Organopolysiloxane having alkenyl groups at both molecular chain terminals, thermally conductive organopolysiloxane composition containing the same, thermally conductive member and heat dissipating structure, and other compositions

Abstract

This invention provides an organopolysiloxane, compositions comprising the organopolysiloxane, and particularly thermally conductive compositions, wherein the organopolysiloxane, even when used as a matrix polymer in a thermally conductive organopolysiloxane composition having high thermal conductivity, can suppress the viscosity of the composition, exhibits excellent extrusion workability during cartridge coating, and optionally provides a uniform crosslinking reactant through curing. It is also less prone to density reduction even under high temperature and prolonged use, thereby suppressing the formation of voids or bubbles to maintain predetermined heat dissipation. The invention also includes an organopolysiloxane with alkenyl groups at both ends of its molecular chain, a living polymerization method and a manufacturing method characterized by end-capping of the polymer, compositions comprising the organopolysiloxane, particularly thermally conductive organopolysiloxane compositions, thermally conductive components made therefrom, and heat dissipation structures using the same, wherein the Mw / Mn ratio of the organopolysiloxane is 1.20 or less.

Description

Technical Field

[0001] This invention relates to an organopolysiloxane with alkenyl groups at both ends of its molecular chain, a method for manufacturing the organopolysiloxane by living polymerization, a thermally conductive organopolysiloxane composition containing the organopolysiloxane, a thermally conductive component thereof, and a heat dissipation structure using the same. The organopolysiloxane has a narrow molecular weight distribution and a relatively low molecular weight, thus exhibiting excellent dischargeability from the cartridge when used as a matrix polymer for the thermally conductive organopolysiloxane, and forming a uniform cross-linked structure during curing. Further preferably, the organopolysiloxane is an organopolysiloxane with alkenyl groups at both ends of its molecular chain, which reduces the content of cyclic siloxanes with similar molecular weights that are difficult to remove using balancing methods. When used as a raw material for a thermally conductive organopolysiloxane composition, it is less prone to density changes even after prolonged heating, thereby suppressing the formation of voids or bubbles, avoiding contact failures, minimizing mold contamination, and exhibiting high heat resistance due to the absence of an alkali catalyst. In addition, the present invention relates to compositions containing organopolysiloxanes with alkenyl groups at both ends of the above-mentioned molecular chains, such as sealants, and other uses. Background Technology

[0002] In recent years, with the increasing density and integration of printed circuit boards (PCBs) housing electronic components such as transistors, ICs, and memory elements, the growing capacity of composite ICs, and the increasing capacity of secondary batteries (cell-type), thermally conductive silicone compositions containing organopolysiloxanes and thermally conductive fillers such as alumina powder and zinc oxide powder have been widely used to efficiently dissipate heat generated by electronic components, batteries, and other electronic / electrical devices. In particular, to address high heat dissipation, thermally conductive silicone compositions filled with a large amount of thermally conductive filler have been proposed. These thermally conductive silicone compositions exhibit excellent heat resistance, and even with high concentrations and high volume percentages of thermally conductive filler, the cured product remains rubbery. Therefore, a certain degree of flexibility and stress mitigation is desirable to maintain the tracking and sealing of heat sources within the heat dissipation structure, thus preserving heat dissipation performance. On the other hand, in recent years, there has been a trend towards higher concentrations of thermally conductive fillers. However, excessive concentrations of thermally conductive fillers often compromise the rubber properties of the cured silicone polymer. If the filler content is too high, the resulting cured product becomes excessively hard, sometimes creating gaps with the heat dissipation target, impairing conformability and stress mitigation, and sometimes failing to achieve adequate heat dissipation. Therefore, in cured thermally conductive silicone compositions, controlling the hardness of the cured product is extremely important for achieving optimal heat dissipation.

[0003] In addition, when highly filled with thermally conductive fillers, the flowability of the composition tends to be impaired. When attempting to fill cartridges and dispensing machines for small-volume or spot coating, sufficient extrusion volume is sometimes difficult to ensure, especially for small-volume packaging, which becomes challenging. Furthermore, reduced workability and coatability after filling can lead to decreased work efficiency. Moreover, the thermally conductive filler may not be uniformly dispersed in the silicone composition, adversely affecting the desired thermal conductivity, curability, and workability in commercial production. Therefore, there is still room for improvement in the performance and workability of highly thermally conductive silicone compositions, especially those with thermal conductivity of 9.0 W / mK or higher, for industrial application.

[0004] On the other hand, as a means of obtaining curable reactivity organopolysiloxanes, there is a known active polymerization method using hexa-organocyclic trisiloxane (D3) as a raw material and lithium salts, sodium salts, etc. as catalysts, and curable compositions (including those cured into a gel state) containing it are also known (see Patent Documents 1-5). However, in these documents, there is no disclosure of the significant usefulness of organopolysiloxanes, which impart fluidity and uniform crosslinking reactivity due to the presence of alkenyl groups at both ends of the molecular chain and a relatively small molecular weight, as matrix polymers for their thermally conductive compositions. In particular, compared with the equilibrium method, there is no record or suggestion of the effect on cyclic siloxanes that cause voids or bubbles.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-163413 (Patent Grant No. 6907978)

[0008] Patent Document 2: Japanese Patent Application Publication No. 01-272633

[0009] Patent Document 3: Japanese Patent Application Publication No. 02-092933

[0010] Patent Document 4: Japanese Patent Application Publication No. 61-275329

[0011] Patent Document 5: Japanese Patent Application Publication No. 01-098631 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] On the other hand, the inventors of this case have discovered new problems with high thermal conductivity organopolysiloxane compositions that contain a large amount of thermally conductive filler and optionally have curing reactivity. In high thermal conductivity compositions, curing-reactive organopolysiloxanes are used as the matrix polymer for carrying the thermally conductive filler. However, when it is desirable to use low-viscosity organopolysiloxanes to ensure the composition's flowability, filling properties in cartridges and dispensing machines, and extrusion performance during coating, these low-polymerization-degree organopolysiloxanes are mainly obtained through equilibrium polymerization. Therefore, they have a wide molecular weight distribution and lack uniform molecular length, making it difficult to form uniform crosslinks, sometimes resulting in insufficient thermal conductivity and rubber properties. Therefore, the performance of thermally conductive components using these matrix polymers is problematic.

[0014] In addition, low-polymerization-degree organopolysiloxanes obtained by equilibrium polymerization can generate volatile cyclic siloxanes during their manufacturing process. If used in electronic materials, this can cause contact failures in electronic components. Furthermore, even if the low polymerization degree (e.g., 3-9 polymers) of these volatile organosilicones is removed beforehand through stripping, the inherent alkaline catalyst in equilibrium polymerization can sometimes lead to the regeneration of volatile cyclic siloxanes over time, resulting in contact failures and mold contamination. Furthermore, the molecular weight range of low-polymerization-degree organopolysiloxanes obtained by equilibrium polymerization is inevitably similar to that of cyclic siloxanes with a molecular weight of less than 20 (specifically 10-20 polymers), making it difficult to sufficiently remove cyclic siloxanes with similar molecular weights. Therefore, regardless of whether a curing reaction occurs, if existing low-polymerization-degree organopolysiloxanes are used as the matrix polymer in high thermal conductivity organopolysiloxane compositions, prolonged use at high temperatures (aging) will cause these cyclic siloxanes to volatilize from the resulting thermally conductive component over time, creating voids or bubbles, leading to a decrease in density. This can sometimes result in deterioration of the performance and durability of the thermally conductive component. Consequently, the originally intended heat dissipation characteristics may not be fully realized.

[0015] This invention was made to solve the above-mentioned problems, and its object is to provide an organopolysiloxane with alkenyl groups at both ends of the molecular chain, a thermally conductive organopolysiloxane composition containing the organopolysiloxane, a thermally conductive component made therefrom, and a heat dissipation structure using the same. The organopolysiloxane contains a very high volume percentage of thermally conductive filler even when the viscosity is relatively low and the degree of polymerization is low. Even when used as a matrix polymer for a thermally conductive organopolysiloxane composition with high thermal conductivity, the viscosity of the final composition can be suppressed. It has excellent filling properties for cartridges, etc., and excellent extrusion workability during coating. It can optionally be cured to provide a uniform crosslinking reactant. Even under high temperature and long-term use, it is not easy to cause a decrease in density. Thus, it can suppress the generation of voids or bubbles to maintain the predetermined heat dissipation, avoid contact failure, and is not prone to mold contamination. It also has high heat resistance due to the absence of an alkali catalyst.

[0016] Solution for solving the problem

[0017] The inventors conducted in-depth research and found that the above-mentioned problems could be solved by using organopolysiloxanes with a weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) of 1.20 or less and alkenyl groups at both ends of the molecular chain, thus completing the present invention. Such organopolysiloxanes are preferably those with a number-average molecular weight of 10,000 or less and a content of cyclic dimethylsiloxanes of 20 polymers or less of less than 0.1% by mass. Furthermore, such organopolysiloxanes can be obtained by a manufacturing method comprising the following steps: step (I), using D3 as a raw material, performing active polymerization in the presence of a lithium-based catalyst; and step (II), end-capping the polymer obtained in step (I) with 1,3-dienyl-1,1,3,3-tetraorganodisilazane.

[0018] Similarly, the above-mentioned problem is solved by a thermally conductive organopolysiloxane composition, a thermally conductive component thereof, and a heat dissipation structure using the same, wherein the thermally conductive organopolysiloxane composition contains: 100 parts by mass of an organopolysiloxane having the above-mentioned narrow molecular weight distribution, preferably a relatively low molecular weight, and the content of cyclic siloxanes being suppressed; and a thermally conductive filler in an amount in the range of 60% to 90% by volume relative to the total solid components in the composition.

