阅读说明：本技术 热传导材料用组合物以及热传导材料 (Composition for heat conductive material and heat conductive material ) 是由 吉野仁人 祐冈辉明 于 2018-06-01 设计创作，主要内容包括：本发明提供使用了非硅树脂的耐热性优异的脂膏状的热传导材料等。本发明的热传导材料用组合物具有：丙烯酸系聚合物(A),具有至少两个包含碳-碳不饱和键的交联性官能团；丙烯酸系聚合物(B),具有至少一个所述交联性官能团；防滴落剂；以及热传导填料,使用点胶控制器在规定的排出压的条件下测定出的排出量为1.50g/min以上且4.25g/min以下。(The invention provides a grease-like heat conductive material using non-silicone resin and having excellent heat resistance. The composition for a heat conductive material of the present invention comprises: an acrylic polymer (A) having at least two crosslinkable functional groups containing carbon-carbon unsaturated bonds; an acrylic polymer (B) having at least one crosslinkable functional group; an anti-drip agent; and a thermally conductive filler, wherein the discharge amount measured by using a dispensing controller under a predetermined discharge pressure is 1.50g/min to 4.25 g/min.)

1. A composition for a heat conductive material, comprising:

an acrylic polymer (A) having at least two crosslinkable functional groups containing carbon-carbon unsaturated bonds;

an acrylic polymer (B) having at least one crosslinkable functional group;

an anti-drip agent; and

the heat-conducting filler is filled in the container,

the discharge amount measured under the condition of a predetermined discharge pressure by using a dispensing controller is 1.50g/min to 4.25 g/min.

2. The composition for heat conductive material according to claim 1,

the ratio of the amount B of the acrylic polymer (B) to the amount a of the acrylic polymer (A), i.e., the mass ratio B/a, is 3 to 20.

3. The composition for heat conductive material according to claim 1 or 2,

the crosslinkable functional groups of the acrylic polymer (A) are located at both ends,

the crosslinkable functional group of the acrylic polymer (B) is located at one end.

4. The composition for heat conductive material according to any one of claims 1 to 3,

the crosslinkable functional group is represented by the following chemical formula (1),

-OC(O)C(R)＝CH₂(1)

wherein R represents a hydrogen atom or an organic group having 1 to 20 carbon atoms.

5. The composition for a heat conductive material according to any one of claims 1 to 4,

the anti-dripping agent is composed of tetrafluoroethylene resin powder.

6. The composition for a heat conductive material according to any one of claims 1 to 5,

the composition for a heat conductive material further comprises a dispersibility improving agent.

7. A grease-like heat conductive material comprising a composition for a heat conductive material according to any one of claims 1 to 6, which is heated to cause a crosslinking reaction.

Technical Field

The present invention relates to a composition for a heat conductive material and a heat conductive material.

Background

A grease (grease) -like heat conductive material used to fill a small gap or the like formed between a heating element and a heat radiating body is known (for example, see patent documents 1 to 3). A grease-like heat conductive material has been widely used in recent years because of its excellent adhesion and high degree of freedom in the size, shape, and the like of a gap that can be filled.

This heat conductive material is mainly composed of a resin component as a base material and a heat conductive filler dispersed therein. Since the heat conductive material is required to have heat resistance (for example, 100 ℃ or higher), a silicone resin (silicone resin) is often used as the resin component.

Disclosure of Invention

The purpose of the present invention is to provide a grease-like heat conductive material or the like having excellent heat resistance using a non-silicone resin.

(means for solving the problems)

The technical scheme is as follows. That is to say that the first and second electrodes,

<1> a composition for a heat conductive material, comprising: an acrylic polymer (A) having at least two crosslinkable functional groups containing carbon-carbon unsaturated bonds; an acrylic polymer (B) having at least one crosslinkable functional group; an anti-drip agent; and a thermally conductive filler, wherein the discharge amount measured by using a dispensing controller under a predetermined discharge pressure is 1.50g/min to 4.25 g/min.

<2> the composition for a heat conductive material according to <1>, wherein a ratio (mass ratio: B/a) of a blending amount B of the acrylic polymer (B) to a blending amount a of the acrylic polymer (A) is 3 to 20.

