Hydrogen polyorganosiloxane and its thermally conductive silicone composition

Abstract

The present disclosure provides compounds of the formula X-[SiR 1 2O]m-[SiR 1 (C a H 2a+1 )O] n -[SiR 1 H.O.] r -[SiR 1 2]-X hydrogen polyorganosiloxane, wherein a is any integer between 6 and 18, n is any number between 0.7 and 30, m is any number between 10 and 1500, r is any number between 0 and 200, and R 1 is independently in each occurrence a C1-C5 alkyl or phenyl, X represents one or more groups selected from hydrogen, alkoxy, and hydroxyl, and 60 mol % or more of X are hydrogen atoms. The hydrogen polyorganosiloxane can significantly reduce the viscosity and improve the flowability of the resulting silicone composition compared to existing hydrogen polyorganosiloxanes with the same thermally conductive filler loading, thereby improving the thermal conductivity.

Description

[Technical Field]

[0001] This disclosure relates to hydrogen polyorganosiloxanes and their thermally conductive silicone compositions. [Background technology]

[0002] In recent years, the electric vehicle industry has grown rapidly. Power batteries are recognized as a key technology in electric vehicles. Heat dissipation is extremely important for power batteries, as rising temperatures in power battery modules lead to degradation of battery performance, which reduces the safety, reliability, and lifespan of electric vehicles.

[0003] Thermally conductive silicone compositions are commonly used heat dissipation materials. However, improving the thermal conductivity of these compositions usually results from increasing the amount of blended filler, which tends to reduce the fluidity of the composition, increase the contact resistance at the interface between the heat source, heat dissipation material, and heat sink, and increase the bond thickness, thus affecting the heat dissipation efficiency. Therefore, the viscosity of thermally conductive filler and the organopolysiloxane blended with the filler are research priorities.

[0004] US664925B discloses a thermally conductive silicone composition obtained by blending a mixture of aluminum powder and zinc oxide powder with specific amounts of organic hydrogen polysiloxane used as crosslinking and chain extenders, resulting in a composition that can closely conform to uneven contact surfaces before curing without losing flexibility, even as the amount of blended filler increases. The patent also discloses that organosilanes containing long-chain alkyls facilitate wetting of thermally conductive fillers together with the silicone component to improve the flexibility of the composition. However, treating the filler surface with a small amount of silane is not ideal because it increases production costs and can impair thermal conductivity due to residual silane on the filler surface.

[0005] Efforts have also been made to introduce long-chain alkyl groups into organosiloxane components. CN105838079A discloses in Examples 2 to 4 a thermally conductive silicone grease composition containing vinyl silicone oil having a long-chain alkyl, where introducing the long-chain alkyl is mainly to slow down the migration rate of the vinyl silicone oil in the thermal grease and reduce the degree of oil bleeding. The problem of the fluidity of thermally conductive grease with a high filler loading amount has not been addressed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] The present disclosure provides a novel hydrogen polyorganosiloxane that can significantly reduce the viscosity of the resulting silicone composition and improve fluidity compared to existing hydrogen polyorganosiloxanes when filled with the same thermally conductive filler, thereby facilitating filling of small gaps and improving the thermal conductivity of the composition. Further, the thermally conductive silicone composition containing the hydrogen polyorganosiloxane of the present disclosure can achieve high filler loading without the presence of a filler surface treatment agent, diluent, and / or plasticizer in order to avoid the possibility of impairing thermal conductivity due to residual treatment agents, leached or volatilized diluents, and / or plasticizers on the filler surface.

Modes for Carrying Out the Invention

[0008] In the present disclosure, unless otherwise specified, the "structural formula" of the hydrogen polyorganosiloxane 1 is measured by 1H NMR spectroscopy (nuclear magnetic resonance spectroscopy) and optional 29 29Si NMR spectroscopy. 1In \(^1H\) NMR spectroscopy, hydrogen-bonded atoms and functional groups can be measured by referring to well-known databases and literature. On the other hand, 29 \(^{29}Si\) NMR is 1 further used to verify or measure hydrogen-bonded atoms and groups that cannot be accurately measured by \(^1H\) NMR spectroscopy. When analyzing the molecular composition of hydrogen polyorganosiloxanes, first 1 normalize the baseline of the \(^1H\) NMR spectrum, and then integrate the signal peaks of different types of hydrogen to obtain the peak area. 29 When \(^{29}Si\) NMR spectroscopy is required, the signal peak areas of different types of silicon are obtained in the same way, and then the signal peak areas of hydrogen and silicon are proportionally converted to calculate the molar number of each group unit of the hydrogen polyorganosiloxane and obtain its structural formula. Generally, the structural formula measured by NMR spectroscopy is an average molecular formula. It is a fact that the structural formula of the hydrogen polyorganosiloxane of the present disclosure can be measured using generally available NMR spectroscopy. However, in order to facilitate the analysis of the structural formula of the hydrogen polyorganosiloxane, in order to obtain a high-quality NMR spectrum, 1 for \(^1H\) NMR spectroscopy, deuterated chloroform as a test solvent and chloroform without tetramethylsilane (TMS) as an internal standard substance are preferred, 29 for \(^{29}Si\) NMR spectroscopy, deuterated benzene as a test solvent and chromium acetylacetonate as a relaxation reagent are preferred.

