Single-end-capped silicone oil for heat-conducting filler treatment and preparation method of single-end-capped silicone oil

Abstract

The invention discloses single-end-capped silicone oil for heat-conducting filler treatment and a preparation method thereof.One end of the silicone oil is C1-C4 alkyl, the other end of the silicone oil is methoxyl, ethyoxyl or other alkoxy, hexamethylcyclotrisiloxane is mixed with organic lithium, silane, a molecular weight regulator and an initiation accelerant to be subjected to a reaction, and the single-end-capped silicone oil for heat-conducting filler treatment is obtained. Adding an end-capping reagent and a catalyst to carry out end-capping reaction; and removing the solvent to obtain the single-end-capped silicone oil for heat-conducting filler treatment. The single-end-capped silicone oil disclosed by the invention has relatively large molecular weight and excellent dispersing performance, can endow heat-conducting fillers such as aluminum oxide and magnesium oxide with excellent dispersing performance, and can reduce the thixotropic value of a heat-conducting material.

Description

Technical Field

[0001] The invention relates to the technical field of materials for heat-conducting filler treatment agents, and relates to a method for preparing single-end-capped silicone oil for heat-conducting filler treatment and a process thereof. Background Art

[0002] Due to the significant differences in physical and chemical properties between organic or silicone materials and filler surfaces, their compatibility is often poor. Therefore, in order to improve this compatibility, it becomes crucial to perform surface treatment on the filler.

[0003] Since silicone materials have excellent high and low temperature resistance, weather resistance, hydrophobicity and low stress characteristics, they are widely used in the field of thermal conductive materials. Common silicone thermal conductive materials include thermal conductive adhesives, thermal conductive gaskets, thermal conductive silicone grease, thermal conductive gel and thermal conductive phase change materials.

[0004] As the integration of electronic components increases, the heat generated will become more concentrated, which urgently requires improving the heat dissipation performance of components. The thermal conductivity of the material is related to the thermal conductivity of the filler itself and the filling amount of the selected thermal conductive filler. Increasing the amount of thermal conductive filler can improve the thermal conductivity of the material, but it will also increase the viscosity of the material, making it impossible to construct the material. In addition, due to the poor compatibility of thermal conductive fillers with silicone, the dispersion of thermal conductive fillers in silicone will deteriorate, causing filler sedimentation and reducing the thermal conductivity of the material. It will also lead to poor contact between the thermal conductive material and the device or heat sink, increase thermal resistance, and thus reduce the overall performance, including mechanical properties.

[0005] In order to solve the above problems, the conventional method is to use silane coupling agent to treat the filler surface to improve its compatibility with silicone, but the surface treatment of the filler is limited. When the amount of filler added increases, the thixotropic value of the thermal conductive material increases and even construction cannot be carried out, and a thermal conductive material with high thermal conductivity cannot be obtained. Summary of the invention

[0006] The prior art uses silane coupling agents to treat fillers to improve their compatibility with silicone, but this increases the thixotropic value of the thermally conductive material and fails to obtain a thermally conductive material with high thermal conductivity. The single-terminated silicone oil used for treating thermally conductive fillers of the present invention has high operability and can impart excellent dispersibility at a relatively low dosage, thereby imparting a higher filler addition amount to the thermally conductive material without increasing the thixotropic value of the thermally conductive filler.

[0007] The present invention is achieved through the following technical solutions.

[0008] A single-terminated silicone oil for treating a thermally conductive filler, the chemical structure of which is shown in Formula 1;

[0009]

[0010] Wherein, X is an alkane group, R is an alkoxy group, and n is a natural number; preferably, X is a substituted or unsubstituted C1-C4 alkane group, and R is a methoxy group, an ethoxy group, or other alkoxy groups; 10≤n≤300, preferably 20≤n≤200, and more preferably 20≤n≤120. The single-terminated silicone oil for thermal conductive filler treatment of the present invention has high operability, can impart excellent dispersibility, has a low dosage and thixotropic value, and has a long service life.