<3> the composition for a thermal conductive material <1> or <2>, wherein the crosslinkable functional group of the acrylic polymer (A) is located at both ends, and the crosslinkable functional group of the acrylic polymer (B) is located at one end.

<4> the composition for a thermal conductive material according to any one of <1> to <3>, wherein the crosslinkable functional group is represented by the following chemical formula (1).

-OC(O)C(R)＝CH₂(1)

(wherein R represents a hydrogen atom or an organic group having 1 to 20 carbon atoms.)

<5> the composition for a heat conductive material according to any one of <1> to <4>, wherein the anti-dripping agent is composed of tetrafluoroethylene resin powder.

<6> the composition for a heat conductive material according to any one of <1> to <5>, wherein the composition for a heat conductive material further comprises a dispersibility improving agent.

<7> a grease-like heat conductive material comprising a composition for a heat conductive material according to any one of <1> to <6> which is heated to cause a crosslinking reaction.

(advantageous effects)

According to the present invention, a grease-like heat conductive material or the like having excellent heat resistance can be provided using a non-silicone resin.

Drawings

Fig. 1 is an explanatory view of a test piece used for evaluating the offset resistance.

Fig. 2 is a view showing a photograph of the heat conductive material of example 2 taken in a state of not sagging in evaluation 2 (thermal cycle test).

Fig. 3 is a photograph showing a slightly sagging state of the heat conductive material of example 3 in evaluation 2 (thermal cycle test).

Fig. 4 is a photograph showing a state in which the heat conductive material of comparative example 1 droops in evaluation 2 (thermal cycle test).

Detailed Description

[ thermally conductive Material ]

The heat conductive material of the present embodiment is used in a form sandwiched between two objects (for example, a heat generating body and a heat radiating body). The heat conductive material is in the form of a grease and is formed of a heat conductive composition to be described later by a crosslinking reaction.

[ composition for thermally conductive Material ]

The composition for a heat conductive material is a composition for forming a heat conductive material, and is soft and low in viscosity as compared with a heat conductive material. The composition for a heat conductive material is mainly composed of a substance containing an acrylic polymer (A), an acrylic polymer (B), an anti-dripping agent and a heat conductive filler.

(acrylic Polymer (A))

The acrylic polymer (a) is an acrylic polymer having at least two crosslinkable functional groups containing carbon-carbon unsaturated bonds, which is used as a base (matrix resin) of a composition for a heat conductive material. The acrylic polymer (a) preferably has the crosslinkable functional group at both ends.

The main chain of the acrylic polymer (a) is composed of, for example, a polymer of a (meth) acrylic monomer shown below or a polymer of a (meth) acrylic monomer and another vinyl monomer. In the present specification, "(meth) acrylic acid" means that both acrylic acid and methacrylic acid are included.

Examples of the (meth) acrylic monomer include: (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, tolyl (meth) acrylate, benzyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, octadecyl (meth) acrylate, glycidyl (meth) acrylate, 2-aminoethyl (meth) acrylate, γ - (methacryloxypropyl) trimethoxysilane, ethylene oxide adduct of (meth) acrylic acid (ethylene oxide adduct), trifluoromethyl (meth) acrylate, 2-trifluoromethylethyl (meth) acrylate, perfluoroethylmethyl (meth) acrylate, 2-perfluoroethylethyl (meth) acrylate, perfluoroethylperfluorobutylmethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate, perfluoroethyl (meth) acrylate, perfluoromethyl (meth) acrylate, diperfluoromethylmethyl (meth) acrylate, di (meth) acrylate, and mixtures thereof, 2, 2-diperfluoromethylethyl (meth) acrylate, perfluoromethylperfluoroethylmethyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethylethyl (meth) acrylate, 2-perfluorohexylmethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorodecylmethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, 2-perfluorohexadecylmethyl (meth) acrylate, 2-perfluorohexadecylethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Examples of the other vinyl monomer include: aromatic vinyl monomers such as styrene, vinyltoluene, α -methylstyrene, chlorostyrene, styrenesulfonic acid and salts thereof; fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene and vinylidene fluoride; silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; maleic anhydride, maleic acid, monoalkyl esters and dialkyl esters of maleic acid; fumaric acid, monoalkyl and dialkyl esters of fumaric acid; maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide and cyclohexylmaleimide; acrylonitrile monomers such as acrylonitrile and methacrylonitrile; amide group-containing vinyl monomers such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; olefins such as ethylene and propylene; conjugated dienes such as butadiene and isoprene; vinyl chloride, vinylidene chloride, allyl alcohol, and the like. These may be used alone or in combination of two or more.