[0009] In the present disclosure, the term "particle size" refers to the equivalent diameter of the particle, that is, the diameter of a homogeneous spherical particle having the same or similar volume as the particle to be tested.

[0010] In the present disclosure, the term "room temperature" refers to \(23\pm2^{\circ}C\).

[0011] The first aspect of the present disclosure provides a hydrogen polyorganosiloxane of formula I.

[0012]

Chemical formula

[0013] In equation I, a can be 6, 8, 10, 12, 14, 16, or 18, and in particular can be any integer between 6 and 16, more specifically any integer between 6 and 12.

[0014] n can be 1, 3, 5, 7, 9, 12, 15, 18, 20, 25, or 30, and can be any number between 3 and 20, for example between 3 and 15.

[0015] m can be 10, 20, 40, 50, 60, 100, 200, 500, 800, 1200, or 1500, and can be any number between 50 and 500, for example between 55 and 250.

[0016] r can be 0, 10, 20, 30, 40, 50, 60, 80, 100, 150, or 200.

[0017] R 1 This can be methyl, ethyl, propyl, butyl, pentyl, or phenyl, and is preferably methyl.

[0018] The molar ratio of hydrogen atoms to all X groups is 60 mol% or more, and more preferably 80 mol% or more. The molar ratio of alkoxy groups and hydroxyl groups to all X groups is preferably 30 mol% or less, and more preferably 20 mol% or less. Appropriate content of alkoxy and hydroxyl groups contributes to further reducing the viscosity of the composition, with the possibility of increased filler filling due to interaction with the filler, thereby improving the thermal conductivity of the composition. However, hydrogen polyorganosiloxanes with too high a content of alkoxy and hydroxyl groups have worse storage stability, and when applied to addition-curable thermally conductive silicone compositions, there is a high possibility of bubble formation that impairs thermal conductivity.

[0019] In preferred embodiments of this specification, 60 mol% or more and less than 100 mol% of X based on the total number of moles of X groups are hydrogen atoms, and more than 0 mol% and less than or equal to 30 mol% of X based on the total number of moles of X groups are alkoxy groups and hydroxyl groups. In more particularly preferred embodiments of this specification, 80 mol% or more and less than 100 mol% of X based on the total number of moles of X groups are hydrogen atoms, and more than 0 mol% and less than or equal to 20 mol% of X based on the total number of moles of X groups are alkoxy groups and hydroxyl groups.

[0020] In preferred embodiments of this specification, the hydrogen polyorganosiloxane has the structural formula shown in formula I, where n is any number between 3 and 15, and a, m, r, R 1 And X are as defined above. Hydrogen polyorganosiloxanes with n within this range are more effective at reducing the viscosity of the composition with the same amount of thermally conductive filler. When n is smaller than the aforementioned range, the hydrogen polyorganosiloxane may not be very effective at reducing viscosity. When n is larger than the aforementioned range, the hydrogen polyorganosiloxane itself clearly has a high viscosity and performs worse at reducing the viscosity of the thermally conductive silicone composition.

[0021] The hydrogen polyorganosiloxanes of this disclosure have a suitable dynamic viscosity of 10 to 3000 mPa·s at 25°C. In one embodiment of this specification, the hydrogen polyorganosiloxane has a dynamic viscosity of 10 to 250 mPa·s at 25°C. In another embodiment of this specification, the hydrogen polyorganosiloxane has a dynamic viscosity of 500 to 2000 mPa·s at 25°C.

[0022] The hydrogen polyorganosiloxanes of this disclosure include single hydrogen polyorganosiloxane compounds and combinations of two or more hydrogen polyorganosiloxane compounds. For individual hydrogen polyorganosiloxane molecules, m, n, and r are integers within the aforementioned range, and in X groups, one of the aforementioned groups accounts for 100%, or one accounts for 50% and the other for 50%. However, for mixtures of two or more different hydrogen polyorganosiloxane compounds, m, n, and r are positive numbers within the aforementioned range, representing the mean, and in X groups, the aforementioned individual percentages can be any number within the range of 0 to 100%, representing the mean, and the total percentage of all X groups is 100%.