[0019] The effects of the invention

[0020] By using the organopolysiloxane with alkenyl groups at both ends of the molecular chain involved in this invention as the matrix polymer, a thermally conductive organopolysiloxane composition, a thermally conductive component thereof, and a heat dissipation structure using the same can be provided. Even when the thermally conductive organopolysiloxane composition is a high-thermal-conductivity composition with a high content of thermally conductive filler, its viscosity can be suppressed, exhibiting excellent filling properties for cartridges and the like, and excellent extrusion workability during coating. It can also optionally cure to provide a uniform crosslinking reactant, and is not prone to density reduction even under high temperature and prolonged use. This suppresses the formation of voids or bubbles to maintain the predetermined heat dissipation, avoids contact failure, and is less prone to mold contamination. Furthermore, it has high heat resistance due to the absence of an alkaline catalyst. Additionally, according to this invention, a composition suitable for use in one or more applications selected from sealant compositions, conductive compositions, and thermally insulating compositions comprising the organopolysiloxane with alkenyl groups at both ends of the molecular chain can be provided. Detailed Implementation

[0021] [(A) Organopolysiloxanes with alkenyl groups at both ends of their molecular chains]

[0022] This component (A) is an organopolysiloxane with a narrow molecular weight distribution, having alkenyl groups at both ends of the molecular chain and a weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) of 1.20 or less, preferably in the range of 1.05 to 1.18, and more preferably in the range of 1.07 to 1.17. It is a characteristic component of this invention. Because the alkenyl groups, which are reactive functional groups, have uniform bonding positions and molecular lengths, this organopolysiloxane, when used as a matrix polymer in a thermally conductive composition, has the following advantages: even under high temperature and prolonged use, it is less prone to density reduction and the resulting deterioration in heat dissipation characteristics and physical strength.

[0023] Here, from the viewpoint of a matrix polymer in a thermally conductive composition with a high content of thermally conductive filler, in order to suppress the overall viscosity of the composition, improve the filling properties of cartridges, and enhance extrusion workability during coating, component (A) is expected to have a low degree of polymerization / high viscosity. Specifically, its number average molecular weight is 10,000 or less, preferably 500 to 10,000, more preferably 1,000 to 7,500, and particularly preferably in the range of 2,000 to 5,000. It should be noted that when the number average molecular weight of component (A) is less than the above lower limit, there is a tendency for the mechanical strength of the organopolysiloxane cured product to decrease. If it exceeds the above upper limit, especially when the content of the obtained thermally conductive filler is high, there is a tendency for the viscosity of the composition to increase. As a result, the low-viscosity matrix polymer may not be able to fully achieve the target technical effect, or the workability and coating properties for fine parts may decrease.

[0024] Furthermore, from the viewpoint of preventing contact failures and mold contamination of electronic components, minimizing density reduction during long-term use of the thermally conductive composition based on component (A) and thermally conductive components made therefrom, and suppressing the generation of voids or bubbles to maintain the predetermined heat dissipation, component (A) preferably contains less than 0.1% by mass of cyclic dimethylsiloxane with 20 or fewer polymers, and particularly preferably less than 0.05% by mass of cyclic dimethylsiloxane with 10 to 15 polymers. It should be noted that, as described later, these cyclic siloxanes are components that are easily generated as byproducts in equilibrium polymerization. Cyclic dimethylsiloxanes with molecular weights close to that of component (A), particularly 10 to 15 polymers, are difficult to remove from component (A) subsequently through stripping or other methods aimed at removing volatile components. Therefore, component (A) is suitably preferably obtained by living polymerization starting with D3. Furthermore, in component (A), the content of each cyclic dimethylsiloxane with 20 or fewer polymers is preferably less than 0.1% by mass (i.e., less than 1000 ppm), and particularly for each cyclic dimethylsiloxane with 10 to 15 polymers, the content is especially preferably less than 0.01% by mass (i.e., less than 100 ppm), and the sum of the contents of cyclic dimethylsiloxanes with 20 or fewer polymers is most preferably less than 0.1% by mass (i.e., less than 1000 ppm). An organopolysiloxane having such a narrow molecular weight distribution and with suppressed content of cyclic dimethylsiloxanes with 20 or fewer polymers can be obtained by the living polymerization method described later.

[0025] Component (A) may consist of one or more organopolysiloxanes with alkenyl groups at both ends of their molecular chains, as long as the requirements related to molecular weight distribution, as described above, are met. The molecular structure of such alkenyl-containing organopolysiloxanes is preferably linear. From the viewpoint of molecular length and uniformity of curing (crosslinking) reaction, linear organopolysiloxanes with alkenyl groups only at both ends of the molecular chain are preferred.

[0026] Examples of alkenyl groups within the molecule of component (A) include vinyl, allyl, butenyl, and hexenyl groups. Furthermore, examples of organic groups other than the alkenyl group in component (A) include alkyl groups such as methyl; aryl groups such as phenyl; and monovalent hydrocarbon groups other than the alkenyl group, such as 3,3,3-trifluoropropyl. Industrially, methyl or phenyl is preferred.

[0027] Particularly preferred component (A) is a linear alkenyl-containing organopolysiloxane, such as dimethylvinylsiloxy-terminated dimethylpolysiloxane at both ends of the molecular chain, and a dimethylvinylsiloxy-terminated dimethylsiloxane / methylphenylsiloxane copolymer. Particularly preferred are linear dimethylpolysiloxanes having alkenyl groups with 2 to 8 carbon atoms only at both ends of the molecular chain, satisfying the above requirements related to molecular weight distribution, cyclic siloxane content, and molecular weight range. Industrially, dimethylvinylsiloxy-terminated dimethylpolysiloxane is preferably exemplified.

[0028] [Availability: including uses selected from one or more of thermally conductive compositions, sealant compositions, conductive compositions, and insulating compositions]

[0029] Component (A), as described above, is suitable as a matrix polymer for thermally conductive compositions, but can also be used as a raw material for other curable or non-curable compositions. For example, curable or non-curable compositions containing component (A) are included within the scope of this invention; in particular, compositions suitable for use in addition to thermally conductive compositions, those selected from sealant compositions, conductive compositions, and thermally insulating compositions, are also included within the scope of this invention. Furthermore, the application of this composition is not limited to electronic materials, electronic components, etc., and can be used for optional purposes.

[0030] [Manufacturing method using living polymerization]

[0031] In order to meet the requirements related to its molecular weight distribution, the content of cyclic siloxanes, and the range of molecular weight, the organopolysiloxane (A) involved in this invention is preferably synthesized by living polymerization rather than equilibrium polymerization. When component (A) is synthesized by equilibrium polymerization, its molecular weight distribution becomes wider, resulting in the inability to achieve uniform crosslinking reactivity. Thermally conductive compositions using such organopolysiloxanes as matrix polymers and thermally conductive components made therefrom are prone to density reduction under high temperature (120°C or 150°C) and long-term use, deterioration due to suppression of voids and bubbles, and sometimes the intended heat dissipation cannot be maintained. In addition, it is difficult to achieve a composition without an alkali catalyst in equilibrium polymerization, especially it is sometimes difficult to achieve a high purity with a content of less than 0.1% by mass of cyclic dimethylsiloxanes of 20 polymers or less. This is because low-polymer cyclic dimethylsiloxanes (e.g., 10-20 polymers) that are close to component (A) are sometimes not sufficiently removed by conventional stripping / reduced pressure distillation methods aimed at removing volatile components (CV). As a result, the content of cyclic dimethylsiloxanes is sometimes not sufficiently suppressed, and a narrow molecular weight distribution of Mw / Mn below 1.2 cannot be ensured.

[0032] The living polymerization method of the present invention preferably includes the following steps: step (I), using a starting material having one or more protons (H) and Li at both ends, to carry out living polymerization of a hexaorganocyclotrisiloxane (D3) in the presence of a lithium-based catalyst; and step (II), a step of end-capping the molecular chain ends of the obtained polymer with an organosilicon compound capable of alkenyl introduction, using one or more known end-capping agents selected from 1,3-dienyl-1,1,3,3-tetraorganodisilazane, alkenyl-containing organochlorosilanes, etc. Preferably, the reaction can be carried out in one or more polar solvents, and particularly preferably a mixed solvent containing a polar solvent for promoting the reaction.

[0033] Specifically, component (A) in this invention is characterized in that it comprises:

[0034] Use starting materials with one or more protons (H) and Li at both ends.

[0035] Process (I): Make (R) A 2SiO)3

[0036] (In the above formula, R) A Each group is an alkyl, aryl, or a group in which a portion of the carbon atom bonded to a hydrogen atom is replaced by a halogen atom.

[0037] The hexaorganocyclic trisiloxanes represented undergo living polymerization in the presence of a lithium-based catalyst; and

[0038] Process (II): Utilizing

[0039] Selected from R B R A 2SiNSiR A 2R B

[0040] (In the above formula, R) A For the same group as above, R B (alkenyl), and

[0041] R B R A 2SiCl

[0042] (In the above formula, R) A R B (For the same groups as above)

[0043] At least one of the alkenyl diorganochlorosilanes represented

[0044] The 1,3-dienyl-1,1,3,3-tetraorganodisilazane represented here is used to cap the molecular chain ends on the polymerization termination side of the polymer obtained through step (I).

[0045] The starting material for this reaction is a substance that serves as the starting point for living polymerization; specifically, it is a starting material whose molecule ends have one or more protons (H) and Li. Here, the proton (H) can be H from water or OH-terminated molecules, and Li can be in the form of a metal salt. Examples of such starting materials include: water, siloxane oligomers with hydroxyl groups (=silanol groups) at both ends of the molecular chain, and LiOH. It should be noted that, in the case of synthesizing polymers with terminal alkenyl groups with high purity, the above-mentioned R-terminated alkenyl groups can be used in part of the starting material. B R A Siloxane oligomers with 2Si-terminal (e.g., vinyldimethylsilyl) and OH-terminal ends, or vinyldimethylsilanols. Additionally, the amount of starting materials such as water can be appropriately adjusted to improve polymerization precision.

[0046] (R A 2SiO)3

[0047] The hexaorganocyclic trisiloxane (D3) represented is the raw material of component (A), where R A Each group, independently of alkyl, aryl, or a portion thereof whose carbon atom is bonded to a hydrogen atom is replaced by a halogen atom, includes, for example, methyl, ethyl, propyl, isopropyl, phenyl, etc. Industrially, R... A The solvent is methyl or phenyl. When performing the living polymerization of the above-mentioned hexaorganocyclic trisiloxane, it is preferable to perform azeotropic dehydration using organic solvents such as toluene, or dehydration treatment using zeolite-based desiccants such as molecular sieves or solid desiccants such as calcium hydride.