The method for synthesizing the main chain of the acrylic polymer (a) is not particularly limited as long as the object of the present invention is not impaired, and for example, a radical polymerization method is possible, and a living radical polymerization method is preferable because the molecular weight distribution (ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn)) can be easily reduced. The living radical polymerization method (particularly, atom transfer radical polymerization method) is preferable because it can obtain a polymer having a narrow molecular weight distribution and a low viscosity and can introduce a monomer having a specific functional group into almost any position of the polymer.

The crosslinkable functional group has a structure containing at least a carbon-carbon unsaturated bond, and is composed of, for example, a structure (functional group) represented by the following chemical formula (1).

-OC(O)C(R)＝CH₂(1)

(wherein R represents a hydrogen atom or an organic group having 1 to 20 carbon atoms.)

As the structure (functional group) represented by the chemical formula (1), for example, an acryloyl group and a methacryloyl group are preferable, and an acryloyl group is particularly preferable.

(acrylic Polymer (B))

The acrylic polymer (B) is an acrylic polymer having at least one crosslinkable functional group containing a carbon-carbon unsaturated bond, which is used as (and as) a binder (base resin) of a composition for a heat conductive material together with the acrylic polymer (a). The acrylic polymer (B) preferably has the crosslinkable functional group at one end. The acrylic polymer (B) preferably has a lower viscosity and a smaller molecular weight (weight average molecular weight, number average molecular weight) than the acrylic polymer (a).

The acrylic polymer (B) is used as a binder (matrix resin) of the composition for a heat conductive material more than the acrylic polymer (a). For example, in the composition for a heat conductive material, the ratio (mass ratio: B/a) of the amount B of the acrylic polymer (B) to the amount a of the acrylic polymer (a) is, for example, preferably 3 or more, more preferably 4 or more, preferably 20 or less, and more preferably 15 or less.

The main chain of the acrylic polymer (B) is basically the same as that of the acrylic polymer (a), and is composed of a polymer of the (meth) acrylic monomer or a polymer of the (meth) acrylic monomer and the other vinyl monomer. The method for synthesizing the main chain of the acrylic polymer (B) is basically the same as that for the main chain of the acrylic polymer (a). However, the main chain of the acrylic polymer (B) is preferably shorter (smaller in molecular weight) than the acrylic polymer (a).

The acrylic polymer (B) has the same structure as the acrylic polymer (a) with respect to the crosslinkable functional group. The crosslinkable functional group of the acrylic polymer (B) has a structure containing at least a carbon-carbon unsaturated bond, and is composed of, for example, a structure (functional group) represented by the above chemical formula (1). Among the crosslinkable functional groups of the acrylic polymer (B), the structure (functional group) represented by the above chemical formula (1) is, for example, also preferably an acryloyl group or a methacryloyl group, and particularly preferably an acryloyl group.

(anti-dripping agent)

The anti-dripping agent has the following functions: and dispersing the dispersion in a composition (matrix resin) for a heat conductive material to adjust the viscosity of the composition for a heat conductive material. As the anti-dripping agent, for example, powder of tetrafluoroethylene resin (PTFE) can be used. The anti-dripping agent has the following functions: when the resin is melt kneaded and dispersed in the composition for a heat conductive material (matrix resin), the resin is easily fiberized to form a network structure in the composition for a heat conductive material (and a heat conductive material obtained therefrom). Specific anti-dripping agents commercially available are, for example, those sold under the trade name "POLYFLON (registered trade name) MPA FA-500H" (manufactured by Daiki industries, Ltd.).

