltd
Priority date: 2018-07-23
Filing date: 2018-07-23
Publication date: 2020-02-04

Abstract

The present invention relates to a resin composition and a sheet containing the resin composition. The purpose of the present invention is to obtain a resin composition and a sheet containing the resin composition, wherein the resin composition has high thermal conductivity, flame retardancy and vibration absorbability, is flexible, has high thickness precision, has stable raw material supply capability during sheet production, and has excellent sheet productivity. A resin composition comprising: (A) 2 to 20% by mass of a copolymer comprising conjugated diene units and vinyl aromatic compound units and/or a hydrogenated product thereof; (B) 2 to 20 mass% of a rubber softener; (C) 70 to 95 mass% of a thermally conductive filler; and (D) 0.1 to 3 mass% of at least one additive selected from the group consisting of silica, talc, calcium carbonate, barium sulfate, kaolin, apatite, diatomaceous earth, zeolite, and mica.

Description

Resin composition and sheet containing resin composition

Technical Field

The present invention relates to a resin composition and a sheet containing the resin composition.

Background

Conventionally, in various fields represented by the vehicle field, the household appliance field, the electric/electronic field, the communication field, and the like, it is necessary to use a heat transfer material, an adhesive, a sealing material, and the like having high heat transfer efficiency in order to cool or radiate a heat source.

In recent years, lithium ion batteries have been used in the field of vehicles, and for the purpose of increasing the travel distance per charge and increasing the output, lithium ion batteries having a larger capacity and a larger output have been mounted in the field of vehicles. As a result, the lithium ion battery becomes larger, and the temperature rise in the lithium ion battery cell further increases along with this.

In order to prevent this, heat transfer materials with higher heat dissipation and cooling effects are required, including systems in which lithium ion battery cells are mounted.

As a heat radiating member, a resin composition in which a thermally conductive filler is added to or dispersed in a resin material has been conventionally used.

For example, a resin composition in which a thermally conductive filler is mixed with a silicone resin is used.

In addition, a thermally conductive resin composition using a thermoplastic elastomer is also used.

For example, patent document 1 discloses a thermally conductive elastomer composition in which a thermally conductive filler composed of aluminum hydroxide is mixed with an elastomer composition mainly composed of a styrene elastomer as a base material. Further, this document also discloses a resin composition in which two kinds of aluminum hydroxide having different average particle diameters are compounded.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5722284

Disclosure of Invention

Problems to be solved by the invention

The heat radiating member is required to have various excellent physical properties depending on the use thereof.

However, the materials proposed in the prior art have a problem that sufficient physical properties as a heat radiating member have not been obtained yet, and there is a room for improvement in productivity.

For example, in vehicle applications, high reliability for ensuring safety is required in addition to a heat radiation effect and a cooling effect. In particular, in the case of an electric vehicle using a lithium ion battery, since there are many components that operate at high voltage and the electrolyte is liable to ignite when it comes into contact with air, it is important that the electrolyte is hard to ignite in an abnormal state and hard to spread even if it is ignited. Therefore, excellent flame retardancy is also required in electric automobile applications.

In addition, in the case of using a lithium ion battery, the shape and size of each cell of the battery are strictly different in many cases, and a more flexible heat conductive sheet is required to compensate for the difference in size of each cell.

Further, in order to bring the heat conductive sheet into close contact with the radiator and the heat sink of each unit or the like, a sheet having a higher thickness accuracy is required, but when the close contact with the unit is low, the heat conductive performance is lowered and vibration cannot be absorbed, and therefore, there is a problem that breakage and ignition of the unit may occur.

In addition, when the resin composition in which the silicone resin and the thermally conductive filler are mixed is used as the material of the thermally conductive sheet, low-molecular-weight siloxane derived from the silicone resin is generated, and the siloxane adheres to a heat radiator such as a semiconductor element, and there is a problem that a contact failure may occur. Further, since the silicone resin is a crosslinked rubber, unevenness in thickness is likely to occur during curing, and there is a problem that recycling is also difficult.

In addition, the sheet of the thermally conductive resin composition using the thermoplastic elastomer may not have practically sufficient physical properties depending on the application. For example, patent document 1 discloses a sheet processing method utilizing the characteristics of a thermoplastic elastomer. Specifically, in order to achieve low hardness, a softening agent such as processing oil is compounded into an elastomer having a specific structure. However, the method disclosed in patent document 1 is difficult to obtain a sheet having a high thickness accuracy required in the field of vehicles. In particular, when a thermally conductive filler is blended at a high concentration, torque variation is likely to occur when melt processing is performed by T-die extrusion, thickness unevenness is likely to occur, and thickness accuracy is lowered. Further, if the torque changes during the melt processing, the productivity is lowered, and it is difficult to efficiently obtain a lot having a unit amount. Further, depending on the melt processing conditions, the resin composition pellets as a raw material may not be stably supplied to the processing machine, which may further reduce the productivity.

Accordingly, an object of the present invention is to provide a resin composition having high thermal conductivity and flame retardancy, being flexible and having high thickness accuracy, and having stable raw material supply capability at the time of sheet production, and a sheet containing the resin composition.

Means for solving the problems

The present inventors have intensively studied to solve the above problems of the prior art, and as a result, have found that a resin composition containing a copolymer comprising a conjugated diene unit and a vinyl aromatic compound unit and/or a hydrogenated product thereof, a rubber softener, a thermally conductive filler, and a specific inorganic substance at a specific ratio, and a sheet containing the resin composition can solve the above problems of the prior art, and have completed the present invention.

Namely, the present invention is as follows.

[1]

A resin composition comprising:

(A) 2 to 20% by mass of a copolymer comprising conjugated diene units and vinyl aromatic compound units and/or a hydrogenated product thereof;

(B) 2 to 20 mass% of a rubber softener;

(C) 70 to 95 mass% of a thermally conductive filler; and

(D) 0.1 to 3% by mass of at least one additive selected from the group consisting of silica, talc, calcium carbonate, barium sulfate, kaolin, apatite, diatomaceous earth, zeolite, and mica.

[2]

The resin composition according to the above [1], wherein the average particle diameter of the thermally conductive filler (C) is 10 to 150 μm.

[3]

The resin composition according to the above [1] or [2], wherein the thermally conductive filler (C) has two or more different maximum values in the particle size distribution thereof, and the difference in particle diameter between the respective maximum values is 50 μm or more.

[4]

The resin composition according to any one of the above [1] to [3], wherein the thermally conductive filler (C) contains:

(C-I) a first thermally conductive filler having an average particle diameter of 60 to 150 [ mu ] m; and

(C-II) a second thermally conductive filler having an average particle diameter of 5 to 60 [ mu ] m.

