Thermally conductive additives, thermally conductive compounds and wiring harnesses

Abstract

Provided are a thermally conductive additive having excellent thermal conductivity-enhancing effects and high processability, and a thermally conductive composite material and wiring harness containing such a thermally conductive additive. The present invention relates to a thermally conductive additive comprising an organic component and a metal-containing component, wherein the organic component is in the form of an organic compound having a coordination portion capable of multidentate coordination with a metal and at least one functional group bonded to the coordination portion and having a conjugated π-electron system, wherein the organic component coordinates with the metal atoms constituting the metal-containing component at the coordination portion to form a complex. The present invention also relates to a thermally conductive composite material comprising the thermally conductive additive and a matrix material, wherein the thermally conductive additive is dispersed in the matrix material. Furthermore, the present invention relates to a wiring harness comprising the thermally conductive composite material.

Description

Technical Field

[0001] The present disclosure relates to thermally conductive additives, thermally conductive composites, and wiring harnesses. Background Art

[0002] Insulating members that make up electrical and electronic components sometimes incorporate thermally conductive additives into organic polymer materials to improve heat dissipation and minimize the effects of heat generation caused by current flow. These thermally conductive additives are typically thermally conductive fillers composed of particles of highly thermally conductive inorganic compounds such as aluminum oxide, aluminum nitride, and boron nitride.

[0003] When adding a thermally conductive filler composed of an inorganic compound as a thermally conductive additive to an organic polymer material, the particles of the thermally conductive filler must be brought into proximity or contact with each other to form a thermally conductive path. Therefore, to achieve sufficient thermal conductivity, the amount of thermally conductive filler added must be increased. In some cases, it is necessary to incorporate a large amount of thermally conductive filler into the organic polymer, such as 50% by volume or more. Adding large amounts of inorganic compounds to organic polymers in this manner can affect the properties of the organic polymer, particularly strength, increase specific gravity, and reduce insulation properties, making it difficult to achieve the desired high material properties.

[0004] On the other hand, as a method other than adding thermally conductive fillers, a method for improving the thermal conductivity of organic polymer materials is also used. For example, it is known to improve the thermal conductivity of organic polymers by increasing the thermal conductivity of the organic polymers themselves or adding thermally conductive additives composed of organic materials to the organic polymers to achieve the improved thermal conductivity. As a method of improving the thermal conductivity of organic molecules, a method of introducing rigid and highly oriented sites such as mesogenic groups and liquid crystal structures into the molecules is sometimes used. As a specific example, patent document 1 discloses an epoxy resin cured product using an epoxy resin monomer having mesogenic groups as a thermally conductive resin cured product. In addition, patent document 2 describes the following: an epoxy resin composition containing a liquid crystal epoxy resin having a mesogenic group in the molecule is subjected to a magnetic field in a certain direction to cure the epoxy resin, thereby producing a thermally conductive epoxy resin molded body with a predetermined degree of orientation. Patent document 3 describes the use of a predetermined liquid crystal thermoplastic resin containing a mesogenic group in the structure as an organic thermally conductive additive added when imparting thermal conductivity to plastics. Patent Documents 4 and 5 do not mention improvement of thermal conductivity, but disclose resins having liquid crystallinity and resins into which mesogenic groups are introduced.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-268070

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-175926

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2016-47934

[0010] Patent Document 4: Japanese Patent Application Laid-Open No. 1-261416

[0011] Patent Document 5: Japanese Patent Application Laid-Open No. 2010-6897 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] As mentioned above, by introducing mesogen groups, having liquid crystal position and utilizing the orientation at these positions in the additive that is made of organic compound that adds in organic polymer itself or in organic polymer, can improve the thermal conductivity of organic polymer.But, when the position with the high orientation such as mesogen groups is introduced in the molecular structure, due to the accompanying intermolecular interaction of the orientation at these positions, the processability of organic polymer, additive is easily reduced.For example, when introducing the high position of orientation in thermoplastic organic polymer, cause the fusing point of organic polymer to become higher, in order to be formed, need to be heated to high temperature.In addition, when using the high material of molecular orientation as additive, in additive, easily cause solubility reduction in solvent, the separation of crystal, the purposes of additive is restricted.Also consider by designing the molecular structure of these organic polymers, additive, reduce intermolecular interaction, improve meltability, solubility, but in this case, cause the reduction of orientation, the increase of intermolecular distance, become difficult to fully improve thermal conductivity.

[0014] Therefore, an object is to provide a thermally conductive additive having an excellent thermal conductivity-improving effect and high processability, and a thermally conductive composite material and a wiring harness containing such a thermally conductive additive.

[0015] Means for solving problems

[0016] The thermally conductive additive of the present disclosure includes an organic component and a metal-containing component. The organic component is constituted in the form of an organic compound having a coordination portion capable of multidentate coordination with a metal and at least one functional group bonded to the coordination portion and having a conjugated π-electron system. The organic component is coordinated with the metal atoms constituting the metal-containing component at the coordination portion to form a complex.

[0017] The thermally conductive composite material of the present disclosure includes a matrix material and the thermally conductive additive, wherein the thermally conductive additive is dispersed in the matrix material.

[0018] The wiring harness of the present disclosure includes the thermally conductive composite material.

[0019] Effects of the Invention

[0020] The thermally conductive additive according to the present disclosure is excellent in improving thermal conductivity and has high processability. Furthermore, the thermally conductive composite material and wiring harness according to the present disclosure contain such a thermally conductive additive. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] [ Figure 1 ] Figure 1 A~ Figure 1 C is a schematic diagram illustrating the structure of a thermally conductive additive according to one embodiment of the present disclosure. Figure 1 A represents a complex in which an organic component is coordinated with a metal atom. Figure 1 B represents the orientation state obtained by stacking multiple complexes. Each complex is shown in the form of a plane. Figure 1 C represents a state in which a complex is formed on the surface of the particle containing the metal component.

[0022] [ Figure 2 ] Figure 2 It is a side view showing a wire harness according to one embodiment of the present disclosure.

[0023] [ Figure 3 ]exist Figure 3 A and Figure 3 Panel B shows images of the additives PB-Mg and PB-MOS prepared in Examples, observed using a polarizing microscope. From left to right, the images show the prepared additives (PB-Mg, PB-MOS), the raw material metal-containing particles (MgCO3, MOS), and the raw material PB.

[0024] [ Figure 4 ] Figure 4 The FT-IR spectrum of the additive PB-Mg prepared in the examples is shown. The thick solid line is the spectrum of the prepared PB-Mg, the dotted line is the spectrum of the raw material PB, and the thin solid line is the spectrum of the raw material MgCO3. DETAILED DESCRIPTION

[0025] [Description of Embodiments of the Present Disclosure]

[0026] First, embodiments of the present disclosure are listed and described.

[0027] The thermally conductive additive disclosed herein comprises an organic component and a metal-containing component. The organic component has a coordination portion capable of multidentate coordination with a metal and at least one functional group bonded to the coordination portion and having a conjugated π-electron system. The organic component coordinates with the metal atoms constituting the metal-containing component at the coordination portion to form a complex.

[0028] In the above-mentioned thermal conductivity additive, the conjugated π electron system is regularly arranged between a plurality of adjacent complexes by the regularity of the coordination structure of the organic component relative to the metal atom and the regularity of the arrangement of the metal atoms in the metal-containing component. Thus, at the adjacent complex, π-π interactions can be generated between the conjugated π electron systems. Through π-π interactions, the orientation of the organic components of the adjacent complexes is consistent. Like this, the structure of the complex containing the organic component oriented along with the intermolecular interaction shows a high thermal conductivity improvement effect. Therefore, when the thermal conductivity additive is added to a matrix material such as an organic polymer, thermal conductivity is effectively improved.

[0029] This thermally conductive additive forms a complex by aligning the organic component with the metal-containing component. Multiple complexes are then regularly assembled, generating reversible interactions between the organic components of adjacent complexes. Strong, irreversible intermolecular interactions within the organic components themselves are not involved. Therefore, irreversible, strong intermolecular interactions do not cause a decrease in solubility or meltability, or an excessive increase in crystallinity. In other words, these phenomena are unlikely to reduce the processability and handling properties of the thermally conductive additive itself or the composite material formed by adding the thermally conductive additive to the matrix material. Thus, the thermally conductive additive combines excellent thermal conductivity enhancement with high processability.