The amount of the anti-dripping agent to be added to the composition for a heat conductive material is not particularly limited as long as the object of the present invention is not impaired, and is, for example, preferably 0.25 parts by mass or more, more preferably 0.45 parts by mass or more, preferably 0.8 parts by mass or less, and more preferably 0.55 parts by mass or less, per 100 parts by mass of the total of the acrylic polymer (a) and the acrylic polymer (B). When the amount of the anti-dripping agent is within such a range, the heat resistance (offset resistance) of the heat conductive material obtained from the heat conductive material composition can be easily ensured.

(dispersibility improving agent)

The composition for a heat conductive material may further include a dispersibility improving agent. The dispersibility improver has a function of uniformly dispersing the heat conductive filler in the composition (matrix resin) for a heat conductive material. Examples of the dispersibility improving agent include: silane coupling agents, surfactants, and the like, and silane coupling agents are preferred.

The amount of the dispersibility improver to be incorporated into the composition for a heat conductive material is not particularly limited as long as the object of the present invention is not impaired, and is, for example, preferably 0.5 parts by mass or more, and preferably 2 parts by mass or less, based on 100 parts by mass of the total of the acrylic polymer (a) and the acrylic polymer (B). When the amount of the dispersibility improver blended is within such a range, the thermally conductive filler can be easily mixed by suppressing the aggregation of the thermally conductive filler with respect to the thermally conductive material composition (matrix resin) when the thermally conductive material composition (matrix resin) and the thermally conductive filler are mixed. This improves the shape stability of the heat conductive material obtained from the heat conductive material composition, and thus easily ensures offset resistance.

(Heat conductive Filler)

As the heat conductive filler, there can be mentioned: silicon carbide, alumina, silica, silicon nitride, boron nitride, and the like. In addition, surface metal-coated particles in which a surface of a core (core) made of hollow particles (for example, glass spheres) or resin particles is coated with a metal may be used. The thermally conductive filler may be used in combination of a plurality of substances, or may be used in combination of one substance.

The average particle diameter of the thermally conductive filler is not particularly limited as long as the object of the present invention is not impaired, and for example, a thermally conductive filler of 0.5 μm to 100 μm can be used. As the heat conductive filler, a plurality of heat conductive fillers having different particle diameters may be used.

The amount of the heat conductive filler to be incorporated in the composition for a heat conductive material is not particularly limited as long as the object of the present invention is not impaired, and is, for example, in the range of 200 parts by mass or more and 5000 parts by mass or less with respect to 100 parts by mass of the total of the acrylic polymer (a) and the acrylic polymer (B).

(other Components)

The composition for a heat conductive material may further include a crosslinking initiator. The crosslinking initiator has the following functions: the acrylic polymer (a) and the acrylic polymer (B) are subjected to heat or light to generate radicals, and the crosslinkable functional group of the acrylic polymer (a) and the crosslinkable functional group of the acrylic polymer (B) are mainly reacted with each other. When a radical is generated from the crosslinking initiator, the crosslinkable functional groups are bonded to each other (polymerized), and the acrylic polymer (a) and the acrylic polymer (B) are crosslinked with each other, the acrylic polymers (B) are crosslinked with each other, and the like.

As the crosslinking initiator, for example, there can be used: organic peroxides such as ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, percarbonates, etc., and percarbonates are particularly preferred.

The crosslinking initiator may be photoreactive to generate radicals upon receiving light (e.g., ultraviolet light) or thermoreactive to generate radicals upon receiving heat. Since the heat conductive filler contained in the composition for a heat conductive material may block light for activating the crosslinking initiator, it is preferable to use a crosslinking initiator that is thermally reactive.

When a thermally reactive crosslinking initiator is used, the reaction temperature is not particularly limited as long as the object of the present invention is not impaired, and for example, from the viewpoint of ensuring the storage stability of the composition for a heat conductive material, it is preferable to use a crosslinking initiator having a reaction temperature (heating temperature) of 100 ℃ or higher.