[5]

The resin composition according to [4], wherein the mass ratio ((C-I)/(C-II)) of the component (C-I) to the component (C-II) is 100/1 to 100/170.

[6]

As described above [1]～[5]The resin composition according to any one of (A) to (B), wherein Na is contained in the thermally conductive filler (C)₂The O concentration is more than 0.20 mass% and 1.00 mass% or less.

[7]

The resin composition according to any one of the above [1] to [6], wherein the content of the vinyl aromatic compound unit in the copolymer (A) and/or the hydrogenated product thereof is less than 30% by mass,

(A) the mass ratio ((A)/(B)) of the copolymer and/or the hydride thereof to the rubber softener (B) is 35/65-60/40.

[8]

The resin composition according to any one of the above [1] to [7], wherein the thermally conductive filler (C) is at least one selected from the group consisting of a silicon-free metal nitride, a silicon-free metal oxide and a silicon-free metal hydroxide.

[9]

The resin composition according to any one of the above [1] to [8], wherein the thermally conductive filler (C) is aluminum hydroxide or aluminum oxide.

[10]

The resin composition according to any one of the above [1] to [9], wherein the additive (D) is silica or talc.

[11]

The resin composition according to any one of the above [1] to [10], further comprising (E) 0.01 to 2% by mass of a plasticizer.

[12]

The resin composition according to any one of the above [1] to [11], wherein the hardness obtained by a type A durometer in accordance with JIS K6253-3 is less than 60.

[13]

A sheet comprising the resin composition according to any one of the above [1] to [12], and having a thickness of 0.1mm to 10 mm.

[14]

The tablet according to [13] above, wherein the water content is 200ppm or less.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a resin composition having high thermal conductivity, flame retardancy, and vibration absorbability, being flexible and having high thickness accuracy, stable raw material supply capability at the time of sheet production, and excellent sheet productivity, and a sheet containing the resin composition can be obtained.

Drawings

Fig. 1 is a schematic configuration diagram showing an example of a battery module for evaluating the characteristics of the resin composition of the present embodiment.

Detailed Description

This embodiment (hereinafter referred to as "the present embodiment") will be described in detail below.

The following embodiments are examples for illustrating the present invention, and the present invention is not limited to the following. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

[ resin composition ]

The resin composition in the present embodiment includes:

(A) a copolymer comprising conjugated diene units and vinyl aromatic compound units and/or a hydride thereof (hereinafter sometimes referred to as "component (a)") in an amount of 2 to 20% by mass;

(B) a softening agent for rubber (hereinafter sometimes referred to as "component (B)") 2 to 20 mass%;

(C) 70 to 95% by mass of a thermally conductive filler (hereinafter sometimes referred to as "component (C)"); and

(D) 0.1 to 3% by mass of at least one additive (hereinafter sometimes referred to as "component (D)") selected from the group consisting of silica, talc, calcium carbonate, barium sulfate, kaolin, apatite, diatomaceous earth, zeolite, and mica.

Here, "and/or" in the component (a) means that both the copolymer containing the conjugated diene unit and the vinyl aromatic compound unit and the hydride may be contained, or only either one may be contained.

In addition, each component contained in the resin composition of the present embodiment may be used alone or in combination of two or more.

The resin composition of the present embodiment has thermal conductivity, flame retardancy, and stable raw material supply capability during sheet production by blending the components (a) to (D) at a specific ratio.

In the resin composition of the present embodiment, it is preferable to use, as the component (C), a thermally conductive filler having two or more different maximum values in its particle size distribution, and having a difference in particle size between the maximum values of 50 μm or more. Thus, a sheet having excellent flexibility and high thickness accuracy is obtained.

((A) a copolymer comprising conjugated diene units and vinyl aromatic compound units and/or a hydrogenated product thereof)

The resin composition of the present embodiment contains, as the component (a), a copolymer containing a conjugated diene unit and a vinyl aromatic compound unit and/or a hydride thereof.

As the component (a), a copolymer obtained by copolymerizing a conjugated diene and a vinyl aromatic compound, or the like can be used.

The component (a) is preferably a styrene-based thermoplastic elastomer or a hydrogenated product thereof, from the viewpoint of flexibility such as hardness and tensile elongation at break.

Examples of the styrene-based thermoplastic elastomer and its hydrogenated product include, but are not limited to, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-propylene-styrene copolymer ((SEEPS), styrene-butadiene random copolymer, and hydrogenated products thereof.

Among them, from the viewpoint of flexibility, a hydrogenated product of a styrene-based thermoplastic elastomer is preferable, and a hydrogenated product of a styrene-ethylene-butylene-styrene block copolymer, a hydrogenated product of a styrene-ethylene-propylene-styrene block copolymer, and a hydrogenated product of a styrene-ethylene-propylene-styrene block copolymer are more preferable.

Any conjugated diene may be used as long as it is a diene having a pair of conjugated double bonds (two double bonds conjugated together).

Examples of the conjugated diene include, but are not limited to, 1, 3-butadiene, 2-methyl-1, 3-butadiene (isoprene), 2, 3-dimethyl-1, 3-butadiene, 1, 3-pentadiene, 2-methyl-1, 3-pentadiene, and 1, 3-hexadiene. Among them, 1, 3-butadiene and 2-methyl-1, 3-butadiene (isoprene) are preferable from the viewpoint of general versatility. These may be used alone or in combination of two or more.

The vinyl aromatic compound includes, but is not limited to, styrene, α -methylstyrene, p-methylstyrene, o-divinylbenzene, m-divinylbenzene, p-divinylbenzene, 1-diphenylethylene, N-dimethyl-p-aminoethylstyrene, N-diethyl-p-aminoethylstyrene, and the like.

(A) The content of the vinyl aromatic compound unit in the component (b) is preferably less than 30% by mass, more preferably 20% by mass or less, and further preferably 15% by mass or less.

In the copolymer of the component (A) or the hydrogenated product thereof, usually, a polymer block of a vinyl aromatic compound unit is present as a hard segment, and a polymer block of a conjugated diene unit is present as a soft segment.

The copolymer of component (a) exhibits rubber properties by the hard segment functioning as a physical crosslinking point of the soft segment at a temperature not higher than the glass transition temperature thereof. On the other hand, the soft segment plays an important role in introducing the filler, and when the soft segment content in the copolymer is high, that is, the content of the vinyl aromatic compound unit is small, the hardness of the copolymer tends to be hard to increase with the increase in the filler content.

Therefore, when the content of the vinyl aromatic compound unit in the component (a) is within the above numerical range, even if the content of the thermally conductive filler (C) described later is large, a resin composition having low hardness can be preferably obtained (although the mechanism of action of the present embodiment is not limited to the above mechanism, and the same is true for the following description of the mechanism of action).