[0030] Here, the organic component can interact between adjacent complexes at the functional groups having a conjugated π electron system. In thermally conductive additives, when π-π interactions are pre-established between complexes, the improved thermal conductivity brought about by these π-π interactions can be effectively achieved. If a thermally conductive compound is prepared in such a state where π-π interactions are pre-established between complexes, it can be easily dispersed in a matrix material such as an organic polymer, achieving an improved thermal conductivity. The formation of π-π interactions is reversible, and even when π-π interactions are pre-established, high processability can be ensured by applying appropriate heating, etc.

[0031] The functional group having a conjugated π-electron system may include an aromatic ring or a fused aromatic ring. Functional groups including aromatic rings or fused aromatic rings are prone to planar stacking due to strong π-π interactions, thus becoming a thermal conductivity additive with particularly excellent thermal conductivity-enhancing effects.

[0032] In this case, the functional group having a conjugated π-electron system may comprise only one aromatic ring or a fused aromatic ring. This reduces the likelihood of π-π interactions between functional groups and excessively increased orientation, which can lead to ineffectively improving the solubility and meltability of the thermally conductive additive.

[0033] In addition to the functional group having a conjugated π-electron system, the organic component may further include at least one hydrocarbon group or alkoxy group having 1 to 8 carbon atoms and not having a conjugated π-electron system. Due to the presence of the hydrocarbon group or alkoxy group not having a conjugated π-electron system, the thermally conductive additive is easily melted or dissolved in various organic polymers or solvents, thereby achieving a significant improvement in processability.

[0034] The coordination moiety may have a β-diketone structure. The β-diketone structure is capable of stably bidentate coordination with various metal atoms and readily adopts a planar coordination structure. Through π-π interactions between planar coordination complexes and the accompanying formation of stacked orientations, the thermal conductivity additive exhibits a high thermal conductivity-enhancing effect. Furthermore, the inclusion of a conjugated π-electron system within the β-diketone structure allows for the binding of multiple functional groups, facilitating the preparation of a variety of thermal conductivity additives.

[0035] In this case, the organic component may have a structure represented by formula (A).

[0036]

[0037] Here, R1 and R2 are each independently a functional group having a conjugated π-electron system, or a hydrocarbon group or alkoxy group having 1 to 8 carbon atoms and not having a conjugated π-electron system; R3 is any one of a functional group having a conjugated π-electron system, a hydrocarbon group or alkoxy group having 1 to 8 carbon atoms and not having a conjugated π-electron system, and a hydrogen atom; and at least one of R1, R2, and R3 is a functional group having a conjugated π-electron system. This also includes the case where at least two of R1, R2, and R3 are linked to each other via a ring structure.

[0038] The structure of the above formula (A) has, in addition to a coordination portion consisting of a β-diketone structure, a functional group having a conjugated π electron system, a hydrocarbon group or alkoxy group having no conjugated π electron system and a relatively small number of carbon atoms, or a hydrogen atom as R1, R2, and R3. It excels in balancing the effect of improving the thermal conductivity due to the orientation associated with the π-π interaction between the complex and the contribution of the conjugated π electron system, and the solubility and meltability mainly due to the contribution of sites other than the conjugated π electron system.

[0039] The metal-containing component can be formed in the form of a fibrous metal compound. Fibrous metal compounds often have high thermal conductivity, and thermal conductivity additives containing such metal compounds are particularly effective in improving thermal conductivity. Thermal conductivity additives can be easily prepared by coordinating metal atoms on the surface of the fibrous metal compound with an organic component having a coordination moiety and a functional group with a conjugated π-electron system.

[0040] The thermally conductive composite material involved in the present disclosure comprises the thermally conductive additive and a matrix material, wherein the thermally conductive additive is dispersed in the matrix material.

[0041] The thermally conductive composite material contains the thermally conductive additive according to the embodiments of the present disclosure described above. In the thermally conductive additive, an organic component having a coordination moiety and a functional group with a conjugated π-electron system forms a complex with a metal-containing component. The thermal conductivity of the composite material is enhanced by the orientation of the organic component associated with π-π interactions within the complex. The reversibility of these π-π interactions allows the thermally conductive additive to be easily dissolved or melted in the matrix material. Therefore, even with the addition of the thermally conductive additive, the composite material maintains high processability.

[0042] Here, the matrix material may include an organic polymer. While most organic polymers have low thermal conductivity, adding the thermally conductive additive can ensure high heat dissipation for the thermally conductive composite material as a whole. The thermally conductive composite material contains organic components and exhibits a high affinity for most organic polymers.

[0043] The wiring harness according to the present disclosure includes the thermally conductive composite material.

[0044] Because the wiring harness contains the thermally conductive composite material described above, it can utilize the high thermal conductivity and processability of the thermally conductive composite material. Consequently, the wiring harness can achieve high heat dissipation, minimizing the effects of heat generation caused by, for example, energizing the electrical wires that comprise the wiring harness. Furthermore, the wiring harness can be manufactured simply, including the step of processing the thermally conductive composite material into a predetermined shape.

[0045] [Details of embodiments of the present disclosure]

[0046] The following describes in detail the thermally conductive additive, thermally conductive composite material, and wiring harness according to embodiments of the present disclosure using the accompanying drawings. A thermally conductive composite material according to embodiments of the present disclosure is formed by including the thermally conductive additive. Furthermore, a wiring harness according to embodiments of the present disclosure is formed by including the thermally conductive composite material.

[0047] Unless otherwise specified, all physical property values in this specification are those measured at room temperature in the atmosphere. Furthermore, in this specification, a component being the main component of a material means that the component accounts for 50% or more of the mass of all components constituting the material. Furthermore, in this specification, the term "organic polymer" also includes substances with a low degree of polymerization, such as oligomers.

[0048] Thermal Conductivity Additives

[0049] First, a thermally conductive additive according to one embodiment of the present disclosure will be described.

[0050] (Summary of composition)

[0051] One embodiment of the present disclosure relates to a thermally conductive additive (hereinafter sometimes referred to as an additive) comprising an organic component and a metal-containing component. The organic component is an organic compound having a coordination moiety capable of multidentate coordination with a metal and at least one functional group bonded to the coordination moiety and having a conjugated π-electron system. The organic component can be represented by the structure of the following formula (1), where the coordination moiety is C and the functional group having a conjugated π-electron system is F1.

[0052] F1-C(1)

[0053] Among them, the functional group F1 can be directly bound to the coordination part C, or it can be bound via a connecting group (except for a group having a conjugated π electron system). The number of functional groups F1 bound to one coordination part C can be only one or more. In the case of multiple functional groups, these functional groups can be the same functional groups as each other, or they can be functional groups of different structures each having a conjugated π electron system. In addition, the coordination part C can also simultaneously bind to functional groups other than the functional group F1 having a conjugated π electron system. The organic component can contain only one compound represented by formula (1) or two or more compounds represented by formula (1).

[0054] The metal-containing component contained in the thermally conductive additive may be composed solely of a metal element or may be a metal compound containing a metal element and a non-metal element. From the perspectives of ease of coordination with the organic component and convenience as a thermally conductive additive, the metal-containing component is preferably a metal compound. The thermally conductive additive may contain only one metal-containing component or two or more metal-containing components.

[0055] In the thermally conductive additive, the organic component coordinates with the metal atoms (including those in an ionic state; the same applies hereinafter) constituting the metal-containing component in the coordination portion to form a complex. When the metal atoms constituting the metal-containing component are represented by M, the organic component represented by the above formula (1) forms a complex represented by the following formula (2).

[0056] F1-C…M(2)

[0057] Here, the dotted line represents a multidentate coordination bond. A plurality of organic components represented by formula (1) can be coordinated with one metal atom M. In this case, the plurality of organic components can be organic components having the same structure as each other, or can be organic components having different structures, i.e., organic components in which the structures of at least one of the functional group F1 and other functional groups and the coordination portion C are different from each other. In addition, in addition to the organic component represented by formula (1) being coordinated with the metal atom M, other types of ligands can also be coordinated with the metal atom M.