The amount of the crosslinking initiator to be added to the composition for a heat conductive material is not particularly limited as long as the object of the present invention is not impaired, and is preferably 0.035 parts by mass or more based on 100 parts by mass of the total of the acrylic polymer (a) and the acrylic polymer (B), for example. The upper limit of the amount of the crosslinking initiator is, for example, preferably 0.1 part by mass or less, more preferably 0.08 part by mass or less, and still more preferably 0.065 part by mass or less, based on 100 parts by mass of the total. When the amount of the crosslinking initiator is within such a range, the heat resistance (offset resistance) of the heat conductive material obtained from the heat conductive material composition can be easily ensured.

Further, the composition for a heat conductive material may further contain an antioxidant. Examples of the antioxidant include: phenolic antioxidants, phosphorus-based processing heat stabilizers, lactone-based processing heat stabilizers, sulfur-based heat stabilizers, phenol-phosphorus-based antioxidants, and the like, with phenolic antioxidants being preferred, and hindered phenol antioxidants being particularly preferred.

The amount of the antioxidant to be added to the composition for a heat conductive material is not particularly limited as long as the object of the present invention is not impaired, and is, for example, in the range of 0.5 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the total of the acrylic polymer (a) and the acrylic polymer (B).

In addition, a plasticizer, a colorant, a filler, and the like may be added to the composition for a heat conductive material as needed, as long as the object of the present invention is not impaired.

The composition for heat conduction material has low viscosity even if it does not contain a solvent such as an organic solvent, and can maintain a grease form. Therefore, the organic solvent is not an essential component and does not need to be positively added to the composition for a heat conductive material. However, an organic solvent may be used in the composition for a heat conductive material as long as the object of the present invention is not impaired.

(viscosity of composition for Heat transfer Material)

The viscosity of the composition for a thermally conductive material can be determined by, for example, the discharge amount measured under a predetermined discharge pressure using a dispensing controller (dispensocontroller). The discharge amount of the composition for a heat conductive material is 1.50g/m or more and 4.25g/m or less. When the discharge amount of the composition for a heat conductive material is within such a range, the heat resistance (offset resistance) of the heat conductive material obtained from the composition for a heat conductive material can be ensured. The discharge pressure is generally in the range of 0.1MPa to 1.0MPa in response to a pressure generated by an operation in a mechanical device such as a dispensing controller from a state where an operator operates the dispensing controller by a manual force.

[ thermally conductive Material ]

The heat conductive material of the present embodiment is composed of a composition for a heat conductive material obtained by crosslinking reaction. When a crosslinking reaction occurs in the composition for a heat conductive material, the acrylic polymer (a), the acrylic polymer (B), and the acrylic polymer (B) in the composition for a heat conductive material are bonded (polymerized) to each other, and finally, a structure in which the acrylic polymers are gradually crosslinked to each other is formed in the heat conductive material. Supposedly: in the heat conductive material, the crosslinking density of the entire acrylic polymer (acrylic polymers (a) and (B)) is moderately low, and a large amount of free chains derived from the acrylic polymer (B) mainly exist. Therefore, even if the grease becomes a heat conductive material, the grease is maintained in a paste form.

When the composition for a heat conductive material contains a crosslinking initiator that is thermally reactive, a heat conductive material can be obtained by heat-treating the composition for a heat conductive material at a predetermined temperature. A heat conductive material is used, for example, in a form sandwiched between a heat generating body and a heat radiating body). In some cases, the composition for a heat conductive material may be sandwiched between two objects to be targeted in a state of the composition for a heat conductive material, and the heat conductive material may be formed from the composition for a heat conductive material by, for example, naturally performing a thermal reaction at the place.

The thermal conductivity of the heat conductive material is set to 2W/mK to 3W/mK, for example.

Since the heat conductive material of the present embodiment uses an acrylic resin as the matrix resin, for example, the generation of siloxane gas does not become a problem. In addition, the thermally conductive material is inhibited from sagging (misalignment) from the installation site (for example, a gap between objects) due to softening or the like under high temperature conditions (for example, 125 ℃ or higher), and is excellent in misalignment resistance.

The rate of change between the viscosity of the heat conductive material immediately after application to the object and the viscosity after 4 hours has elapsed after application is 10% or less. The change rate is obtained from the following formula (2).

The rate of change (%) in the viscosity of the heat conductive material { (viscosity after application) - (viscosity before application) }/(viscosity before application) × 100 … … (2)