[0011] The invention discloses a method for preparing the above-mentioned single-end-capped silicone oil for treating thermal conductive fillers, comprising the following steps: mixing hexamethylcyclotrisiloxane with a solvent, n-butyl lithium, silane, a molecular weight regulator and an initiator and then reacting, then adding an end-capping agent and a catalyst to carry out an end-capping reaction, and then removing the solvent to obtain the single-end-capped silicone oil for treating thermal conductive fillers.

[0012] The invention discloses a method for surface treatment of fillers, comprising the following steps: mixing hexamethylcyclotrisiloxane with a solvent, n-butyl lithium, silane, a molecular weight regulator and an initiator and accelerator, and reacting the mixture; then adding a capping agent and a catalyst to carry out a capping reaction; then removing the solvent to obtain a single-end-capped silicone oil for treating a thermally conductive filler; and then using the single-end-capped silicone oil for treating a thermally conductive filler to treat the filler surface.

[0013] In the present invention, the solvent is any one of toluene, xylene and n-heptane; the molecular weight regulator is trimethylsilanol; the initiator accelerator is any one or more of tetrahydrofuran, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide and trimethyl urea; the end-capping agent is methyl orthosilicate; the catalyst is one of formic acid, acetic acid, propionic acid and citric acid; and the silane is trimethylchlorosilane.

[0014] Preferably, when hexamethylcyclotrisiloxane and n-butyl lithium are mixed, the temperature is 30-40° C., the time is 10-20 min, and then a molecular weight regulator is added and the mixture is reacted at 10-80° C. for 3-8 h.

[0015] Preferably, the mass ratio of the solvent to hexamethylcyclotrisiloxane is 0.8-1.0, the mass ratio of n-butyl lithium to hexamethylcyclotrisiloxane is 0.2%-1%, the mass ratio of the molecular weight regulator to hexamethylcyclotrisiloxane is 0.004-0.12, the mass ratio of the initiator accelerator to hexamethylcyclotrisiloxane is 0.2-0.5, the mass ratio of the end-capping agent to hexamethylcyclotrisiloxane is 0.5-1.0, the mass ratio of the catalyst to hexamethylcyclotrisiloxane is 0.2%-1.2%, and the mass ratio of silane to hexamethylcyclotrisiloxane is 0.2%-0.5%.

[0016] The invention discloses the application of the single-terminated silicone oil used for treating thermal conductive fillers as a surface treatment agent.

[0017] The invention discloses application of the single-end silicone oil for treating heat-conductive fillers in treating the surface of fillers.

[0018] The invention discloses application of the above-mentioned single-end-capped silicone oil for treating thermal conductive fillers in improving the dispersibility of fillers and / or reducing the thixotropic value of fillers.

[0019] When the single-end-capped silicone oil for treating thermal conductive fillers is used for surface treatment, the molecular weight distribution index of the single-end-capped silicone oil is 1.0-1.5, preferably 1.0-1.2.

[0020] Furthermore, the filler surface-treated with the single-terminated silicone oil used for treating the thermally conductive filler is used in an organic silicon material system, such as a vinyl silicone oil system.

[0021] Therefore, the present invention discloses a thermally conductive organic silicon material, comprising an organic silicon raw material and a surface-treated thermally conductive filler, wherein the surface-treated thermally conductive filler is the thermally conductive filler surface-treated with the single-capped silicone oil for thermally conductive filler treatment.

[0022] As an example, the present invention discloses a method for preparing the above-mentioned single-terminated silicone oil for thermal conductive filler treatment, comprising the following steps performed in sequence:

[0023] (1) dissolving hexamethylcyclotrisiloxane (D3) in a solvent, wherein the solvent is any one of toluene, xylene, and n-heptane;

[0024] (2) When the material temperature is 30-40° C., n-butyl lithium is added as a reaction initiator, and the reaction is allowed to proceed for 10-20 minutes;

[0025] (3) adding trimethylsilyl chloride to the reaction system and reacting for 60 min;

[0026] (4) adding a molecular weight regulator and a promoter to the reaction system, and continuing the reaction for 3-8 hours at a reaction temperature of 10-50° C., preferably 30-40° C.;