[0048] The lithium-based catalyst is the catalyst used for living polymerization in the manufacturing method involved in this invention. Metallic lithium, lithium hydride, butyllithium, lithium hydroxide, or mixtures of two or more thereof can be used, with lithium hydroxide being preferred. It should be noted that if substances other than lithium-based catalysts, such as other alkali metal compounds, are used, the yield of the target general-form organopolysiloxane may sometimes decrease. The lithium-based catalyst can be added to the system in the form of an aqueous solution, for example, in the form of a 0.5% to 5% by mass aqueous solution in the range of 0.005% to 0.050% by mass relative to D3 as a raw material.

[0049] The reaction solvent used in the living polymerization reaction involved in this invention (which is common in steps (I) and (II)) is not particularly limited, but from the viewpoint of ensuring the smooth progress of the living polymerization reaction, a mixed solvent comprising (S1) one or more polar solvents selected from acetonitrile, methyl ethyl ketone, and methyl isobutyl ketone, and (S2) one or more polar solvents selected from dimethyl sulfoxide and dimethylformamide is preferred. Here, the polar solvent as (S2) is a polar solvent used for the purpose of promoting the reaction, and the mass ratio of (S1):(S2) can be appropriately selected in the range of 9:1 to 3:1 depending on the reaction conditions and the scale of the reaction. However, the use of other known reaction solvents in living polymerization, such as tetrahydrofuran, is not prohibited.

[0050] The active polymerization reaction in step (I) is a ring-opening polymerization reaction of D3. Depending on the reaction scale, D3 as raw material is stirred together with a lithium catalyst under heating conditions of 10°C to 40°C, preferably room temperature to 35°C. There is no particular limitation on the reaction time, but it is usually carried out in the range of 30 minutes to 10 hours, preferably 2 hours to 8 hours, while monitoring the conversion rate of D3 using GLC (gas chromatography).

[0051] Step (II) is a process of end-capping the molecular chain of the organopolysiloxane polymer obtained in step (I) with 1,3-dienyl-1,1,3,3-tetraorganodisilazane, wherein an alkenyl group from this disilazane is introduced into the molecular chain end of the organopolysiloxane. Here, from the viewpoint of making the purity and molecular weight distribution of the final product close to a single peak, it is preferable to remove low-boiling-point components by vacuum distillation before step (II) and after step (I), or optionally, a filtration operation may be performed.

[0052] Process (II) is the following process: using a selection from R B R A 2SiNSiR A 2R B

[0053] (In the above formula, R) A For the same group as above, R B (Alkenyl)

[0054] The 1,3-dienyl-1,1,3,3-tetraorganodisilazane represented

[0055] and R B R A 2SiCl (in the above formula, R) A R B (For the same groups as above)

[0056] At least one of the alkenyl diorganochlorosilanes represented herein shall cap the polymer chain ends on the polymerization termination side of the organopolysiloxane polymer obtained by step (I). R in the formula... A The same group as described above is preferred, specifically methyl. Additionally, R in the formula... B From the viewpoint of the alkenyl group in the final obtained component (A), it is preferable to have an alkenyl group having 2 to 8 carbon atoms, especially a vinyl or hexenyl group. As a capping agent, examples include tetramethyldivinyldisilazane, vinyldimethylchlorosilane, etc., and these are preferred.

[0057] As for the reaction conditions during end-capping, it is preferable to add an acidic catalyst such as trifluoroacetic acid (containing a neutralizing salt) to the organopolysiloxane polymer obtained in step (I) or the reaction solution containing it, and carry out the molecular chain end-capping reaction while stirring the reaction solution at 40°C to 140°C for a reaction time typically of 1 hour to 8 hours. This reaction can also be carried out without a solvent. If the reaction temperature is too low, the molecular end-capping may not be sufficient; if the reaction temperature is too high, the end-capping agent, such as silazane, used for end-capping may volatilize, resulting in insufficient end-capping. Furthermore, if the reaction time is too short, the molecular end-capping may not be sufficient, sometimes resulting in the inability to obtain the desired organopolysiloxane with alkenyl groups at both ends of the molecular chain with high purity.

[0058] After the reaction in step (II) is completed, unreacted components, solid components, reaction residues, etc., that did not participate in the polymerization reaction in the initial raw material components can be removed by known methods such as filtration and / or vacuum distillation. Specifically, as for the conditions for vacuum distillation removal, it is desirable to carry out vacuum distillation removal under conditions of reduced pressure of 1,000 Pa or less, preferably 500 Pa or less, more preferably 300 Pa or less, and preferably around 100°C to 180°C, more preferably around 120°C to 150°C. In addition, from the viewpoint of ensuring the quality of component (A), the filtration step is preferably a sterile filtration step.

[0059] [Thermoconductive organopolysiloxane composition]

[0060] Preferably, the thermally conductive organopolysiloxane composition involved in this invention...

[0061] The matrix polymer comprises (A) an organopolysiloxane with alkenyl groups at both ends of the molecular chain and (B) a thermally conductive filler, and contains, relative to 100 parts by mass of component (A), component (B) in an amount ranging from 60 vol% to 90 vol% relative to the total solid components in the composition. The thermally conductive organopolysiloxane composition preferably has a thermal conductivity of 9.0 W / mK or higher, and optionally possesses curing reactivity. It may also be a composition forming a tackifier, gel, or cured product, or a non-curing composition such as a grease. When the composition possesses curing reactivity, since the curing reactivity group of component (A) is alkenyl, it preferably possesses one or more curing reactivity selected from hydrosilylation and free radical polymerization.

[0062] Furthermore, the thermally conductive organopolysiloxane composition of the present invention may comprise (C) an organohydrogen polysiloxane, (D) a catalytic amount of a catalyst for the hydrosilylation reaction, (E) an organosilicon compound that functions as a specific surface treatment agent, (F) at least one selected from fatty acids, fatty acid esters, and fatty acid metal salts, (G) a heat-resistant agent, and (H) a component selected from hydrosilylation reaction inhibitors, adhesion promoters, organic solvents, and other additives. Additionally, the composition of the present invention may be a one-component composition or a two-component composition or other multi-component composition. The components and their amounts will be described below.

[0063] Component (A) is the matrix polymer of the thermally conductive organopolysiloxane composition of the present invention. The alkenyl groups, which are reactive functional groups, have uniform bonding positions and molecular lengths and narrow molecular weight distributions, and are of high purity. Therefore, when used as the matrix polymer of the thermally conductive composition, it has the following advantages: even under high temperature and long-term use, it is not easy to cause a decrease in density and the resulting deterioration of exothermic properties and physical strength.

[0064] This composition can be designed as a curable or non-curable composition. Here, the curing reactive group is a functional group that can cure the entire composition (including gelation, the same below) through a crosslinking reaction, and is alkenyl in component (A), having hydrogen silanization reactivity and free radical polymerization reactivity.

[0065] Component (A) has alkenyl groups at both ends of its molecular chain, making it suitable as a main agent for curable thermally conductive organopolysiloxane compositions, such as curable thermally conductive elastomers, thermally conductive gels, and curable thermally conductive gap-filling materials. It should be noted that, when designing curable compositions, the curing agent for the compositions described later may include (C) an organohydrogen polysiloxane and (D) a catalytic amount of a catalyst for the hydrosilylation reaction, which is preferred.

[0066] [(B) Thermally conductive filler]

[0067] Component (B) is a thermally conductive filler used to impart thermal conductivity to the composition and the thermally conductive component formed by curing the composition. As such a component (B), it is preferably selected from at least one powder and / or fiber selected from the group consisting of pure metals, alloys, metal oxides, metal hydroxides, metal nitrides, metal carbides, metal silicides, carbon, soft magnetic alloys, and ferrite, preferably metal-based powders, metal oxide-based powders, metal nitride-based powders, or carbon powders. The shape of component (B) is not particularly limited, and examples include spherical, needle-like, disc-like, rod-like, and amorphous shapes, with spherical and amorphous shapes being preferred. Furthermore, the average particle size of component (B) is not particularly limited, preferably in the range of 0.01 to 500 μm, and more preferably in the range of 0.01 to 300 μm.

[0068] As component (B), silver powder, aluminum powder, alumina powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, boron nitride powder, or graphite are preferred. Furthermore, where electrical insulation is required in this composition, metal oxide powders or metal nitride powders are preferred, with alumina powder, zinc oxide powder, magnesium oxide powder, or aluminum nitride powder being particularly preferred.

[0069] The thermally conductive filler can be surface-treated, in whole or in part, with the following component (E), i.e., an organosilicon compound, and is preferred. Furthermore, along with these components, various surface-treatment agents known as coupling agents, such as powders and / or fibers, which are thermally conductive fillers, can be used. Besides component (E), examples of surface-treatment agents for treating the powders and / or fibers used to treat component (B) include surfactants, other silane coupling agents, aluminum-based coupling agents, and organosilicon-based surface-treatment agents.

[0070] For component (B), to improve its filling efficiency, for example, by combining powders with large particle sizes and powders with small particle sizes in a ratio according to the distribution curve of the densest filling theory, the filling efficiency is improved, thereby achieving low viscosity and high thermal conductivity. In this invention, in order to improve the filling efficiency, a mixture of two or more powders with different particle sizes or shapes can also be used from (B1) spherical and fragmented alumina powders with an average particle size of 0.01 μm to 100 μm, (B2) spherical and fragmented magnesium oxide powders with an average particle size of 0.01 μm to 100 μm, and (B3) amorphous aluminum nitride powders with an average particle size of 0.01 μm to 50 μm.

