Thermally conductive composition and thermally conductive molded article

Abstract

The present invention is a thermally conductive composition containing (A) an organopolysiloxane that is liquid at 25 DEG C and (B) a thermally conductive filler having pi electrons, the organopolysiloxane (A) containing a polysiloxane phosphor. According to the present invention, it is possible to provide a thermally conductive composition containing an organopolysiloxane and a thermally conductive filler having pi electrons, the viscosity of the thermally conductive composition being further reduced compared to conventional thermally conductive compositions.

Description

Technical Field

[0001] The present invention relates to a thermally conductive composition and a thermally conductive molded article. Background Art

[0002] In electronic devices such as computers, automotive parts, and mobile phones, heat sinks, such as heat sinks, are commonly used to dissipate heat generated by heat-generating elements such as semiconductor components and mechanical parts. To improve the efficiency of heat transfer to the heat sink, it is known to place a thermally conductive molded article formed from a thermally conductive composition containing a thermally conductive filler between the heat-generating element and the heat sink.

[0003] For example, Patent Document 1 discloses an invention related to a thermally conductive silicone composition comprising: a thermally conductive filler material comprising magnesium oxide, aluminum oxide, and aluminum hydroxide; and a surface treatment agent for the thermally conductive filler material. The surface treatment agent is characterized by being a dimethylpolysiloxane having a trialkoxy end capped at one end of the molecular chain and containing 5 to 100 repeating siloxane (Si-O) units. Furthermore, the invention describes that the surface treatment agent is blended to uniformly disperse the thermally conductive filler material within the silicone matrix, and that the thermally conductive silicone composition containing this surface treatment agent has a low viscosity and is easy to process.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 7136065 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] With the recent trend toward higher performance and smaller devices, thermally conductive compositions are required to exhibit even greater heat dissipation. Consequently, there is a desire for technologies to further reduce the viscosity of compositions containing thermally conductive fillers, thereby improving the filling properties of the thermally conductive filler and enhancing thermal conductivity.

[0009] While the use of the specific surface treatment agent having an alkoxy group described in Patent Document 1 demonstrates a certain degree of viscosity-reducing effect on the thermally conductive silicone composition, this effect is insufficient from the perspective of further increasing the filling rate of the thermally conductive filler and improving thermal conductivity. In particular, there is room for improvement in reducing the viscosity of the composition when using a thermally conductive filler having π electrons.

[0010] Therefore, an object of the present invention is to provide a thermally conductive composition and a thermally conductive molded article which contain an organopolysiloxane and a thermally conductive filler having π electrons and have a viscosity further reduced than conventional ones.

[0011] Means for solving problems

[0012] The present inventors have discovered that a thermally conductive composition comprising (A) an organopolysiloxane that is liquid at 25°C and (B) a thermally conductive filler having π electrons, wherein the organopolysiloxane (A) contains a polysiloxane phosphor, can solve the above-mentioned problems, thereby completing the following invention. Specifically, the present invention provides the following [1] to

[21] .

[0013] [1] A thermally conductive composition comprising (A) an organopolysiloxane that is liquid at 25°C and (B) a thermally conductive filler having π electrons, wherein the organopolysiloxane (A) contains a polysiloxane phosphor.

[0014] [2] The thermally conductive composition according to [1] above, wherein the polysiloxane phosphor has a polycyclic aromatic structure.

[0015] [3] The thermally conductive composition according to [1] or [2], wherein the polysiloxane phosphor has a fluorescence peak X of a non-association complex, or has a fluorescence peak X of a non-association complex and a fluorescence peak Y of an excimer complex.

[0016] [4] The thermally conductive composition according to any one of [1] to [3] above, wherein the polysiloxane phosphor has a fluorescence peak X of a non-association complex and a fluorescence peak Y of an excimer complex, and the ratio of the fluorescence peak intensity FY of the excimer complex to the fluorescence peak intensity FX of the non-association complex (FY / FX) is 0.01 or more and 6.0 or less.

[0017] [5] The thermally conductive composition according to any one of [2] to [4] above, wherein the polycyclic aromatic structure is selected from any one of pyrene, a pyrene derivative, perylene, and a perylene derivative.

[0018] [6] The thermally conductive composition according to [4], wherein the polysiloxane phosphor has a fluorescence peak X of the non-association complex at a wavelength of 370 nm to 430 nm, and a fluorescence peak Y of the excimer complex at a wavelength of 430 nm to 550 nm.

[0019] [7] The thermally conductive composition according to [4], wherein the polysiloxane phosphor has a fluorescence peak X of the non-association complex at a wavelength of 430 nm to 530 nm, and a fluorescence peak Y of the excimer complex at a wavelength of 490 nm to 700 nm.

[0020] [8] The thermally conductive composition according to any one of [1] to [7] above, wherein the molecular weight of the polysiloxane phosphor is 4,000 to 25,000.

[0021] [9] The thermally conductive composition according to any one of [1] to [8] above, wherein the polysiloxane phosphor has a structure represented by the following formula (1).

[0022]

[0023] (In formula (1), each R1 is independently a group represented by AB or a monovalent hydrocarbon group having 1 to 4 carbon atoms, at least one R1 among the plurality of R1 is a group represented by AB, the above-mentioned A is a divalent organic group bonded to a silicon atom, the above-mentioned B has a conjugated aromatic six-membered ring of 3 or more and 6 or less, and among the atoms constituting the above-mentioned A, when the atom bonded to the aromatic six-membered ring possessed by the above-mentioned B is an α-atom, the atom bonded to the α-atom is a β-atom, and the atom bonded to the β-atom and other than the α-atom is a γ-atom, any one of the α-atom, the β-atom, and the γ-atom is a heteroatom, and n is an integer greater than 1.)

[0024]

[10] The thermally conductive composition according to [9] above, wherein the polysiloxane phosphor has a structure represented by the following formula (2).

[0025]

[0026] (In formula (2), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B, and n have the same meanings as A, B, and n in formula (1).)

[0027]

[11] The thermally conductive composition according to [9] above, wherein the polysiloxane phosphor has a structure represented by the following formula (3).

[0028]

[0029] (In formula (3), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B, and n have the same meanings as A, B, and n in formula (1).)

[0030]

[12] The thermally conductive composition according to any one of [1] to

[11] above, wherein the organopolysiloxane (A) contains an addition reaction type silicone.

[0031]

[13] The thermally conductive composition according to any one of [1] to

[12] , wherein the average particle size of the thermally conductive filler (B) having π electrons is 1 μm or more and 500 μm or less.

[0032]

[14] The thermally conductive composition according to any one of [1] to

[13] above, wherein the (B) thermally conductive filler having π electrons comprises an anisotropic filler.

[0033]

[15] The thermally conductive composition according to

[14] , wherein the anisotropic filler comprises one or more selected from the group consisting of carbon fibers, flaky graphite, and boron nitride.

[0034]

[16] The thermally conductive composition according to any one of [1] to

[15] , further comprising a thermally conductive filler having no π electrons.

[0035]

[17] The thermally conductive composition according to any one of [1] to

[16] above, further comprising at least one selected from an organopolysiloxane having a hydroxyl group and an organopolysiloxane having an alkoxy group.

[0036]

[18] A thermally conductive molded body comprising a matrix composed of a cured product of an organopolysiloxane and a thermally conductive filler having π electrons, wherein the organopolysiloxane contains a polysiloxane phosphor.

[0037]

[19] The thermally conductive molded article according to

[18] above, comprising an anisotropic filler oriented in a predetermined direction.

[0038]

[20] The thermally conductive molded article according to

[18] or

[19] , further comprising at least one selected from an organopolysiloxane having a hydroxyl group and an organopolysiloxane having an alkoxy group.

[0039]

[21] A device comprising a heating element, a heat dissipating element, and a thermally conductive molded body according to any one of

[18] to

[20] above, disposed between the heating element and the heat dissipating element.

[0040] Effects of the Invention

[0041] According to the present invention, a thermally conductive composition and a thermally conductive molded article can be provided, which contain an organopolysiloxane and a thermally conductive filler having π electrons and have a viscosity further reduced than conventional compositions. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic perspective view showing an example of a method for producing a thermally conductive molded body.

[0043] Figure 2 A diagram illustrating an instrument for measuring thermal resistance.

[0044] Figure 3 A diagram illustrating the measurement of fluorescence spectra.

[0045] Figure 4 is a graph showing the fluorescence spectrum.

[0046] Figure 5 The graph shows the fluorescence spectrum.

[0047] Figure 6 The graph shows the fluorescence spectrum. DETAILED DESCRIPTION

[0048] [Thermal conductive composition]

[0049] The thermally conductive composition of the present invention comprises (A) an organopolysiloxane that is liquid at 25°C and (B) a thermally conductive filler having π electrons, wherein the organopolysiloxane (A) contains a polysiloxane phosphor. The components constituting the thermally conductive composition are described in detail below.

[0050] <(A) Organopolysiloxane that is liquid at 25°C>

[0051] The thermally conductive composition of the present invention contains (A) an organopolysiloxane that is liquid at 25° C. Furthermore, the organopolysiloxane (A) contains a polysiloxane phosphor.

[0052] (Polysiloxane phosphor)

[0053] The polysiloxane phosphor of the present invention is a compound having a polysiloxane backbone and the ability to emit fluorescence. Alternatively, the polysiloxane phosphor of the present invention can be described as a compound having a polysiloxane backbone and a fluorescent skeleton. Examples of structures capable of emitting fluorescence include a wide range of conjugated systems, such as polycyclic aromatic structures. Specifically, the polysiloxane phosphor of the present invention preferably has a polycyclic aromatic structure. Examples of polycyclic aromatic structures include structures having three or more conjugated aromatic six-membered rings, as described below.

[0054] The polysiloxane phosphors of the present invention, due to their fluorescent structural moieties, such as the aforementioned polycyclic aromatic structure, readily interact with thermally conductive fillers having π electrons through π-π stacking. Furthermore, due to their polysiloxane structure, they exhibit high compatibility with organopolysiloxanes (matrices) other than the polysiloxane phosphors. Therefore, it is believed that the polysiloxane phosphors of the present invention can improve the dispersibility of thermally conductive fillers having π electrons, thereby reducing the viscosity of the composition.

[0055] As described below, the polycyclic aromatic structure is preferably a fused ring compound selected from pyrene, a pyrene derivative, perylene, and a perylene derivative, and more preferably pyrene or perylene.

[0056] In the thermally conductive composition of the present invention, the polysiloxane phosphor has a fluorescence peak X of a non-association complex, or has a fluorescence peak X of a non-association complex and a fluorescence peak Y of an excimer complex.

[0057] Here, the non-aggregate fluorescence peak X is a fluorescence peak emitted by individual phosphor molecules constituting the polysiloxane phosphor in a state where no aggregate is formed.

[0058] The fluorescence peak Y of the exciplex is the fluorescence peak emitted by the individual phosphor molecules constituting the polysiloxane phosphor in the state of forming an association. The term "association" refers to a state in which phosphor molecules are stacked (stacked) by π-π interactions or the like.

[0059] When both non-aggregated fluorescent molecules and aggregated fluorescent molecules are present in the thermally conductive composition, both the non-aggregated fluorescent peak X and the excimer fluorescent peak Y are observed. Furthermore, the non-aggregated fluorescent peak X is observed on the shorter wavelength side of the excimer fluorescent peak Y.

[0060] In the thermally conductive composition of the present invention, the polysiloxane phosphor preferably has the fluorescence peak X of the non-association complex at a wavelength of 370 nm to 430 nm, and the fluorescence peak Y of the excimer complex at a wavelength of 430 nm to 550 nm. Having such specific fluorescence peaks effectively reduces the viscosity of the thermally conductive composition. For example, when the polysiloxane phosphor has a polycyclic aromatic structure, and the polycyclic aromatic structure is pyrene or a pyrene derivative described below, the fluorescence peak X of the non-association complex is at a wavelength of 370 nm to 430 nm, and the fluorescence peak Y of the excimer complex is at a wavelength of 430 nm to 550 nm.

[0061] The wavelength range (370 nm to 430 nm) in which the fluorescence peak X of the non-aggregate is confirmed is preferably 370 nm to 410 nm, and more preferably 370 nm to 390 nm.

[0062] The wavelength range (430 nm to 550 nm) in which the fluorescence peak Y of the excimer is confirmed is preferably 450 nm to 530 nm, and more preferably 460 nm to 500 nm.

[0063] In the thermally conductive composition of the present invention, the polysiloxane phosphor preferably has a fluorescence peak X of the non-association complex at a wavelength of 430 nm to 530 nm, and a fluorescence peak Y of the excimer complex at a wavelength of 490 nm to 700 nm. Having such specific fluorescence peaks effectively reduces the viscosity of the thermally conductive composition. For example, when the polysiloxane phosphor has a polycyclic aromatic structure, and the polycyclic aromatic structure is perylene or a perylene derivative described below, the non-association complex has a fluorescence peak X at a wavelength of 430 nm to 530 nm, and the excimer complex has a fluorescence peak Y at a wavelength of 490 nm to 700 nm.

[0064] The wavelength range (430 nm to 530 nm) in which the fluorescence peak X of the non-aggregate is confirmed is preferably 430 nm to 500 nm, and more preferably 440 nm to 460 nm.