The content of the vinyl aromatic compound unit in the component (a) can be controlled by adjusting the amount of the monomer added in the polymerization step of the copolymer, and can be measured by using a nuclear magnetic resonance apparatus (NMR). Specifically, the measurement can be carried out by the method described in examples.

(A) The weight average molecular weight of the component (C) is not particularly limited. Preferably 5X 10⁴～100×10⁴More preferably 8X 10⁴～80×10⁴More preferably 9X 10⁴～30×10⁴。

Weight sharingA quantum of 5X 10⁴In the above case, the resin composition of the present embodiment has improved toughness and exhibits smaller compression set. Further, the weight average molecular weight was 100X 10⁴In the following cases, the resin composition of the present embodiment has improved flexibility.

(A) The weight average molecular weight of the component (d) can be measured by Gel Permeation Chromatography (GPC). Specifically, the molecular weight of the peak of the chromatogram can be calculated from the calibration curve calculated from a commercially available standard polystyrene measurement.

(A) When the component (a) includes a hydrogenated product of the copolymer (hereinafter also referred to as "hydrogenated copolymer"), the hydrogenation ratio of the conjugated diene-based double bonds of the copolymer before hydrogenation is preferably 10% or more, more preferably 75% or more, and still more preferably 85% or more. When the hydrogenation ratio is within the above numerical range, it is possible to suppress a decrease in flexibility, strength, elongation, and the like due to thermal degradation, and to exhibit more favorable heat resistance.

The hydrogenation ratio of the double bonds based on the conjugated diene means a ratio of the double bonds after hydrogenation to the double bonds of the conjugated diene contained in the copolymer before hydrogenation. The hydrogenation rate of the hydrogenated copolymer can be measured by a nuclear magnetic resonance apparatus (NMR). Specifically, the measurement can be carried out by the method described in examples.

(B) softener for rubber)

The resin composition of the present embodiment contains a softening agent for rubber as the component (B).

Examples of the component (B) include, but are not limited to, mineral oil-based rubber softeners and synthetic rubber softeners used for the purpose of softening, increasing the volume and improving the processability of rubber.

Examples of the mineral oil-based softening agent for rubber include, but are not limited to, process oil, extender oil, and the like. Specific examples thereof include a mixture containing any two or more selected from the group consisting of a compound having an aromatic ring, a compound having a cycloalkane ring, and a compound having a paraffin chain.

Examples of the softener for synthetic rubber include, but are not limited to, silicone oil and fluorine oil.

The component (B) is preferably a paraffin oil, a naphthene oil or an aromatic oil, more preferably a paraffin oil or a naphthene oil, and still more preferably a paraffin oil, from the viewpoint of improving the softening property and processability of the rubber. Among the paraffin-based oils, oils with a small aromatic content are particularly preferable in view of cold resistance and durability. These may be used alone or in combination of two or more.

The paraffin oil preferably has a kinematic viscosity at 40 ℃ of 100mm²Sec or more, more preferably 100mm²/sec～10000mm²Sec, more preferably 200mm²/sec～5000mm²And/sec. When the kinematic viscosity of the paraffin oil is within the above numerical range, the affinity with rubber is good, and the oil tends to be less likely to bleed out. The kinematic viscosity can be calculated as follows: the kinematic viscosity can be calculated by measuring the time (sec: absolute viscosity) required for a certain volume of oil to naturally flow down through a capillary of a viscometer (for example, "FENSKE type viscometer" manufactured by Canon) under a certain temperature condition and dividing the absolute viscosity by the sample density.

As the paraffin oil, commercially available products can be used. Examples of the commercially available products include, but are not limited to, "NA Solvent" manufactured by Nippon fat company, "Diana Process oil PW-90" and "Dianaprocess oil PW-380" manufactured by Shikino, and "IP Solvent 2835" manufactured by Shikino petrochemical company and "Neothiozole" manufactured by Sanko Industrial Co.

(B) The flash point of the component is preferably 170 ℃ to 300 ℃. The flash point was determined as follows: the flash point was determined by filling a predetermined amount of a sample cup with a sample using a Cleveland open cup flash point tester, raising the temperature, passing a test flame over the sample cup at predetermined temperature intervals to ignite the vapor of the sample, and measuring the lowest temperature of the sample when the flame propagates over the liquid surface. (B) When the flash point of the component (b) is within the above numerical range, the flame retardancy of the resin composition of the present embodiment tends to be improved.

(B) The weight average molecular weight of the component (B) is preferably 100 to 5000. The weight average molecular weight can be measured by GPC. (B) When the weight average molecular weight of the component (b) is within the above numerical range, the volatility is low and a sufficient softening effect tends to be imparted to the resin composition.

((C) thermally conductive Filler)

The resin composition of the present embodiment contains a thermally conductive filler as the component (C).

The thermally conductive filler is a granular or powdery substance mainly composed of an inorganic material or a metal having a high thermal conductivity.

(C) The thermally conductive filler is blended to increase the thermal conductivity by forming a thermal conduction path inside the resin composition of the present embodiment.

The component (C) is not limited to the following, and examples thereof include a metal nitride, a metal oxide, and a metal hydroxide, and preferably at least one selected from the group consisting of a metal nitride not containing silicon, a metal oxide not containing silicon, and a metal compound not containing a metal hydroxide not containing silicon, from the viewpoints of thermal conductivity of the resin composition of the present embodiment, productivity and handling in obtaining the resin composition and the sheet, and easiness of obtaining.

When the metal compound contains silicon, the metal compound is not preferable because the thermal conductivity is lowered, and as a result, the thermal conductivity of the resin composition is lowered, but the metal compound may contain a small amount of impurity components derived from the raw materials thereof, within a range not to impair the object of the present invention.

Examples of the metal nitride include, but are not limited to, boron nitride, aluminum nitride, and the like.

Examples of the metal oxide include, but are not limited to, alumina, magnesia, zinc oxide, zirconia, and calcium oxide.

Examples of the metal hydroxide include, but are not limited to, aluminum hydroxide, magnesium hydroxide, zinc hydroxide, calcium hydroxide, and tin hydroxide.

As the component (C), aluminum hydroxide, magnesium hydroxide and aluminum oxide are preferable. More preferably, aluminum hydroxide or aluminum oxide.

By using aluminum hydroxide or magnesium hydroxide as the component (C), not only the thermal conductivity but also the flame retardancy tends to be further improved. Further, by using alumina as the component (C), even when the filler content is small, the thermal conductivity tends to be obtained efficiently. Alumina has a high thermal conductivity, and tends to impart a high thermal conductivity to the resin composition, and tends to provide a good balance between flexibility and thermal conductivity.

(C) The components may be appropriately pretreated. For example, a component having a surface modified by pretreating the metal compound with a silane coupling agent, a titanate coupling agent, stearic acid, or the like can be used.