[0058] In the thermally conductive additive according to this embodiment, as described in detail below, when multiple complexes such as those represented by formula (2) are adjacent to each other, π-π interactions occur between the functional groups having conjugated π electron systems in the organic components of the adjacent complexes, resulting in the orientation of the functional groups. That is, the functional groups of the multiple complexes uniformly adopt a certain orientation angle. It should be noted that, at least in the state of use, for example, after addition to a matrix material such as an organic polymer, the thermally conductive additive may be a complex formed by the organic component and the metal-containing component. Before use, for example, before addition to a matrix material, the organic component and the metal-containing component may not form a complex, and the organic component and the metal-containing component may be independent.

[0059] As described above, the metal-containing component can be composed solely of a metal element or a metal compound containing both a metal element and a non-metallic element. However, when the organic component coordinates with the metal atom to form a complex, the thermally conductive additive as a whole, including the complex, becomes charge-neutral and solid. In the solid state, the charge state of the complex is not restricted. Specifically, the organic component can coordinate with the metal atom to form a neutral complex, with the solid state consisting solely of this neutral complex. Alternatively, the organic component can coordinate with the metal atom to form a positively charged complex ion, which forms a solid state together with a counterion derived from the non-metallic element in the metal-containing component.

[0060] In the state where the organic component is coordinated with the metal atoms, the specific shape taken by the metal-containing component is not particularly specified, and a continuum of any shape such as particles can be formed within the range that can be dispersed in the desired matrix material. As particle shapes that are easily dispersed in the matrix material, amorphous granular, fibrous, rod-like shapes and the like can be exemplified. Among the metal atoms of the metal-containing component constituting the continuum, the metal atoms to which the organic component is coordinated to form a complex can be all the metal atoms or a portion of the metal atoms. In the case of all the metal atoms, the organic component coordinates with the metal atoms occupying the entire region of the continuum containing the metal component such as particles to form a complex. As the case of a portion of the metal atoms, the following form can be exemplified: the organic component coordinates only with the metal atoms occupying the surface of the continuum containing the metal component such as particles and its vicinity to form a complex, while the organic component does not coordinate with the metal atoms occupying the inner region of the continuum. The production method of the thermally conductive additive will be described in detail later. However, the former form can be suitably achieved by dissolving or finely dispersing the metal-containing component in a solvent to form a complex, and then obtaining the complex in a solid state through precipitation or other methods. The latter form can be suitably achieved by maintaining the metal-containing component in a solid state with a predetermined shape and directly contacting it with a solution containing an organic component to form a complex. In the latter case, in particular, since the complex is formed on the surface of particles in which the metal atoms are pre-arranged in a predetermined structure, the orientation and continuity of the organic component due to intermolecular interactions can be easily improved.

[0061] (Details of organic ingredients)

[0062] As described above, as shown in formula (1), the organic component constituting the thermally conductive additive according to this embodiment has a structure in which at least one functional group F1 is bonded to a coordination portion C capable of multidentate coordination with a metal, and the functional group F1 has a conjugated π-electron system, i.e., a structure in which carbon-carbon double bonds and single bonds are alternately arranged, as part or as a whole. As long as such a structure is present, the specific structure of the organic component is not particularly limited. Preferred structures of the organic component are described below.

[0063] There is no particular limitation on the type of functional group having a conjugated π-electron system possessed by the organic component. The conjugated π-electron system may be a chain-like conjugated π-electron system or a cyclic conjugated π-electron system, or may have both a chain portion and a cyclic portion. However, from the perspective of the stability of the conjugated state, the conjugated π-electron system preferably comprises a cyclic structure.

[0064] It is particularly preferred that the conjugated π electron system contained in the functional group of the organic component is composed of an aromatic ring or a fused aromatic ring. This is because the aromatic ring and the fused aromatic ring not only have excellent stability in the conjugated state, but also adopt a planar structure, which can effectively form π-π interactions between the organic components of the adjacent complexes. The aromatic ring contained in the conjugated π electron system (the aromatic ring contained alone or the aromatic ring constituting the fused aromatic ring) can be a benzene ring, or it can be a ring structure of other types with aromaticity such as a pyrrole ring and a thiophene ring. In the case of a fused aromatic ring, a variety of aromatic rings can be fused. The aromatic ring that preferably constitutes the conjugated π electron system can be a benzene ring. That is, the functional group with a conjugated π electron system can be an aryl group or a substituted aryl group. As aryl groups and substituted aryl groups, phenyl and substituted phenyl groups, naphthyl and substituted naphthyl groups, anthracenyl and substituted anthracenyl groups, phenanthrenyl and substituted phenanthrenyl groups can be exemplified. In the organic component, from the viewpoint of obtaining intermolecular interactions of appropriate size, phenyl and substituted phenyl groups, naphthyl and substituted naphthyl groups are particularly preferred. There is no particular limitation on the substituents constituting the substituted aryl group, and alkyl, alkenyl, and alkoxy groups can be exemplified. Alternatively, an aryl group can be introduced as a substituent. In this case, as a functional group comprising a conjugated π electron system as a whole, a structure obtained by polymerizing multiple (fused) benzene rings via a single bond is adopted. From the viewpoint of ensuring the planarity of the functional group, the number of carbon atoms in these substituents is preferably 1 or more and 4 or less. Substituents such as alkenyl groups can form a continuous conjugated π electron system with the aromatic ring.

[0065] In the present embodiment, as described above, the functional group comprising a conjugated π electron system can take a structure in which multiple (fused) benzene rings are polymerized via a single bond. In this case, the effect of improving the orientation brought about by the π-π interaction is also brought into play, but compared with the structure in which multiple (fused) aromatic rings are included in a functional group like this, it is more preferred that the structure in which only one aromatic ring or a fused aromatic ring is contained in each functional group of the organic component. That is, it is more preferred that a mode in which multiple aromatic rings are not included in a single functional group (F1) in a state in which multiple aromatic rings are not fused to each other is included. By not including multiple aromatic rings that are not fused to each other in a single functional group, the interaction and orientation between the organic components of the adjacent complexes can be appropriately suppressed so that they do not become too strong. As described in detail later, in the thermally conductive additive involved in the present embodiment, in the organic component itself, the intermolecular interaction of the molecular orientation is not so strongly generated, thereby ensuring high solubility and solubility, and therefore preferably the intermolecular interaction and orientation of the single functional group are suppressed to be small to a certain extent. Among the functional groups comprising multiple aromatic rings that are not fused together, there are also functional groups known as mesogenic groups, such as biphenyl and phenylbenzoate. Without being limited to these, in the present embodiment, it is preferred that the organic component does not have a mesogenic group. Similarly, from the perspective of suppressing intermolecular interactions and orientation to a certain extent, the organic component preferably does not contain hydrogen-bonding substituents such as ester groups, amide groups, and imide groups, except for the groups contained in the coordination portion. It is further preferred that the organic component also does not contain hydrogen-bonding substituents in the coordination portion.

[0066] In the functional group having a conjugated π electron system, from the viewpoint of ensuring the interaction between the organic components, the number of carbon atoms of each functional group may be 4 or more, preferably 6 or more. On the other hand, from the viewpoint of avoiding excessive increase in the interaction between the organic components, the number of carbon atoms of each functional group may be 24 or less, preferably 12 or less. In the case where the organic component has multiple functional groups having a conjugated π electron system in the molecule, these multiple functional groups having a conjugated π electron system may be connected to each other to form a ring structure including the coordination part. In addition, in the case where the organic component contains a functional group that does not have a conjugated π electron system in addition to the functional group having a conjugated π electron system in the molecule, these two functional groups may be connected to each other.

[0067] As described above, the organic component may further have a functional group that does not have a conjugated π electron system on the basis of a functional group having a conjugated π electron system. By containing a functional group that does not have a conjugated π electron system in the organic component, it is easy to suppress the intermolecular interaction of the organic component to be moderately small compared to the case where the functional groups contained in the organic component are only functional groups having a conjugated π electron system. Thus, it is easy to ensure the solubility and meltability of the thermally conductive additive. There is no restriction on the specific type and structure of the functional group that does not have a conjugated π electron system. As preferred examples, hydrocarbon groups such as alkyl and cycloalkyl groups and alkoxy groups can be listed. From the viewpoint of not hindering the intermolecular interaction at the functional group having a conjugated π electron system, the number of carbon atoms of these functional groups is preferably greater than 1 and less than 8. The functional group is particularly preferably an alkyl or alkoxy group having a carbon atom number within this range.