[0065] The wavelength range (490 nm to 700 nm) in which the fluorescence peak Y of the excimer is confirmed is preferably 500 nm to 650 nm, and more preferably 520 nm to 600 nm.

[0066] The polysiloxane phosphor preferably has a non-association fluorescence peak X and an excimer fluorescence peak Y, and the ratio of the excimer fluorescence peak intensity FY to the non-association fluorescence peak intensity FX (FY / FX) is 0.01 to 6.0.

[0067] The fluorescence intensity ratio (FY / FX) varies mainly depending on the concentrations of the thermally conductive filler (B) and the polysiloxane phosphor in the thermally conductive composition. However, as described above, when the fluorescence intensity ratio (FY / FX) is within the range of 0.01 to 6.0, the viscosity of the thermally conductive composition can be effectively reduced.

[0068] From the viewpoint of enhancing the viscosity-reducing effect of the thermally conductive composition, the fluorescence intensity ratio (FY / FX) is preferably 0.02 to 1.5, more preferably 0.03 to 0.7, and particularly preferably 0.05 to 0.4.

[0069] In addition, when multiple peaks are confirmed in the wavelength range for confirming the fluorescence peak of a non-associate, the peak with the shortest wavelength is defined as the fluorescence peak of the non-associate. Similarly, when multiple peaks are confirmed in the wavelength range for confirming the fluorescence peak of an excimer, the peak with the shortest wavelength is defined as the fluorescence peak of the excimer.

[0070] The fluorescence intensity ratio (FY / FX) was calculated by determining the intensity ratio of each fluorescence peak in the measured fluorescence spectrum.

[0071] In addition, as an adjustment of the above-mentioned fluorescence intensity ratio (FY / FX), for example, by increasing the amount of polysiloxane phosphor, reducing the molecular weight of the polysiloxane phosphor, and reducing the amount of thermally conductive filler having π electrons, the proportion of the excited group complex can be relatively increased, and the fluorescence intensity ratio (FY / FX) can be increased.

[0072] The presence or absence of the fluorescence peak X of the non-association complex and the fluorescence peak Y of the excimer complex of the polysiloxane phosphor in the thermal conductive composition, as well as the fluorescence intensity ratio (FY / FX), were measured after the thermal conductive composition was prepared and then heat-treated. The heat treatment was performed at 80°C to 160°C for at least 2 hours.

[0073] The molecular weight of the polysiloxane phosphor is preferably 4,000 or more and 25,000 or less, more preferably 5,000 or more and 25,000 or less, more preferably 10,000 or more and 19,000 or less, more preferably 12,000 or more and 18,000 or less, and further preferably 13,000 or more and 17,000 or less. If the molecular weight of the polysiloxane phosphor is above the above lower limit, the compatibility of the polysiloxane phosphor with the components other than the polysiloxane phosphor in (A) the organopolysiloxane is improved, and the dispersibility of the polysiloxane phosphor is easily improved. If the molecular weight of the polysiloxane phosphor is below the above upper limit, it is easy to adjust the viscosity of the thermally conductive composition to a low value. The molecular weight refers to the number average molecular weight. In addition, in this specification, the number average molecular weight is a value converted to standard polystyrene measured by gel permeation chromatography (GPC).

[0074] <Polysiloxane phosphor represented by formula (1)>

[0075] The polysiloxane phosphor in the present invention preferably has a structure represented by the following formula (1).

[0076]

[0077] In formula (1), R1 is independently a group represented by AB or a monovalent hydrocarbon group having 1 to 4 carbon atoms, and at least one R1 among the plurality of R1 is a group represented by AB. The above-mentioned A is a divalent organic group bonded to a silicon atom. The above-mentioned B has a conjugated aromatic 6-membered ring having 3 or more and 6 or less. When the atom bonded to the aromatic 6-membered ring possessed by the above-mentioned B among the atoms constituting the above-mentioned A is set as an α-atom, the atom bonded to the α-atom is set as a β-atom, and the atom bonded to the β-atom and other than the α-atom is set as a γ-atom, any one of the α-atom, the β-atom, and the γ-atom is a heteroatom, and n is an integer greater than 1.

[0078] The polysiloxane phosphor having the structure represented by formula (1) has conjugated aromatic six-membered rings of at least three and at most six members, and has a large conjugated system in its molecular structure. Therefore, the polysiloxane phosphor has a high adsorption capacity for thermally conductive fillers having π electrons through π-π interactions, making it easy to disperse the thermally conductive filler.

[0079] In the formula (1), R1 is independently a group represented by AB or a monovalent hydrocarbon group having 1 to 4 carbon atoms.

[0080] At least one R1 among the plurality of R1s is a group represented by AB. A is a divalent organic group and is bonded to the silicon atom of formula (1).

[0081] Among the atoms constituting A, any one of the α-, β-, and γ-atom is a heteroatom. This improves the fluidity of the polysiloxane phosphor. From the perspective of improving the fluidity of the polysiloxane phosphor, it is preferred that the α- or β-atom be a heteroatom, and it is more preferred that the α-atom be a heteroatom.

[0082] Here, the α-atom is an atom among the atoms constituting A that is bonded to the aromatic 6-membered ring possessed by B (i.e., one of the conjugated 3 or more and 6 or less aromatic 6-membered rings possessed by B). The β-atom is an atom among the atoms constituting A that is bonded to the α-atom. The γ-atom is an atom other than the α-atom that is bonded to the β-atom. Furthermore, A may have heteroatoms in portions other than the α-atom, β-atom, and γ-atom.

[0083] The hetero atom is not particularly limited, and examples thereof include an oxygen atom, a nitrogen atom, a sulfur atom, and a boron atom. Among them, an oxygen atom is preferred from the viewpoint of effectively improving the fluidity of the polysiloxane phosphor.

[0084] A is preferably a divalent organic group having 11 or fewer carbon atoms, more preferably 10 or fewer carbon atoms. Polysiloxane phosphors having A having a certain carbon number or less are preferred because they tend to improve the dispersibility of the thermally conductive filler. While the lower limit of the carbon number of A is not particularly limited, A is preferably a divalent organic group having 4 or more carbon atoms.

[0085] As described above, A contains a heteroatom and thus has a structural unit containing a heteroatom. Examples of such structural units include ethers, esters, amides, carbamates, thioethers, and thioesters. Of these, ethers and esters are preferred from the perspective of improving dispersibility in the thermally conductive filler and enhancing fluidity, ethers are more preferred, and cyclic ethers are particularly preferred. A cyclic ether is an ether having a structure in which a carbon atom of a cyclic hydrocarbon is replaced by an oxygen atom.

[0086] Furthermore, from the viewpoint of improving the dispersibility of the thermally conductive filler and improving the fluidity, A preferably has a skeleton represented by the following formula (5-1) or formula (5-2).

[0087]

[0088] In formula (5-1), *1 and *2 are bonds, and R4 is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrogen atom. The two R4s may be the same or different. R3 is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrocarbon group having 1 to 4 carbon atoms, more preferably a hydrocarbon group having 1 to 3 carbon atoms, and even more preferably an ethyl group. R5 is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrogen atom. The oxygen atom in formula (5-1) is the aforementioned β- or γ-position atom, preferably the β-position atom.

[0089] In formula (5-2), *3 and *4 are bonds. The oxygen atom having the bond of *3 is the aforementioned α-position atom, β-position atom, or γ-position atom.

[0090] Among the above, A preferably has a skeleton represented by formula (5-1).

[0091] Furthermore, from the viewpoint of improving the dispersibility of the thermally conductive filler and improving the fluidity, A is preferably any one of the structures represented by the following formulae (6) to (10).

[0092]

[0093] In formulae (6) to (10), *5 is a bond to the aromatic six-membered ring possessed by B, and *6 is a bond to the silicon atom in formula (1).

[0094] B in formula (1) has three or more and six or less conjugated aromatic six-membered rings. Conjugation refers to the alternating connection of unsaturated bonds and single bonds in the molecular structure, resulting in stabilization due to the interaction of p orbitals, electron delocalization (existing in the entire conjugated system), etc. In addition, three or more and six or less conjugated aromatic six-membered rings are included in the concept of the above-mentioned polycyclic aromatic structure.

[0095] When the number of aromatic six-membered rings is 6 or less, the fluidity of the polysiloxane phosphor is improved, and when the number of aromatic six-membered rings is 2 or more, the adsorption property with the thermally conductive filler is improved, thereby improving the dispersibility of the thermally conductive filler.

[0096] From the viewpoint of improving both the adsorption property with the thermally conductive filler and the fluidity in a well-balanced manner, the number of the aromatic six-membered rings is preferably 4 or more and 5 or less.

[0097] The conjugated three or more and six or less aromatic six-membered rings may be a fused ring compound composed of three or more and six or less aromatic six-membered rings, or a non-fused ring compound, but is preferably a fused ring compound. Thus, when B comprises a fused ring compound, or when B is a fused ring compound, the adsorption of the thermally conductive filler is further improved, which is preferred from the perspective of improving dispersibility.

[0098] Examples of the fused ring compound include anthracene, anthracene derivatives, phenanthrene, phenanthrene derivatives, benzo[9,10]phenanthrene, benzo[9,10]phenanthrene derivatives, pyrene, pyrene derivatives, tetracene, tetracene derivatives, chrysene, chrysene derivatives, perylene, perylene derivatives, pentaphene, pentaphene derivatives, pentacene, pentacene derivatives, hexylene, hexylene derivatives, and the like. Among these, pyrene, pyrene derivatives, perylene, and perylene derivatives are preferred. Here, the term "derivative" means having a substituent. For example, an anthracene derivative refers to anthracene having a substituent, and the same applies to other derivatives.

[0099] When the fused ring compound has a substituent, at least one of the hydrogen atoms constituting the fused ring compound is replaced by a substituent. Examples of the substituent include organic groups having 1 to 10 carbon atoms.

[0100] From the viewpoint of improving the fluidity of the polysiloxane phosphor in the present invention, the fused ring compound preferably has no substituent. Therefore, B is particularly preferably pyrene or perylene.

[0101] In addition, the above-mentioned fused ring compound may be any one of the carbon atoms constituting the fused ring as long as it is bonded to the above-mentioned A.

[0102] In the present invention, the above-mentioned groups can be used as B without particular limitation, and suitable structures of B are shown below.

[0103]

[0104] In the above formulae (11) to (14), * represents a bond to A.

[0105] Among the above-mentioned formulae (11) to (14), any one of the compounds of formulae (11) to (13) as fused ring compounds is preferred, among which pyrene of formula (11) or perylene of formula (12) is more preferred, and perylene of formula (12) is even more preferred.

[0106] In formula (1), at least one R1 is a group represented by AB, and the remaining R1s are hydrocarbon groups having 1 to 4 carbon atoms. In formula (1), the number of groups represented by AB among the multiple R1s is preferably 1 or more and 5 or less, more preferably 1 or 2, and the remaining R1s are preferably monovalent hydrocarbon groups having 1 to 4 carbon atoms. When there are multiple groups represented by AB, the multiple groups represented by AB may be the same or different.

[0107] Examples of the monovalent hydrocarbon group having 1 to 4 carbon atoms include methyl, ethyl, propyl, and butyl, with methyl being preferred. When there are multiple monovalent hydrocarbon groups having 1 to 4 carbon atoms, these multiple monovalent hydrocarbon groups having 1 to 4 carbon atoms may be the same or different.

[0108] In formula (1), n ​​refers to the number of repetitions, and n is an integer greater than or equal to 1. There are no particular limitations on n as long as it is an integer greater than or equal to 1. However, from the viewpoint of achieving good fluidity, n is preferably 400 or less, more preferably 300 or less, and even more preferably 250 or less, and is preferably 10 or more, more preferably 40 or more, and even more preferably 200 or more.

[0109] The polyorganosiloxane having the structure represented by formula (1) may have a group represented by AB at one terminal, at both terminals, in a side chain, at one terminal and in a side chain, or at both terminals and in a side chain. The polyorganosiloxane having the structure represented by formula (1) preferably has a group represented by AB at one terminal.

[0110] The polysiloxane phosphor in the present invention may be a compound having the following formula (a-1) or formula (a-2) instead of AB in formula (1) or AB in formulas (2) to (4) described later.

[0111]

[0112] In formula (a-1) and formula (a-2), *5 is a bond to the aromatic 6-membered ring possessed by B, and *6 is a bond to the silicon atom of formula (1) to formula (4).

[0113] <Polysiloxane phosphor represented by formula (2)>

[0114] The polysiloxane phosphor according to one embodiment of the present invention preferably has a structure represented by the following formula (2): This polysiloxane phosphor has a group represented by AB at one end.

[0115]

[0116] (In formula (2), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B, and n have the same meanings as A, B, and n in formula (1).)

[0117] In formula (2), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, for example, methyl, ethyl, propyl, butyl, etc., with methyl being preferred. Multiple R2s may be the same or different. In formula (2), A, B, and n have the same meanings as A, B, and n in formula (1), as described above.

[0118] The polysiloxane phosphor represented by formula (2) is preferably one having a group represented by AB at one end because it can easily improve the dispersibility of the thermally conductive filler.

[0119] <Polysiloxane phosphor represented by formula (3)>

[0120] The polysiloxane phosphor according to one embodiment of the present invention has a structure represented by the following formula (3): The polysiloxane phosphor has groups represented by AB at both ends.