[0071] [Content of component (B)]

[0072] In this invention, to achieve high thermal conductivity, the content of component (B) is in the range of 60% to 90% by volume relative to the total solid components (components that form a cured product through a curing reaction) in the composition, preferably in the range of 65% to 90%, 70% to 90%, or 70% to 85% by volume. If the content of component (B) is less than the lower limit mentioned above, it is sometimes impossible to achieve the high thermal conductivity, especially the high thermal conductivity of 9.0 W / mK or higher, which is the target of this invention. On the other hand, if the upper limit of the above range is exceeded, even when component (A), component (E) is used, or component (B) is used for surface treatment, the viscosity of the resulting composition becomes significantly higher, or the initial cured product becomes significantly harder, and sometimes its workability, stress relief characteristics on the substrate, and adhesion are reduced.

[0073] It should be noted that the amount of component (B) used is more preferably in the range of 600 to 4500 parts by mass relative to 100 parts by mass of component (A), and particularly preferably in the range of 800 to 4000 parts by mass. When the amount of component (B) used meets the above-mentioned volume percentage range and the amount of component (A) used meets the above-mentioned range, the technical problem of the present invention can be solved particularly appropriately.

[0074] [Other inorganic fillers]

[0075] Regarding the composition of the present invention, as an arbitrary component, inorganic fillers (also referred to as "inorganic filler materials") such as fumed silica, wet silica, pulverized quartz, titanium dioxide, magnesium carbonate, zinc oxide, iron oxide, diatomaceous earth, and carbon black can be formulated, and the surface of such inorganic fillers can be hydrophobically treated using the component (E) described later and / or other organosilicon compounds (silazanes, etc.). From the viewpoint of balancing high thermal conductivity, the softness and stress relief properties of the cured product, and adhesion to the substrate, the composition can be substantially free of fillers other than component (B). On the other hand, for the purpose of improving (strengthening) mechanical strength, adjusting viscosity, and other functions, the above-described fillers can be used within a range that does not impair the technical effects of the present invention, and are included in one of the preferred embodiments of the present invention.

[0076] [Surface treatment of component (B)]

[0077] The component (B) involved in this invention is preferably surface-treated using component (E) described later. There are no particular limitations on the surface treatment method using these components, but direct treatment of the thermally conductive inorganic filler as component (B), the integral blend method, dry separation, etc., can be used. In this invention, from the viewpoint of improving the overall filling properties of the composition and the adhesive strength of the cured product, the following heated surface treatment method is most preferably exemplified: component (A) is pre-mixed with component (E), component (B) is sequentially mixed into the mixture, homogenized, and then heated (base heat). This surface treatment method can be performed by heating and stirring the mixture under reduced pressure at 100–200°C. The temperature conditions and stirring time can be designed according to the amount of sample, preferably in the range of 120–180°C and 0.25–10 hours. It should be noted that the surface treatment process of component (B) is optional, but from the viewpoint of improving the flowability, gap filling and thixotropy of the composition, it can be a staged treatment process including the following steps: surface treatment of at least a portion of component (B) with component (E1) or (E2), followed by surface treatment of component (B) with component (E3).

[0078] There are no particular limitations on the apparatus used for the above mixing, but examples include: single-shaft or twin-shaft continuous mixers, two-roll mixers, Ross mixers, Hobart mixers, toothed mixers, planetary mixers, kneaders, Henschel mixers, etc.

[0079] [(C) Organohydrogen polysiloxane]

[0080] Component (C) is the main crosslinking agent of the composition of the present invention. Organohydrogen polysiloxanes having two or more silicon atoms bonded to hydrogen atoms within the molecule can be used without particular limitation. However, from the viewpoint of the softness of the resulting cured product and its adhesion retention to the substrate, the number (average) of silicon atoms bonded to hydrogen atoms in the organohydrogen polysiloxane molecule is preferably not more than eight. Particularly preferred is a linear organohydrogen polysiloxane containing at least (C1) a viscosity of 1 to 1,000 mPa·s at 25°C, an average of 2 to 4 silicon atoms bonded to hydrogen atoms within the molecule, wherein the side chains of the molecular chain have at least an average of one silicon atom bonded to hydrogen atom.

[0081] Examples of such components (C1) include: trimethylsiloxy-terminated methylhydrosiloxane / dimethylsiloxane copolymers at both ends of the molecular chain, and dimethylsiloxy-terminated methylhydrosiloxane / dimethylsiloxane copolymers at both ends of the molecular chain. It should be noted that these examples are not limiting; some methyl groups may also be replaced by phenyl, hydroxyl, alkoxy, etc.

[0082] The viscosity of component (C1) at 25°C is not particularly limited, but is preferably in the range of 1 to 500 mPa·s, and particularly preferably in the range of 1 to 100 mPa·s. Furthermore, from the viewpoint of preventing contact failure, it is preferable to reduce or remove low molecular weight siloxane oligomers (octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5)).

[0083] [Amount of organohydrogen polysiloxane (crosslinking agent) in the composition]

[0084] From the perspective of the rubber properties, mechanical strength and adhesive properties of the obtained organopolysiloxane cured product, in the composition of the present invention, for component (C), it is particularly preferred that the amount of silicon atoms bonded to hydrogen atoms in component (C) is in the range of 0.2 moles to 5.0 moles, 0.3 moles to 3.0 moles, or 0.4 moles to 2.0 moles, at least relative to 1 mole of alkenyl groups contained in component (A).

[0085] [(D) Catalyst for hydrosilylation reaction]

[0086] The catalyst for the hydrosilylation reaction is a component used for curing this composition. Examples include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. From the viewpoint of significantly promoting the curing of this composition, platinum-based catalysts are preferred. Examples of platinum-based catalysts include platinum micropowder, chloroplatinic acid, alcoholic solutions of chloroplatinic acid, platinum-alkenylsiloxane complexes, platinum-olefin complexes, platinum-carbonyl complexes, and catalysts in which these platinum-based catalysts are dispersed or encapsulated in thermoplastic resins such as silicone resins, polycarbonate resins, and acrylic resins. Platinum-alkenylsiloxane complexes are particularly preferred. Platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes are particularly preferred, and it is preferable to add them in the form of an alkenylsiloxane solution of this complex. Furthermore, from the viewpoint of improving workability and the pot life of the composition, particulate platinum-containing hydrosilylation reaction catalysts dispersed or encapsulated in thermoplastic resins can also be used. It should be noted that non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt can be used as catalysts to promote the hydrosilylation reaction.

[0087] On the other hand, as catalysts for the hydrosilylation reaction, so-called high-energy ray-activated catalysts or photoactivated catalysts such as (methylcyclopentadienyl)trimethylplatinum(IV) complex and bis(2,4-pentanedione)platinum(II) complex can be used. By using such catalysts for the hydrosilylation reaction, the overall composition can sometimes achieve the following characteristics: it can be cured even at low temperatures when triggered by high-energy ray irradiation, exhibits excellent storage stability, and the reaction is easy to control, thus resulting in excellent workability. In this case, ultraviolet light is preferred as the high-energy ray from the perspective of catalytic activation efficiency, and from the viewpoint of industrial application, ultraviolet light in the wavelength range of 280–380 nm is preferred. Furthermore, the irradiation dose varies depending on the type of high-energy ray-activated catalyst, but in the case of ultraviolet light, the cumulative irradiation dose at a wavelength of 365 nm is preferably 100 mJ / cm². 2 ~100J / cm 2 Within the range.

[0088] The amount of catalyst added for the hydrosilylation reaction is only the amount of catalyst. More specifically, relative to the whole composition, the amount of metal atoms is in the range of 0.01ppm to 500ppm, 0.01ppm to 100ppm, or 0.01ppm to 50ppm by mass.

[0089] [Component (E)]

[0090] Component (E) is a surface treatment agent that functions as component (B) and other inorganic fillers mentioned above. It can coexist with these components in the composition. Preferably, component (E) is used...

[0091] At least a portion of (E) has undergone surface treatment of the aforementioned component (A), but it is particularly preferred from the viewpoint of uniform dispersion of these components and workability of the resulting composition. Component (E) is one or more components selected from siloxane compounds with a single alkoxy group at the end (=components (E1), (E2)) and / or alkoxysilanes with a long-chain alkyl group (=component (E3)), and more specifically, it is one or more components selected from components (E1) to (E3).

[0092] (E1) General formula (1):

[0093] [Chemical Formula 1]

[0094]

[0095] (where R) 1 R is an independent, unsubstituted or substituted monovalent hydrocarbon group without a carbon-carbon double bond. 2Independently a hydrogen atom, alkyl, alkoxyalkyl, or acyl group, where a is an integer from 5 to 250 and b is an integer from 1 to 3. (This refers to an organopolysiloxane with a viscosity of 10 to less than 10,000 mPa·s at 25°C.)

[0096] In general formula (1), R 1 Independently, a monovalent hydrocarbon group without a carbon-carbon double bond, whether unsubstituted or substituted, includes, as examples, straight-chain alkyl, branched-chain alkyl, cyclic alkyl, aryl, aralkyl, and haloalkyl. Industrially, R... 1 Methyl or phenyl is preferred, and from the viewpoint of heat resistance, methyl is preferred.

[0097] R 2 Independently, it can be a hydrogen atom, alkyl, alkoxyalkyl, alkenyl, or acyl group. From a surface treatment point of view, R 2 Alkyl groups are preferred, and methyl or ethyl groups are particularly preferred.

[0098] In general formula (1), a is an integer ranging from 5 to 250, preferably from 10 to 200. Furthermore, b is an integer ranging from 1 to 3, preferably 2 or 3. As a component (E1) of the present invention, preferably, by example, b is 3, having a trialkoxysilyloxy group at a single end of the molecular chain, R 1 It is a methyl polydimethylsiloxane.

[0099] (E2) From general formula (2):

[0100] R alk R 3 2SiO(R 3 2SiO) c R 3 2Si-R 4 -SiR 3 (3-d) (OR 5 ) d

[0101] (where R) alk It is an alkenyl group, R 3 R is an independent, unsubstituted or substituted monovalent hydrocarbon group without a carbon-carbon double bond. 4 R is an oxygen atom or a divalent hydrocarbon group. 5 A siloxane compound whose molecular chain ends have an alkenyl group and a hydrolyzable silane group, which are independently represented by a hydrogen atom, alkyl group, alkoxyalkyl group or acyl group, c is an integer from 1 to 250 and d is an integer from 1 to 3, and whose viscosity at 25°C is in the range of 10 to 10,000 mPa·s.