The average particle diameter of the component (C) is preferably 10 to 150. mu.m, more preferably 20 to 100 μm, and still more preferably 25 to 80 μm, from the viewpoint of thermal conductivity, and productivity during mixing and sheet production.

As described above, the thermally conductive filler of component (C) has two or more different maximum values in its particle size distribution, and the difference in particle size between the maximum values is preferably 50 μm or more, more preferably 55 μm or more, and still more preferably 60 μm or more. When the difference in particle size of the maximum value is 50 μm or more, a sheet having more excellent flexibility can be obtained, and the extrusion stability when processed into a sheet is improved, and therefore a sheet having excellent thickness accuracy tends to be obtained.

As the component (C), two or more thermally conductive fillers having different average particle diameters are preferably used.

More preferably, a thermally conductive filler containing (C-I) a first thermally conductive filler having an average particle diameter of 60 to 150 μm and (C-II) a second thermally conductive filler having an average particle diameter of 5 to 60 μm is used. This tends to provide a composition having an excellent balance between flame retardancy and flexibility.

The difference in average particle diameter between the above (C-I) and the above (C-II) is preferably 50 μm or more in view of flame retardancy, sheet processability, thickness accuracy and vibration absorbability.

The mass ratio ((C-I)/(C-II)) of the component (C-I) to the component (C-II) is preferably 100/1 to 100/170, more preferably 100/10 to 100/170, still more preferably 100/20 to 100/150, and still more preferably 100/25 to 100/120. When the mass ratio of the component (C-I) to the component (C-II) ((C-I)/(C-II)) is in the above numerical range, the thermal conductivity and flame retardancy tend to be improved in a well-balanced manner.

(C) The composition is preferably in the form of granules. The particle shape referred to herein means, for example, a spherical shape, a shape in which spheres are aggregated, a shape in which spheres are flattened, a shape in which flattened spheres are aggregated, an amorphous crushed shape, a shape in which amorphous crushed materials are aggregated, a shape in which pores are formed, and a shape in which these shapes are granulated.

In particular, when the component (C) has a particle shape and the average particle diameter is in the above range, the thermal conductivity tends to be more effectively exhibited.

The average particle diameter is an average value of volume-based particle diameters measured by a laser diffraction/scattering particle size distribution measuring apparatus. In general, the particle size is measured by dispersing a thermally conductive filler in water or ethanol. In this case, when the dispersion is impossible, a surfactant may be used as appropriate, or the dispersion may be performed by using a homogenizer or ultrasonic waves. The concentration of the thermally conductive filler dispersed at this time is usually 1 mass% or less.

(C) The component is preferably Na₂The O concentration is more than 0.20 mass% and 1.00 mass% or less. More preferably 0.50% by mass or less, and still more preferably 0.35% by mass or less.

In view of the dielectric breakdown strength of the resin composition of the present embodiment, Na in the component (C)₂The O concentration is preferably 1.00 mass% or less. Further, Na as the component (C)₂The lower limit of the O concentration is not particularly limited, but is preferably more than 0.20 mass% in view of productivity. In order to be 0.2 mass% or less, the component (C) needs to be purified or the like, and this tends to be disadvantageous in terms of productivity for obtaining the thermally conductive filler.

Na in the component (C)₂The O concentration can be determined by fluorescent X-ray spectroscopy or the like.

((D) additive)

The resin composition of the present embodiment contains, as the component (D), at least one additive selected from the group consisting of silica, talc, calcium carbonate, barium sulfate, kaolin, apatite, diatomaceous earth, zeolite, and mica.

(D) The component (b) is added for the purpose of serving as a flame retardant aid. The flame retardant auxiliary is a component added to exhibit the following effects: the component exhibiting flame retardancy, which is generated when the resin and/or the component added for improving flame retardancy are burned, is mainly diffused on the surface of the resin composition. For example, when a gas phase process silicon oxide is used as a flame retardant aid and aluminum hydroxide is used as a component exhibiting flame retardancy, the aluminum hydroxide generates water vapor when the resin composition is burned, and the gas phase process silicon oxide diffuses the generated water vapor to the surface of the resin composition to effectively shield oxygen as a combustion supporter from the surface of the resin composition, thereby improving flame retardancy.

Further, the component (D) is also added for the purpose of being an anti-blocking agent. Antiblocking agents refer to ingredients added for the following purposes: the above-mentioned component (A) and/or component (B) and the raw material of the resin composition are prevented from adhering to each other or from adhering to each other among the resin compositions, and the raw material and the resin composition are prevented from adhering randomly to a hopper or a screw of a production machine. If the component (a) and/or the component (B) and the raw material of the resin composition are bonded to each other or the resin compositions are bonded to each other and the raw material or the resin composition is randomly bonded to a hopper or a screw of a production machine, it is sometimes difficult to continuously supply the raw material or the resin composition of the resin composition in a constant amount at the time of production. In addition, in the case where the resin composition is a pellet, the pellet may be bonded when the pellet is stored, and a step of crushing again before sheet molding is required. By using the component (D), the above-mentioned problems can be prevented.

That is, by adding the component (D), a resin composition having an improved balance between thermal conductivity and flame retardancy and a stable raw material supply ability in sheet production can be obtained.

As described above, the component (D) contains at least one selected from the group consisting of silica, talc, calcium carbonate, barium sulfate, kaolin, apatite, diatomaceous earth, zeolite, and mica.

These may be used alone or in combination of two or more.

(D) The component (c) may be any of natural products and synthetic products, and known materials may be used. In use, commercially available products can be used because of availability. In addition, the component (D) may contain a trace amount of impurity components derived from natural products, raw materials derived from synthetic products, and the like, within a range not to impair the object of the present invention.

(D) The composition is preferably in the form of granules. The particle shape referred to herein means, for example, a spherical shape, a shape in which spheres are aggregated, a shape in which spheres are flattened, a shape in which flattened spheres are aggregated, an amorphous crushed shape, a shape in which amorphous crushed materials are aggregated, a shape in which pores are formed, and a shape in which these shapes are granulated. The particles may be porous or may be substantially porous by aggregation of small particles. When the component (D) is in the above-mentioned shape, the effects as a flame retardant aid and an antiblocking agent tend to be more effectively exhibited.

Silica, talc, diatomaceous earth and zeolite are preferable as the component (D) because of their high effects of improving flame retardancy with respect to the amount added and improving the stable raw material supply ability during sheet production. Silica or talc are particularly preferred.

When silicon oxide is used as the component (D), it may be either crystalline silicon oxide or amorphous silicon oxide.