[0023] A second aspect of this disclosure is a method for preparing a hydrogen polyorganosiloxane according to the first aspect of this disclosure, a) At least one organosilicon compound A) selected from hydroxyl-terminated polysiloxanes and compounds of formulas II and III, and at least one organosilicon compound B) optionally selected from compounds of formulas IV and V, are reacted in the presence of catalyst 1.

[0024] [ka] [In the formula, R 2 In each case, is independently methyl, ethyl, or hydrogen. R 3In each case, independently, is a C6-C18 alkyl group, for example, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, preferably a C6-C16 alkyl group, and particularly a C6-C12 alkyl group. R 4 In each case, independently, is a C1-C5 alkyl group, for example, methyl, ethyl, propyl, butyl, or pentyl, preferably methyl. R 5 In each case, independently, is a C1-C5 alkyl group, for example, methyl, ethyl, propyl, butyl, or pentyl, preferably methyl. s is any number between 1 and 20, for example, 1, 2, 4, 6, 8, 10, 15, 20. t is any number between 3 and 20, for example, 3, 4, 5, 6, 8, 10, 15, 20. u is any number between 1 and 100, for example, 1, 20, 30, 40, 50, 60, 80, 100. v is any number between 3 and 100, for example, 3, 4, 5, 6, 8, 10, 20, 50, 80, 100. b) A method is provided comprising reacting the product of step (a) with an endcapper in the presence of catalyst 2 to obtain a hydrogen polyorganosiloxane.

[0025] In step (a), the hydroxyl-terminated polysiloxane is typically of formula VI.

[0026] [ka] [In the formula, R 6 In each case, independently, is a C1-C5 alkyl group, for example, methyl, ethyl, propyl, butyl, and pentyl, or phenyl, preferably methyl. p is appropriately any number between 3 and 150, for example, any number between 10 and 100, and especially any number between 10 and 60, for example, 15, 20, 25, 30, 35, 40, 45, 50, 55. In some embodiments of this specification, p is any number between 15 and 55, and especially any number between 20 and 50.

[0027] In step (a), the reaction includes a condensation reaction and an equilibrium reaction. The condensation reaction and the equilibrium reaction often occur simultaneously. The reaction in step a) is carried out at a temperature of 80°C to 110°C, particularly 90°C to 105°C, for a period of 15 minutes to 4 hours, if appropriate.

[0028] The reaction in step (a) is advantageously carried out under reduced pressure to extract the low molecular weight alcohol and water produced therefrom, where the pressure is reduced to less than 100 mbar, for example, less than 80 mbar.

[0029] In step (a), organosilicon compound A) may be a dialkoxysilane of formula II or a linear oligomer thereof, or a cyclic oligomer of a dialkoxysilane of formula III. The latter is more advantageous for obtaining a hydrogen polyorganosiloxane having a large number of long-chain alkyl groups (≧3).

[0030] The oligomers of formula II or III can be prepared by hydrolysis condensation of a dialkoxysilane, which comprises i) reacting a long-chain alkyl-containing dialkoxysilane with water in the presence of catalyst 3, and ii) removing the by-products of the reaction, water, and catalyst 3. In step i), considering that the hydrolysis condensation of dialkoxysilane is exothermic, it is preferable to carry out the reaction at a lower temperature, for example, at a temperature below 30°C, such as room temperature or below 10°C. In step i), considering that the reaction is highly exothermic, it is preferable to add water dropwise to the long-chain alkyl-containing dialkoxysilane. To slow down the reaction rate, it is preferable to add an organic solvent, such as acetonitrile or ethanol, in step i). The molar ratio of water to long-chain alkyl-containing dialkoxysilane is preferably greater than 0.5:1, particularly greater than 2:1, for example greater than 3:1 and greater than 5:1. The reaction in step i) is carried out appropriately for 1 to 8 hours, for example, 3 to 6 hours. In step i), catalyst 3 is generally an acidic catalyst, for example, concentrated sulfuric acid or hydrochloric acid. In step ii), by-products, mainly low molecular weight alcohols, are usually removed by distillation. Catalyst 3 can be removed, for example, by neutralization with an alkaline substance. If an organic solvent is added in step i), the organic solvent can be removed by rinsing or distillation. In some embodiments herein, oligomers of formula II or III are prepared by a process comprising the following steps: i) reacting a long-chain alkyl-containing dialkoxysilane with water dropwise in the presence of catalyst 3, such as hydrochloric acid, and an organic solvent, such as ethanol, until the molar ratio of water to the long-chain alkyl-containing dialkoxysilane exceeds 2:1; and ii) removing by-products, water, organic solvent, and catalyst 3.