[0121]

[0122] (In formula (3), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B, and n have the same meanings as A, B, and n in formula (1).)

[0123] R2 in formula (3) has the same meaning as R2 in formula (2), and A, B and n have the same meaning as A, B and n in formula (1).

[0124] <Polysiloxane phosphor represented by formula (4)>

[0125] The polysiloxane phosphor according to one embodiment of the present invention has a structure represented by the following formula (4): The polysiloxane phosphor has a group represented by AB in a side chain.

[0126]

[0127] (In formula (4), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, m is an integer from 1 to 10, and A, B, and n have the same meanings as A, B, and n in formula (1))

[0128] R2 in formula (4) has the same meaning as R2 in formula (2), and A, B and n have the same meaning as A, B and n in formula (1).

[0129] In formula (4), m is an integer of 1 to 10, preferably an integer of 1 to 5, and more preferably 1 or 2. When m is within this range, the adsorptivity with the thermally conductive filler is improved while also improving the fluidity, which is preferable.

[0130] The polysiloxane phosphor represented by formula (4) may be a random polymer or a block polymer. More specifically, the units represented by the brackets of m and the units represented by the brackets of n may be present in blocks or randomly in the molecule.

[0131] In a portion of R1 in the above formula (1) and a portion of R2 in the above formulas (2) to (4), a portion of the monovalent hydrocarbon group having 1 to 4 carbon atoms may be any of an alkenyl group and a (meth)acryloyl group, or a hydrosilyl group. Furthermore, as described above, at least one of the plurality of R1s is a group represented by AB.

[0132] The polysiloxane phosphor having either an alkenyl group or a (meth)acryloyl group, or a hydrosilyl group, allows for reaction with addition-reaction silicones, thereby reducing oil bleed from the thermally conductive molded article, which is a cured product of the thermally conductive composition. Furthermore, compression set can be reduced, and tensile elongation and tensile strength at break can be increased.

[0133] The polysiloxane phosphor may have two or more alkenyl groups, (meth)acryloyl groups, or hydrosilyl groups, but preferably has one. Furthermore, when a group represented by AB is present at one end, it preferably has an alkenyl group, (meth)acryloyl group, or hydrosilyl group at the other end.

[0134] The number of any of the alkenyl and (meth)acryloyl groups, or the number of the hydrosilyl groups in one molecule of the above-mentioned organopolysiloxane phosphor can be 0 or more, but is preferably 1 to 10, more preferably 1 to 5, and even more preferably 2. By having the number of any of the alkenyl and (meth)acryloyl groups, or the number of the hydrosilyl groups being 1 or more, the bleeding and tensile elongation at break can be improved. In addition, by having the number of 2 or more, the compression set can be reduced and the tensile strength at break can be increased. In addition, in one molecule of the above-mentioned organopolysiloxane phosphor, both "any of the alkenyl and (meth)acryloyl groups" and "hydrosilyl groups" can be present, but from the perspective of storage stability, it is preferred to have only one of them.

[0135] The thermally conductive composition of the present invention contains the aforementioned polysiloxane phosphor and may further contain byproducts generated during the production of the polysiloxane phosphor. As described below, the polysiloxane phosphor can be obtained by reacting a polyorganosiloxane having functional groups with a compound having multiple conjugated aromatic six-membered rings and having functional groups reactive with the functional groups of the polyorganosiloxane. Examples of such byproducts include polyorganosiloxane condensates formed by condensation reactions of functional groups of polyorganosiloxanes having functional groups such as hydroxyl groups.

[0136] <Method for producing polysiloxane phosphor represented by formulas (1) to (4)>

[0137] The method for producing the polysiloxane phosphor represented by the above formulas (1) to (4) is not particularly limited. The phosphor can be obtained by reacting a generally available polyorganosiloxane having a functional group with a compound having three or more and six or less conjugated aromatic six-membered rings and having a functional group reactive with the functional group of the polyorganosiloxane. For example, the polysiloxane phosphor can be produced by an acetalization reaction between an aldehyde and a diol, a hydrosilylation reaction between a hydrosilyl group and a carbon-carbon unsaturated bond, or the like.

[0138] For example, the polysiloxane phosphor of the present invention can be produced by reacting a polyorganosiloxane having a diol structure with a compound having an aldehyde group and conjugated 3 or more and 6 or less aromatic 6-membered rings. Alternatively, the polysiloxane phosphor of the present invention can be produced by reacting a polyorganosiloxane having a hydrosilyl group at the end and / or in a side chain with a compound having a group having a carbon-carbon unsaturated bond, such as an acrylate group or a methacrylate group, and conjugated 3 or more and 6 or less aromatic 6-membered rings.

[0139] The polysiloxane phosphor in the present invention is contained in (A) an organopolysiloxane that is liquid at 25°C. When the total amount of (A) an organopolysiloxane that is liquid at 25°C is 100% by mass, the content of the polysiloxane phosphor in (A) the organopolysiloxane is preferably 1% by mass to 95% by mass, more preferably 5% by mass to 70% by mass, and even more preferably 10% by mass to 50% by mass, from the viewpoint of effectively reducing the viscosity of the composition.

[0140] Furthermore, when the total amount of the organopolysiloxane (A) that is liquid at 25° C. is set to 100% by mass, the content of the polysiloxane phosphor in the organopolysiloxane (A) is preferably from 1% by mass to 50% by mass, more preferably from 5% by mass to 40% by mass, and even more preferably from 10% by mass to 25% by mass, from the viewpoint of effectively reducing the viscosity of the composition, making oil bleed-out of the thermally conductive molded article, which is its cured product, less likely to occur, and reducing the compression set.

[0141] In the thermally conductive composition of the present invention, the ratio of the amount of the polysiloxane phosphor to the amount of the thermally conductive filler having π electrons (amount of polysiloxane phosphor / amount of the thermally conductive filler having π electrons) is preferably 0.003 or more and 0.5 or less, more preferably 0.01 or more and 0.4 or less, and even more preferably 0.02 or more and 0.3 or less.

[0142] In the thermally conductive composition of the present invention, the ratio of the amount of the polysiloxane phosphor to the total specific surface area of ​​the thermally conductive filler having π electrons (amount of the polysiloxane phosphor / total specific surface area of ​​the thermally conductive filler having π electrons: unit: mg / m 2 ) is preferably 3.00 or more and 500 or less, more preferably 10.0 or more and 400 or less, and further preferably 20.0 or more and 300 or less. The specific surface area of ​​the thermally conductive filler can be measured by a BET method using nitrogen adsorption.

[0143] (Organopolysiloxane having hydroxyl group)

[0144] From the perspective of further reducing viscosity, the thermally conductive composition of the present invention preferably contains at least one selected from an organopolysiloxane having a hydroxyl group and an organopolysiloxane having an alkoxy group. Furthermore, the organopolysiloxane having a hydroxyl group and the organopolysiloxane having an alkoxy group are included in (A) the organopolysiloxane that is liquid at 25°C. That is, the organopolysiloxane having a hydroxyl group and the organopolysiloxane having an alkoxy group are liquid at 25°C.

[0145] The organopolysiloxane containing hydroxyl groups in the present invention has hydroxyl groups at a portion of the main chain terminals, on side chains, or both. Specifically, the organopolysiloxane containing hydroxyl groups in the present invention may have hydroxyl groups at a portion of the main chain terminals or on side chains, or may have hydroxyl groups at both a portion of the main chain terminals and on side chains. The above-mentioned organopolysiloxane containing hydroxyl groups is a polyorganosiloxane containing hydroxyl groups other than organopolysiloxanes containing hydroxyl groups at both main chain terminals. The term "terminal end" herein refers to the end of the longest portion of the molecular chain (the linear portion with the largest number of constituent atoms in the molecular structure).

[0146] The hydroxyl-containing organopolysiloxane having this specific structure, due to the presence of hydroxyl groups, readily reacts or interacts with functional groups on the surface of the thermally conductive filler. Furthermore, since this hydroxyl-containing organopolysiloxane does not have hydroxyl groups at both ends, it does not react or interact with the thermally conductive filler at either end. Therefore, it is believed that the dispersibility of the thermally conductive filler in the composition can be improved, effectively reducing the viscosity.

[0147] The organopolysiloxane having a hydroxyl group of the present invention may have only one hydroxyl group or may have two or more hydroxyl groups. The upper limit of the number of hydroxyl groups is not particularly limited, but the number of hydroxyl groups is preferably 6 or less, more preferably 3 or less, and even more preferably 3 or less. Organopolysiloxanes having two hydroxyl groups are particularly preferred because they exhibit a high viscosity-lowering effect.

[0148] The organopolysiloxane having a hydroxyl group in the present invention may have one hydroxyl group. As one embodiment, an organopolysiloxane having a hydroxyl group only at one terminal of the main chain can be mentioned.

[0149] The organopolysiloxane having a hydroxyl group of the present invention has a siloxane skeleton (-Si-O-), and the number of repeating units n of the siloxane skeleton is preferably 11 or more. The number of repeating units n of the siloxane skeleton is preferably 11 or more and 350 or less, more preferably 20 or more and 300 or less, further preferably 50 or more and 270 or less, and further preferably 100 or more and 250 or less. If the number of repeating units n of the siloxane skeleton is above the above lower limit, the compatibility with the organopolysiloxane forming the matrix is ​​easily improved. In addition, if the number of repeating units n of the siloxane skeleton is below the above upper limit, the viscosity of the composition is easily adjusted to be low.

[0150] The organopolysiloxane having a hydroxyl group in the present invention preferably has a structure represented by the following formula (X).

[0151]

[0152] In the above formula (X), R6 and R7 are each independently an alkyl group, D is an ester, amide, ether, alkylene or alkylene ether group, E is an organic group having 1 to 10 carbon atoms and having one or more hydroxyl groups, and n is an integer greater than 1.

[0153] In the above formula (X), R6 is an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, but is preferably a linear alkyl group. The linear alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group. Multiple R6 groups may be the same or different.

[0154] In the above formula (X), R7 is an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, but is preferably a linear alkyl group. The linear alkyl group is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably a butyl group.

[0155] In the above formula (X), D is an ester, amide, ether, alkylene, alkylene ether, ethylene oxide, or oxime ester. The oxime ester is "-C=NOC(=O)-." Among these, D is preferably an alkylene or alkylene ether, and more preferably an alkylene ether.

[0156] The alkylene group has, for example, 1 to 10 carbon atoms, and preferably 2 to 6 carbon atoms.

[0157] The number of carbon atoms constituting the alkylene ether group is, for example, 2 to 10, preferably 2 to 6. Furthermore, the alkylene ether group has an oxygen atom between two alkylene groups and is represented by "-R1-O-R2-", where R1 and R2 are each an alkylene group and the total number of carbon atoms of R1 and R2 is, for example, 2 to 10, preferably 2 to 6.

[0158] Among the alkylene ether groups, "-CH2CH2CH2OCH2-" is particularly preferred. In formula (X), the left-end carbon atom of "-CH2CH2CH2OCH2-" is bonded to a silicon atom, and the right-end carbon atom is bonded to E.

[0159] In the above formula (X), E is an organic group having 1 to 10 carbon atoms and having one or more hydroxyl groups. In other words, E is a structure in which one or more hydroxyl groups are bonded to an organic group having 1 to 10 carbon atoms. E may have only one hydroxyl group or may have two or more hydroxyl groups. The upper limit of the number of hydroxyl groups is not particularly limited, but the number of hydroxyl groups is preferably 6 or less, more preferably 3 or less. The number of hydroxyl groups is preferably 1 or 2, more preferably 2.

[0160] Furthermore, E preferably has a structure in which one or more hydroxyl groups are bonded to a hydrocarbon group having 1 to 10 carbon atoms, and more preferably has a structure in which one or more hydroxyl groups are bonded to a hydrocarbon group having 2 to 6 carbon atoms.

[0161] E in formula (X) is preferably a structure represented by the following formula (15).

[0162]

[0163] In formula (15), each Z is independently a hydrogen atom, a hydroxyl group, or a group having a hydroxyl group, and at least one of the plurality of Zs is a hydroxyl group or a group having a hydroxyl group. * represents a bond to D.

[0164] Examples of the group having a hydroxyl group include a group in which a hydroxyl group is bonded to a hydrocarbon group having 1 to 4 carbon atoms, and "-CH2OH" is preferred.

[0165] In addition, among the formula (15), the structure represented by the following formula (16) or formula (17) is particularly preferred.

[0166]

[0167] In formula (16) and formula (17), * represents a bond to D.

[0168] In the above formula (X), n refers to the number of repetitions, and n is an integer greater than or equal to 1. n is preferably greater than or equal to 11, more preferably greater than or equal to 11 and less than or equal to 350, further preferably greater than or equal to 20 and less than or equal to 300, further preferably greater than or equal to 50 and less than or equal to 270, and further preferably greater than or equal to 100 and less than or equal to 250.

[0169] From the perspective of improving the dispersibility of the thermally conductive filler and reducing the viscosity of the thermally conductive composition, the molecular weight of the organopolysiloxane having hydroxyl groups is preferably 1,000 to 25,000, more preferably 3,000 to 20,000, and even more preferably 7,000 to 18,000. This molecular weight refers to the number average molecular weight. In this specification, the number average molecular weight is the value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0170] From the perspective of reducing the viscosity of the composition, the hydroxyl equivalent weight of the organopolysiloxane having a hydroxyl group is preferably 300 g / eq or more and 25,000 g / eq or less, and more preferably 500 g / eq or more and 7,500 g / eq or less. The hydroxyl equivalent weight is the value obtained by dividing the number average molecular weight by the number of hydroxyl groups per molecule.