[0027] (5) removing low boiling substances by vacuum distillation, the vacuum distillation conditions being a pressure of -90 kPa to -100 kPa and a temperature of 90-120°C;

[0028] (6) After the desulfurization reaction in step (5) is completed, a capping agent and a catalyst are added to carry out a capping reaction, the reaction time is 3-6 hours, and the reaction temperature is 90-120° C.;

[0029] (7) After the end-capping reaction in step (6) is completed, the low-boiling substances other than the silicone oil polymer are removed by vacuum distillation, the vacuum distillation conditions being a pressure of -90 kPa to -100 kPa and a temperature of 160-180° C.;

[0030] (8) Filter and remove impurities to obtain a colorless and transparent product, namely, a single-end-capped silicone oil for thermal conductive filler treatment.

[0031] The invention discloses the application of the single-terminated silicone oil for heat-conductive filler treatment as surface treatment.

[0032] The invention discloses application of the single-end silicone oil for treating thermal conductive fillers in treating fillers, especially the surface of thermal conductive fillers.

[0033] The beneficial effects of the invention include high reaction yield, which is ≥95%.

[0034] The beneficial effects of the present invention include uniform molecular weight distribution and narrow molecular weight distribution (PDI<1.5).

[0035] The beneficial effects of the present invention include that silicone oils with different molecular weights and different numbers of chain links, n being between 10 and 300, can be customized, and silicone oils with different chain links can be prepared according to different use environments.

[0036] The beneficial effects of the present invention include that single-end-capped silicone oils end-capped with different functional groups can be customized and applied to different types of thermal conductive filler processing fields.

[0037] The advantage of the present invention over traditional thermal conductive filler treatment agents is that the structure and molecular weight can be directionally regulated according to different use environments, and the advantage of one end of the structure being inert and the other end being active is used to achieve directional bonding between the surface treatment material and the base material, and low molecular weight polysiloxane products can easily penetrate the base material, making repeated surface treatment fillers and base materials more integrated. The single-end-capped silicone oil used for thermal conductive filler treatment of the present invention can impart excellent dispersibility at a relatively low dosage, giving the thermal conductive material a higher filler addition amount without increasing the thixotropic value of the thermal conductive filler. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the infrared spectrum of the product of Example 1.

[0039] Figure 2 This is the infrared spectrum of the product of Example 2.

[0040] Figure 3 This is the infrared spectrum of the product of Example 3.

[0041] Figure 4 This is the infrared spectrum of the product of Example 4. DETAILED DESCRIPTION

[0042] The present invention discloses a method for preparing a single-end-capped silicone oil for treating a thermally conductive filler, which specifically comprises the following steps:

[0043] (1) dissolving hexamethylcyclotrisiloxane (D3) in a solvent, wherein the solvent is any one of toluene, xylene, and n-heptane;

[0044] (2) When the material temperature is 20-40° C., n-butyl lithium is added as a reaction initiator, and the reaction is allowed to proceed for 10-20 minutes;

[0045] (3) adding trimethylsilyl chloride to the reaction system and reacting for 60 min;

[0046] (4) adding a molecular weight regulator and a promoter to the reaction system, and continuing the reaction for 3-8 hours at a reaction temperature of 10-50° C., preferably 20-40° C.;

[0047] (5) removing low boiling substances by vacuum distillation, the vacuum distillation conditions being a pressure of -90 kPa to -100 kPa and a temperature of 90-120°C;

[0048] (6) After the desulfurization reaction in step (5) is completed, a capping agent and a catalyst are added to carry out a capping reaction, the reaction time is 3-6 hours, and the reaction temperature is 90-130° C.;

[0049] (7) After the end-capping reaction in step (6) is completed, the low-boiling substances other than the silicone oil polymer are removed by vacuum distillation, the vacuum distillation conditions being a pressure of -90 kPa to -100 kPa and a temperature of 160-180° C.;

[0050] (8) Filter and remove impurities to obtain a colorless and transparent product, namely, a single-end-capped silicone oil for thermal conductive filler treatment.

[0051] Furthermore, the initiator used in step (2) can be any one of organic lithiums such as methyl lithium, n-butyl lithium, sec-butyl lithium, etc.