[0031] In step (a), organosilicon compound B) can be selectively added depending on the desired structure of the hydrogen polyorganosiloxane and is generally added in the synthesis process of polyhydrogen polyorganosiloxanes. Organosilicon compound B) may be a dialkoxysilane of formula IV or its linear oligomer, or a cyclic oligomer of a dialkoxysilane of formula V.

[0032] In step (b), the end capper is typically of equation VII.

[0033] [ka] [In the formula, R 7 In each case, independently, is a C1-C5 alkyl group, for example, methyl, ethyl, propyl, butyl, or pentyl, preferably methyl. q is any number between 0 and 20, for example, 0, 3, 6, 9, 12, 15, 18.

[0034] In step (b), the reaction is typically an equilibrium reaction, which takes place at a temperature of 100°C to 140°C, particularly 110°C to 130°C, for a period of 3 to 8 hours. Generally, the longer the time the equilibrium reaction proceeds, the more uniform the reaction tends to be. However, considering economics, the above reaction time is preferable.

[0035] In one embodiment of this specification, the end capper is, in the formula, R 7 The structure has the structural formula shown in formula VII, where is methyl and q is 0. Considering that the end capper in this embodiment is in a gaseous state at the reaction temperature of step (b) and needs to be refluxed due to its low boiling point, the oligomer of formula VII with q≧1 is preferred for its function as an end capper from a operability standpoint.

[0036] In steps (a) and (b), the amounts of hydroxyl-terminated polysiloxane, organosilicon compounds A) and B), and end capper can be selected according to the number of M and D structural units in the desired hydrogen polyorganosiloxane.

[0037] In step (a), catalyst 1 is preferably an acidic catalyst, such as phosphonitrile chloride, trifluoromethanesulfonic acid, or an acidic ion exchange resin. Catalyst 1 should be used in the minimum amount necessary to ensure effective condensation and equilibrium reactions. In step (b), catalyst 2 is preferably an acidic catalyst, specifically as described above. Catalyst 2 should be used in the minimum amount necessary to ensure effective equilibrium reactions. To avoid introducing catalyst impurities that are more difficult to remove later, catalyst 2 is preferably the same as catalyst 1. In this case, catalyst 2 in step (b) can be supplied together with catalyst 1 in step (a) to simplify the supply operation. Phosphonitrile chloride is preferred as the catalyst in this disclosure.

[0038] In steps (a) and (b), the reaction is carried out appropriately in the absence of water, and further in the absence of both water and solvent. The term “absence” as used herein means that water or solvent is present in the reaction system in an amount of less than 0.1% by weight, for example, less than 0.05% by weight.

[0039] The preparation method of this disclosure may further include step (c) removing the catalyst to minimize the effect of catalyst impurities on the performance of the product. Generally, acidic catalysts are neutralized with alkaline substances. Considering that Si-H groups will be converted to Si-OH groups in the presence of a strongly alkaline substance, weakly alkaline substances such as sodium carbonate, sodium bicarbonate, magnesium oxide, and zinc oxide are preferred for neutralizing the catalysts of this disclosure. The temperature and time for neutralization can be selected depending on the specific catalyst and alkaline substance, combined with economic considerations.

[0040] In this disclosure, steps (a), (b), and (c) are advantageously carried out in the presence of an inert atmosphere, which is usually a nitrogen or argon atmosphere.

[0041] The preparation process of the present disclosure also includes step (d) removing low-boiling substances, including small molecule cyclosiloxane, low molecule alcohol, water, and unreacted organosilicon compounds A) and B), preferably by vacuum distillation at a suitable pressure of less than 100 mbar, e.g., less than 60 mbar, and a suitable temperature of 140°C to 190°C, e.g., 160°C to 180°C.

[0042] A third aspect of this disclosure also provides the use of a hydrogen polyorganosiloxane according to the first aspect of this disclosure in a thermally conductive silicone composition, particularly a silicone composition with a high amount of thermally conductive filler.

[0043] Non-limiting examples of suitable thermally conductive fillers include metals (such as aluminum, copper, nickel, gold, silver, gallium, indium, and silicon), metal oxides (such as alumina, zinc oxide, magnesium oxide, titanium oxide, iron oxide, chromium oxide, zirconium oxide, and silicon dioxide), metal nitrides (such as boron nitride, aluminum nitride, and silicon nitride), metal carbides (such as boron carbide and silicon carbide), and nonmetals (such as graphite and graphene). In one embodiment of this specification, the thermally conductive filler includes alumina. In another embodiment of this specification, the thermally conductive filler includes alumina and zinc oxide.