[0068] The coordination part contained in the organic component is not particularly limited as long as it is a coordination part that can carry out multidentate coordination with the metal atom, and can be a coordination part of bidentate coordination or a coordination part of tridentate coordination or more. In either case, the coordination part is preferably a coordination part that can carry out planar coordination with the metal atom. As the coordination part of bidentate coordination, the coordination parts with the structures of β-diketone (β-diketone root when coordinated), ethylenediamine, bipyridine, diphosphine, phenanthroline, glycine (glycine root when coordinated), and catechol (catechol root when coordinated) can be exemplified. As the coordination part that is tridentate or more and can be coordinated in a planar shape, the macrocyclic structures such as porphyrin, phthalocyanine, and crown ether can be exemplified. It should be noted that in the macrocyclic structure, the distinction between the functional group part other than the coordination part and the coordination part is sometimes unclear. From the viewpoints of the degree of freedom of combination of functional groups and the ease of preparation of organic components, the coordination portion is preferably bidentate coordination, and particularly preferably has a β-diketone structure. The β-diketone structure can be stably planar coordinated with various metal atoms and can be combined with various functional groups. The coordination portion can take a resonance structure (tautomer) such as an enol structure relative to the β-diketone structure. In addition, a portion of the structure of the coordination portion can continuously constitute a conjugated π electron system with the functional group.

[0069] Preferred examples of the organic component having a β-diketone structure as a coordination portion include molecules represented by the following formula (A).

[0070]

[0071] R1 and R2 are each independently a functional group having a conjugated π electron system or a functional group not having a conjugated π electron system, R3 is any one of a functional group having a conjugated π electron system, a functional group not having a conjugated π electron system, and a hydrogen atom, and at least one of R1, R2, and R3 is a functional group having a conjugated π electron system. This also includes the case where at least two of R1, R2, and R3 are linked to each other through a ring structure. Here, in the form in which multiple functional groups are linked through a ring structure, the carbon atoms constituting the β-diketone structure (the C atoms contained in the structure of O=CCC=O) are included in the ring structure formed by the functional group. In addition, in this case, it also includes a form in which these ring structures form a conjugated π electron system such as an aromatic ring or a condensed aromatic ring in the enolate generated by the resonance of the β-diketone structure (see HAN in the example).

[0072] As described above, R1, R2, and R3 are each selected from any one of a functional group having a conjugated π electron system or a functional group not having a conjugated π electron system. As for R3, it can also be a hydrogen atom. Among them, at least one of R1, R2, and R3 is a functional group having a conjugated π electron system. In addition, one of these three can be a functional group not having a conjugated π electron system. As a functional group having a conjugated π electron system and a functional group not having a conjugated π electron system, the functional groups described above as preferred examples are preferably applied. Specifically, as a functional group having a conjugated π electron system, a functional group having an aromatic ring or a condensed aromatic ring is preferred. In addition, as a functional group not having a conjugated π electron system, a hydrocarbon group or an alkoxy group having a carbon number of 1 or more and 8 or less is preferred. It is particularly preferred that two of R1, R2, and R3 are functional groups having a conjugated π electron system. In this embodiment, when the two functional groups having conjugated π-electron systems are not linked to each other, R1 and R2 at both ends can be functional groups having conjugated π-electron systems. On the other hand, when the number of functional groups having conjugated π-electron systems is 1, R3 at the center can be a functional group having a conjugated π-electron system.

[0073] (Details of metal components included)

[0074] As described above, the metal-containing component that constitutes the thermally conductive additive according to this embodiment is not particularly limited in type as long as it contains a metal element. It may be composed solely of a metal element or a metal compound containing a metal element and a non-metal element, but is preferably composed of a metal compound. In the thermally conductive additive, the metal-containing component is in a solid state, such as particles. Preferred metal compounds include metal hydroxides, chlorides, carbonates, sulfates, and alkoxides.

[0075] There are no particular limitations on the metal elements that constitute the metal-containing component. Preferred metal elements include alkaline earth metals such as Mg and Ca, Al, and Zn. Metal compounds containing these metal elements have relatively high thermal conductivity and, when used in conjunction with organic components as thermal conductivity additives, exhibit a significant effect in improving thermal conductivity. Furthermore, metal compounds containing these metal elements have a relatively low specific gravity, making it easy to obtain a low-density thermal conductivity additive.

[0076] As long as the metal-containing component can be in the form of solid particles, there is no particular restriction on the particle shape. Examples of particle shapes include amorphous powder, rod-shaped, fibrous, etc. It is particularly preferred to adopt shapes with high anisotropy such as rod-shaped and fibrous. This is because most metal compound particles with high anisotropy show high thermal conductivity, and even when they are made into thermal conductive additives by coordinating with organic components, they also show high thermal conductivity. In particular, the metal compound is preferably fibrous. As a fibrous metal compound showing high thermal conductivity, basic magnesium sulfate can be exemplified. There is no particular restriction on the particle size of the metal-containing component. From the perspective of improving dispersibility in the matrix material, the particle size (the major diameter in the case of anisotropic shapes such as rod-shaped and fibrous) can be approximately 50 μm or less.

[0077] (Interactions in Complexes)

[0078] As described above, in the thermally conductive additive according to this embodiment, the organic component having a conjugated π-electron system forms a multidentate coordination with the constituent metal of the metal-containing component at the coordination moiety, thereby forming a complex. Because the coordination moiety forms a multidentate coordination with the metal in the metal-containing component, the organic component containing a functional group having a conjugated π-electron system is stably bonded to the metal atom in a predetermined positional relationship and angular arrangement in the complex, compared to the case of monodentate coordination.

[0079] Figure 1 A schematically illustrates the structure of the complex, taking the case where the coordination portion adopts a β-diketone structure as an example. Here, M represents a metal atom, and φ represents a functional group having an aromatic ring or a condensed aromatic ring. Figure 1 In A, a four-coordinate situation is assumed.

[0080] In complex, organic component forms coordination bond under the state of metal atom configuration regularly with predetermined positional relationship.And, by the crystallinity of metal-containing component, under the state that metal atom is arranged regularly, multiple complexes can form aggregate.Like this, when the complex formed by organic component and metal atom coordination takes regular configuration and assembles multiple, gravitational interaction may be produced between the organic components of adjacent complex.That is, the conjugated π electron system contained in the organic component of the complex of adjacent configuration produces π-π interaction mutually.In addition, by π-π interaction, the organic components of adjacent complex are oriented in unison in a predetermined direction.

[0081] For example, in Figure 1 The complex shown in A has a planar structure and Figure 1 The conjugated π electrons in B are distributed in the vertical direction of the complex surface shown as a quadrilateral plane. In addition, π-π interactions are generated between the adjacent complex surfaces. Therefore, through the attractive interaction generated between the surfaces, as shown in FIG. Figure 1 As shown in B, adjacent complexes are oriented in a direction such that the surfaces of the complexes are aligned parallel to each other, and the complexes take a stacked structure. Alternatively, as shown in Figure 1 As shown in Figure C, the organic component is positioned on the metal atoms (not shown) on the surface of the solid particle-shaped metal-containing component (shown by shadow) to form a complex. At this time, π-π interactions occur between the adjacent coordinated organic components. Through this π-π interaction, the organic component adopts a structure oriented in a specific direction on the surface of the metal-containing component. It should be noted that Figure 1 In C, only one organic component is shown for each complex to simplify the display.

[0082] In this way, an attractive interaction is generated between the organic components of multiple complexes, and the functional groups having a conjugated π-electron system oriented in a predetermined direction as a collection, by suppressing phonon scattering, play a role in improving thermal conductivity. Therefore, the complex in such an oriented state acts as a thermal conductivity additive, and by mixing with a matrix material such as an organic polymer material, the thermal conductivity of the material can be improved. There is no particular limitation on the specific orientation structure of the complex as long as the orientation is consistent between the complexes, but it is particularly preferred that the planes constituting the conjugated π-electron system adopt a stacked orientation structure in which parallel layers are stacked. When the conjugated π-electron system is composed of aromatic rings or fused aromatic rings, a stacked orientation structure is easily formed.