[0102] In general formula (2), R alkAlkenyl groups, such as vinyl, allyl, and hexenyl, have 2 to 10 carbon atoms. Because component (E2) has an alkenyl group at a single end of its molecular chain, it can sometimes improve curing and adhesion properties when used in conjunction with other crosslinking agents.

[0103] In the formula, R 3 Independently, it can be an unsubstituted or substituted monovalent hydrocarbon group without a carbon-carbon double bond, including: straight-chain alkyl, branched alkyl, cyclic alkyl, alkenyl, aryl, aralkyl, haloalkyl, methyl or phenyl from an industrial point of view, with methyl preferred from a heat resistance point of view. R 4 It is an oxygen atom or a divalent hydrocarbon group. As R... 4 Divalent hydrocarbon groups can be listed as: alkylene groups such as methylene; alkylene oxides such as ethylene oxide and propylene oxide. On the other hand, R... 4 Oxygen atoms are acceptable and preferred.

[0104] In the formula, R 5 Independently, it is a hydrogen atom, alkyl, alkoxyalkyl, or acyl group, preferably alkyl, and from the viewpoint of surface treatment, particularly preferably methyl or ethyl. Component (G2) is obtained through Si(OR) 5 The single-terminal structure shown in the figure has hydrolyzable silanes within the molecule, thus providing excellent surface treatment results when used in conjunction with component (C).

[0105] In the formula, c is the degree of polymerization (excluding the end) of the diorganosiloxane unit of component (E2), which is an integer from 1 to 250, preferably an integer from 1 to 100, and particularly preferably an integer from 1 to 50. In the formula, d is an integer from 1 to 3, preferably 3. When d is 3, the single end of component (E2) is particularly preferably trimethoxysilyl (-Si(OMe)3).

[0106] The amount of components (E1) and (E2) (total amount when both are used together) is not particularly limited as long as it is sufficient for the surface treatment of the filler. As an example, the amount is in the range of 0.005 to 100 parts by mass relative to 100 parts by mass of component (F) in the whole composition, preferably 0.05 to 100 parts by mass, and more preferably 0.5 to 50 parts by mass.

[0107] (E3) Alkoxysilanes or their hydrolytic condensates having an alkyl group having 6 or more carbon atoms in the molecule.

[0108] Like components (E1) or (E2), component (E3) acts as a surface treatment agent in the composition, serving as a thermally conductive filler containing components (A) to (D). It improves the dosage and overall viscosity and flowability of the composition, while also enhancing adhesive properties. Such alkoxysilanes require an alkyl group with C6 or more. When using alkylalkoxysilanes containing only alkyl groups smaller than C6, such as methyl groups, or their hydrolysed condensates, sufficient adhesive properties are sometimes not achieved, even with the use of adhesive-imparting agents described later.

[0109] Specific examples of alkyl groups having 6 or more carbon atoms include: hexyl, octyl, dodecyl, tetradecyl, hexadecyl, octadecyl, etc.; aralkyl groups such as benzyl and phenylethyl, etc., with alkyl groups having 6 to 20 carbon atoms being particularly preferred.

[0110] Preferably, component (E3) is an alkoxysilane represented by the following structural formula:

[0111] Y n Si(OR) 4-n

[0112] (In the formula, Y is an alkyl group with 6 to 18 carbon atoms, R is an alkyl group with 1 to 5 carbon atoms, and n is a number from 1 to 3.)

[0113] Examples of OR groups include methoxy, ethoxy, propoxy, and butoxy groups, with methoxy and ethoxy groups being particularly preferred. It should be noted that n is 1, 2, or 3, with 1 being particularly preferred.

[0114] Such a component (E3) can be specifically exemplified by: C6H 13 Si(OCH3)3, C8H 17 Si(OC2H5)3, C 10 H 21 Si(OCH3)3, C 11 H 23 Si(OCH3)3, C 12 H 25 Si(OCH3)3, C 14 H 29 Si(OC2H5)3, etc., the most preferred is decyltrimethoxysilane.

[0115] There is no particular limitation on the amount of component (E3) as long as it is sufficient to surface treat the filler. As an example, the amount of component (B) in the composition is in the range of 0.005 parts to 20 parts by weight relative to 100 parts by weight in the whole composition, preferably 0.05 parts to 10 parts by weight, and more preferably 0.5 parts to 7.5 parts by weight.

[0116] [(F) Fatty acid compounds]

[0117] In the case of a curable composition of the present invention, in addition to the above-described components, optionally, at least one fatty acid compound selected from fatty acid esters and fatty acid metal salts may be included. This component is responsible for suppressing hardness changes during heat aging in the present composition and the cured product, which is a silicone-based thermally conductive component formed by curing the present composition. In particular, when the amount of the thermally conductive filler is within the above-described range, without the use of component (F), the cured product hardens rapidly during heat aging, sometimes resulting in impaired stress relief, flexibility, and substrate adhesion. However, by using component (F) and preferably component (G) as a heat-resistant agent in the hydrosilylation curing reactive composition, the resulting cured product exhibits high thermal conductivity and maintains its initial hardness and rubber properties, achieving good stress relief, flexibility, and substrate adhesion.

[0118] Specifically, component (F) is selected from at least one of fatty acids, fatty acid esters, and fatty acid metal salts. Examples include: fatty acids such as hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, benzyl acid, and oleic acid; fatty acid esters as alkyl esters; alkali metal salts of fatty acids such as sodium, lithium, and potassium; and alkaline earth metal salts of fatty acids such as calcium. Preferably, component (F) is (F1), which is selected from at least one of saturated fatty acids and saturated fatty acid metal salts. Particularly preferred is (F1-1), which is selected from at least one of stearic acid, alkali metal salts of stearic acid, and alkaline earth metal salts of stearic acid.

[0119] The exact mechanism by which component (F), particularly in systems used in combination with component (G), inhibits changes in the hardness of the cured product is not fully understood, but it is speculated to be as follows: Fatty acid compounds such as fatty acids, fatty acid salts (soaps), and fatty acid esters exist in limited quantities within the heat-resistant silicone cured product matrix in the presence of component (G). This results in the formation of a water-resistant and lubricating film or localized structure composed of these fatty acid compounds on or near the surface of the thermally conductive filler particles. This reduces or deactivates the chemical activity of the particle surface at high temperatures and effectively prevents agglomeration or the formation of coarse particles between the surfaces of the thermally conductive filler. However, component (F) can exert its technical effect simply by being uniformly mixed with other components, even if it is not used as a surface treatment agent for the thermally conductive filler. Therefore, in this invention, there is no limitation on the timing of adding component (F) to the composition.

[0120] The amount of component (F) is preferably in the range of 0.05 to 2.0 parts by mass relative to 100 parts by mass of the thermally conductive filler (total amount when composed of multiple components). In particular, to achieve the aforementioned technical effect, the amount of component (F) needs to be within the aforementioned range, which has a critical significance. That is, if the amount of component (F) is less than the lower limit, even when used in conjunction with component (G), it may sometimes be impossible to suppress changes in the hardness of the cured product. On the other hand, if the amount of component (F) exceeds the upper limit, it may sometimes be impossible to suppress changes in the hardness of the cured product.

[0121] [(G) Heat resistance enhancer]

[0122] In addition to the above-described components, the compositions of the present invention may optionally contain a heat-resistant agent. The heat-resistant agent can be formulated alone, but the compositions and cured products of the present invention, by containing a certain amount of the above-described (F) fatty acid compound and using the (G) heat-resistant agent, can more preferably achieve their technical effects. The amount of the heat-resistant agent can be in the range of 0.01 to 5.0% by mass of the total composition (solid components), or in the range of 0.05 to 2.0% by mass and 0.07 to 0.5% by mass.

[0123] Examples of heat-resistant agents include: metal oxides such as iron oxide, titanium oxide, cerium oxide, magnesium oxide, and zinc oxide; metal hydroxides such as cerium hydroxide; phthalocyanine compounds; cerium silanolates; cerium salts of fatty acids; and reaction products of organopolysiloxanes with cerium carboxylates. Phthalocyanine compounds (G1) are particularly preferred. For example, additives selected from the group consisting of metal-free phthalocyanine compounds and metal-containing phthalocyanine compounds disclosed in Japanese Patent Application Publication No. 2014-503680 are preferred. Among metal-containing phthalocyanine compounds, copper phthalocyanine compounds are particularly preferred. An example of a most preferred, but not limited, heat-resistant agent is 29H,31H-phthalocyanate (2-)-N29,N30,N31,N32 copper. Such phthalocyanine compounds are commercially available, for example, Stan-tone (trademark) 40SP03 from PolyOne Corporation (Avon Lake, Ohio, USA).

[0124] [(H) Hydrosilylation reaction inhibitors, adhesion promoters, organic solvents and other additives]

[0125] In cases where the composition of the present invention has curing reactivity, it is preferable to further include component (H), and more preferably to include one or more components selected from components (F) and (G), particularly preferably components (F) and (G) are used together, but may also further include other components as follows. In particular, in cases where the composition has curing reactivity, it is particularly preferable to use a hydrogen silanization reaction inhibitor.

[0126] [Inhibitor of hydrosilylation reaction]

[0127] In cases where the composition of the present invention has curable properties, from the viewpoint of its workability, it is preferable to further include a hydrosilylation reaction inhibitor. The hydrosilylation reaction inhibitor is a component used to inhibit the hydrosilylation reaction of the thermally conductive organopolysiloxane composition of the present invention. Specifically, examples include, for instance, acetylene-based, amine-based, carboxylic acid ester-based, phosphite-based, and other reaction inhibitors such as acetylenol. The amount of reaction inhibitor added is typically 0.001 to 5% by mass of the total thermally conductive organopolysiloxane composition. In particular, for the purpose of improving the workability of this composition, acetylene compounds such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-phenyl-1-butyn-3-ol (=phenylbutynol) may be used without particular restriction; enynyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; cycloalkenylsiloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and triazole compounds such as benzotriazole may be used.