[0044] The average particle size of the thermally conductive filler is not particularly limited, but is preferably in the range of 0.1 to 120 μm, and more preferably in the range of 0.1 to 50 μm. In one embodiment of this specification, the thermally conductive filler includes filler i) a thermally conductive filler having an average particle size of 20 μm or more, and filler ii) a thermally conductive filler having an average particle size of less than 20 μm. In another embodiment of this specification, the thermally conductive filler includes filler i) a thermally conductive filler having an average particle size of 20 μm or more and 100 μm or less, for example, more than 30 μm and 60 μm or less, and filler ii) a thermally conductive filler having an average particle size of 0.1 μm or more and less than 20 μm, for example, 1 μm or more and 10 μm or less. In any of the above embodiments, the mass ratio of filler i) to filler ii) is appropriately in the range of 0.3:1 to 5:1, for example, 0.3:1 to 2:1.

[0045] Hydrogen polyorganosiloxanes according to the first aspect of this disclosure are particularly advantageous as high-filling thermal conductive fillers that can reduce the viscosity of the resulting silicone composition, thereby improving its thermal conductivity. The high-filling level of thermal conductive filler can be determined by those skilled in the art according to the density of a particular thermal conductive filler and its compatibility with polyorganosiloxane, and generally varies depending on the type of thermal conductive filler. For example, for alumina fillers, an amount of 88% to 93% by weight based on the total weight of the thermal conductive silicone composition can be considered high-filling. For boron nitride fillers, an amount of 50% to 60% by weight based on the total weight of the composition can be considered high-filling. However, for graphite fillers, an amount of 20% by weight based on the total weight of the composition can be considered high-filling. In some embodiments herein, alumina, or a thermal conductive filler comprising alumina and zinc oxide, is used in an amount of 88% to 93% by weight based on the total weight of the thermal conductive silicone composition.

[0046] A fourth aspect of this disclosure provides a thermally conductive silicone composition comprising the following: a) At least one hydrogen polyorganosiloxane according to a first aspect of the present disclosure, and b) At least one thermally conductive filler according to a third aspect of the present disclosure.

[0047] This composition may further comprise c) at least one organopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule. The position of the alkenyl groups is not particularly limited, and they may exist as side groups only, or as both side groups and terminal groups. Organopolysiloxane c) is typically R a R b 2SiO 1 / 2 , R b 2SiO 2 / 2 , R b 3SiO 1 / 2 and R a R b SiO 2 / 2 Essentially, it consists of units selected from, where R a In each case, independently, is an alkenyl group having 2 to 6 carbon atoms, for example, vinyl, allyl, propenyl, preferably vinyl, and R b In each case, independently, is a substituted or unsubstituted monovalent organic group having 1 to 20, preferably 1 to 10, carbon atoms, such as alkyl, aryl, or alkaryl, preferably methyl and phenyl, more preferably methyl.

[0048] The composition may further contain d) a hydrosilylation catalyst, which may be various hydrosilylation catalysts used in the prior art for addition-cured silicone rubber, preferably platinum-based catalysts, such as chloroplatinic acid, chloroplatinate salts, platinum olefin complexes, and platinum alkenylsiloxane complexes. The platinum-based catalyst may be used in an amount that depends on the desired curing rate and economic considerations, which is usually the minimum level required to ensure an effective hydrosilylation reaction.

[0049] The compositions may further contain an inhibitor, which may be a variety of inhibitors used in the art, such as acetylene alcohols such as 1-ethynyl-1-cyclohexanol and 2-methyl-3-butyne-2-ol, polyvinylsiloxanes such as 1,3,5,7-tetravinyltetramethyltetracyclosiloxane, or alkyl maleates. The amount of the inhibitor can be selected according to its chemical structure and the desired curing rate.

[0050] In some embodiments of this specification, the thermally conductive silicone composition includes the following: a) At least one hydrogen polyorganosiloxane according to the first aspect of this specification, b) At least one thermally conductive filler according to the third aspect of this specification, c) At least one organopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule, as defined above, and d) The hydrosilylation catalyst, and e) The aforementioned inhibitor, optionally.

[0051] The composition may further contain other components, such as filler surface treatment agents, diluents, and plasticizers, provided that such components do not impair the effects of the present invention. [Examples]

[0052] The present invention is further illustrated by the following embodiments, but is not limited thereto. Experimental methods not specified in the following embodiments are all selected according to conventional methods and conditions or the product specifications.