[0171] The organopolysiloxane having a hydroxyl group in the present invention is contained in (A) the organopolysiloxane that is liquid at 25°C. When the total amount of (A) the organopolysiloxane that is liquid at 25°C is taken as 100% by mass, from the viewpoint of effectively reducing the viscosity of the composition, the content of the organopolysiloxane having a hydroxyl group in (A) the organopolysiloxane is preferably from 1% by mass to 70% by mass, more preferably from 2% by mass to 50% by mass, and even more preferably from 5% by mass to 45% by mass.

[0172] A part of the alkyl groups of R6 and R7 in the above formula (X) may be any of an alkenyl group and a (meth)acryloyl group, or a hydrosilyl group.

[0173] When the hydroxyl-containing organopolysiloxane has either an alkenyl group or a (meth)acryloyl group, or a hydrosilyl group, it reacts with an addition-reaction-type organosilicon, thereby reducing oil bleed from the thermally conductive molded article, which is a cured product of the thermally conductive composition. Furthermore, compression set can be reduced, and the tensile elongation at break and tensile strength at break can be increased.

[0174] The above-mentioned organopolysiloxane having a hydroxyl group may have two or more alkenyl groups and (meth)acryloyl groups, or hydrosilyl groups, but preferably has one. In addition, when it is preferred to have a hydroxyl group at one end, it is preferred to have an alkenyl group and (meth)acryloyl groups, or hydrosilyl groups at the other end. The number of alkenyl groups and (meth)acryloyl groups, or the number of hydrosilyl groups in one molecule of the above-mentioned organopolysiloxane having a hydroxyl group can be 0 or more, but is preferably 1 to 10, more preferably 1 to 5, and even more preferably 2. By having one or more alkenyl groups and (meth)acryloyl groups, or the number of hydrosilyl groups, the oozing out and tensile elongation at break can be improved. In addition, by having two or more, the compression set can be reduced and the tensile strength at break can be increased. The organopolysiloxane having a hydroxyl group may contain both "either an alkenyl group or a (meth)acryloyl group" and a "hydrosilyl group" in one molecule, but preferably contains only one of them from the viewpoint of storage stability.

[0175] (Organopolysiloxane having an alkoxy group)

[0176] The organopolysiloxane having an alkoxy group is an organopolysiloxane having at least one alkoxy group, and the number of the alkoxy groups is preferably 1 to 3, more preferably 3. The alkoxy group is preferably an alkoxy group bonded to a silicon atom, and the organopolysiloxane preferably has an alkoxy group at a terminal.

[0177] The organopolysiloxane having an alkoxy group can easily reduce the viscosity of the thermally conductive composition.

[0178] The organopolysiloxane having an alkoxy group preferably has a structure represented by the following formula (Y).

[0179]

[0180] In formula (Y), R 8 、R 9 、R 11 、R 12 are each independently a saturated hydrocarbon group, R 10 is an oxygen atom or a divalent hydrocarbon group, n is an integer of 10 to 350, and m is an integer of 0 to 2.

[0181] The use of an organopolysiloxane having an alkoxy group represented by formula (Y) further enhances the viscosity-reducing effect of the thermally conductive composition. This is presumably because the organopolysiloxane having an alkoxy group represented by formula (Y) has an alkoxy group at its terminal end, making it easy to react or interact with functional groups and the like present on the surface of the thermally conductive filler. Furthermore, the specific structure of the polysiloxane reduces friction with the filler, facilitating a reduction in viscosity.

[0182] In formula (Y), R 8 、R 9 、R 11 、R 12 are each independently a saturated hydrocarbon group.

[0183] Examples of the saturated hydrocarbon group include alkyl groups such as linear alkyl groups, branched alkyl groups, and cyclic alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups.

[0184] Examples of the linear alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl.

[0185] Examples of the branched alkyl group include isopropyl, tert-butyl, isobutyl, 2-methylundecyl, and 1-hexylheptyl.

[0186] Examples of the cyclic alkyl group include cyclopentyl, cyclohexyl, and cyclododecyl.

[0187] Examples of the aryl group include phenyl, tolyl, and xylyl groups.

[0188] Examples of the aralkyl group include a benzyl group, a phenethyl group, and a 2-(2,4,6-trimethylphenyl)propyl group.

[0189] Examples of the haloalkyl group include 3,3,3-trifluoropropyl and 3-chloropropyl.

[0190] From the viewpoint of improving the viscosity-lowering effect, R in formula (Y) 8 ~R 12 , m, and n are preferably as follows.

[0191] R in formula (Y) 8 An alkyl group having 1 to 8 carbon atoms is preferred, an alkyl group having 2 to 6 carbon atoms is more preferred, and a butyl group is particularly preferred.

[0192] R in formula (Y) 9 、R 11 、R 12 Each independently is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group.

[0193] R in formula (Y) 10 is an oxygen atom or a divalent hydrocarbon group, preferably a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include methylene, ethylene, propylene, butylene, and methylethylene, among which ethylene (-CH2CH2-) is preferred.

[0194] n in formula (Y) is an integer of 15-315, preferably an integer of 18-280, and more preferably an integer of 20-220.

[0195] In formula (Y), m is an integer of 0 to 2, preferably 0 or 1, and more preferably 0.

[0196] The organopolysiloxane having an alkoxy group in the present invention is contained in (A) the organopolysiloxane that is liquid at 25°C. When the total amount of (A) the organopolysiloxane that is liquid at 25°C is taken as 100% by mass, from the viewpoint of effectively reducing the viscosity of the composition, the content of the organopolysiloxane having an alkoxy group in (A) the organopolysiloxane is preferably from 1% by mass to 70% by mass, more preferably from 5% by mass to 50% by mass, and even more preferably from 10% by mass to 40% by mass.

[0197] A part of the saturated hydrocarbon groups of R8 and R9 in the above formula (Y) may be any of an alkenyl group and a (meth)acryloyl group, or a hydrosilyl group.

[0198] When the organopolysiloxane having an alkoxy group has either an alkenyl group or a (meth)acryloyl group, or a hydrosilyl group, it reacts with an addition-reaction-type organosilicon, thereby reducing oil bleed from the thermally conductive molded article, which is a cured product of the thermally conductive composition. Furthermore, compression set can be reduced, and the tensile elongation at break and tensile strength at break can be increased.

[0199] The organopolysiloxane having an alkoxy group may have two or more alkenyl groups, (meth)acryloyl groups, or a hydrosilyl group, but preferably has one. Furthermore, when an alkoxy group is present at one terminal, it is preferred that the other terminal have an alkenyl group, (meth)acryloyl group, or a hydrosilyl group.

[0200] The number of any of the alkenyl and (meth)acryloyl groups, or the number of the hydrosilyl groups in one molecule of the above-mentioned organopolysiloxane having an alkoxy group may be 0 or more, but is preferably 1 to 10, more preferably 1 to 5, and even more preferably 2. By having the number of any of the alkenyl and (meth)acryloyl groups, or the number of the hydrosilyl groups being 1 or more, the oozing out and the tensile elongation at break can be improved. In addition, by having the number of 2 or more, the compression set can be reduced and the tensile strength at break can be increased. In addition, in one molecule of the above-mentioned organopolysiloxane having an alkoxy group, both "any of the alkenyl and (meth)acryloyl groups" and "hydrosilyl groups" may be present, but from the viewpoint of storage stability, it is preferred to have only one of them.

[0201] The organopolysiloxane having a hydroxyl group and the organopolysiloxane having an alkoxy group are commercially available from, for example, Shin-Etsu Chemical Co., Ltd. and JNC Corporation.

[0202] (Addition reaction type silicone)

[0203] The organopolysiloxane (A) that is liquid at 25°C of the present invention preferably contains an addition-reaction-type silicone. The addition-reaction-type silicone preferably forms a matrix after curing, and therefore, the addition-reaction-type silicone is preferably the main component of the organopolysiloxane (A) that is liquid at 25°C. The term "main component" herein refers to an amount greater than that of other organopolysiloxanes constituting component (A), and means, for example, a content of 25% by mass or more, preferably 50% by mass or more, and more preferably 70% by mass or more, based on the total amount of component (A).

[0204] From the viewpoint of facilitating high filling of thermally conductive fillers, the addition reaction type silicone preferably contains at least one of an alkenyl group-containing organopolysiloxane or a (meth)acryloyl group-containing organopolysiloxane as a main agent and a hydrogen-containing organopolysiloxane as a curing agent.

[0205] The alkenyl groups in the alkenyl-containing organopolysiloxane may be contained at either the terminal or midway of the molecular chain of the polysiloxane structure, or may be contained at both the terminal and midway. However, they are preferably contained at least at the terminal, more preferably at both terminals of the molecular chain composed of the polysiloxane structure, and even more preferably only at both terminals.

[0206] The alkenyl group is not particularly limited, and examples thereof include alkenyl groups having 2 to 8 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, and octenyl. Among these, vinyl is preferred from the perspectives of ease of synthesis and reactivity. Furthermore, the alkenyl group is preferably an alkenyl group directly bonded to a silicon atom.

[0207] The number of alkenyl groups in one molecule of the alkenyl group-containing organopolysiloxane may be one or more, but is preferably two or more, more preferably 2 to 25, further preferably 2 to 10, further preferably 2 to 3, and particularly preferably 2.

[0208] As the remaining groups bonded to the silicon atom other than the alkenyl group, alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl, aryl groups such as phenyl, aralkyl groups such as 2-phenylethyl and 2-phenylpropyl, and further substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl are exemplified as specific examples. Among them, methyl is preferred from the perspective of ease of synthesis. In addition, it is preferred that 80 mol% or more of the remaining groups bonded to the silicon atom be methyl, more preferably 90 mol% or more be methyl, and even more preferably 100 mol% be methyl. In addition, it is preferred that the organopolysiloxane containing the alkenyl group does not have a hydrogen atom as the remaining group bonded to the silicon atom, that is, the organopolysiloxane containing the alkenyl group does not contain a hydrosilyl group.

[0209] The alkenyl group-containing organopolysiloxane may be used alone or in combination of two or more.

[0210] Hydrogen-containing organopolysiloxanes are organopolysiloxanes having hydrosilyl groups. The hydrosilyl groups may be present at either the terminal or midway of the molecular chain of the polysiloxane structure, or at both terminals. However, they are preferably present at least at the terminal, and more preferably at both terminals of the molecular chain of the polysiloxane structure.

[0211] The number of hydrosilyl groups in one molecule is not particularly limited as long as it is 1 or more, but is preferably 2 or more, more preferably 2 to 25, and even more preferably 2 to 20.

[0212] In hydrogen-containing organopolysiloxanes, examples of the remaining groups bonded to silicon atoms other than the hydrosilyl group include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl, aryl groups such as phenyl, and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl. Specific examples include substituted hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl. Among these, methyl groups are preferred from the perspective of ease of synthesis. Furthermore, preferably, 80 mol% or more of the remaining groups bonded to silicon atoms are methyl groups, more preferably 90 mol% or more, and even more preferably 100 mol% are methyl groups. Furthermore, it is preferred that the hydrogen-containing organopolysiloxane not have alkenyl groups as the remaining groups bonded to silicon atoms, that is, the hydrogen-containing organopolysiloxane does not contain alkenyl groups.

[0213] The hydrogen-containing organopolysiloxane may be used alone or in combination of two or more.

[0214] (Other organopolysiloxanes)

[0215] The organopolysiloxane (A) in the present invention that is liquid at 25°C may contain other organopolysiloxanes in addition to the above-mentioned organopolysiloxanes. Examples of such other organopolysiloxanes include radical reaction-curable silicones, condensation reaction-curable silicones, ultraviolet or electron beam-curable silicones, moisture-curable silicones, and non-reactive silicones. Examples of non-reactive silicones include linear silicone oils such as dimethyl silicone oil and phenylmethyl silicone oil.

[0216] The content of the organopolysiloxane (A) that is liquid at 25° C. in the thermally conductive composition is preferably 5 mass % to 80 mass %, more preferably 8 mass % to 50 mass %, and even more preferably 10 mass % to 30 mass %.

[0217] <(B) Thermally conductive filler with π electrons>

[0218] The thermally conductive composition of the present invention contains (B) a thermally conductive filler having π electrons (hereinafter sometimes referred to as the (B) thermally conductive filler). As described above, the thermally conductive composition of the present invention contains a polysiloxane phosphor. Therefore, even if the thermally conductive filler (B) is contained, the viscosity can be reduced, resulting in excellent processability and handling properties, and the content of the thermally conductive filler can be increased.

[0219] (B) The average particle size of the thermally conductive filler is not particularly limited, but is preferably 1 μm to 500 μm, more preferably 10 μm to 200 μm. By setting the average particle size above these lower limits, the fillers are more likely to come into contact with each other, ensuring a heat transfer path. On the other hand, setting the average particle size below these upper limits reduces the volume, making it easier to fill the thermally conductive filler.