Representative examples of crystalline silicon oxide include quartz, quartz crystal, tridymite, cristobalite, chrysolite, and quartz. As typical examples of the amorphous silica, quartz glass, silica gel, keatite, fibrous silica W having a siloxane chain obtained by oxidation of silicon monoxide, and the like can be given. Among these, amorphous silicon oxide is preferable because it can obtain a good balance between thermal conductivity and flame retardancy. Among these, vapor phase method silica is particularly preferable because of its high effect of obtaining a resin composition having stable raw material supply ability in sheet production.

As the vapor phase method silica, commercially available products can be used. Examples of commercially available products include, but are not limited to, "AEROSIL 130", "AEROSIL 200", "AEROSIL 300", "AEROSILR 106", manufactured by Nippon AEROSIL, and "REOLOSIL" manufactured by Tokuyama, and "CAB-O-SIL" and "CAB-O-SPERSE" manufactured by Cabot.

When talc is used as the component (D), commercially available products can be used. Examples of commercially available products include, but are not limited to, grades (hereinafter referred to as "NANO ACE") manufactured by Talcum, Japan, series "SG", "MICROACE", "MS-P", "MS-K", "SWE", "SIMGON", "SSS", "RA", "PA-OG", "SANO; "FT" series, "MF" series, "PS" series, manufactured by Fugang Talc industries, Ltd; "CROWN TALC" series, "HI-FILER" series, manufactured by Sonmura industries, Inc.; "FH" series, "FL" series, "FG" series, "FS" series, "ML" series, "MG" series, "MS" series, "RL" series, "RG" series, "RH" series, "RS" series, etc., manufactured by Fuji Talc industries, Inc.

The component (D) may be pretreated as appropriate within a range not to impair the object of the present invention. For example, the silica may be surface-modified by pretreatment with a silane coupling agent, a titanate coupling agent, stearic acid, or the like.

((E) plasticizer)

From the viewpoint of obtaining more excellent flexibility, the resin composition in the present embodiment preferably further contains (E) a plasticizer.

The plasticizer is not limited to, for example, phthalic acid ester, aliphatic carboxylic acid ester, polyester polymer plasticizer, higher fatty acid ester, higher aliphatic amide, and metal salt of higher fatty acid. Here, the higher fatty acid means a fatty acid having 6 or more carbon atoms.

Among these, higher fatty acids are preferable, and myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, and arachidic acid are more preferable, and palmitic acid and stearic acid are still more preferable.

((F) fluororesin and/or fluororesin-modified product)

The resin composition of the present embodiment may further contain (F) a fluororesin and/or a modified fluororesin.

When the fluororesin and/or the fluororesin modified product (F) is contained in the resin composition of the present embodiment, these components are effectively dispersed in a fibrous form (fibril form), and the fibrils form a physical network, which tends to improve the melt tension of the resin composition. As a result, the processability of the resin is improved, and anti-dripping properties (for example, a flame droplet is prevented from dripping during burning, which is effective for preventing the spread) tend to be imparted.

The component (F) is preferably a tetrafluoroethylene polymer such as polytetrafluoroethylene or a tetrafluoroethylene-propylene copolymer, and more preferably polytetrafluoroethylene, from the viewpoint of fibril-forming ability.

The form of the component (F) is not particularly limited, and any suitable form may be adopted depending on the purpose, use, and the like. Examples of the form include a finely powdered fluororesin, an aqueous dispersion of a fluororesin, a powdery mixture with another resin such AS an acrylonitrile-styrene copolymer resin (AS resin) or polymethyl methacrylate (PMMA) (an acrylic modified product of a fluororesin, hereinafter also referred to AS a "modified fluororesin"), and the like.

As the fluororesin modifier, an acrylic modified Polytetrafluoroethylene (PTFE) is preferred from the viewpoint of anti-dripping performance and roll releasability at the time of sheet processing.

The acrylic modified product contains polytetrafluoroethylene and an alkyl ester of (meth) acrylic acid polymer as main components. The acrylic modified product is obtained, for example, by: the polymer is obtained by polymerizing a monomer containing 70 mass% or more of an alkyl (meth) acrylate having an alkyl group with 1 to 4 carbon atoms in a dispersion in which polytetrafluoroethylene particles having an average particle diameter of 0.05 to 1.0 [ mu ] m are dispersed to form an alkyl (meth) acrylate polymer, and then solidifying the solid content in the dispersion or spray-drying the solid content. In addition, this is obtained, for example, by: the dispersion liquid is obtained by mixing a dispersion liquid in which polytetrafluoroethylene particles having an average particle diameter of 0.05 to 1.0 [ mu ] m are dispersed and a dispersion liquid in which alkyl (meth) acrylate polymer particles (the alkyl (meth) acrylate polymer particles contain 70 mass% or more of a structural unit composed of an alkyl (meth) acrylate having an alkyl group with 1 to 4 carbon atoms) are dispersed, and then solidifying or spray-drying the solid content in the mixed dispersion liquid.

As the modified fluororesin, commercially available products such as "METABLEN (trademark) A-3800" and "METABLEN (trademark) A-3750" manufactured by Mitsubishi corporation may be used.

The content of the component (a) in the resin composition of the present embodiment is 2 to 20 mass%, preferably 2 to 15 mass%, and more preferably 4 to 10 mass%.

When the content of the component (a) is 20% by mass or less, sufficient thermal conductivity and flame retardancy can be obtained. Further, by setting the content of the component (a) to 2% by mass or more, good moldability can be obtained.

The content of the component (B) in the resin composition of the present embodiment is 2 to 20% by mass, preferably 4 to 20% by mass, and more preferably 6 to 14% by mass.

When the content of the component (B) is 20% by mass or less, the component (B) can be prevented from bleeding out and sufficient flame retardancy can be obtained. Further, when the content of the component (B) is 2% by mass or more, the hardness of the resin composition is sufficiently reduced.

(A) The mass ratio ((A)/(B)) of the component (B) to the component (B) is preferably 35/65 to 60/40, more preferably 35/65 to 50/50, and still more preferably 35/65 to 45/55.

When the mass ratio ((a)/(B)) of the component (a) to the component (B) is 35/65 or more and the ratio of the component (a) is increased, bleeding of the component (B) can be prevented and high flame retardancy can be obtained.

When the mass ratio ((a)/(B)) of the component (a) to the component (B) is 60/40 or less, the ratio of the component (a) tends to be low enough to reduce the hardness of the resin composition.

The content of the component (C) in the resin composition of the present embodiment is 70 to 95% by mass, preferably 75 to 90% by mass, and more preferably 75 to 85% by mass.

When the content of the component (C) is 70% by mass or more, sufficient thermal conductivity and flame retardancy can be obtained. When the content of the component (C) is 95% by mass or less, the hardness of the resin composition is sufficiently lowered.

The content of the component (D) in the resin composition of the present embodiment is 0.1 to 3% by mass, preferably 0.1 to 2% by mass, and more preferably 0.5 to 2% by mass.