[0053] Characterization of molecular structure

[0054] 1 H NMR spectroscopy Test solvent: Deuterated chloroform (without TMS) Spectrometer:Bruker Avance III HD 400 Sampling head: 5mm BBO probe Measurement parameters: Pulse sequence (Pulprog) = zg30 TD=65536 NS=64 SW=18ppm AQ = 4.54 seconds D1=5 seconds

[0055] Depending on the type of spectrometer, several measurement parameters may need to be adjusted appropriately.

[0056] 29 Si NMR spectroscopy Test solvent: Deuterated benzene (containing the relaxation agent chromium acetylacetonate, without the addition of an internal standard) Spectrometer:Bruker Avance III HD 400 Sampling head: 5mm BBO probe Measurement parameters: Pulse sequence = zgig60 TD=65536 NS=2048 SW = 200 ppm AQ = 2.04 seconds D1=5 seconds

[0057] Depending on the type of spectrometer, several measurement parameters may need to be adjusted appropriately.

[0058] Characterization of molecular weight distribution Silane hydrolysis oligomers with different degrees of polymerization were separated using PSS SECcurity gel permeation chromatography, and their molecular weights were determined by comparison with a reference. Tetrahydrofuran was used as the solvent, and Agilent's PLgel 5um Guard and PLgel 5um 100A columns were used. The column oven temperature was 45°C, the feed rate was 1 ml / min, and the injection volume was 20 μl.

[0059] Measurement of polymer viscosity The viscosity of hydrogen polyorganosiloxane or hydrogen-terminated polydimethylsiloxane is measured using a Brookfield viscometer with a No. 3 spindle at 25°C and 300 rpm for 30 seconds.

[0060] Measurement of the viscosity of the composition The viscosity of the composition is measured according to DIN EN ISO3219: Determination of viscosity of polymers and resins in the liquid state or as emulsions or dispersions using a rotational viscometer with defined shear rate (ISO3219:1993).

[0061] All raw materials used in the examples are commercially available, and detailed information is as follows. Hydroxyl-terminated polydimethylsiloxane, WACKER(R) FINISH WS 62 M, has a dynamic viscosity of 50-110 mPa·s measured at 25°C according to DIN51562, supplied by Wacker Chemicals. Phosphonitrile chloride, WACKER(R) PNCL 2 / 100 PERCENT, supplied by Wacker Chemicals. 1,1,3,3-Tetramethyldisiloxane, supplied by Guike New Material. Alumina A, spherical alumina powder with an average particle size of 40 μm. Alumina B, spherical alumina powder with an average particle size of 5 μm. Zinc oxide, non-spherical zinc oxide powder with an average particle size of 5 μm, Hydrogen-terminated polydimethylsiloxane C1, XJY-707, has a dynamic viscosity of 145 mPa·s at 25°C, supplied by Xinjiayi New Material, and hereafter referred to as H polymer C1. Hydrogen-terminated polydimethylsiloxane C2, having a kinematic viscosity of 85 mPa·s at 25°C, supplied by Wacker Chemicals, hereafter referred to as H polymer C2. Hydrogen-terminated polydimethylsiloxane C3, with a dynamic viscosity of 1,040 mPa·s at 25°C, is supplied by Wacker Chemicals and hereafter referred to as H polymer C3.

[0062] [Synthesis Example 1] 68.5 g of dodecyldiethoxymethylsilane, 110 g of ethanol, and 1.22 g of 5% hydrochloric acid aqueous solution were added to a flask at room temperature and stirred. Then, 25 g of water was added dropwise to the flask and the mixture was reacted at room temperature for 4 hours, followed by heating at 65°C for 1 hour to obtain a white solid precipitate. The precipitate was then transferred to a distillation flask and subjected to rotary evaporation at 85°C and 100 mbar for 1 hour to obtain an oligomer of hydrolyzed dodecyldiethoxymethylsilane. As measured by NMR, the oligomer was 53.60 wt% trimethyltridodecylcyclotrisiloxane D3C 12 H 25 , 18.17% by weight of tetramethyltetradodecylcyclotetrasiloxane D4C 12 H 25 , 6.83% by weight of CH3(OR)(C 12 H 25 )SiO 1 / 2 The unit (R is -C2H5 or H, mainly -C2H5) and 21.40% by weight of CH3(C 12 H 25 )SiO 2 / 2 The oligomers include units, cyclic pentamers, cyclic hexamers, and cyclic oligomers with a higher degree of polymerization. As measured by GPC, the oligomers consist of 52.17% by weight trimers, 18.75% by weight tetramers, 6.36% by weight pentamers, and 22.73% by weight hexamers and oligomers with a higher degree of polymerization.