[0128] [Adhesive-enhancing agent]

[0129] In the compositions of the present invention, adhesive-improving agents may be formulated to improve the adhesive strength and permanent adhesion to the substrate of the cured product, etc. Adhesive-improving agents that can be used in the present invention may be selected from one or more of the following adhesive-improving agents: a reaction mixture of an amino-containing organoalkoxysilane and an epoxy-containing organoalkoxysilane (containing cyclocarbasilatrane derivatives or heteroazosilane tricyclic derivatives having specific structures), an organic compound having two or more alkoxysilyl groups in its molecule, represented by a disilaalkane compound (e.g., 1,6-bis(trimethoxysilyl)hexane), an epoxy-containing silane, or a partially hydrolyzed condensate thereof; and two or more adhesive-improving agents selected from these may be used in combination, preferably.

[0130] Preferably, the adhesive agent comprises (L-1) and (L-2) in a mass ratio of 5:95 to 95:5, more preferably in a mass ratio of 50:50 to 95:5, and even more preferably in a mass ratio of 60:40 to 90:30.

[0131] (L-1) From the general formula:

[0132] R a n Si(OR b ) 4-n

[0133] (where R) a R is a monovalent organic group containing an epoxy group. b It consists of alkyl groups or hydrogen atoms with 1 to 6 carbon atoms. (n is a number in the range of 1 to 3)

[0134] The epoxy-containing silane or its partially hydrolyzed condensate shown; and

[0135] (L-2) An organic compound having at least two alkoxysilyl groups in a molecule and containing bonds other than silicon-oxygen bonds between these silyl groups.

[0136] It should be noted that while these components can improve the initial adhesion of organopolysiloxane cured products even when used individually, when used together in the aforementioned mass ratio, they can sometimes significantly improve the initial adhesion, adhesion durability, and adhesion strength (permanent adhesion) of organopolysiloxane cured products.

[0137] Examples of the above-mentioned components (L-1) include: 3-glycidylpropoxyprolyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane.

[0138] Examples of the above-mentioned components (L-2) include: 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,4-bis(trimethoxysilyl)hexane, 1,5-bis(trimethoxysilyl)hexane, 2,5-bis(trimethoxysilyl)hexane, 1-methyldimethoxysilyl-6-trimethoxysilylhexane, 1-phenyldiethoxysilyl-6-triethoxysilylhexane, 1,6-bis(methyldimethoxysilyl)hexane, and other disilane-based heteroalkyl groups.

[0139] As an adhesive agent other than the aforementioned components (L-1) and (L-2), it may further be used in the reaction mixture of an amino-containing organoalkoxysilane and an epoxy-containing organoalkoxysilane disclosed in Japanese Patent Publication No. 52-8854 and Japanese Patent Application Publication No. 10-195085 (including cyclocarbon nitrosiloxane derivatives and heteroazosilane tricyclic derivatives with specific structures).

[0140] [Other organic solvents and additives]

[0141] In addition to the components described above, the thermally conductive composition of the present invention may contain any other components formulated without prejudice to the purpose of the present invention. Examples of such arbitrary components include, for instance, cold-resistant agents, flame-retardant agents, pigments, dyes, etc. Furthermore, the thermally conductive composition of the present invention may, as needed, contain one or more antistatic agents composed of known surfactants, dielectric fillers, conductive fillers, release agents, thixotropic agents, antifungal agents, etc. Additionally, organic solvents may be added as needed.

[0142] [Preparation method and dosage form of the composition]

[0143] The thermally conductive composition of the present invention can be prepared by mixing the above-described components. An example of a mixing device is the same as that shown in the surface treatment of the filler. Furthermore, as described above, component (F) can be added after the surface treatment / basic heating of the filler, or it can be added together with the surface treatment agent of the filler; regardless of when it is added, the technical effects of the present invention can be achieved.

[0144] More specifically, the composition involved in this invention is preferably prepared by:

[0145] i) A manufacturing method comprising a step of mixing the above-mentioned component (A), filler and component (E) and heating the mixture, and then optionally mixing component (F) and other components;

[0146] ii) A manufacturing method comprising a step of mixing the above-mentioned component (A), filler, optional component (E) and component (G), heating and mixing the mixture, and then mixing the other components.

[0147] It can be manufactured using any of the manufacturing methods (mixing processes) described above. It should be noted that the heating conditions are the same as the basic heating conditions previously described in the surface treatment of the filler, and mixing is preferably carried out in a substantially uniform manner.

[0148] The thermally conductive composition involved in this invention can be a single-component composition, optionally containing the above-mentioned hydrogenation silylation reaction inhibitor and other components, or a multi-component composition consisting of two or more compositions stored separately. In the case of a multi-component composition, it is necessary not to simultaneously contain the above-mentioned components (A), (C), and (D). This is because if these components (main agent, crosslinking agent, and catalyst) are prepared simultaneously, the crosslinking reaction will automatically begin, and the storage stability of the composition will be lost within a short period of time, sometimes failing to achieve the long-term storage stability and workability intended for a multi-component composition. It should be noted that when using a multi-component composition, it is stirred in a common container using mechanical force such as a stirrer, or mixed using a dispensing machine or similar device corresponding to multi-component mixing for application or application.

[0149] The thermally conductive composition of this invention has extremely high thermal conductivity, and its cured product exhibits excellent flexibility and stress-relieving properties. It is also easily extruded from cartridges or dispensing machines, offering excellent work efficiency, filling properties, and coating properties. Therefore, even when used in small-scale applications such as syringes (e.g., 10-300 ml), it provides excellent coating and extrusion performance for heat-dissipating areas. Thus, this composition is easy to fill into small-scale cartridges or syringes and readily applicable to small-volume packaging production.

[0150] [Use of non-curing / uncured compositions]

[0151] The thermally conductive composition of the present invention can be applied to a heat dissipation component or a circuit board on which the heat dissipation component is mounted in a non-cured or uncured state to obtain a heat dissipation structure having an uncured heat dissipation component (e.g., thermal grease or uncured thermally conductive filler material).

[0152] [Curing properties]

[0153] When using a crosslinking agent (component (C)), the thermally conductive organopolysiloxane composition of the present invention can be cured by a hydrosilylation reaction, thereby forming a cured product with excellent thermal conductivity, suppressed hardness change even after heat aging, and excellent softness and stress relief properties. The temperature conditions for curing this hydrosilylation-cured composition are not particularly limited, but are generally in the range of 20°C to 200°C, preferably in the range of 20°C to 150°C, and more preferably in the range of 20°C to 80°C. It is also possible to cure it at a high temperature for a short time, or at a low temperature such as room temperature for a long time (e.g., several hours to several days), without particular limitation. It should be noted that curing triggered by high-energy ray irradiation can also be carried out by selecting a high-energy ray activated catalyst or a photoactivated catalyst as at least part of component (D).

[0154] By using the thermally conductive composition of the present invention, it is possible to obtain a heat dissipation structure having a heat dissipation member formed by applying the above-mentioned curable thermally conductive composition to a heat dissipation component or a circuit board on which the heat dissipation component is mounted, forming a cured product in the range of 20°C to 150°C, preferably less than 130°C, for example 20°C to 125°C.

[0155] [Thermal conductivity]

[0156] The thermally conductive organopolysiloxane composition of the present invention has the following characteristics: even when stably highly filled with a thermally conductive filler,

[0157] Excellent extrusion properties from the cartridge, and the formation of a uniform cross-linked structure during curing. Therefore, even after prolonged heating at high temperatures, density changes are not easily observed, thus suppressing the formation of voids or bubbles, avoiding contact failures, minimizing mold contamination, and exhibiting high heat resistance due to the absence of an alkali catalyst. Therefore, a thermal conductivity of 9.0 W / mK or higher, and particularly preferably 9.1 W / mK or higher, is preferred. It should be noted that the thermally conductive composition of the present invention can be designed to have thermal conductivity of 9.0 W / mK to 15.0 W / mK, and, as needed, 9.1 W / mK to 14.0 W / mK, and has the following advantages: excellent workability such as extrusion and dispensing properties from the cartridge; no density change even after prolonged heating at high temperatures, ensuring that heat dissipation characteristics and physical strength are not compromised. Furthermore, the composition can be non-curable or curable. In the case of curable composition, by optionally using component (F) / (G), hardness changes are suppressed even after heat aging, thereby enabling the achievement of a thermally conductive cured product with excellent softness and stress relief properties.

[0158] [Applications and Heat Dissipation Structure]

[0159] The thermally conductive composition and its cured form of the present invention are useful as a heat transfer material (thermally conductive member) between the thermal boundary surface of the heat-generating component and the interface of a heat-dissipating component such as a heat sink or circuit board, for cooling heat-generating components by thermal conduction, and can form a heat-dissipating structure incorporating the composition. Here, the type, size, and structural details of the heat-generating component are not particularly limited, but the thermally conductive composition of the present invention, or the cured form thereof, not only possesses high thermal conductivity and excellent initial adhesion and bonding strength to the component, but also suppresses hardness changes over a long period even after heat aging, maintaining flexibility and stress-relieving properties. Therefore, it is not easily peeled off from the heat-generating component or develops voids due to vibration, exhibits high sealing and conformability, and has excellent industrial productionability. Therefore, it is suitable for application in heat-dissipating structures of electrical / electronic equipment including automotive parts, electrical / electronic components, or secondary batteries in the form of battery cells.

[0160] The structure of such a heat dissipation structure is not particularly limited, but examples include a heat dissipation structure in which a heat dissipation component is mounted on a heat dissipation member or a circuit board on which the heat dissipation component is mounted, via the thermally conductive composition or its cured form. Such a structure exemplifies, for instance, an electronic component serving as a heat dissipation element mounted on a circuit board, where heat generated by the electronic component is dissipated through a thin film layer of the thermally conductive composition or its cured form via the heat dissipation component. Because these components exhibit minimal hardness change after heat aging, a characteristic of this invention, they maintain excellent flexibility, stress relief, fit, and conformability, and therefore can be suitably mounted not only on a horizontal plane but also on an inclined or vertical plane.