[0220] The average particle size is determined by microscopic observation and as the average value (arithmetic mean) of 50 or more particles. If the thermally conductive filler (B) is an anisotropic filler, as described below, the fiber length and major diameter of 50 or more particles of the anisotropic filler can be measured using an electron microscope or an optical microscope, and the average value (arithmetic mean) of these values ​​can be used as the average particle size. If the thermally conductive filler (B) is a non-anisotropic filler, as described below, the major diameter of 50 or more particles of the non-anisotropic filler can be measured using an electron microscope or an optical microscope, and the average value (arithmetic mean) of these values ​​can be used as the average particle size.

[0221] Examples of the thermally conductive filler (B) include carbon materials and boron nitride. Examples of the carbon materials include carbon fibers, graphite such as flaky graphite, graphene, and carbon nanotubes. The boron nitride is preferably hexagonal boron nitride.

[0222] (B) The thermally conductive filler may be used alone or in combination of two or more.

[0223] (B) The thermally conductive filler may be an anisotropic filler or a non-anisotropic filler, but preferably includes an anisotropic filler. An anisotropic filler is a filler having an anisotropic shape and is capable of orientation. Specifically, by including an anisotropic filler in the thermally conductive composition, a thermally conductive molded article formed from the thermally conductive composition can contain the anisotropic filler oriented in a predetermined direction, thereby facilitating improved thermal conductivity in a specific direction.

[0224] Anisotropic fillers have a high aspect ratio. Specifically, the aspect ratio exceeds 2, and preferably is greater than 5. An aspect ratio greater than 2 facilitates orientation of the anisotropic filler, thereby improving thermal conductivity. The upper limit of the aspect ratio is not particularly limited, but is practically 100.

[0225] The so-called aspect ratio is the ratio of the length of the anisotropic filling material in the long axis direction to the length in the short axis direction. In fibrous materials, it refers to the fiber length / fiber diameter, and in flaky materials, it refers to the length of the flaky material in the long axis direction / thickness.

[0226] (B) The anisotropic filler contained in the thermally conductive filler preferably contains one or more selected from the group consisting of carbon fibers, flaky graphite, and boron nitride. The shape of the boron nitride is not limited, but is preferably plate-shaped.

[0227] As described above, these anisotropic fillers have improved dispersibility by the polysiloxane phosphor, which can reduce the viscosity of the composition. Furthermore, since they are anisotropic fillers, they are easily oriented in a specific direction, which can improve thermal conductivity.

[0228] (B) The thermally conductive filler may contain a non-anisotropic filler. The non-anisotropic filler has an aspect ratio of 2 or less, preferably 1.5 or less.

[0229] The content of the anisotropic filler contained in the thermally conductive filler (B) is preferably 50% by mass or more, more preferably 80% by mass, and even more preferably 100% by mass, based on the total amount of the thermally conductive filler (B).

[0230] The content of the thermally conductive filler (B) in the thermally conductive composition is preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 80 parts by mass or more and 300 parts by mass or less, and even more preferably 100 parts by mass or more and 200 parts by mass or less, based on 100 parts by mass of the organopolysiloxane (A).

[0231] The thermally conductive composition of the present invention may contain a thermally conductive filler that does not have π electrons. Examples of thermally conductive fillers that do not have π electrons include aluminum, copper, nickel, aluminum oxide (aluminum oxide), magnesium oxide, zinc oxide, aluminum hydroxide, aluminum nitride, and diamond. Among them, aluminum oxide (aluminum oxide) and aluminum hydroxide are preferred.

[0232] The thermally conductive filler without π electrons is preferably a non-anisotropic filler with an aspect ratio of 2 or less. This allows the non-anisotropic filler to be interposed between the thermally conductive filler (B) as the anisotropic filler, thereby facilitating improved thermal conductivity in the molded article. Examples of the non-anisotropic filler include spherical and amorphous shapes.

[0233] The average particle size of the thermally conductive filler without π electrons is preferably 0.1 to 50 μm, more preferably 0.5 to 35 μm, and particularly preferably 0.5 to 15 μm. By setting the average particle size to 50 μm or less, problems such as disruption of the anisotropic filler's orientation are less likely to occur. Furthermore, by setting the average particle size to 0.1 μm or greater, the specific surface area is not excessively increased, and even when added in large quantities, the viscosity of the thermally conductive composition is less likely to increase, facilitating high-filling.

[0234] The average particle size of the thermally conductive filler having no π electrons can be measured by the same method as described in the above-mentioned (B) thermally conductive filler.

[0235] The amount of the thermally conductive filler having no π electrons in the thermally conductive composition is preferably 100 parts by mass to 1500 parts by mass, more preferably 200 parts by mass to 1000 parts by mass, and even more preferably 300 parts by mass to 700 parts by mass, based on 100 parts by mass of the organopolysiloxane (A).

[0236] Volatile compounds

[0237] The thermally conductive composition of the present invention preferably contains a volatile compound. By using a thermally conductive composition containing a volatile compound, a composition containing a higher content of a thermally conductive filler than conventional compositions can be prepared, thereby improving the thermal conductivity of the thermally conductive molded article.

[0238] In this specification, a volatile compound refers to a compound having at least one of the following properties: a temperature T1 at which the weight loss reaches 90% when the temperature is increased at 2°C / minute in thermogravimetric analysis, and a boiling point (at 1 atm) within the range of 60°C to 200°C. The 90% weight loss temperature T1 refers to the temperature at which the weight of the sample before thermogravimetric analysis is reduced by 90%, with the weight of the sample before thermogravimetric analysis being 100% (i.e., the temperature at which the weight reaches 10% of the weight before measurement).

[0239] Examples of the volatile compound include volatile silane compounds and volatile solvents, and among these, volatile silane compounds are preferred.

[0240] Examples of the volatile silane compounds include alkoxysilane compounds. Alkoxysilane compounds are compounds having a structure in which one to three of the four bonds of a silicon atom (Si) are bonded to an alkoxy group, and the remaining bonds are bonded to an organic substituent. Examples of the alkoxy groups in alkoxysilane compounds include methoxy, ethoxy, propoxy, butoxy, pentyloxy, and hexyloxy groups. Alkoxysilane compounds may be present as dimers or trimers.

[0241] Among alkoxysilane compounds, those having a methoxy group or an ethoxy group are preferred from the perspective of ease of availability. From the perspective of improving affinity with the inorganic thermally conductive filler, the number of alkoxy groups possessed by the alkoxysilane compound is preferably 3. More preferably, the alkoxysilane compound is at least one selected from a trimethoxysilane compound and a triethoxysilane compound.

[0242] Examples of the functional group contained in the organic substituent of the alkoxysilane compound include acryloyl, alkyl, carboxyl, vinyl, methacryloyl, aromatic, amino, isocyanate, isocyanurate, epoxy, hydroxyl, and mercapto groups.

[0243] To improve the dispersibility of the thermally conductive filler and facilitate high-filling of the thermally conductive filler, the alkoxysilane compound preferably includes an alkylalkoxysilane compound having an alkyl group bonded to a silicon atom, that is, an alkoxysilane compound having an alkyl group as an organic substituent. The number of carbon atoms in the alkyl group bonded to the silicon atom is preferably 4 or more. Furthermore, to maintain a low viscosity of the alkoxysilane compound itself and thus to suppress the viscosity of the thermally conductive composition, the number of carbon atoms in the alkyl group bonded to the silicon atom is preferably 16 or less.

[0244] One or more alkoxysilane compounds can be used. Specific examples of the alkoxysilane compound include alkoxysilane compounds containing an alkyl group, alkoxysilane compounds containing a vinyl group, alkoxysilane compounds containing an acryl group, alkoxysilane compounds containing a methacryloyl group, alkoxysilane compounds containing an aromatic group, alkoxysilane compounds containing an amino group, alkoxysilane compounds containing an isocyanate group, alkoxysilane compounds containing an isocyanurate group, alkoxysilane compounds containing an epoxy group, and alkoxysilane compounds containing a mercapto group.

[0245] As the alkoxysilane compound containing an alkyl group, there can be mentioned, for example, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane and n-decyltrimethoxysilane. Among the alkoxysilane compounds containing an alkyl group, at least one selected from isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane and n-decyltrimethoxysilane is preferred, at least one selected from n-octyltriethoxysilane and n-decyltrimethoxysilane is more preferred, and n-decyltrimethoxysilane is particularly preferred.

[0246] Examples of vinyl-containing alkoxysilane compounds include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of acryloyl-containing alkoxysilane compounds include 3-acryloyloxypropyltrimethoxysilane. Examples of methacryloyl-containing alkoxysilane compounds include 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane. Examples of aromatic-containing alkoxysilane compounds include phenyltrimethoxysilane and phenyltriethoxysilane. Examples of amino-containing alkoxysilane compounds include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. As the alkoxysilane compound containing an isocyanate group, for example, 3-isocyanate propyl triethoxy silane can be mentioned. As the alkoxysilane compound containing an isocyanurate group, for example, tris-(trimethoxysilylpropyl) isocyanurate can be mentioned. As the alkoxysilane compound containing an epoxy group, for example, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane can be mentioned. As the alkoxysilane compound containing a mercapto group, for example, 3-mercaptopropyltrimethoxysilane can be mentioned.

[0247] In addition, the specific examples of the alkoxysilane compound are merely examples and are not limited thereto.

[0248] The volatile solvent may have a boiling point (1 atm) of 60 to 200° C., preferably 100 to 130° C. The volatile solvent preferably has a boiling point 10° C. or higher, more preferably 20° C. or higher, than the curing temperature of the organopolysiloxane.

[0249] The type of the volatile solvent can be appropriately selected from those that satisfy the above requirements, but aromatic compounds such as toluene and aliphatic compounds such as n-hexadecane are preferably used.

[0250] The content of the volatile compound in the thermally conductive composition is preferably 1 to 100 parts by mass, more preferably 5 to 75 parts by mass, and even more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the (A) organopolysiloxane.

[0251] <Additives>

[0252] The thermally conductive composition of the present invention may contain additives. Examples of additives include at least one selected from adhesives, flame retardants, antioxidants, colorants, and anti-settling agents. Furthermore, when an addition-reactive silicone is included as described above, a curing catalyst for accelerating curing and a curing retarder for delaying curing may be incorporated. Examples of curing catalysts include platinum-based catalysts.

[0253] Viscosity

[0254] The viscosity of the thermally conductive composition of the present invention at a shear rate of 0.1 (1 / s) at 25°C is preferably 50 Pa·s or more and 20×10 3 Pa·s or less, more preferably 250 Pa·s or more and 10×10 3 Pa·s or less, more preferably 1×10 3 Pa·s or above and 5×10 3 Pa·s or less.

[0255] Viscosity example using The temperature of the thermally conductive composition was adjusted to 25°C using a Peltier plate using a rheometer "MCR-302e" manufactured by the company. The viscosity was measured while continuously changing the shear rate within the range of 0.0001 to 100 (1 / s) using a 25 mm φ parallel plate.

[0256] <Puncture load>

[0257] The puncture load is measured using either the puncture load 1 or puncture load 2 methods described below. The measurement method involves first measuring with puncture load 1, and then measuring with puncture load 2 when the load exceeds the upper limit of the device load (also called "OL" or "overload").

[0258] <Puncture load 1>

[0259] Puncture load 1 is measured as follows. First, the thermally conductive composition is degassed, and then 25g of the thermally conductive composition is introduced into a cylindrical container with a diameter of 25mm. Next, a puncture rod having a disc-shaped member with a diameter of 10mm at the front end is pressed from the front end of the puncture rod to the thermally conductive composition introduced into the container at a speed of 10mm / minute. When a load of 0.2gf is applied, it is pressed into the depth of 0mm, and the load (gf) when the depth is 2mm and 6mm is measured. The measurement is carried out at 25°C. Furthermore, the slope of the straight line of the graph of the depth of 0mm and the graph of the depth of 2mm when the horizontal axis is displacement and the vertical axis is load is taken as "slope 1-1", and the slope of the straight line of the graph of the depth of 0mm and the graph of 6mm is taken as "slope 1-2". In addition, the maximum value of the load pressed into a depth of 15mm (maximum load 1 (gf)) is further measured.

[0260] <Puncture load 2>

[0261] Puncture load 2 is measured as follows. First, the thermally conductive composition is degassed, and then 25 g of the thermally conductive composition is introduced into a cylindrical container with a diameter of 25 mm. Next, a puncture rod having a disc-shaped member with a diameter of 5 mm at the front end is pressed from the front end of the puncture rod to the thermally conductive composition introduced into the container at a speed of 10 mm / min. When a load of 0.2 gf is applied, it is pressed to a depth of 0 mm, and the load (gf) when it reaches a depth of 2 mm and 6 mm is measured. The measurement is carried out at 25°C. Furthermore, the slope to a depth of 0 mm to 2 mm when the horizontal axis is displacement and the vertical axis is load is referred to as "slope 2-1", and the slope to a depth of 0 mm to 6 mm is referred to as "slope 2-2". In addition, the maximum value of the load pressed to a depth of 15 mm (maximum load 2 (gf)) is further measured. In addition, for samples with extremely large loads, the load of a displacement of 2 mm is also recorded as a reference value.