[0063] [Synthesis Example 2] 500 g of hydroxyl-terminated polydimethylsiloxane, 28.9 g of octyldimethoxymethylsilane, and 0.135 g of phosphonitrile chloride were added to a flask, stirred, and then heated to 100°C. The reaction was carried out under a nitrogen stream at 100°C and 50 mbar for 0.5 hours. Next, 11.26 g of 1,1,3,3-tetramethyldisiloxane was added to the flask and heated to 120°C and reacted for 5 hours. After the reaction was complete, sodium carbonate solid was added, and the phosphonitrile chloride was treated at 50°C for 1.5 hours, followed by filtration. The resulting reaction product was then transferred to a distillation flask and distilled at 170°C and 30 mbar for 1.5 hours to remove low-boiling substances. After cooling to room temperature, a hydrogen polyorganosiloxane called H polymer 1 with the following structural formula and a dynamic viscosity of 140 mPa·s at 25°C was obtained. (H(CH3)2SiO) 1.67 ((CH3)2SiO) 74.25 ((CH3)(C6H 17 )SiO) 1.51 (Si(CH3)2(OH)) 0.05 (Si(CH3)2(OCH3)) 0.28

[0064] [Synthesis Example 3] 200 g of hydroxyl-terminated polydimethylsiloxane, 30.8 g of the hydrolyzed dodecyldiethoxymethylsilane oligomer obtained in Synthesis Example 1, and 0.0592 g of phosphonitrile chloride were added to a flask, stirred, and heated to 95°C. The reaction was carried out under a nitrogen stream at 95°C and 50 mbar for 0.5 hours. Next, 6 g of 1,1,3,3-tetramethyldisiloxane was added to the flask and heated to 120°C and reacted for 5 hours. After the reaction was complete, sodium carbonate solid was added, and the phosphonitrile chloride was treated at 50°C for 1.5 hours, then filtered. The resulting reaction product was then transferred to a distillation flask and distilled at 170°C and 30 mbar for 1.5 hours to remove low-boiling substances. After cooling to room temperature, a hydrogen polyorganosiloxane called H polymer 2 with the following structural formula and a dynamic viscosity of 95 mPa·s at 25°C was obtained. (H(CH3)2SiO) 1.88 ((CH3)2SiO) 60.95((CH3)(C 12 H 25 )SiO) 3.02 (Si(CH3)2(OH)) 0.09 (Si(CH3)2(OC2H5)) 0.03

[0065] [Synthesis Example 4] 220 g of hydroxyl-terminated polydimethylsiloxane, 7.7 g of the hydrolyzed dodecyldiethoxymethylsilane oligomer obtained in Synthesis Example 1, and 0.0573 g of phosphonitrile chloride were added to a flask, stirred, and heated to 95°C. The reaction was carried out under a nitrogen stream at 95°C and 50 mbar for 0.5 hours. Next, 1.5 g of 1,1,3,3-tetramethyldisiloxane was added to the flask and heated to 120°C and reacted for 5 hours. After the reaction was complete, sodium carbonate solid was added and the phosphonitrile chloride was treated at 50°C for 1.5 hours, then filtered. The resulting reaction product was then transferred to a distillation flask and distilled at 170°C and 30 mbar for 1.5 hours to remove low-boiling substances. After cooling to room temperature, a hydrogen polyorganosiloxane called H polymer 3 with the following structural formula and a dynamic viscosity of 1,155 mPa·s at 25°C was obtained. (H(CH3)2SiO) 1.63 ((CH3)2SiO) 241.14 ((CH3)(C 12 H 25 )SiO) 3.78 (Si(CH3)2(OH)) 0.35 (Si(CH3)2(OC2H5)) 0.02

[0066] According to Table 1, when H polymers 1-3 and H polymers C1-C3 were mixed with a thermally conductive filler, the viscosity of the resulting composition was measured at a shear rate of 1s. -1 and 10s -1 It was measured using [this method].

[0067] [Table 1]

[0068] Table 1 shows that H polymers 1-3 are more effective at reducing the viscosity of a composition than corresponding H polymers C1-C3, which have similar viscosities, in the same thermally conductive filler filling, thereby improving the thermal conductivity of the composition. H polymers 2-3, which have higher viscosities than corresponding H polymers C2-C3, reduce the viscosity of the composition more effectively due to the appropriate content of alkoxy and hydroxyl groups and the numerous long-chain alkyl groups introduced.