When the content of the component (D) is 0.1% by mass or more, a stable raw material supplying ability can be obtained in the sheet production. When the content of the component (D) is 3% by mass or less, a stable raw material supplying ability can be obtained in sheet production. In addition, sufficient flexibility can be obtained.

The content of the component (E) in the resin composition of the present embodiment is preferably 0.01 to 2% by mass, more preferably 0.1 to 1.5% by mass, and still more preferably 0.3 to 1% by mass. (E) When the content of the component (c) is within the above range, the hardness of the resin composition is lowered, and the sheet formability (stickiness and roll adhesiveness) tends to be improved.

The content of the component (F) in the resin composition of the present embodiment is preferably 0.01 to 5% by mass, more preferably 0.1 to 2% by mass, and still more preferably 0.3 to 1.5% by mass. (F) When the content of the component is within the above range, flame retardancy, mechanical properties, and sheet formability (stickiness and roll adhesiveness) tend to be improved.

The resin composition of the present embodiment has a hardness of preferably less than 60, more preferably less than 40, and still more preferably less than 30 as measured by a type a durometer in accordance with JIS K6253-3.

When the hardness of the resin composition is in the above range, when a sheet obtained from the resin composition is used as a thermally conductive sheet, stress to a heat radiating element or the like can be effectively reduced, dimensional tolerance of a component can be absorbed, and a heat radiating function tends to be effectively exhibited.

(other Components)

The resin composition of the present embodiment may further contain a tackifier as necessary within a range not impairing the object of the present invention.

For example, when the resin composition of the present embodiment is used in a sheet form, a thickener is added to fix an electronic component, a semiconductor device, a display device, and a heat sink. The tackifier is not particularly limited, and conventionally known ones can be used. Examples of the resin include rosin-based resins, modified rosin-based resins, rosin ester-based resins, petroleum-based resins, terpene-based resins, coumarone-indene resins, phenol-based resins, xylene-based resins, and the like. These may be used alone or in combination of two or more. These tackifiers may be contained in the entire resin composition or may be present only in the surface layer of the sheet.

The resin composition of the present embodiment may further contain, if necessary, other additives such as an antioxidant, a crosslinking agent, a thermoplastic resin other than those described above, and a rubber.

Examples of the antioxidant include, but are not limited to, 1, 2-dihydro-2, 2, 4-trimethylquinoline, N-isopropyl-N' -phenyl-p-phenylenediamine, diphenyl-p-phenylenediamine, octylated diphenylamine, and the like.

Examples of the crosslinking agent include, but are not limited to, 2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane, 2, 5-dimethyl-2, 5-bis (t-butylperoxy) -3-hexyne, 1, 3-bis (t-butylperoxyisopropyl) benzene, and the like.

Examples of the thermoplastic resin other than the above-mentioned thermoplastic resin include, but are not limited to, polyethylene, polypropylene, (meth) acrylic resin, polystyrene, and the like.

Examples of the rubber include, but are not limited to, isoprene rubber, styrene-butadiene rubber, styrene-isoprene-butadiene rubber, and the like.

The resin composition of the present embodiment is also one of preferable embodiments in combination with a woven fabric such as a glass fiber cloth or an organic fiber cloth. In particular, when the resin composition of the present embodiment is compounded with a glass fiber cloth, the strength, dimensional stability, and flame retardancy can be further improved when the resin composition is formed into a sheet, and the resin composition can be provided in the form of a thin sheet.

(method for producing resin composition)

The resin composition of the present embodiment can be produced by kneading the above components. The kneading method is not particularly limited, and conventionally known methods can be applied. For example, a blade type kneader (kneader, Banbury mixer, etc.), a roll type kneader (twin roll, three roll, roll mill, conical roll, etc.), a screw type kneader (extruder, etc.) and the like can be used. Among them, a pressure kneader, a Banbury mixer, an extruder, and the like are preferably used.

(use of resin composition)

The resin composition of the present embodiment can be used for various purposes.

In this case, the shape of the resin composition may be appropriately changed depending on the use thereof. Among these, the resin composition of the present embodiment is preferably used as a sheet such as a heat sink, and is particularly suitable as a heat sink for a lithium battery.

The thickness of the sheet obtained from the resin composition of the present embodiment is not particularly limited, but is preferably 0.1mm to 10mm, more preferably 0.2mm to 5mm, and further preferably 0.3mm to 3 mm. The sheet having a thickness in the above numerical range can be suitably used as a heat sink for a battery.

When the thickness of the sheet is 0.1mm or more, the difference in size of the heat dissipation element on the substrate can be effectively compensated, and efficient heat dissipation tends to be possible. When the thickness of the sheet is 10mm or less, the thermal resistance value can be kept low, and sufficient heat dissipation tends to be exhibited.

When the resin composition of the present embodiment is formed into a sheet, the water content of the sheet is preferably 200ppm or less. When the water content of the sheet is 200ppm or less, the extrusion processability is stable, and a sheet having high thickness accuracy tends to be obtained. Examples of the water content of the resin composition include: a method of controlling the water content of the resin composition in advance and then feeding the resin composition to a molding machine; a method of performing vacuum devolatilization at the time of melt processing of the resin composition; and the like, among them, a method of controlling the water content contained in the resin composition to 1000ppm or less in advance and then feeding the resin composition into a molding machine is preferably used.

Here, the water content in the sheet or the resin composition can be measured by a karl fischer moisture meter.

The sheet obtained from the resin composition of the present embodiment may be a single layer or a multilayer.

In the case of multiple layers, the layers may be of the same composition or may be different. The thickness of the entire multilayer sheet is preferably within the above-described thickness range. The thickness of the entire multilayer sheet is preferably within the above-described thickness range. The multilayer sheet may be formed by a multilayer extruder, or may be stacked without using an adhesive layer and then heated, pressurized, or the like to be in close contact with the adhesive layer.

In the case where the resin composition is made into a sheet, an adhesive layer may be provided on one or both surfaces thereof. The adhesive layer can be formed by a method such as attaching or coating (coating). The adhesive layer is not particularly limited in its composition, and may be made of, for example, an acrylic adhesive. The adhesive layer may further contain other components such as a flame retardant.

The sheet obtained from the resin composition of the present embodiment can be wound up in a roll form with a release film or a transfer adhesive film interposed therebetween. The size of the sheet is not particularly limited, and may be processed into a desired size according to the use.

The method for processing the resin composition into a sheet is not particularly limited, and examples thereof include extrusion molding, compression molding, and calender molding. Among them, extrusion molding and calender molding are preferable in terms of continuous molding and easy winding.