[0262] From the viewpoint of obtaining a low-viscosity composition, the maximum load 1 in the puncture load measurement of the thermally conductive composition of the present invention is preferably 0.2 gf to 500 gf, more preferably 2.0 gf to 250 gf, and even more preferably 5 gf to 160 gf.

[0263] From the viewpoint of obtaining a low-viscosity composition, the maximum load 2 in the puncture load measurement of the thermally conductive composition of the present invention is preferably 0.2 gf to 200 gf, more preferably 10 gf to 100 gf, and even more preferably 20 gf to 40 gf.

[0264] The slope 1-1 in the thermally conductive composition of the present invention is preferably 0.15 to 30, more preferably 3 to 10. The slope 1-2 in the thermally conductive composition is preferably 0.2 to 40, more preferably 10 to 30.

[0265] The slope 2-1 in the thermally conductive composition of the present invention is preferably 0.2 to 30, more preferably 3 to 15. The slope 2-2 in the thermally conductive composition is preferably 3 to 30, more preferably 4 to 10.

[0266] [Thermal conductive molded article]

[0267] The present invention can also provide a thermally conductive molded article comprising a matrix composed of a cured product of an organopolysiloxane and a thermally conductive filler having π electrons, wherein the organopolysiloxane contains a polysiloxane phosphor.

[0268] Since the thermally conductive molded article contains the polysiloxane phosphor, the dispersibility of the thermally conductive filler having π electrons is improved. Therefore, the filling capacity of the thermally conductive filler having π electrons is also improved, and the thermal conductivity is increased.

[0269] The thermally conductive molded article can be obtained by curing the thermally conductive composition. The method for producing the thermally conductive molded article will be described in detail below.

[0270] The matrix composed of a cured organopolysiloxane is a cured organopolysiloxane (A) that is liquid at 25°C. The details of the organopolysiloxane (A) that is liquid at 25°C are as described above. As described above, the main component of the organopolysiloxane (A) that is liquid at 25°C is preferably an addition reaction type silicone. In this case, the matrix is ​​mainly composed of the cured addition reaction type silicone.

[0271] In the thermally conductive molded article of the present invention, the polysiloxane phosphor preferably has a fluorescence peak X of the non-associate at a wavelength of 370 nm to 430 nm, and a fluorescence peak Y of the excimer at a wavelength of 430 nm to 550 nm. For example, when the polysiloxane phosphor has a polycyclic aromatic structure, and the polycyclic aromatic structure is pyrene or a pyrene derivative, the non-associate fluorescence peak X has a wavelength of 370 nm to 430 nm, and the excimer fluorescence peak Y has a wavelength of 430 nm to 550 nm.

[0272] The wavelength range (370 nm to 430 nm) in which the fluorescence peak X of the non-aggregate is confirmed is preferably 370 nm to 410 nm, and more preferably 370 nm to 390 nm.

[0273] The wavelength range (430 nm to 550 nm) in which the fluorescence peak Y of the excimer is confirmed is preferably 450 nm to 530 nm, and more preferably 460 nm to 500 nm.

[0274] In the thermally conductive molded article of the present invention, the polysiloxane phosphor also preferably has a fluorescence peak X of the non-association complex at a wavelength of 430 nm to 530 nm, and a fluorescence peak Y of the excimer complex at a wavelength of 490 nm to 700 nm. For example, when the polysiloxane phosphor has a polycyclic aromatic structure, and the polycyclic aromatic structure is perylene or a perylene derivative, the fluorescence peak X of the non-association complex is at a wavelength of 430 nm to 530 nm, and the fluorescence peak Y of the excimer complex is at a wavelength of 490 nm to 700 nm.

[0275] The wavelength range (430 nm to 530 nm) in which the fluorescence peak X of the non-aggregate is confirmed is preferably 430 nm to 500 nm, and more preferably 440 nm to 460 nm.

[0276] The wavelength range (490 nm to 700 nm) in which the fluorescence peak Y of the excimer is confirmed is preferably 500 nm to 650 nm, and more preferably 520 nm to 600 nm.

[0277] In the thermally conductive molded article, the polysiloxane phosphor preferably has a non-associative fluorescence peak X and an excimer fluorescence peak Y, and the ratio of the excimer fluorescence peak intensity FY to the non-associative fluorescence peak intensity FX (FY / FX) is 0.01 to 6.0.

[0278] From the viewpoint of improving the dispersibility of the polysiloxane phosphor in the thermally conductive molded article, the fluorescence intensity ratio (FY / FX) is preferably 0.02 to 1.5, more preferably 0.03 to 0.7, and particularly preferably 0.05 to 0.4.

[0279] The organopolysiloxane (A) that is liquid at 25°C preferably contains at least one selected from organopolysiloxanes having a hydroxyl group and organopolysiloxanes having an alkoxy group. In this case, the thermally conductive molded article contains at least one selected from organopolysiloxanes having a hydroxyl group and organopolysiloxanes having an alkoxy group.

[0280] The contents of the polysiloxane phosphor, organopolysiloxane having a hydroxyl group, and organopolysiloxane having an alkoxy group in the matrix are equivalent to those in the polyorganosiloxane (A).

[0281] The matrix content in the thermally conductive molded article is preferably 5% to 80% by mass, more preferably 8% to 50% by mass, and even more preferably 10% to 30% by mass, based on the total amount of the thermally conductive molded article.

[0282] The thermally conductive filler in the thermally conductive molded article is the same as the (B) thermally conductive filler contained in the thermally conductive composition.

[0283] The thermally conductive filler having π electrons preferably includes an anisotropic filler. In this case, a thermally conductive molded article containing the anisotropic filler oriented in a predetermined direction can be obtained, and the thermal conductivity in the orientation direction can be improved.

[0284] The content of the thermally conductive filler (B) in the thermally conductive molded article is preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 80 parts by mass or more and 300 parts by mass or less, and even more preferably 100 parts by mass or more and 200 parts by mass or less, based on 100 parts by mass of the matrix.

[0285] The thermally conductive molded article may contain a thermally conductive filler having no π electrons. The thermally conductive filler having no π electrons is the same as that described as a substance that can be contained in the thermally conductive composition.

[0286] The amount of the thermally conductive filler having no π electrons in the thermally conductive molded article is preferably 100 parts by mass to 1500 parts by mass, more preferably 200 parts by mass to 1000 parts by mass, and even more preferably 300 parts by mass to 700 parts by mass, based on 100 parts by mass of the matrix.

[0287] [Method for producing thermally conductive molded article]

[0288] The method for producing the thermally conductive molded article of the present invention is not particularly limited, but is preferably a method comprising the following steps (1), (2), (3), and (4).

[0289] That is, the method for producing a thermally conductive molded body is preferably a method for producing a thermally conductive molded body comprising the following steps: a step (1) of forming the thermally conductive composition of the present invention into a sheet to obtain a sheet-like molded body; a step (2) of curing the sheet-like molded body while the sheet-like molded body is disposed between two films, at least one of which is a gas-permeable film, to obtain a primary sheet; a step (3) of preparing a plurality of the primary sheets, laminating the plurality of primary sheets, and bonding the plurality of primary sheets to form a laminated block; and a step (4) of cutting the laminated block into a sheet-like shape along the lamination direction to obtain a thermally conductive molded body.

[0290] <Process (1)>

[0291] Step (1) is the step of forming the thermally conductive composition into a sheet to obtain a sheet-like molded article. The thermally conductive composition is obtained by mixing the constituent components. The components can be mixed using, for example, a known kneader, mixing roll, mixer, or vibrating stirrer. The thermally conductive composition is a liquid composition, typically in the form of grease or clay.

[0292] The thermally conductive composition preferably contains the aforementioned volatile compound. By using a thermally conductive composition containing a volatile compound, the content of the thermally conductive filler can be increased compared to conventional methods, and coating can be facilitated during sheet molding.

[0293] The sheet-shaped molding can be carried out by applying the thermally conductive composition to a substrate film. In the case where the thermally conductive filler having π electrons contained in the thermally conductive composition includes an anisotropic filler, the anisotropic filler is easily oriented along the coating direction (the surface direction of the sheet) by the shear force during coating. Here, the thermally conductive composition can be applied to the substrate film by, for example, a coating applicator such as a rod coater or a scraper, or by extrusion molding, discharge from a nozzle, etc. By such a method, a shear force along the coating direction of the thermally conductive composition can be provided. Under the shear force, the anisotropic filler in the thermally conductive composition is oriented along the coating direction. In addition, the above-mentioned substrate film can be a gas permeable film described later.

[0294] As another method for obtaining a sheet-like molded body, a method of sandwiching the thermally conductive composition between, for example, two films and stretching the composition with stretching rolls can also be applied.

[0295] <Process (2)>

[0296] Step (2) is a step of curing the sheet-like molded body obtained in step (1) while placing it between two films, at least one of which is a gas-permeable film, to obtain a primary sheet.

[0297] In step (2), the sheet-like molded body is placed between two films. Specifically, the two films are placed in contact with both surfaces of the sheet-like molded body. At least one of the two films is preferably a gas permeable film.

[0298] When the sheet-like molded body contains a volatile compound, the use of a gas permeable membrane allows the volatile compound to be appropriately volatilized, thereby suppressing the generation of bubbles in the primary sheet formed by the sheet-like molded body. In addition, the surface of the primary sheet also has few unevenness, making it easier to form a laminated block in step (3).

[0299] Here, the gas permeability refers to the property that liquid cannot pass through but gas can pass through. The oxygen permeability of the gas permeable membrane is preferably 1×10 -16 mol·m / (m 2 ·s·Pa) or more. In addition, the moisture permeability of the gas permeable membrane is more preferably 1×10 -15 mol·m / (m 2 The moisture permeability herein is a value measured according to the gas permeability test method of JIS K7126-2:2006.

[0300] Examples of the gas permeable membrane include membranes made porous by a mixture of a polymer and a filler, a mixture of polymers, and the like. Alternatively, the membrane may be a membrane having gas permeability even without being made porous.

[0301] The polymer constituting the gas-permeable membrane is not particularly limited, and examples include low-density polyethylene, linear low-density polyethylene, poly(4-methylpentene-1), ethyl cellulose, polytetrafluoroethylene, and fluorine-modified resins, among others. Preferred among these are non-porous gas-permeable membranes formed from poly(4-methylpentene-1) and porous gas-permeable membranes formed from fluorine-based resins. Using a gas-permeable membrane formed from poly(4-methylpentene-1) and a fluorine-based resin allows for proper volatilization of volatile compounds, furthermore, providing excellent release properties when the gas-permeable membrane is peeled from the primary sheet. Furthermore, a non-porous gas-permeable membrane formed from poly(4-methylpentene-1) is particularly preferred. When a non-porous gas-permeable membrane made from poly(4-methylpentene-1) is used, liquid resin does not enter the pores when the thermally conductive composition is applied, resulting in particularly excellent release properties. Furthermore, the membrane surface lacks pores, eliminating the formation of irregularities caused by the pores, thereby producing a primary sheet with a smooth surface with minimal irregularities.

[0302] It is preferred that at least one of the two films used in step (2) is a gas permeable film, or both films may be gas permeable films. Alternatively, one of the two films may be a gas permeable film, and the other may be a non-gas permeable film such as a polyester film or a polyolefin film.

[0303] In step (2), the method for placing the sheet-like molded body obtained in step (1) between two films is not particularly limited. For example, in step (1), when the sheet-like molded body is produced by coating a thermally conductive composition on a substrate film, the sheet-like molded body can be placed so that the substrate film is one of the two films and the other film is in contact with the sheet-like molded body. In addition, when the sheet-like molded body is obtained alone in step (1), two films can be prepared and the sheet-like molded body can be placed between the two films.

[0304] The sheet-like molded body can be cured by heating. The heating temperature can be, for example, about 65 to 100°C. The heating time can be, for example, about 10 minutes to 24 hours. A primary sheet can be obtained by this operation.

[0305] <Process (3)>

[0306] Step (3) is a step of preparing a plurality of primary sheets obtained in the above-mentioned step (2), laminating the plurality of primary sheets, and bonding the plurality of primary sheets to form a laminated block.

[0307] Regarding steps (3) and (4), a case where the thermally conductive filler having π electrons includes the anisotropic filler 14 will be described using the drawings.

[0308] like Figure 1 As shown in (a) and (b), a plurality of primary sheets 21 are stacked so that the orientation directions of the anisotropic filler 14 become the same.

[0309] The primary sheets 21 can be bonded simply by overlapping them as described above. However, to achieve a more secure bond, pressure may be applied along the stacking direction x of the primary sheets 21. The pressure may be applied at a level sufficient to prevent significant deformation of the primary sheets 21. For example, a roller or press may be used. For example, when a roller is used, the pressure is preferably 0.3 to 3 kgf / 50 mm.

[0310] The laminated primary sheets 21 may be heated appropriately, for example, during pressing, but since adhesion is possible even without heating, it is preferable not to heat the laminated primary sheets 21. Therefore, the temperature during pressing is, for example, 0 to 50°C, preferably about 10 to 40°C.

[0311] <Step (4)>

[0312] Step (4) is a step of cutting the stacked block obtained in step (3) into a sheet shape along the stacking direction to obtain a thermally conductive sheet.