[0069] According to Table 2, when H polymers 1-3 and H polymers C1-C3 were mixed with a thermally conductive filler, the viscosity of the resulting composition was measured at a shear rate of 1s. -1 and 10s -1 It was measured using [this method].

[0070] [Table 2]

[0071] Table 2 shows that H polymers 1-3 are more effective at reducing the viscosity of the composition than corresponding H polymers C1-C3, which have similar viscosities, in the same thermally conductive filler filling, thereby improving the thermal conductivity of the composition.

[0072] Table 3 shows the viscosity changes of H polymers 1-3 after being left at room temperature for 10 months. The viscosity change was within ±5%, indicating good storage stability.

[0073] [Table 3]

Claims

1. A hydrogen polyorganosiloxane characterized by the following structural formula shown in Formula I: 【Chemistry 1】 wherein a is any integer between 6 and 18; n is any number between 0.7 and 30; m is any number between 10 and 1500; r is any number between 0 and 200; R １ is independently at each occurrence C1-C5 alkyl or phenyl; X represents one or more groups selected from hydrogen, alkoxy, and hydroxyl, and 60 mol % or more of X are hydrogen atoms, based on the total number of moles of X groups.

2. 2. The hydrogen polyorganosiloxane according to claim 1, wherein 60 mol % or more but less than 100 mol % of X are hydrogen atoms, based on the total number of moles of X groups.

3. 3. The hydrogen polyorganosiloxane according to claim 1 or 2, wherein, based on the total number of moles of X groups, more than 0 mol% to 30 mol% of X groups are alkoxy groups and / or hydroxyl groups.

4. Based on the total number of moles of X groups, 80 mol% or more but less than 100 mol% of X are hydrogen atoms, and more than 0 mol% but less than 20 mol% of X are alkoxy groups and / or hydroxyl groups. The hydrogen polyorganosiloxane according to any one of claims 1 to 3, characterized in that

5. The hydrogen polyorganosiloxane according to any one of claims 1 to 4, wherein n is any number between 3 and 15.

6. The hydrogen polyorganosiloxane according to any one of claims 1 to 5, wherein m is any number between 50 and 500.

7. The hydrogen polyorganosiloxane according to any one of claims 1 to 6, wherein a is an integer between 6 and 16.

8. The hydrogen polyorganosiloxane according to any one of claims 1 to 7, characterized by a dynamic viscosity of 10 to 3000 mPa·s at 25°C.

9. A method for preparing the hydrogen polyorganosiloxane according to any one of claims 1 to 8, comprising: a) reacting a hydroxyl-terminated polysiloxane and at least one organosilicon compound A) selected from the compounds of formulae II and III, and optionally at least one organosilicon compound B) selected from the compounds of formulae IV and V, in the presence of a catalyst 1; 【Chemistry 2】 [In the formula, R ２ is independently at each occurrence methyl, ethyl, or hydrogen; R ３ is independently at each occurrence C6-C18 alkyl; R ４ is independently at each occurrence C1-C5 alkyl; R ５ is independently at each occurrence C1-C5 alkyl; s is any number between 1 and 20; t is any number between 3 and 20; u is any number between 1 and 100, v is any number between 3 and 100. b) reacting the product of step (a) with an end-capping agent in the presence of catalyst 2 to obtain the hydrogenpolyorganosiloxane; A method comprising:

10. 10. The method of claim 9, wherein the hydroxyl-terminated polysiloxane in step (a) is of formula VI: 【Transformation 3】 [In the formula, R ６ is independently at each occurrence C1-C5 alkyl or phenyl; p is any number between 10 and 100.

11. 11. The process according to claim 9 or 10, characterized in that the reaction of step (a) is carried out at a temperature of from 80°C to 110°C.

12. 12. The method according to any one of claims 9 to 11, characterized in that the endcapper in step (b) is of formula VII 【Chemistry 4】 [In the formula, R ７ is independently at each occurrence C1-C5 alkyl; q is any number between 0 and 20.

13. 13. The process according to any one of claims 9 to 12, characterized in that the reaction of step (b) is carried out at a temperature of from 100°C to 140°C.

14. 14. The process according to any one of claims 9 to 13, characterized in that both catalyst 1 and catalyst 2 are phosphonitrile chlorides.

15. Use of the hydrogenpolyorganosiloxane according to any one of claims 1 to 8 in a thermally conductive silicone composition.

16. 16. Use according to claim 15, characterized in that the thermally conductive filler used in the composition comprises alumina.

17. 17. Use according to claim 16, characterized in that the thermally conductive filler is used in an amount of 88% to 93% by weight, based on the total weight of the composition.