[0083] The thermally conductive additive of this embodiment achieves its thermal conductivity-enhancing effect not through a single intramolecular structure or through strong or highly irreversible interactions between molecules, but rather through relatively weak, reversible intermolecular interactions such as coordination and π-π interactions. Therefore, the thermally conductive additive of this embodiment exhibits excellent solubility in solvents and melting properties upon heating. By utilizing its solubility in solvents and melting properties upon heating, it achieves excellent processability when added to, mixed with, or kneaded into matrix materials such as organic polymers. It is also less likely to cause unwanted crystallization.

[0084] like Figure 1 B. Figure 1 Shown in C, under the state of forming π-π interaction between the organic component of adjacent complex, by adding thermal conductive additive in matrix material and mixing, suitably use solvent, heat, can easily reduce or eliminate the π-π interaction between complex.If in this state, carry out operations such as mixing, mixing, then can be by the influence of the complex aggregation caused by reducing π-π interaction, easily carry out dissolving, melting of complex.Then, if suitably carry out utilizing the solvent removal of volatilization etc., heating stop, then can again form π-π interaction between adjacent complex.Thus, thermal conductive additive uniformity is highly dispersed in matrix material, and by the π-π interaction between complex and the orientation accompanying therewith, can form the state of performance thermal conductivity improving effect. When not only the π-π interaction but also the coordination bond between the organic component and the metal-containing component is eliminated along with dissolution in a solvent or melting caused by heating, or when the organic component and the metal-containing component are independently added to a base material or a solvent and then form a complex within the base material, the organic component and the metal-containing component constituting the thermally conductive additive can be dissolved or melted with higher solubility and meltability.

[0085] As disclosed in Patent Documents 1-5, additives and organic polymers composed of organic molecules containing mesogenic groups or liquid crystal structures can also, like the thermally conductive additives of this embodiment, achieve a thermal conductivity-enhancing effect by suppressing phonon scattering through intermolecular interactions and the accompanying molecular orientation. However, in the case of materials containing mesogenic groups or liquid crystal structures, strong intermolecular interactions result in difficulties dissolving in solvents and melting upon heating, often leading to reduced processability. In contrast, as described above, the thermally conductive additives of the embodiments of the present disclosure achieve a thermal conductivity-enhancing effect based on the coordination structure of the organic component and the metal-containing component, resulting in excellent processability.

[0086] (Method for producing thermally conductive additive)

[0087] Next, an example of a method for producing a thermally conductive additive according to the embodiment of the present disclosure described above will be described. First, the metal-containing component to be used is dissolved in a solvent such as a highly polar solvent together with the organic component, or finely dispersed in the form of fine particles that do not retain the shape of the raw metal-containing component. Then, by mixing the solution while appropriately performing operations such as heating, stirring, and adding reactants, the organic component is coordinated with the metal atoms of the metal-containing component. Then, the solvent is removed from the prepared reaction solution by volatilization, etc., and the organic component is coordinated by precipitation, etc. to form a metal-containing component in a complex state in a solid state. Alternatively, the prepared reaction solution is first dispersed in a matrix material, and then the solvent is removed. Alternatively, as another method for producing a thermally conductive additive, the metal-containing component and the organic component in a state that has not formed a complex can be added to a matrix material together with an appropriate solvent and dispersed to form a complex in the matrix material. In these cases, the composition of the metal-containing component constituting the resulting product can be the same as that of the metal-containing component originally used as the raw material, or it can be different after reactions such as coordination.

[0088] In this way, by forming a complex by causing the organic component to coordinate with the dissolved or finely dispersed metal-containing component to form a complex and then generating the complex in a solid state, or by forming the complex in a matrix material, it is easy to obtain a thermal conductive additive in a state where the complex is formed in substantially the entire region of the solid metal-containing component. Figure 1 As shown in Figure B, multiple complexes are easily aggregated into a predetermined orientation such as a stacked shape through π-π interactions, resulting in particles of the thermally conductive additive. This production method, in which the metal-containing component is dissolved or finely dispersed and then the organic component is positioned, is applicable to all embodiments described below, except for the case where basic magnesium sulfate inorganic fibers are used as the metal-containing component.

[0089] Alternatively, the metal-containing component particles may be brought into contact with the organic component without dissolving or finely dispersing the particles to eliminate their initial particle shape. The thermally conductive additive may also be produced by directly bringing the metal-containing component into contact with the organic component while maintaining the original particle shape. In this case, the organic component may be brought into contact with the metal-containing component while dissolved in a solvent. It is necessary to select a solvent that does not dissolve the metal-containing component. When the metal-containing component is brought into contact with the organic component by these methods, as in Figure 1As shown in Figure C, the organic component coordinates with the metal atoms on the surface of the metal-containing component particles to form a complex. Furthermore, the organic component can be placed in a predetermined orientation through π-π interactions between adjacent complexes. This production method, which maintains the shape of the metal-containing component particles while directly orienting the organic component, is preferably employed when using a poorly soluble metal-containing component. In the examples described below, this method is suitable for using basic magnesium sulfate inorganic fibers as the metal-containing component.

[0090] Whether the resulting complex exhibits orientation due to π-π interactions, whether this method is used, can be confirmed by, for example, observation using a polarizing microscope or FT-IR spectroscopy. For example, when observing the resulting thermally conductive additive particles using a polarizing microscope, particles or portions of a particle aligned in a specific orientation corresponding to the polarization direction appear particularly bright compared to other particles or portions. This indicates that the organic component is aligned in the desired direction. Alternatively, in FT-IR measurements, the wavenumber shift of the infrared absorption peak originating from the organic component can sometimes be correlated with π-π interactions.

[0091] Thermally conductive composite materials

[0092] Next, a thermally conductive composite material (hereinafter sometimes referred to as a composite material) according to one embodiment of the present disclosure will be described. The thermally conductive composite material according to this embodiment includes the thermally conductive additive according to the embodiment of the present disclosure described above and a matrix material. The thermally conductive additive is dispersed in the matrix material.

[0093] In the thermally conductive composite material of this embodiment, the organic components contained in the complexes that constitute the added thermally conductive additive form π-π interactions between adjacent complexes, and are then aligned in a predetermined orientation through these π-π interactions. This orientation enhances thermal conductivity, and thus the thermally conductive composite material of this embodiment exhibits high thermal conductivity. In addition, in the thermally conductive composite material, when the particles of the metal-containing component that constitutes the thermally conductive additive contact each other via an appropriate organic component, the metal-containing component itself forms a thermal conductive path, functioning as a thermally conductive filler, and the thermal conductivity of the thermally conductive composite material is also improved. However, by including an organic component in the thermally conductive additive, the thermal conductivity-enhancing effect brought about by the π-π interactions in the organic component can be utilized. Thus, compared to the case of using only the metal-containing component as a thermally conductive filler, a high thermal conductivity-enhancing effect can be achieved even if the amount of the metal-containing component added itself is reduced. As a result, it is possible to suppress the effects that can occur when adding a large amount of metal-containing components, such as an increase in specific gravity, a deterioration in matrix material properties such as material strength, and a decrease in insulation properties, while effectively achieving improved thermal conductivity. The placement of an organic component on the surface of the metal-containing component also enhances the affinity between the metal-containing component and the matrix composed of an organic material.

[0094] There is no particular limitation on the type of matrix material. The matrix material preferably contains an organic polymer, and it is more preferred if it is a material with an organic polymer as the main component. Specific examples of the organic polymer constituting the matrix material include various resins, thermoplastic elastomers, rubbers, and the like. When a resin material is used as the matrix material, it can be a curable resin, a thermoplastic resin, or a plastic that can be dissolved in a solvent, depending on the desired use. Examples of the type of resin constituting the matrix material include: olefin resins such as polyethylene and polypropylene; halogen resins such as polyvinyl chloride; polylactic acid, polystyrene resins, polyvinyl acetate, ABS resin, AS resin, acrylic resin, methacrylic resin, polyamide resin, polyurethane resin, polysiloxane resin, fluorine-containing resin, polyvinyl alcohol, polyimide, polyacetal, polycarbonate, modified polyphenylene ether (PPE), polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, and epoxy resin; or copolymers and polymer alloys of these resins. The matrix material may comprise only one organic polymer or may comprise multiple organic polymers. It should be noted that the matrix material preferably does not contain a mesogenic group or a liquid crystal structure in its molecular structure. In addition to the organic polymer, the matrix material may also contain additives such as flame retardants, fillers, and colorants. However, it is preferred that, other than unavoidable impurities, no other additives such as inorganic fillers that have a thermal conductivity-enhancing effect are added to the thermally conductive composite material.