[0313] like Figure 1 As shown in (c), the laminated block 22 is cut along the lamination direction x of the primary sheet 21 using a cutter 18 to obtain a thermally conductive molded body 10. At this time, the laminated block 22 can be cut in a direction perpendicular to the orientation direction of the anisotropic filler 14. This cutting orients the anisotropic filler 14 in the thickness direction of the thermally conductive molded body 10, thereby increasing the thermal conductivity in the thickness direction.

[0314] The blade 18 may be a double-edged razor blade, a cutter, a single-edged blade, a round blade, a wire blade, a saw blade, or the like. The laminated block 22 is cut using the blade 18 by, for example, pressing, shearing, rotating, or sliding.

[0315] From the viewpoint of volatilizing the remaining volatile compounds, the thermally conductive molded body obtained after cutting is preferably subjected to a heat treatment. The heat treatment may be performed at a heating temperature of 80 to 160° C. and for a heating time of 2 to 48 hours.

[0316] Furthermore, while the above-described manufacturing method describes a method in which a sheet-like molded body (primary sheet) is formed and then multiple primary sheets are stacked to form a laminated block, a material equivalent to a laminated block can also be produced by the following method. Specifically, if the anisotropic filler 14 has anisotropic diamagnetic susceptibility, a method can be employed in which a thermally conductive composition is injected into a block-shaped mold to form a block in which the anisotropic filler 14 is oriented in a predetermined direction using a magnetic field orientation method. By cutting the thus-formed block in a direction perpendicular to the orientation direction of the anisotropic filler 14, a thermally conductive molded body 10 can be obtained in which the anisotropic filler 14 is oriented in the thickness direction of the thermally conductive molded body 10, resulting in a thermally conductive molded body having high thermal conductivity in the thickness direction.

[0317] [Device]

[0318] The present invention can provide a device comprising a heating element, a heat sink, and the thermally conductive molded body disposed between the heating element and the heat sink. The thermally conductive molded body is interposed between the heating element and the heat sink, and heat generated by the heating element is transferred to the heat sink by thermal conductivity, and dissipated from the heat sink. Examples of the heating element include CPUs, LEDs, coils, and lithium-ion batteries. Examples of the heat sink include heat sinks, heat pumps, and electronic device housings. Furthermore, a Peltier element may be used in place of the heat sink.

[0319] Example

[0320] Hereinafter, the present invention will be described in further detail with reference to Examples, but the present invention is not limited to these Examples.

[0321] The thermally conductive compositions in the present examples and comparative examples and the thermally conductive molded articles as their cured products were evaluated by the following methods.

[0322] [Curing properties]

[0323] The curability of the thermally conductive compositions of the Examples and Comparative Examples was confirmed based on the following criteria: Curing was performed under two conditions: 80° C. for 8 hours and 150° C. for 6 hours.

[0324] (evaluate)

[0325] A: The heat-treated thermally conductive composition sandwiched between a pair of release films can be peeled off at the interface when peeling is performed.

[0326] B: The heat-treated thermally conductive composition sandwiched between a pair of release films could not be peeled off at the interface when peeling was performed.

[0327] [Viscosity]

[0328] The viscosity at 25° C. immediately after preparation of the thermally conductive composition of each Example and Comparative Example was measured as follows.

[0329] use The viscosity was measured using a rheometer "MCR-302e" manufactured by the company. The sample temperature was adjusted to 25°C using a Peltier plate and a 25mm φ parallel plate was used while continuously changing the shear rate in the range of 0.0001 to 100 (1 / s). -4 (1 / s), 10 -1 The viscosity at (1 / s) is respectively described in the table.

[0330] <Puncture load 1>

[0331] Puncture load 1 was measured as follows. First, the thermally conductive composition was degassed, and then 25 g of the thermally conductive composition was introduced into a cylindrical container with a diameter of 25 mm. Next, a puncture rod having a disc-shaped member with a diameter of 10 mm at the front end was pressed from the front end of the puncture rod to the side of the thermally conductive composition introduced into the container at a speed of 10 mm / min. When a load of 0.2 gf was applied, it was pressed to a depth of 0 mm, and the load (gf) when it reached a depth of 2 mm and 6 mm was measured. The measurement was carried out at 25 ° C. Furthermore, the slope of the straight line of the graph of the depth of 0 mm and the graph of the depth of 2 mm when the horizontal axis is displacement and the vertical axis is load is referred to as "slope 1-1", and the slope of the straight line of the graph of the depth of 0 mm and the graph of 6 mm is referred to as "slope 1-2". In addition, the maximum value of the load pressed to a depth of 15 mm (maximum load 1 (gf)) was further measured.

[0332] <Puncture load 2>

[0333] Puncture load 2 was measured as follows. First, the thermally conductive composition was degassed, and then 25 g of the thermally conductive composition was introduced into a cylindrical container with a diameter of 25 mm. Next, a puncture rod having a disc-shaped member with a diameter of 5 mm at the front end was pressed from the front end of the puncture rod to the thermally conductive composition introduced into the container at a speed of 10 mm / min. When a load of 0.2 gf was applied, it was pressed to a depth of 0 mm, and the load (gf) when it reached a depth of 2 mm and 6 mm was measured. The measurement was carried out at 25°C. Furthermore, the slope to a depth of 0 mm to 2 mm when the horizontal axis was displacement and the vertical axis was load was referred to as "slope 2-1", and the slope to a depth of 0 mm to 6 mm was referred to as "slope 2-2". In addition, the maximum value of the load pressed to a depth of 15 mm (maximum load 2 (gf)) was further measured. In addition, for samples with extremely large loads, the load of a displacement of 2 mm was also recorded as a reference value.

[0334] [Effect of improving the fluidity of the thermally conductive composition]

[0335] By shear speed 10 -4 Viscosity reduction rate (%) under (1 / s), shear rate 10 -1 The viscosity reduction rate (%) under (1 / s), the reduction rate of maximum load 1 (%), the reduction rate of maximum load 2 (%), the reduction rate of slope 1-1 (%), the reduction rate of slope 1-2 (%), the reduction rate of slope 2-1 (%), and the reduction rate of slope 2-2 (%) were evaluated to confirm the fluidity improvement effect. Each evaluation was carried out by comparing the embodiment and the comparative example having the same composition of the thermally conductive filler. Specifically, the evaluation was carried out based on the following formula. The higher the numerical value of each evaluation, the higher the fluidity improvement effect (viscosity reduction effect).

[0336] <Shear speed 10 -4 (1 / s) and 10 -1 Viscosity reduction rate (1 / s) (%)>

[0337] Viscosity reduction (%) = 100 × (viscosity of the comparative example used as a reference - viscosity of the example) / (viscosity of the comparative example used as a reference)

[0338] <Reduction rate of maximum load 1 (%), reduction rate of maximum load 2 (%)>

[0339] Reduction rate of maximum load (%) = 100 × (maximum load of the comparative example serving as a reference - maximum load of the embodiment) / (maximum load of the comparative example serving as a reference)

[0340] <Reduction rate of slope 1-1 (%), reduction rate of slope 1-2 (%), reduction rate of slope 2-1 (%), reduction rate of slope 2-2 (%)>

[0341] Slope reduction rate (%) = 100 × (slope of the comparative example serving as a reference - slope of the embodiment) / (slope of the comparative example serving as a reference)

[0342] [Fluorescence spectrum]

[0343] The fluorescence spectra of the thermally conductive molded articles obtained in each of the Examples and Comparative Examples were measured. The wavelength of the fluorescence peak X of the non-associate (the wavelength of the maximum peak on the short wavelength side) and the wavelength of the fluorescence peak Y of the excimer (the wavelength of the maximum peak on the long wavelength side) were measured using a "spectrofluorimeter F-2700" manufactured by the company at an excitation wavelength of 339 nm (when B is pyrene) and 420 nm (when B is perylene). The ratio of the fluorescence peak intensity FY of the excimer to the fluorescence peak intensity FX of the non-associate (FY / FX) was calculated.

[0344] In the above examples and comparative examples, the fluorescence spectrum measurement sample was prepared by preparing a 1 cm × 1 cm and 1 mm thick sheet of cured product (thermally conductive molded body), and sandwiching the cured product between a slide glass ( system" "Material: Crown glass) was used to prepare the measurement samples of each example. In addition, for the sample in which the anisotropic filler was oriented, the major axis of the anisotropic filler was made to be the thickness direction of the sheet.

[0345] Furthermore, the above test sample was placed in the sample holder of the spectrofluorophotometer and the fluorescence spectrum was measured. Figure 3 As shown, the sample chamber of the spectrofluorophotometer is positioned with a fluorescence detector at a 90° angle relative to the incident direction of the excitation light. The sample surface (cured material surface) of the measurement sample is positioned at a 60° angle relative to the incident direction and a 30° angle relative to the detector. Fluorescence spectra were measured using a 5 nm slit width on the excitation side, a 5 nm slit width on the fluorescence side, and a scanning speed of 1500 nm / min.

[0346] When the structure of the polysiloxane phosphor is unknown, the fluorescence spectrum is measured using the wavelength at which the fluorescence peak intensity FX of the fluorescence peak X reaches a maximum as the excitation wavelength.

[0347] The above fluorescence peak X and fluorescence peak Y are Figures 4-6The fluorescence peak Y of the excimer complex may not be observed when the excimer complex is not formed, but the fluorescence peak Y can be estimated in advance. Specifically, by stirring the thermally conductive composition or thermally conductive member in tetrahydrofuran solvent (THF), the polysiloxane fluorescence can be extracted in THF. Then, for a sample in which the extract is concentrated by volatilizing a portion of THF, the fluorescence spectrum ( Figure 6 (reference example) Estimate the wavelength at which the peak of the excimer appears.

[0348] [Thermal conductivity 1]

[0349] Thermal resistance value 1 use Figure 2 The thermal resistance measuring instrument shown in the figure was used for measurement by the method shown below. Specifically, a test piece S of 10 mm × 10 mm was prepared for each sample and used in this test. Each test piece S was then attached to a copper block 32 having a measuring surface of 10 mm × 10 mm and the sides covered with a heat insulating material 31. The test piece S was then sandwiched between the upper copper block 33 and a load was applied via a load cell 36, with the thickness set to 80% of the original thickness. Here, the lower copper block 32 was connected to a heater 34. In addition, the upper copper block 33 was connected to a heat sink 35 with a fan. Next, the heater 34 was heated to a heat output of 25 W. After 10 minutes when the temperature reached a roughly stable state, the temperature of the upper copper block 33 (θj0), the temperature of the lower copper block 32 (θj1), and the heat output of the heater (Q) were measured. The thermal conductivity of each sample was calculated using the following equations (1) and (2).

[0350] Thermal resistance = (θj1 - θj0) / Q ··· Formula (1)

[0351] Thermal conductivity = T / thermal resistance (2)

[0352] In equation (1), θj1 is the temperature of the lower copper block 32, θj0 is the temperature of the upper copper block 33, and Q is the calorific value. In equation (2), T is the thickness of the sample during the thermal resistance measurement.

[0353] [Thermal conductivity 2]

[0354] Thermal resistance value 2 use Figure 2The thermal resistance measuring instrument shown in the figure was used for measurement by the method shown below. Specifically, a test piece S of 10 mm × 10 mm was prepared for each sample and used in this test. Each test piece S was then attached to a copper block 32 having a measuring surface of 10 mm × 10 mm and the sides covered with a heat insulating material 31. The test piece S was then sandwiched between the upper copper block 33 and a load was applied via a load cell 36. The thickness was set so that it would be 80% of the original thickness. Here, the lower copper block 32 was connected to a heater 34. In addition, the upper copper block 33 was connected to a heat sink 35 with a fan. Next, the heater 34 was heated to a heat output of 5 W. After 10 minutes when the temperature reached a roughly stable state, the temperature of the upper copper block 33 (θj0), the temperature of the lower copper block 32 (θj1), and the heat output of the heater (Q) were measured. The thermal conductivity of each sample was calculated using the following equations (1) and (2).

[0355] Thermal resistance = (θj1 - θj0) / Q ··· Formula (1)

[0356] Thermal conductivity = T / thermal resistance (2)

[0357] In equation (1), θj1 is the temperature of the lower copper block 32, θj0 is the temperature of the upper copper block 33, and Q is the calorific value. In equation (2), T is the thickness of the sample during the thermal resistance measurement.

[0358] [Compression load]

[0359] The compressive load (kgf) of the thermally conductive molded articles obtained in each Example and Comparative Example was measured in an area of ​​10 mm x 10 mm. The compressive load was measured by measuring the load when a 20% compression was applied perpendicularly to the bonding surfaces of the multiple unit layers.

[0360] The samples used in Examples and Comparative Examples are as follows.