More preferred examples of the method for producing the sheet include the following methods: the sheet is molded by extruding the components into a T die while kneading them with an extruder, and is wound up together with a release film or a transfer adhesive film by a sheet drawing device. The extrusion conditions are preferably adjusted so that the temperature of the extruder is set to 80 to 190 ℃, the screw rotation speed is 5 to 80rpm, and the L/D ratio (the ratio of the length (L) of the screw to the diameter (D) of the screw) is 20 or more, depending on the material used or the width of the sheet to be molded.

Further, the sheet can be obtained by the following method: dissolving and dispersing the resin composition in a solvent, casting the solution on a film or a release paper, and then volatilizing the solvent to obtain a sheet; the sheet is obtained by impregnating a glass fiber cloth or an organic fiber cloth with the solvent and then removing the solvent.

The resin composition and the sheet thereof in the present embodiment can be used for various electric/electronic components, semiconductor devices, display devices, communication devices, power devices, and the like. More specifically, the CPU of a computer, a liquid crystal backlight, a plasma display panel, an LED element, a secondary battery or its peripheral devices, a peltier element, a thermoelectric conversion element, a temperature sensor, an inverter, a transformer, an inverter, a (high) power transistor, and the like can be given. The secondary battery referred to herein may be a nickel-cadmium battery or a lithium ion battery. The shape of the lithium ion battery may be square or flat, or may be cylindrical or laminated.

When the sheet obtained from the resin composition of the present embodiment is used as a heat sink for a lithium ion battery, the sheet can be used anywhere as long as the sheet can transmit heat generated from a battery cell. It can also be used between the cell and the heat sink, as long as the purpose is size absorption of the lithium ion battery.

Examples

The present embodiment will be described specifically below by referring to specific examples and comparative examples, but the present embodiment is not limited to the following examples.

The following were used as the components constituting the resin composition.

[ raw materials ]

< A) copolymer comprising conjugated diene units and vinyl aromatic compound units and/or hydrogenated product thereof >

(A-1) (hydrogenated styrene-ethylene-butylene-styrene Block copolymer (SEBS))

"Tuftec (registered trademark) H1221", manufactured by Asahi Kasei corporation (content of vinyl aromatic Compound Unit: 12% by mass, hydrogenation ratio: 99%)

(A-2) (hydrogenated styrene-ethylene-propylene Block copolymer (SEEPS))

"HYBRAR (registered trademark) 7311", manufactured by KURAAY corporation (content of vinyl aromatic compound unit: 12% by mass, hydrogenation rate: 99%)

(A-3) (hydrogenated styrene-butadiene random copolymer)

"S.O.E (registered trademark) L606", manufactured by Asahi Kasei corporation (content of vinyl aromatic compound unit: 52% by mass, hydrogenation rate: 99%)

(B) softener for rubber

(B-1) Paraffin-based Process oil

"Diana Process oil (trademark) PW-380", manufactured by Dakko Kogyo Co., Ltd

< C thermally conductive Filler >

(aluminum hydroxide)

(C-1) "SB 73", manufactured by Nippon light metals Co., Ltd. (average particle diameter: 85 μm, Na)₂O content 0.25 mass%)

(C-2) "SB 303", manufactured by Nippon light metals Co., Ltd. (average particle diameter 25 μm, Na)₂O content 0.25 mass%)

(C-2) "SB 153", manufactured by Nippon light metals Co., Ltd. (average particle diameter: 10 μm, Na)₂O content 0.26 mass%)

< silicon oxide >

(vapor phase method silica)

(D-1) "AEROSIL (trade Mark) 200", manufactured by NIPPON AEROSIL, Inc

< E) plasticizer

(higher fatty acid)

(E-1) stearic acid

Stearic acid 300 manufactured by Nippon Japan chemical and physical Co Ltd

< acrylic acid-modified PTFE >

(F-1) acrylic acid modified Polytetrafluoroethylene (PTFE)

"METABLEN (trademark) A-3800", manufactured by Mitsubishi Yang corporation

The sheet was produced according to the following method.

[ method for producing sheet ]

< kneading step >

The raw materials were melt-kneaded using a 48mm twin-screw extruder. The raw materials were fed by the respective feeders in a constant amount, and pellets of the resin composition were obtained under conditions of a cylinder temperature of 160 ℃, a screw rotation speed of 170rpm, and a discharge rate of 150 kg/hr.

< sheet processing >

The resin composition pellets obtained in the kneading step were processed into a sheet by using a 65mm single screw extruder equipped with a T die having a width of 600 mm.

The cylinder temperature and the die temperature were set to 110 ℃ and the roll temperature was set to 50 ℃, and pellets of the resin composition were extruded in a sheet form from a T die while being melted by an extruder, and were subjected to a cooling process while being rolled to obtain a sheet having a predetermined thickness (about 1.5 mm).

The physical properties and characteristics were measured by the following methods.

[ measurement method ]

< content of vinyl aromatic Compound Unit >

(A) The content of the vinyl aromatic compound unit in the component (a) was measured by a nuclear magnetic resonance apparatus (NMR). Specifically, it was carried out using a nuclear magnetic resonance apparatus (NMR, ECA-500: manufactured by Japan electronic Co., Ltd.) according to the method described in Y.tanaka, et al Rubber Chemistry and Technology 54.685 (1981). As a sample, a sample obtained by dissolving 30mg of the copolymer in 1g of deuterated chloroform was used.

< hydrogenation Rate >

(A) The hydrogenation rate of the component was measured by NMR ("ADVANCE 600 MHz") using a nuclear magnetic resonance apparatus.

< particle size/particle size distribution/average particle size >

The particle size, particle size distribution and average particle size of the component (C) were measured using a laser diffraction/scattering particle size distribution measuring apparatus ("Microtrac MT3300 EX-II" (manufactured by Nikkiso Co., Ltd.).

The measurement sample was prepared by adding the subject particles to a dispersion liquid (dispersion solvent: water, dispersant: sodium hexametaphosphate (0.2 mass%)) and performing ultrasonic dispersion (80W, 5 minutes).

The refractive index of the solvent was 1.333 and the refractive index of the particles was 1.57.

The particle diameter at 50% of the cumulative value in the particle size distribution obtained by the above laser diffraction/scattering method was defined as the average particle diameter.

< Water content >

About 1g of the sample was measured and measured by a Karl Fischer type moisture meter under the conditions of heating temperature of 150 ℃ and carrier gas dry nitrogen purge.

As a sample for measurement, a mixed pellet was used in the case of the resin composition, and cut into about 1g in the case of a sheet.

<Na₂Content of O>

(C) Na in the component₂The O content was measured by fluorescent X-ray spectroscopy.

< thermal conductivity >

Measured by the steady state method in accordance with ASTM D5470. Specifically, the measurement was performed at a measurement temperature of 80 ℃ and a test piece thickness of 1.0mm using a resin material thermal resistance measuring apparatus (manufactured by Hitachi Ltd.).