[0095] In the thermally conductive composite material according to this embodiment, the content of the thermally conductive additive can be appropriately determined so as to achieve the desired thermal conductivity for the thermally conductive composite material as a whole. The greater the content of the thermally conductive additive, the higher the thermal conductivity of the composite material. For example, the content of the thermally conductive additive can be determined so that the thermal conductivity of the composite material is at least 1.5 times, further at least 2.0 times, or at least 2.5 times the thermal conductivity of the matrix material. It should be noted that the higher the thermal conductivity of the thermally conductive composite material, the more preferable. However, to avoid an increase in specific gravity due to excessive addition of the thermally conductive additive, the content of the thermally conductive additive can be determined so that the thermal conductivity of the composite material is no more than 5 times, further at least 4 times, the thermal conductivity of the matrix material without the thermally conductive additive. Alternatively, the content of the additive can be determined so that the specific gravity of the composite material is no more than 1.5 times, further at least 1.2 times, the specific gravity of the matrix material without the thermally conductive additive.

[0096] When the content of the thermally conductive additive is determined by the proportion of the additive in the overall thermally conductive composite material, the content of the thermally conductive additive may be approximately 20% by volume or greater, or approximately 30% by volume or greater, from the perspective of sufficiently improving the thermal conductivity of the thermally conductive composite material. On the other hand, from the perspective of suppressing an increase in the specific gravity of the thermally conductive composite material, the content of the thermally conductive additive may be 60% by volume or less, or alternatively 50% by volume or less.

[0097] The thermally conductive composite material of this embodiment can be manufactured by adding a thermally conductive additive comprising a complex containing a metal component and an organic component, manufactured using the manufacturing method described above, to a matrix material in a predetermined ratio and then mixing and kneading the mixture. Alternatively, the thermally conductive composite material can be manufactured by dispersing the metal component and the organic component, which are not yet in a complex, into a matrix material to form a complex within the matrix material. When the thermally conductive composite material containing the complex is dispersed or formed into a matrix material using these methods, the π-π interactions formed between the organic components and the formation and elimination of coordination bonds between the organic components and the metal component are reversible, making the complex and the organic component easily dispersed in the matrix material and achieving high processability. In this case, even higher processability can be achieved by using a solvent or heating the material. In the manufacturing process of the thermally conductive composite material, if a solvent is used, the material can be appropriately heated, dried, and degassed after manufacturing to remove the solvent in advance. The manufactured thermally conductive composite material can be used directly or formed into the desired shape through processes such as melting, dissolving, and solidification.

[0098] As described above, the thermally conductive composite material according to this embodiment combines high thermal conductivity with low specific gravity and excellent processability. Therefore, this thermally conductive composite material is a preferred material for components requiring both lightweight and heat dissipation properties, and can be easily manufactured and processed. While there are no particular limitations on the specific applications of the thermally conductive composite material, the following describes a detailed example of its use as a component of a wiring harness.

[0099] <Wiring harness>

[0100] Finally, the wiring harness according to the embodiment of the present disclosure is described. The wiring harness according to the present embodiment includes the thermally conductive composite material according to the embodiment of the present disclosure described above. Figure 2 As shown, the wiring harness 5 includes a connector 52 including a connection terminal (not shown) at the distal end of an insulated wire 51 having an insulating coating provided on the outer periphery of the wire conductor. The wiring harness 5 may also include a plurality of insulated wires 51 bundled together. In this case, an adhesive tape 53 may be used as an outer covering material for bundling the insulated wires 51.

[0101] In the wiring harness 5 according to the present embodiment, the thermally conductive composite material according to the embodiment of the present disclosure described above can be used to form various components that require heat dissipation. It is preferred that a thermally conductive composite material obtained by adding a thermally conductive additive to an organic polymer serving as a base material be used as a constituent material of the insulating component. Examples of such insulating components include the insulating coating forming the insulated wire 51, the tape 53 disposed on the outside of the insulated wire 51, outer packaging materials such as protective tubes, adhesives for fixing and waterproofing components, and connector housings forming the connector 52. Furthermore, the thermally conductive composite material can be disposed between a protective tube such as a corrugated tube and the insulated wire 51.

[0102] In recent years, in the automotive field, especially in electric vehicles and hybrid vehicles, there has been a tendency for the current flowing through the wires to increase, and the heat generated from the wires to increase accordingly. In addition, a plurality of wires and electrical connection components have become closely arranged. In these cases, from the viewpoint of minimizing the effect of heat dissipation from the wires and electrical connection components, it is important that the various components constituting the wiring harness 5 have high heat dissipation properties. In the wiring harness 5, by using the above-mentioned thermally conductive composite material having high thermal conductivity to constitute such components that may be affected by heat dissipation, heat can be effectively dissipated. In addition, in the automotive field, lightweighting of constituent components is an important issue, and by using the above-mentioned thermally conductive composite material with a suppressed specific gravity, lightweighting of the wiring harness 5 can also be contributed. In addition, by utilizing the high processability of the thermally conductive composite material, various constituent components having various shapes and configurations can be easily manufactured.

[0103] Example

[0104] The following examples are presented. The present invention is not limited to these examples. Here, a thermally conductive additive comprising a complex formed by disposing an organic component onto a metal-containing component was prepared, and the state of the thermally conductive additive, as well as the specific gravity and thermal conductivity of the thermally conductive composite material containing the thermally conductive additive, were evaluated. Unless otherwise specified, sample preparation and evaluation were performed in air at room temperature.

[0105] [Test method]

[0106] (1) Preparation of additives

[0107] First, various additives are prepared as additives comprising a complex in which an organic component is positioned on a metal-containing component.

[0108] (1-1) Organic ingredients used

[0109] The following lists the names and abbreviations (indicated by <>), molecular weights (MW), and structural formulas of the compounds used as organic components in the preparation of the additives. For HBP and HAN, the resonance structures are also shown.

[0110] ·1-Phenyl-1,3-butanedione<PB>MW:162.2

[0111]

[0112] ·1,3-Diphenyl-1,3-propanedione<DPP>MW:224.3

[0113]

[0114] ·1,3-Bis(4-methoxyphenyl)-1,3-propanedione<BMPP>MW:284.3

[0115]

[0116] ·3-Phenyl-2,4-pentanedione<PP>MW:176.2

[0117]

[0118] ·2-Hydroxybenzophenone<HBP>MW:198.2

[0119]

[0120] ·1'-Hydroxy-2'-acetylnaphthalene<HAN>MW:186.2

[0121]

[0122] ·Acetylacetone<AA>MW:100.1

[0123]

[0124] (1-2) Metal-containing components used

[0125] The following lists the names and abbreviations (indicated by <>) of the metal compounds used as the metal-containing components in the preparation of the additives, and the molar contents of the metal elements.

[0126] Calcium methylate <Ca-MET> (9.8 mmol Ca / g)

[0127] Aluminum isopropoxide <Al-IP> (4.9 mmol Al / g)

[0128] Basic magnesium carbonate <MgCO3> (10 mmol Mg / g)

[0129] Basic zinc carbonate <ZnCO3> (9.0 mmol Zn / g)

[0130] · Basic magnesium sulfate inorganic fiber <MOS> (13 mmol Mg / g)

[0131] (1-3) Preparation method of additives

[0132] The above-listed materials were combined to prepare the additives in the following manner: The names of the additives and the preparation methods are listed below.

[0133] PB-Ca

[0134] 10 g (61.7 mmol) of PB and 3.16 g (31 mmol) of Ca-MET were stirred and homogenized in an isopropyl alcohol / methanol solvent for 30 minutes, and then the solvent was distilled off using an evaporator, followed by vacuum drying.

[0135] PB-Al

[0136] 10 g (61.7 mmol) of PB and 4.29 g (21 mmol) of Al-IP were stirred and homogenized in an isopropyl alcohol / toluene solvent for 30 minutes, and then the solvent was distilled off using an evaporator, followed by vacuum drying.