[0361] <A: Organopolysiloxane that is liquid at 25°C>

[0362] [Addition reaction curing silicone]

[0363] · Organopolysiloxane containing alkenyl groups: Organopolysiloxane having vinyl groups at both ends of the molecular chain and a vinyl functional group concentration of 158 μmol / g

[0364] Hydrogen-containing organopolysiloxane 1: an organopolysiloxane having a vinyl group at the terminal, a hydrosilyl group on the side chain and the terminal, a vinyl functional group concentration of 158 μmol / g, and a hydrosilyl functional group concentration of 774 μmol / g

[0365] Hydrogen-containing organopolysiloxane 2: an organopolysiloxane having a cyclic structure and a hydrosilyl functional group concentration of 4415 μmol / g

[0366] [Polysiloxane phosphor]

[0367] Perylene dispersant 1: organopolysiloxane containing perylene as described in the synthesis method below, number average molecular weight 15,300

[0368] Pyrene dispersant 1: an organopolysiloxane containing pyrene as described in the synthesis method below, number average molecular weight 15,300

[0369] Pyrene dispersant 2: an organopolysiloxane containing pyrene as described in the synthesis method below, number average molecular weight 4,800

[0370] (Synthesis of Perylene Dispersant 1)

[0371] 98.6 g of an organosiloxane compound (n=210) having a 1,3-diol group, 1.7 g of 3-perylenecarboxaldehyde, 50 g of toluene as a solvent, and a catalyst ( 0.6 g of "Amberlyst 15 dry") was reacted at 100°C for 24 hours under a nitrogen atmosphere. After the reaction, the catalyst was removed by filtering with a 5.0 μm PTFE filter, and the filtrate was concentrated using a rotary evaporator and a vacuum dryer to obtain a perylene dispersant 1. The reaction formula is as follows. In addition, 1 The following reaction was confirmed by H NMR measurement using JEOL's "ECX-400" NMR measuring apparatus, deuterated chloroform as a solvent, at a sample concentration of 1 wt%, 25°C, a measurement frequency of 400 MHz, and 8 integration times.

[0372]

[0373] (Synthesis of Pyrene Dispersant 1)

[0374] 98.6 g of an organosiloxane compound (n=210) having a 1,3-diol group, 1.4 g of 1-pyrenecarboxaldehyde, 50 g of toluene as a solvent, and a catalyst ( 0.6 g of "Amberlyst 15 dry") was reacted at 100°C for 24 hours under a nitrogen atmosphere. After the reaction, the catalyst was removed by filtering with a 5.0 μm PTFE filter, and the filtrate was concentrated using a rotary evaporator and a vacuum dryer to obtain pyrene dispersant 1. The reaction formula is as follows. In addition, 1The following reaction was confirmed by H NMR measurement using JEOL's "ECX-400" NMR measuring apparatus, deuterated chloroform as a solvent, at a sample concentration of 1 wt%, 25°C, a measurement frequency of 400 MHz, and 8 integration times.

[0375]

[0376] (Synthesis of Pyrene Dispersant 2)

[0377] 98.6 g of an organosiloxane compound (n=70) having a hydrosilyl group, 5.7 g of 2-(1-pyrene)ethyl methacrylate, 50 g of toluene as a solvent, and 0.01 g of a Karstedt catalyst (platinum-based catalyst) as a catalyst were reacted at 100° C. under a nitrogen atmosphere for 24 hours. The reaction solution was then concentrated using a rotary evaporator and a vacuum dryer to obtain a pyrene dispersant 2. The reaction formula is as follows. In addition, by 1 The progress of the following reaction was confirmed by H NMR measurement.

[0378]

[0379] [Organopolysiloxane containing hydroxyl groups]

[0380] OH type dispersant 1: number average molecular weight 1,000, hydroxyl equivalent weight 500

[0381] OH type dispersant 2: number average molecular weight 5,000, hydroxyl equivalent weight 2,500

[0382] OH type dispersant 3: number average molecular weight 15,000, hydroxyl equivalent weight 7,500

[0383] The above-mentioned OH-type dispersants 1 to 3 are commercially available products and have the following structures.

[0384]

[0385] [Organopolysiloxane having an alkoxy group]

[0386] Alkoxy dispersant 1: number average molecular weight 2,500

[0387] Alkoxy-type dispersant 1 is a commercially available product and has the following structure.

[0388]

[0389] [Other organopolysiloxanes]

[0390] Dimethyl silicone oil

[0391] <B: Thermally conductive filler with π electrons>

[0392] Graphitized carbon fiber 1: average fiber length 174 μm, specific surface area 0.499 m 2 / g, anisotropic filling material

[0393] Graphitized carbon fiber 2: average fiber length 169 μm, specific surface area 0.581 m 2 / g, anisotropic filling material

[0394] Graphitized carbon fiber 3: average fiber length 85 μm, specific surface area 1.11 m 2 / g, anisotropic filling material

[0395] Flake graphite: average particle size 15μm, specific surface area 8.6m 2 / g, anisotropic filling material

[0396] Boron nitride powder 1: average particle size 7 μm, specific surface area 7 m 2 / g, anisotropic filling material

[0397] Boron nitride powder 2: average particle size 50 μm, specific surface area 0.7 m 2 / g, anisotropic filling material

[0398] Thermally conductive fillers without π electrons

[0399] Aluminum hydroxide 1: average particle size 1 μm, specific surface area 266 m 2 / g, amorphous, non-anisotropic filling material

[0400] Aluminum hydroxide 2: average particle size 10 μm, specific surface area 211 m 2 / g, amorphous, non-anisotropic filling material

[0401] Alumina 1: average particle size 0.5 μm, specific surface area 3.2 m 2 / g, spherical, non-anisotropic filling material

[0402] Alumina 2: average particle size 3 μm, specific surface area 0.6 m 2 / g, spherical, non-anisotropic filling material

[0403] Alumina 3: average particle size 3 μm, specific surface area 1.04 m 2 / g, crushed, non-anisotropic filling material

[0404] Aluminum 1: average particle size 3.5 μm, specific surface area 0.633 m 2 / g

[0405] Volatile compounds

[0406] n-Decyltrimethoxysilane: In thermogravimetric analysis, the temperature T1 at which the weight loss reaches 90% when the temperature is increased at 2°C / min is 187°C.

[0407] <Other additives>

[0408] platinum catalyst

[0409] [Examples 1 to 53, Comparative Examples 1 to 12]

[0410] The thermally conductive composition obtained by mixing the components shown in each table was applied in one direction at 25° C. using a bar coater as a coating applicator on a gas permeable membrane (Mitsui Chemicals " ”) formed on a substrate film. The long axis of the thermally conductive filler having π electrons as an anisotropic filler is oriented toward the coating direction, and the short axis is oriented toward the normal direction of the coating surface. Next, a gas permeable membrane (Mitsui Chemicals “ ”). The sheet-like molded body was then heated at 80°C for 8 hours while being sandwiched between two films, thereby partially volatilizing the volatile compounds and simultaneously curing the thermally conductive composition contained in the sheet-like molded body, thereby obtaining a primary sheet having a thickness of 1.0 mm.

[0411] Thirty of the resulting primary sheets were stacked and pressed with a roller at a pressure of 1.6 kgf / 50 mm at 25°C to produce a laminated block. The resulting laminated block was sliced ​​with a cutter parallel to the stacking direction and perpendicular to the orientation direction of the anisotropic filler, and then heated at 150°C for 6 hours. This produced a thermally conductive molded article with a thickness of 1000 μm per unit layer and a total thickness of 2 mm. The evaluation results are shown in Tables 1 to 10.

[0412]

[0413]

[0414]

[0415]

[0416]

[0417]

[0418]

[0419]

[0420] In addition, "OL" in the table means that the value cannot be measured.

[0421]

[0422]

[0423] Examples 1 to 53 are thermally conductive compositions of the present invention comprising an organopolysiloxane containing a polysiloxane phosphor and a thermally conductive filler having π electrons, and the shear rate is 10 -4 Viscosity reduction rate (%) under (1 / s), shear rate 10 -1 The results show that the values ​​of each evaluation of viscosity reduction rate (%) at (1 / s), reduction rate at maximum load 1 (%), reduction rate at maximum load 2 (%), reduction rate at slope 1-1 (%), reduction rate at slope 1-2 (%), reduction rate at slope 2-1 (%), and reduction rate at slope 2-2 (%) are large. These results show that the thermally conductive composition of the present invention has a high viscosity reducing effect.

[0424] Comparing Examples 4 to 6 with Examples 10 to 12, and Example 43 with Example 45, the perylene dispersant exhibited a greater viscosity-lowering effect than the pyrene dispersant in the polysiloxane phosphor. Furthermore, comparing Example 38 with Example 40, and Example 43 with Example 44, even for the same polysiloxane phosphor, the one with a higher number average molecular weight (15,300) tended to exhibit a greater viscosity-lowering effect than the one with a lower number average molecular weight (4,800).

[0425] Furthermore, it was confirmed that the viscosity-lowering effect tends to be more enhanced by blending an organopolysiloxane having a hydroxyl group and / or an organopolysiloxane having an alkoxy group in addition to the polysiloxane phosphor.

[0426] On the other hand, the thermally conductive compositions of the comparative examples in which the polysiloxane phosphor was not blended all had a higher viscosity than the thermally conductive compositions of the examples.

[0427] Explanation of symbols

[0428] 10 Thermally conductive molded body

[0429] 14 Anisotropic filling materials

[0430] 18 Cutting Tools

[0431] 21 1 times

[0432] 22 stacking blocks

[0433] 31. Insulation materials

[0434] 32 Copper block below

[0435] 33 The copper block above

[0436] 34 Heater

[0437] 35 heat sink

[0438] 36 load cells

[0439] S test piece.

Claims

1. A thermally conductive composition comprising (A) an organopolysiloxane that is liquid at 25°C, and (B) a thermally conductive filler material having π electrons, The (A) organopolysiloxane contains a polysiloxane phosphor. 2 . The thermally conductive composition according to claim 1 , wherein the polysiloxane phosphor has a polycyclic aromatic structure. 3 . The thermally conductive composition according to claim 1 , wherein the polysiloxane phosphor has a fluorescence peak X of a non-association complex, or has a fluorescence peak X of a non-association complex and a fluorescence peak Y of an excimer complex.

4. The thermally conductive composition according to claim 1 or 2, wherein the polysiloxane phosphor has a fluorescence peak X of a non-association complex and a fluorescence peak Y of an excimer complex, and a ratio of the fluorescence peak intensity FY of the excimer complex to the fluorescence peak intensity FX of the non-association complex (FY / FX) is 0.01 to 6.

0. The thermally conductive composition according to claim 2 , wherein the polycyclic aromatic structure is selected from any one of pyrene, pyrene derivatives, perylene, and perylene derivatives. The thermally conductive composition according to claim 4 , wherein the polysiloxane phosphor has a fluorescence peak X of the non-association complex at a wavelength of 370 nm to 430 nm, and a fluorescence peak Y of the excimer complex at a wavelength of 430 nm to 550 nm. 7 . The thermally conductive composition according to claim 4 , wherein the polysiloxane phosphor has a fluorescence peak X of the non-association complex at a wavelength of 430 nm to 530 nm, and a fluorescence peak Y of the excimer complex at a wavelength of 490 nm to 700 nm. 8 . The thermally conductive composition according to claim 1 , wherein the molecular weight of the polysiloxane phosphor is 4,000 to 25,000.

9. The thermally conductive composition according to claim 1 or 2, wherein the polysiloxane phosphor has a structure represented by the following formula (1): In formula (1), R1 is independently a group represented by AB or a monovalent hydrocarbon group having 1 to 4 carbon atoms, At least one R1 among the plurality of R1s is a group represented by AB, wherein A is a divalent organic group bonded to a silicon atom, and B has three to six conjugated aromatic six-membered rings. Among the atoms constituting A, when the atom bonded to the aromatic 6-membered ring possessed by B is defined as an α-atom, the atom bonded to the α-atom is defined as a β-atom, and the atom bonded to the β-atom and other than the α-atom is defined as a γ-atom, any one of the α-atom, the β-atom, and the γ-atom is a heteroatom, n is an integer of 1 or greater.

10. The thermally conductive composition according to claim 9, wherein the polysiloxane phosphor has a structure represented by the following formula (2): In formula (2), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B and n have the same meanings as A, B and n in formula (1).

11. The thermally conductive composition according to claim 9, wherein the polysiloxane phosphor has a structure represented by the following formula (3): In formula (3), R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and A, B and n have the same meanings as A, B and n in formula (1). 12 . The thermally conductive composition according to claim 1 , wherein the (A) organopolysiloxane comprises an addition reaction type organosilicon. 13 . The thermally conductive composition according to claim 1 , wherein the average particle size of the thermally conductive filler (B) having π electrons is 1 μm to 500 μm. The thermally conductive composition according to claim 1 or 2, wherein the (B) thermally conductive filler having π electrons comprises an anisotropic filler. 15 . The thermally conductive composition according to claim 14 , wherein the anisotropic filler comprises at least one selected from the group consisting of carbon fiber, flaky graphite, and boron nitride. The thermally conductive composition according to claim 1 or 2, further comprising a thermally conductive filler having no π electrons. 17 . The thermally conductive composition according to claim 1 , further comprising at least one selected from the group consisting of an organopolysiloxane having a hydroxyl group and an organopolysiloxane having an alkoxy group.

18. A thermally conductive molded body comprising A matrix composed of a cured product of an organopolysiloxane, and Thermally conductive filling material with π electrons, The organopolysiloxane contains a polysiloxane phosphor. The thermally conductive formed article according to claim 18 , comprising an anisotropic filler oriented in a predetermined direction. 20 . The thermally conductive molded article according to claim 18 , further comprising at least one selected from the group consisting of an organopolysiloxane having a hydroxyl group and an organopolysiloxane having an alkoxy group.

21. A device comprising a heating element, a heat dissipating element, and the thermally conductive molded body according to claim 18 or 19 provided between the heating element and the heat dissipating element.

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