< flexibility (hardness) >

The measured value after 15 seconds was recorded by a type A durometer (JIS A durometer, manufactured by Polymer Meter Co., Ltd.) in accordance with JIS K6253-3. The test piece was measured by stacking a plurality of test pieces to a thickness of 6 mm.

< tensile elongation at Break >

In accordance with JIS K7127, a long test piece having a width of 10mm in the MD direction and TD direction of the piece was prepared and measured under the conditions of an inter-chuck distance of 115mm and a stretching speed of 50 mm/min.

< flame retardancy >

The measurements were carried out according to the UL94 (Standard established by the underwriters laboratories, USA) vertical burning test.

The test piece had a length of 130mm, a width of 13mm and a thickness of 1.0 mm. Specifically, the combustion time from leaving the flame to disappearance of the flame after 10 seconds of contact with the flame was measured, and the combustion time from leaving the flame to disappearance of the flame was measured after 10 seconds of contact with the flame was again measured. The evaluation was carried out on 5 of these groups as 1 group (total combustion time was measured 10 times). The maximum combustion time of 10 cycles, the total combustion time of 10 cycles, and the presence or absence of dripping during combustion were evaluated. The result is determined based on the following criteria.

V-0: a maximum combustion time of 10 seconds or less, a total combustion time of 50 seconds or less, and no dripping

V-1: a maximum combustion time of 30 seconds or less, a total combustion time of 250 seconds or less, and no dripping

V-2: a maximum combustion time of 30 seconds or less, a total combustion time of 250 seconds or less, and dripping

NG: do not satisfy the above conditions

< evaluation of stability of raw Material feeding ability >

The screw rotation speed was adjusted by the equipment and conditions in the above [ method for producing sheet ] so that the extrusion torque reached 30 amperes on average. At this time, the screw rotation speed was measured for a certain period of time as a standard for the stability of the raw material feed capacity. The smaller the amplitude of the screw rotation speed, the more stably the evaluation material is supplied to the molding machine.

< evaluation of sheet processability >

The following evaluation was performed while adjusting the screw rotation speed to an average extrusion torque of 30 amperes under the equipment and conditions in [ method for producing sheet ] described above.

Discharge amount: the sheet extrusion mass was measured over time.

Torque change: the upper and lower limits of the torque change value for 30 minutes of extrusion were measured.

< precision of thickness >

The thickness of the central portion of the sheet obtained under the conditions and equipment described above in [ method for producing a sheet ] was measured at intervals of 50mm in the MD direction at 3m portions, and the maximum value and the minimum value were compared.

< vibration absorbability >

As shown in fig. 1, two upper and lower heat sinks 2 are bonded between lithium ion battery cells 3 (66) and a heat sink 1, thereby producing a battery module. An electrode 4 is mounted on the upper part of the lithium ion battery.

The thickness of the heat sink is 1.5 mm. An acceleration sensor was attached to the battery module, and the battery module was fixed to a vibration tester (Index co., LTD) and subjected to a vibration test under conditions of a frequency of 40Hz, an acceleration of 1.25G, and a vibration time of 60 minutes.

The Z-axis acceleration of the acceleration sensor and the shape change of the heat sink after the test were measured.

○ the acceleration was suppressed to 20% or more compared with the state without the heat sink, and no cracking of the heat sink occurred.

△ acceleration is suppressed to less than 20% compared to the no fin condition, but no cracking of the fin occurs.

X: the acceleration is suppressed to less than 20% compared with the state without the heat sink, and the fracture of the fin is occurred.

Examples 1 to 12 and comparative examples 1 to 5

With respect to examples 1 to 12 and comparative examples 1 to 5, resin compositions and sheets were produced in the formulation shown in table 1 and table 2, and hardness, tensile elongation at break, thermal conductivity, flame retardancy, raw material supply ability stability, sheet processability, and thickness accuracy were evaluated.

Further, the vibration absorbability when the sheet was sandwiched between the battery modules was evaluated.

The results are shown in tables 1 and 2.

[ TABLE 1]

[ TABLE 2]

As is clear from tables 1 and 2, it was confirmed that the resin compositions and sheets of examples 1 to 12 had thermal conductivity and flame retardancy, were flexible and had high thickness accuracy, and had stable raw material supply ability and vibration absorbability at the time of sheet production.

Industrial applicability

The resin composition of the present invention has industrial applicability as a heat conductive material for various electric/electronic parts, semiconductor devices, display devices, communication devices, power devices, and the like.

Description of the symbols

1 Heat sink

2 Heat sink

3 unit

4 electrodes

Claims

1. A resin composition comprising:

(B) 2 to 20 mass% of a rubber softener;

(C) 70 to 95 mass% of a thermally conductive filler; and

2. The resin composition according to claim 1, wherein the average particle diameter of the thermally conductive filler (C) is 10 to 150 μm.

3. The resin composition according to claim 1 or 2, wherein the (C) thermally conductive filler has two or more different maximum values in its particle size distribution, and shows a difference in particle diameter of each maximum value of 50 μm or more.

4. The resin composition according to any one of claims 1 to 3, wherein the (C) thermally conductive filler comprises:

5. The resin composition according to claim 4, wherein the mass ratio of the component (C-I) to the component (C-II) (C-I)/(C-II) is 100/1 to 100/170.

6. The resin composition according to any one of claims 1 to 5, wherein Na in the (C) thermally conductive filler₂The O concentration is more than 0.20 mass% and 1.00 mass% or less.

7. The resin composition according to any one of claims 1 to 6, wherein the content of the vinyl aromatic compound unit in the copolymer (A) and/or the hydrogenated product thereof is less than 30% by mass,

(A) the mass ratio (A)/(B) of the copolymer and/or the hydride thereof to the softening agent for rubber (B) is 35/65-60/40.

8. The resin composition according to any one of claims 1 to 7, wherein the (C) thermally conductive filler is at least one selected from the group consisting of a silicon-free metal nitride, a silicon-free metal oxide and a silicon-free metal hydroxide.

9. The resin composition according to any one of claims 1 to 8, wherein the (C) thermally conductive filler is aluminum hydroxide or aluminum oxide.

10. The resin composition according to any one of claims 1 to 9, wherein the additive (D) is silica or talc.

11. The resin composition according to any one of claims 1 to 10, further comprising (E) 0.01 to 2% by mass of a plasticizer.

12. The resin composition according to any one of claims 1 to 11, wherein the hardness obtained by a type a durometer in accordance with JIS K6253-3 is less than 60.

13. A sheet comprising the resin composition according to any one of claims 1 to 12, having a thickness of 0.1mm to 10 mm.

14. A tablet as claimed in claim 13 wherein the water content is 200ppm or less.