[0137] PB-Mg

[0138] 10 g (61.7 mmol) of PB and 3.10 g (31 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0139] PB-Zn

[0140] 10 g (61.7 mmol) of PB and 3.44 g (31 mmol) of ZnCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0141] PB-MOS

[0142] 10 g (61.7 mmol) of PB and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0143] ·DPP-Al

[0144] 10 g (44.6 mmol) of DPP and 3.04 g (14.9 mmol) of Al-IP were stirred and homogenized in an isopropyl alcohol / toluene solvent for 30 minutes, and then the solvent was distilled off using an evaporator, followed by vacuum drying.

[0145] ·DPP-Mg

[0146] 10 g (44.6 mmol) of DPP and 2.23 g (22.3 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0147] DPP-MOS

[0148] 10 g (44.6 mmol) of DPP and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0149] BMPP-Mg

[0150] 10 g (35.2 mmol) of BMPP and 1.76 g (17.6 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0151] BMPP-MOS

[0152] 10 g (35.2 mmol) of BMPP and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, followed by vacuum drying.

[0153] PP-Mg

[0154] 10 g (56.8 mmol) of PP and 2.84 g (28.4 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0155] PP-MOS

[0156] 10 g (56.8 mmol) of PP and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0157] \HPB-Mg

[0158] 10 g (50.5 mmol) of HPB and 2.53 g (25.3 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0159] HPB-MOS

[0160] 10 g (50.5 mmol) of HPB and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0161] HAN-Mg

[0162] 10 g (53.7 mmol) of HAN and 2.69 g (26.9 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0163] \HAN-MOS

[0164] 10 g (53.7 mmol) of HAN and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0165] AA-Mg

[0166] 10 g (99.9 mmol) of AA and 4.99 g (49.9 mmol) of MgCO 3 were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0167] AA-MOS

[0168] 10 g (99.9 mmol) of AA and 10 g (130 mmol) of MOS were stirred and homogenized in an isopropyl alcohol / water solvent for 30 minutes, and then the solvent was distilled off using an evaporator, and the mixture was vacuum dried.

[0169] (2) Preparation of composite materials

[0170] The additives prepared above were dispersed in a matrix material to prepare composite materials according to Samples A1 to A16 and Samples B1 to B8. Here, the matrix material constituting the composite material was a cured product of the following two-component epoxy resin.

[0171] Epoxy base: Glycidyl ether of bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation; epoxy equivalent: 190 g / eq.)

[0172] Epoxy curing agent: Amine type ("ST12" manufactured by Mitsubishi Chemical Corporation; amine value: 345 KOHmg / g to 385 KOHmg / g)

[0173] Various additives, an epoxy base, and an epoxy curing agent were mixed in an agate mortar at room temperature in the mass ratios shown in Table 1. The mixture was then degassed under vacuum at room temperature for one minute. The mixture was then heated at 100°C for 10 minutes in a hot press to cure. For Samples A1 to A16, partial changes in the particle shape of the additives were observed during heating at 100°C, suggesting that the aggregated state (stacked structure) of the organic components contained in the additives was temporarily eliminated during heating.

[0174] Cut out the part in which no bubble is visually confirmed in the produced solidified body, and make the resin solidified material test piece (10mm×10mm×1mm). Except for sample B1, based on the content (unit: mass %) of each additive shown in Table 1 and the specific gravity determined by the following evaluation test, the amount per unit volume is set to 30 volume%. For sample B1, no additive is added, and a solidified material test piece consisting only of epoxy resin is made. In Table 1, as other additives, for additives such as PB and MgCO3, the abbreviations of the raw materials are directly recorded, and the additives are not prepared by mixing the organic component and the metal-containing component, but the raw materials are directly added to the epoxy resin.

[0175] (3) Evaluation of the state of additives and properties of composite materials

[0176] PB-Mg and PB-MOS, representative of the additives prepared above, were observed using a polarizing microscope to confirm the orientation of their constituent components. In addition to observing the prepared additives (PB-Mg and PB-MOS), the raw material metal-containing components (MgCO3 and MOS) and organic component (PB) were also observed after being dispersed in liquid paraffin.

[0177] In addition, PB-Mg was subjected to FT-IR measurement to investigate the interaction between the organic components. In addition to the prepared PB-Mg, the raw materials MgCO3 and PB were also measured using the powder attenuated total reflection method (ATR method).

[0178] The specific gravity and thermal conductivity of each cured resin test piece prepared as the composite material were also measured. Specific gravity was measured using the water displacement method. Thermal conductivity was measured using a laser flash method using a thermal conductivity device ("LFA447" manufactured by NETZSCH). The thermal conductivity was measured perpendicular to the surface of the cured resin test piece.

[0179] [Test results]

[0180] (1) Status of additives

[0181] exist Figure 3 A and 3B show observation images of the additives PB-Mg and PB-MOS, respectively, obtained by observing them using a polarizing microscope. From the left, they are images of the prepared additives (PB-Mg, PB-MOS), the raw material metal-containing particles (MgCO3, MOS), and the raw material PB. Figure 3 A and Figure 3 The same image is shown in Figure B. When observing with a polarizing microscope, when a substance is oriented in a specific direction, a region appears in the image that is brighter than the surrounding area.

[0182] exist Figure 3 A and Figure 3 In B, brightly observed crystal grains were observed in a portion of the raw material PB, confirming a certain degree of orientation. Regarding the metal-containing components of the raw material, MgCO3 had a certain degree of orientation similar to PB, but MOS was observed as a uniform dark fibrous particle throughout, suggesting that the crystal structure of the particles did not have a high degree of orientation. On the other hand, in the prepared additives, Figure 3 A PB-Mg and Figure 3In all of the PB-MOSs of B, there are particles that are observed to be particularly bright. In addition, within a single particle, there are also particles with both bright and dark regions. These results indicate that in all additives, the constituent materials have high orientation and are oriented in a certain direction. It is believed that the organic component (PB) that constitutes the additive generates π-π interactions between adjacent molecules in the conjugated π electron system. Due to the attractive effect of this interaction, the organic component is oriented in the direction of stacking, aligning the planes of the conjugated π electron system with each other.

[0183] Here, in the image of PB-MOS, the size and shape of the particles do not change significantly compared to the case of MOS alone. In contrast, in the image of PB-Mg, the particle diameter becomes smaller and the particle shape becomes anisotropic compared to the case of MgCO3 alone. It is believed that in PB-MOS, during manufacturing, the particle shape of the raw material MOS particles does not change in the solvent, and PB is only coordinated on the particle surface. On the other hand, it is believed that in PB-Mg, during manufacturing, the raw material MgCO3 is finely dispersed in the solvent, the particle shape of the raw material is first eliminated, and then PB is coordinated to newly form PB-Mg particles, so the size and shape of the particles change compared to the original MgCO3 raw material. It is believed that the π-π interaction between the coordinated PB molecules contributes to the increase in the anisotropy of the particle shape. It should be noted that for the various additives prepared above, for the additives using MOS as the metal-containing component, the original particle shape is maintained and the additive is directly formed, just like PB-MOS. On the other hand, in the case of additives using components other than MOS as the metal component, the initial particle shape is first eliminated and then the additive is formed, similarly to PB-Mg.

[0184] exist Figure 4 The FT-IR measurement results of the additive PB-Mg are shown in FIG. The thick solid line is the spectrum of the prepared PB-Mg, the dotted line is the spectrum of the raw material PB, and the thin solid line is the spectrum of the raw material MgCO3. The horizontal axis represents the wave number and the vertical axis represents the transmittance (T). In the spectra of PB and PB-Mg, at 1550 cm -1 ~1400cm -1 The absorption peak corresponding to C=C stretching vibration was observed in the region of 760 cm -1 ~680cm -1 Absorption peaks corresponding to C=CH out-of-plane vibrations are observed in the region of . However, as indicated by the arrows in the figure, all peaks in PB-Mg are shifted toward lower wavenumbers compared to PB. These peak shifts suggest that π-π interactions occur between stacked adjacent molecules in the aromatic rings of PB. In particular, the low-wavenumber shift of the C=CH out-of-plane vibrations could be attributed to the restriction of the out-of-plane vibrations of the aromatic rings due to intermolecular interactions.