[0161] In such a heat dissipation structure, the thickness of the thermally conductive composition or its cured form is not particularly limited, and can be in the range of 0.1 to 100 mm, which can efficiently transfer the heat generated by electronic components that are filled with the composition or its cured form without gaps to the heat dissipation component.

[0162] There are no particular limitations on electrical / electronic devices incorporating components formed from the above-described thermally conductive composition. Examples include: secondary batteries such as cell-type lithium-ion electrode secondary batteries and battery stack-type fuel cells; electronic circuit boards such as printed circuit boards; IC chips encapsulating light semiconductor elements such as diodes (LEDs), organic electroluminescent elements (organic ELs), laser diodes, and LED arrays; CPUs used in electronic devices such as personal computers, digital video discs, mobile phones, and smartphones; and LSI chips such as driver ICs and memory. In particular, in high-performance digital / switching circuits formed with high integration density, heat removal (heat dissipation) becomes a major factor for the performance and reliability of integrated circuits. Thermally conductive components made from the thermally conductive organopolysiloxane composition of the present invention exhibit excellent heat dissipation and operability even when applied to power semiconductor applications such as engine control, powertrain, and air conditioning control in conveyors. Even when used in harsh environments with embedded electronic control units (ECUs) and other automotive electronic components, they maintain strong adhesion to the component, achieving excellent heat resistance and thermal conductivity.

[0163] Example

[0164] The present invention is illustrated below with examples, but the invention is not limited to these examples. In the examples and comparative examples shown below, the following compounds or compositions were used as raw materials.

[0165] [Example 1 (Synthesis Example) *Active Polymer]

[0166] After purging the flask with nitrogen in a 3L flask equipped with a stirrer, thermometer, dropping funnel, and condenser, 1000 g (4.50 mol) of hexamethylcyclotrisiloxane (D3) and 830 g of toluene were added and mixed. The mixture was then subjected to azeotropic dehydration for 1 hour and cooled to room temperature. A mixture of 67 g of dimethylformamide, 333 g of acetonitrile, and 8.23 ​​g of a 1.5% (w / w) lithium hydroxide aqueous solution was added and stirred at room temperature. The conversion rate of D3 was monitored by gas chromatography (GLC). After 3 hours and 30 minutes, when the conversion rate reached 97%, 5.13 g of acetic acid was added to stop the polymerization. Further, low-boiling-point substances were removed by heating and vacuum distillation, followed by sterile filtration. In another reaction flask, 891 g of the filtrate, 125 g of tetramethyldivinyldisilazane, and 0.5 g of trifluoroacetic acid were added and stirred at 80°C for 2 hours. Low-boiling-point substances were removed by heating and vacuum distillation, followed by sterile filtration, yielding 1024 g of a colorless, transparent liquid.

[0167] The kinematic viscosity of the obtained reaction product was 27.7 mm. 2 According to gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) analysis, it is a polydimethylsiloxane with vinyl groups at both ends of the molecular chain, with a number average molecular weight of 3890, a dispersity (weight average molecular weight to number average molecular weight ratio (Mw / Mn)) of 1.15, and a vinyl content of 2.16 by mass.

[0168] The low-molecular-weight dimethylsiloxane in the polydimethylsiloxane was extracted with acetone. Using n-undecane as a standard, quantitative analysis was performed using a temperature-increasing GLC equipped with an FID detector. The results showed that the content of cyclic polydimethylsiloxane D13 was 47 ppm and the content of D14 was 60 ppm.

[0169] [Comparative Example 1 (Comparative Synthesis Example) *Equilibrium Polymer]

[0170] After purging the flask with nitrogen, a 3L flask equipped with a stirrer, thermometer, small Dean-Stark tube, and condenser was filled with 854 g (2.89 mol) of hexamethylcyclotetrasiloxane (D4), 795 g of polydimethylsiloxane with vinyl end caps containing 7.6% by mass, and 0.5 g of a 25% by mass aqueous solution of tetramethylammonium hydroxide [(CH3)4NOH]. The mixture was stirred at 80°C for 3 hours under a nitrogen stream to remove moisture. Then, the mixture was heated to 180°C, reduced to below 70 hPa, and subjected to heated vacuum distillation to remove low-boiling-point substances. The mixture was then sterilized and filtered to obtain 1148 g of a colorless, transparent liquid.

[0171] The kinematic viscosity of the obtained reaction product was 28 mm. 2According to GPC and NMR analysis, it is a polydimethylsiloxane with vinyl groups at both ends, with a number average molecular weight of 3480, a dispersion (weight average molecular weight to number average molecular weight ratio (Mw / Mn)) of 1.38, and a vinyl content of 2.20 by mass.

[0172] The low-molecular-weight dimethylsiloxane in the polydimethylsiloxane was extracted with acetone. Using n-undecane as a standard, quantitative analysis was performed using a temperature-increasing GLC equipped with an FID detector. The results showed that the content of cyclic polydimethylsiloxane D13 was 325 ppm and the content of D14 was 254 ppm.

[0173] [summary]

[0174] The polydimethylsiloxane with vinyl groups at both ends of the molecular chain obtained by living polymerization (Example 1) has a molecular weight dispersion (Mw / Mn) of 1.15, a number average molecular weight of 3890, and the contents of 13-mer and 14-mer cyclic siloxanes (D13, D14) are both less than 100 ppm. In contrast, the polydimethylsiloxane with vinyl groups at both ends of the molecular chain obtained by equilibrium polymerization (Comparative Example 1) has a molecular weight dispersion (Mw / Mn) of 1.37, a number average molecular weight of 3480, and the contents of 13-mer and 14-mer cyclic siloxanes (D13, D14) are both greater than 100 ppm.

[0175] [Preparation of the composition and fabrication of thermally conductive organopolysiloxane cured products (evaluation samples)]

[0176] The components were mixed using the method described later to obtain the thermally conductive compositions of Example 2 and Comparative Example 2 (hereinafter, sometimes referred to as "thermally conductive organopolysiloxane compositions"). The thermally conductive organopolysiloxane compositions were filled into a mold with a height of 6 mm, a length of 50 mm, and a width of 30 mm. After curing at 80°C for 30 minutes, the mold was removed to obtain the cured thermally conductive organopolysiloxane. The hardness of the obtained cured thermally conductive organopolysiloxane was determined using the following method.

[0177] [Hardness (E type hardness)]

[0178] For hardness testing, two pieces of thermally conductive organopolysiloxane cured material obtained under the above conditions were overlapped, and the value was measured after 3 seconds using an ASKER TYPE E hardness tester manufactured by ASKER Corporation.

[0179] [Thermal and electrical conductivity]

[0180] For the determination of thermal conductivity, two pieces of thermally conductive organopolysiloxane cured material obtained under the above conditions were used, and the measurement was performed using a TPS-500 (hot plate method) manufactured by Kyoto Electronics Industries, Ltd.

[0181] [Density, density change]

[0182] For density determination, the thermally conductive organopolysiloxane cured material obtained under the above conditions was used. The specific gravity in water was measured using an EW-300SG manufactured by ALFAMIRAGE Co., Ltd., and then converted into density for measurement.

[0183] The density change is calculated based on the initial density of the thermally conductive organopolysiloxane cured product obtained under the above conditions, and the density of the cured product after aging in an oven at 120°C or 150°C for 100 hours.

[0184] If voids are generated inside due to aging, the density will decrease compared to the initial density, which can be judged as internal foaming or cracking.

[0185] [Extrusion volume]

[0186] Extrusion volume was determined by filling a 30cc EFD syringe (Nordson) with the thermally conductive composition and extruding at an extrusion pressure of 80 psi, measuring the extruded weight per minute.

[0187] The composition of the present invention is formed from the following components.

[0188] Ingredients (A):

[0189] AP: Dimethylvinylsiloxy-terminated dimethylpolysiloxane (molecular weight dispersion 1.15, number average molecular weight 3890, Vi content 2.16% by mass) *Example 1

[0190] AC: Dimethylvinylsiloxy-terminated dimethylpolysiloxane (molecular weight dispersion 1.37, number average molecular weight 3480, Vi content 2.20% by mass) *Comparative Example 1

[0191] Ingredient (B):

[0192] B-1: Amorphous zinc oxide powder with an average particle size of 0.12 μm

[0193] B-2: Polyhedral spherical α-type alumina powder with an average particle size of 2μm

[0194] B-3: Amorphous aluminum nitride powder with an average particle size of 30 μm

[0195] B-4: Spherical aluminum nitride powder with an average particle size of 80 μm

[0196] B-5: Spherical magnesium oxide powder with an average particle size of 120 μm

[0197] Ingredient (C):

[0198] C-1: A copolymer of trimethylsiloxy-terminated methylhydrosiloxane and dimethylsiloxane with an average of 2 intramolecular and 2 side chains (viscosity 20 mPa·s, Si-H content 0.10% by mass).

[0199] C-2: A copolymer of trimethylsiloxy-terminated methylhydrosiloxane and dimethylsiloxane with an average of 5 intramolecular and 5 side chains (viscosity 5 mPa·s, Si-H content 0.75% by mass).

[0200] Ingredient (D):

[0201] D-1: A complex of platinum (0.6% by weight) with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane.

[0202] Ingredient (E):

[0203] E-1: Formula: (CH3)3SiO[(CH3)2SiO] 30 Si(OCH3)3

[0204] The organopolysiloxane shown

[0205] E-2: Decyltrimethoxysilane

[0206] Ingredients (F):

[0207] F-1: Calcium stearate (manufactured by Fujifilm and Kojun Pharmaceutical)

[0208] Ingredients (G):

[0209] G-1: 29H,31H-phthalocyanine (2-)-N29,N30,N31,N32 copper

[0210] Component (H):

[0211] H-1: Phenylacetyl butynol

[0212] [Example 2: The two-component thermally conductive organopolysiloxane composition involved in Example 1]

[0213] Weigh 100.0 parts by mass of component (AP), 58.8 parts by mass of component (E-1), 7.84 parts by mass of component (E-2), and 3.92 parts by mass of component (F-1). Mix 647 parts by mass of component (B-1), 1157 parts by mass of component (B-2), 706 parts by mass of component (B-3), 424 parts by mass of component (B-4), and 813 parts by mass of component (B-5) sequentially over 60 minutes. Then, mix uniformly over 30 minutes. After homogenization, heat and mix at 160°C under reduced pressure for 60 minutes, then cool to room temperature to obtain a mixture. Mix 0.89 parts by mass of component (D-1) uniformly into this mixture to obtain liquid (I) of the thermally conductive organopolysiloxane composition.