[0185] (2) Characteristics of composite materials

[0186] Table 1 summarizes the composition and property measurement results for the composite materials of Samples A1 to A16 and Samples B1 to B8. The top column shows the additive-to-matrix ratio (unit: mass %), along with the additive dosage (unit: volume %). The bottom column summarizes the specific gravity and thermal conductivity measurement results. The left column also shows the measured specific gravity values for each additive.

[0187]

[0188] Samples A1 to A16 all add additives prepared from metal-containing components, organic components having a coordination portion and a conjugated π electron system to the base material. In these samples, the thermal conductivity is increased to more than twice that of sample B1 without additives. By adding additives, a good thermal conductivity improvement effect can be obtained. By adding additives, if the thermal conductivity rises to about 2 times, it can be said to be fully useful as a thermal conductivity additive in practical terms. The increase in thermal conductivity can be explained as the following result: the organic component coordinates with the metal constituting the metal-containing component to form a complex, and then generates π-π interactions between the conjugated π electron systems of adjacent complexes, followed by the orientation of the complex to a stacked shape. This is also consistent with the analysis results of the additive state using polarization microscopy and FT-IR described above.

[0189] Furthermore, the specific gravity of the composite materials in Samples A1 to A16 was suppressed to less than 1.1 times that of Sample B1. This is due to the small amount of additives added and the fact that the additives contain not only a metal-containing component with a high specific gravity but also an organic component with a low specific gravity. Thus, the thermal conductivity additive containing the predetermined organic and metal-containing components provides a high thermal conductivity-enhancing effect without significantly increasing the specific gravity of the material.

[0190] Comparing the thermal conductivity measurements of samples A1 to A16, samples A5, A8, A10, A12, A14, and A16 achieved thermal conductivities exceeding 0.50 W / (m / K), which is 2.8 times greater than that of sample B1 and higher than the other samples. The additives used in all of these samples contained MOS as a metal-containing component. This is presumably because, in addition to being a metal compound with high thermal conductivity, MOS, unlike other metal-containing components, maintains its fibrous particle shape while directly coordinating the organic component to the surface, resulting in excellent orientation and continuity of the organic component.

[0191] Next, samples B2 to B8 were investigated. In samples B2 and B3, no metal-containing component was used, and the organic component was added to the matrix material alone. In these samples, no improvement in thermal conductivity was observed compared to sample B1. That is, even if the organic component has a conjugated π electron system, the thermal conductivity improvement effect based on intermolecular interaction and molecular orientation cannot be obtained simply by dispersing it in the matrix material. It can be said that in order for the organic component with a conjugated π electron system to exert the effect of improving thermal conductivity, the organic component must coordinate with the metal atom of the metal-containing component to form a complex, and in the state of the complex assembly, the adjacent organic components adopt a regular relative configuration and are sufficiently close to each other. As a result, π-π interactions are generated between the conjugated π electron systems of the organic components, which can make the orientation consistent.

[0192] In samples B4 and B5, no organic component was used, and the metal-containing component was added separately to the matrix material. In these samples, although an increase in thermal conductivity was observed compared to sample B1, it remained at a small value of about 1.2 to 1.3 times that of sample B1. That is, the effect of improving thermal conductivity is limited by simply dispersing the metal-containing component in the matrix material. The particles containing the metal component are particles that can function as thermally conductive fillers and impart some thermal conductivity improvement effects, but in order to impart a high thermal conductivity improvement effect, it is necessary to make adjacent particles contact each other to form a thermal conduction path. The 30% by volume addition used here can be said to be insufficient to form a thermal conduction path. When the addition amount of the metal-containing component is further increased, it is possible to obtain a high thermal conductivity improvement effect, but in this case, the specific gravity of the composite material is increased, and it is also possible to cause degradation of the properties. In contrast, in samples A1 to A16, even with the same addition amount of 30 volume % as in samples B4 and B5, a high thermal conductivity improvement effect can be obtained. From the comparison with samples B4 and B5, it can be said that in samples A1 to A16, the metal-containing component does not only function as a thermally conductive filler, but the thermal conductivity improvement effect brought about by the contribution of the organic component coordinated to the metal-containing component is dominant.

[0193] In samples B6 and B7, acetylacetone (AA) is used as an organic component constituting the additive. Acetylacetone does not have a functional group having a conjugated π electron system. In these samples, the results of the thermal conductivity measurements increased compared to sample B1, but remained at about 1.3 times that of sample B1, becoming a value roughly equivalent to that of samples B4 and B5 in which no organic component was used. That is, in samples B6 and B7, the thermal conductivity improvement effect produced by using an additive in which an organic component is positioned on a metal-containing component is greatly limited. The reason for this is explained as being that since the organic component does not have a conjugated π electron system, even if a complex is formed, a strong attractive interaction is not exhibited between adjacent complexes, and the effect of improving thermal conductivity due to the orientation of the interaction is hardly obtained. That is, in order to improve thermal conductivity, it is important that the organic component positioned with the metal-containing component has a conjugated π electron system.

[0194] In sample B8, the organic component PB and the metal-containing component MgCO3 were independently added to the matrix material. Sample B8 contained the same amounts of PB and MgCO3 as sample A3, but while sample A3 achieved a thermal conductivity 2.4 times that of sample B1, sample B8 achieved a thermal conductivity only 1.2 times that of sample B1. In sample A3, the organic component and the metal-containing component were premixed to form a thermally conductive additive comprising a complex, which was then added to the matrix material. In contrast, in sample B8, no such complex was formed. Therefore, it can be said that a high thermal conductivity improvement effect cannot be achieved simply by allowing an organic component having a conjugated π electron system and a metal-containing component to coexist in a matrix material. Instead, the two form a complex, and π-π interactions are formed between the complexes, thereby causing orientation, which is important for improving thermal conductivity.

[0195] Explanation of symbols

[0196] 5. Wiring harness

[0197] 51 Insulated wire

[0198] 52 connectors

[0199] 53 tape

Claims

1. A thermally conductive composite material, wherein: The thermally conductive composite material comprises a thermally conductive additive and a matrix material, The thermal conductivity additive is dispersed in the matrix material, The thermal conductivity of the thermally conductive composite material is more than 1.5 times the thermal conductivity of the matrix material. The thermal conductivity additive comprises an organic component and a metal-containing component, The organic component is constituted in the form of the following organic compounds, The organic compound has a coordination part having a β-diketone structure capable of multidentate coordination with a metal, and has at least one functional group bonded to the coordination part and having a conjugated π electron system. The organic component is coordinated with the metal atoms constituting the metal-containing component in the coordination portion to form a complex.

2. The thermally conductive composite material according to claim 1, wherein The organic components interact with each other at the functional groups having a conjugated π-electron system between adjacent complexes.

3. The thermally conductive composite material according to claim 1 or claim 2, wherein: The functional group having a conjugated π-electron system includes an aromatic ring or a condensed aromatic ring.

4. The thermally conductive composite material according to claim 3, wherein The functional group having a conjugated π electron system contains only one aromatic ring or condensed aromatic rings.

5. The thermally conductive composite material according to claim 1 or claim 2, wherein: The organic component further has, in addition to the functional group having a conjugated π-electron system, at least one hydrocarbon group or alkoxy group having 1 to 8 carbon atoms and not having a conjugated π-electron system.

6. The thermally conductive composite material according to claim 1 or claim 2, wherein: The organic component has a structure represented by formula (A), wherein R1 and R2 are each independently a functional group having a conjugated π electron system, or a hydrocarbon group or alkoxy group having 1 to 8 carbon atoms and not having a conjugated π electron system, R3 is any one of a functional group having a conjugated π electron system, a hydrocarbon group or alkoxy group having 1 to 8 carbon atoms and not having a conjugated π electron system, and a hydrogen atom. At least one of R1, R2, and R3 is a functional group having a conjugated π electron system, This also includes the case where at least two of R1, R2, and R3 are connected to each other via a ring structure.

7. The thermally conductive composite material according to claim 1 or claim 2, wherein: The metal-containing component is in the form of a fibrous metal compound.

8. The thermally conductive composite material according to claim 1 or claim 2, wherein: The matrix material comprises an organic polymer.

9. A wiring harness, wherein: The wiring harness includes the thermally conductive composite material according to any one of claims 1 to 8.

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