[0214] Next, 39.2 parts by mass of component (AP), 51.0 parts by mass of component (C-1), 58.8 parts by mass of component (E-1), 7.84 parts by mass of component (E-2), and 3.92 parts by mass of component (F-1) were weighed and then mixed sequentially over 60 minutes. This process was followed by uniform mixing over 30 minutes. After achieving uniformity, the mixture was heated and mixed at 160°C under reduced pressure for 60 minutes, and then cooled to room temperature to obtain a mixture. 2.0 parts by mass of component (C-2), 3.92 parts by mass of component (G-1), and 0.12 parts by mass of component (H-1) were then uniformly mixed into this mixture to obtain liquid (II) of the thermally conductive organopolysiloxane composition.

[0215] After measuring the extrusion amount using liquid (I) and liquid (II) of the above thermally conductive organopolysiloxane composition, the two liquids were mixed with the same mass, and then the hardness, thermal conductivity, density, and density change were measured.

[0216] [Comparative Example 2: The two-component thermally conductive organopolysiloxane composition involved in Comparative Example 1]

[0217] By replacing component (AP) with component (AC) in Example 2, a thermally conductive organopolysiloxane composition was obtained in the same manner as in Example 2.

[0218] Regarding the thermally conductive organopolysiloxane compositions of Example 2 and Comparative Example 2, the composition, extrusion amount, thermal conductivity, hardness, density, and density change after heating and aging of the obtained thermally conductive organopolysiloxane cured products are shown in Table 1.

[0219]

[0220] [Summarize]

[0221] The thermally conductive organopolysiloxane composition described in Example 2, which uses AP: dimethylvinylsiloxy-terminated dimethyl polysiloxane obtained by Example 1 (living polymerization), achieves a high thermal conductivity exceeding 11 W / m·K. Furthermore, its density change after 100 hours at high temperatures (120°C or 150°C) is less than 1%, void or bubble formation is suppressed, and ejection from the cartridge (extrusion workability) is excellent. Therefore, it is strongly expected that the thermally conductive organopolysiloxane composition described in this application, in addition to its workability, will maintain the desired exothermic properties and mechanical strength, such as rubber-like properties, even under prolonged use at high temperatures.

[0222] In contrast, the thermally conductive organopolysiloxane composition of Comparative Example 2, which used AC: dimethylvinylsiloxy-terminated dimethyl polysiloxane obtained by Comparative Example 1 (equilibrium polymerization), showed similarly good results in terms of thermal conductivity, hardness, and dischargeability from the cartridge (extrusion workability) as Example 2. However, after 100 hours at high temperatures (120°C or 150°C), a large density change occurred, and the density reduction rate due to the formation of voids or bubbles was significant. Therefore, in the thermally conductive organopolysiloxane of Comparative Example 2, especially under prolonged use at high temperatures, its heat dissipation characteristics and mechanical strength, such as rubber properties, may deteriorate.

Claims

1. An organopolysiloxane, wherein the organopolysiloxane has alkenyl groups at both ends of the molecular chain, and the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is 1.20 or less.

2. The organopolysiloxane according to claim 1, wherein, The content of cyclic dimethylsiloxanes with a number average molecular weight of less than 10,000 and less than 20 polymers is less than 0.1% by mass.

3. The organopolysiloxane according to claim 1, wherein the organopolysiloxane is a linear dimethyl polysiloxane having alkenyl groups with 2 to 8 carbon atoms only at both ends of the molecular chain, and the content of 10 to 20 polymeric cyclic dimethylsiloxane is less than 0.1% by mass.

4. The organopolysiloxane according to claim 1, wherein the organopolysiloxane is a linear dimethyl polysiloxane having a weight-average molecular weight to number-average molecular weight ratio (Mw / Mn) in the range of 1.05 to 1.18, a number-average molecular weight in the range of 2000 to 5000, a content of 10 to 15 polymeric cyclic dimethylsiloxane less than 0.01% by mass, and having alkenyl groups with 2 to 8 carbon atoms only at both ends of the molecular chain.

5. A method for manufacturing an organopolysiloxane according to any one of claims 1 to 4, characterized in that, include: Process (I): reacting (R A 2SiO)3 (In the above formula, R) A Each group is an alkyl, aryl, or a group in which a portion of the carbon atom bonded to a hydrogen atom is replaced by a halogen atom. The hexaorganocyclic trisiloxanes represented undergo living polymerization in the presence of a lithium-based catalyst; and Process (II): Utilizing Selected from R B R A 2SiNSiR A 2R B (In the above formula, R) A For the same group as above, R B (Alkenyl) The 1,3-dienyl-1,1,3,3-tetraorganodisilazane and R B R A 2SiCl (In the above formula, R) A R B (For the same groups as above) At least one of the alkenyl diorganochlorosilanes represented herein shall be used to cap the molecular chain ends on the polymerization termination side of the polymer obtained by process (I).

6. The method for manufacturing organopolysiloxane according to claim 5, wherein, In steps (I) and (II), the reaction solvent is a mixed solvent comprising (S1) one or more polar solvents selected from acetonitrile, methyl ethyl ketone and methyl isobutyl ketone, and (S2) one or more polar solvents selected from dimethyl sulfoxide and dimethylformamide.

7. A thermally conductive organopolysiloxane composition, said thermally conductive organopolysiloxane composition comprising: (A) The organopolysiloxane according to any one of claims 1 to 4: 100 parts by weight; (B) Thermally conductive filler: in an amount ranging from 60% to 90% by volume relative to the total solid components in the composition.

8. The thermally conductive organopolysiloxane composition according to claim 7, wherein the thermally conductive organopolysiloxane composition is non-curable.

9. The thermally conductive organopolysiloxane composition according to claim 7, wherein the thermally conductive organopolysiloxane composition has one or more curing reactivity selected from hydrosilylation reaction and free radical polymerization reaction.

10. The thermally conductive organopolysiloxane composition according to claim 7, further comprising: (C) an organohydrogen polysiloxane: relative to 1 mole of the curing reactive group having a carbon-carbon double bond contained in component (A), the amount of silicon atoms bonded to hydrogen atoms in component (C) is 0.2 moles to 5 moles; and (D) Catalyst for the hydrosilylation reaction in catalytic amounts It also exhibits hydrogenation and silylation reactivity.

11. The thermally conductive organopolysiloxane composition according to claim 7, wherein the thermally conductive organopolysiloxane composition further comprises a component selected from... (E1) General formula (1): [Chemical Formula 1] (where R) 1 R is an independent, unsubstituted or substituted monovalent hydrocarbon group without a carbon-carbon double bond. 2 Organopolysiloxanes, which are independently represented by hydrogen atoms, alkyl groups, alkoxyalkyl groups or acyl groups, where a is an integer from 5 to 250 and b is an integer from 1 to 3, and have a viscosity of 10 to less than 10,000 mPa·s at 25°C; (E2) From general formula (2): R alk R 3 2SiO(R 3 2SiO) c R 3 2Si-R 4 -SiR 3 (3-d) (OR 5 ) d (where R) alk It is an alkenyl group, R 3 R is an independent, unsubstituted or substituted monovalent hydrocarbon group without a carbon-carbon double bond. 4 R is an oxygen atom or a divalent hydrocarbon group. 5 Siloxane compounds, defined as those independently consisting of a hydrogen atom, alkyl group, alkoxyalkyl group, or acyl group (where c is an integer from 1 to 250 and d is an integer from 1 to 3), and having a viscosity at 25°C in the range of 10 to 10,000 mPa·s, with an alkenyl group and a hydrolyzable silane group at the end of their molecular chains; and (E3) Alkoxysilanes or their hydrolytic condensates having an alkyl group having 6 or more carbon atoms in the molecule; One or more of the components.

12. The thermally conductive organopolysiloxane composition according to claim 7, wherein the thermally conductive organopolysiloxane composition further comprises a component selected from... (F) Selected from at least one of fatty acids, fatty acid esters, and fatty acid metal salts, and (G) Heat resistance enhancer One or more of the components.

13. The thermally conductive organopolysiloxane composition according to any one of claims 7 to 12, characterized in that, The composition or its cured reactant has a thermal conductivity of 9.0 W / mK or higher.

14. The thermally conductive organopolysiloxane composition according to any one of claims 7 to 13, wherein, Even after 100 hours at 150°C, the density change of the composition or its cured reactants is less than 1%.

15. A thermally conductive component, said thermally conductive component being composed of any one of the thermally conductive organopolysiloxane compositions or their cured reactants according to claims 7 to 13.

16. A heat dissipation structure comprising the thermally conductive component as described in claim 15.

17. A heat dissipation structure, wherein the heat dissipation structure is formed by providing a heat dissipation component on a heat dissipation component or a circuit board on which the heat dissipation component is mounted, with the thermally conductive organopolysiloxane composition or its cured reactant as described in any one of claims 7 to 13 as a buffer.

18. The heat dissipation structure according to claim 16 or claim 17, wherein the heat dissipation structure is an electrical / electronic device.

19. The heat dissipation structure according to claim 16 or claim 17, wherein the heat dissipation structure is an electrical / electronic component or a secondary battery.

20. A method for manufacturing a heat dissipation structure, the method comprising the steps of: applying the thermally conductive composition according to any one of claims 7 to 12 onto a heat dissipation component or a circuit board on which the heat dissipation component is mounted, and curing it at a temperature of less than 130°C.

21. A composition suitable for use in one or more of the categories of sealant compositions, conductive compositions, and thermal insulation compositions, wherein the composition contains an organopolysiloxane according to any one of claims 1 to 4.

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