[0052] Furthermore, the initiator used in step (3) is any one or more of tetrahydrofuran, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, and trimethyl urea.

[0053] Furthermore, the molecular weight regulator used in step (4) is any one of trimethylsilanol and dimethylvinylsilanol.

[0054] Furthermore, in step (6), the end-capping agent is any one of tetramethoxysilane, vinyltrimethoxysilane and tetraethoxysilane.

[0055] Furthermore, the catalyst in step (6) is any one of acetic acid, propionic acid, formic acid and citric acid.

[0056] In order to make the technical principles, objects and advantages of the present invention more understandable, the present invention is further elaborated in detail below in conjunction with examples. The exemplary scheme of the present invention is only for the purpose of explaining the present invention and does not limit the technical scheme of the present invention. The raw materials used are existing products, and the specific preparation operations and performance tests are all conventional techniques.

[0057] Example 1

[0058] According to the present invention, the target silicone oil product synthesized in Example 1 is described below with a specific case:

[0059]

[0060] The preparation method is carried out in sequence as follows:

[0061] Step 1: Weigh 19 kg of hexamethylcyclotrisiloxane (D3) and 16 kg of toluene into a conventional reactor and heat to 40°C;

[0062] Step 2: Add 470mL of n-butyl lithium (2.5mol / L in hexane) into the kettle, wait for the reaction of the materials in the kettle for 15 minutes, then add 0.057kg of trimethylsilyl chloride into the kettle, wait for the reaction of the materials in the kettle for 60 minutes, then add 0.67kg of trimethylsilanol and 4kg of N,N-dimethylformamide mixed solution into the kettle; keep N2 gas flowing into the kettle, set the oil temperature to 35°C, and time the reaction for 3 hours; Step 3: Remove the solvent at 95-100°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0063] Step 4: Weigh 10.6 kg of methyl orthosilicate and 0.18 kg of anhydrous acetic acid, add them from the feeding port, and then perform end-capping reaction at 125° C. The reaction is completed after 4 hours;

[0064] Step 5: Remove the solvent at 155-160°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0065] Step 6: Filter to obtain a colorless and transparent product.

[0066] The obtained product was characterized by gel permeation chromatography: number average molecular weight was 2516, weight average molecular weight was 3039, molecular weight distribution coefficient was 1.208; viscosity (25°C) = 32 mm 2 / s.

[0067] Figure 1 The infrared spectrum of the obtained product is 801 cm -1 The strong peak at 1023 cm is the Si-C bond stretching vibration absorption peak. -1 The strong peak at 1261 cm is the Si-O-Si stretching vibration absorption peak.-1 The peak at 2963cm is the stretching vibration absorption peak of Si-CH3; -1 The peaks appearing near are the stretching vibrations of -CH3, 2844 cm -1 There is a weak absorption peak at the stretching vibration absorption peak of Si-OCH3.

[0068] Example 2

[0069] According to the present invention, the target silicone oil product synthesized in Example 2 is described below with a specific case:

[0070]

[0071] The preparation method is carried out in sequence according to Example 1:

[0072] Step 1: Weigh 15 kg of hexamethylcyclotrisiloxane (D3) and 13 kg of toluene into a conventional reactor and heat to 40°C;

[0073] Step 2: Add 350mL of n-butyl lithium (2.5mol / L in hexane) into the kettle, wait for the reaction of the materials in the kettle for 15 minutes, then add 0.07kg of trimethylsilyl chloride into the kettle, wait for the reaction of the materials in the kettle for 60 minutes, then add 0.29kg of trimethylsilanol, 2.4kg of N,N-dimethylformamide, and 1kg of acetonitrile mixed solution into the kettle; keep N2 gas flowing into the kettle, set the oil temperature to 35°C, and time the reaction for 4 hours;

[0074] Step 3: Remove the solvent at 95-100°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0075] Step 4: Weigh 8.5 kg of methyl orthosilicate and 0.15 kg of anhydrous acetic acid, add them from the feeding port, and then perform end-capping reaction at 130° C. The reaction is completed after 3 hours;

[0076] Step 5: Remove the solvent at 155-160°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0077] Step 6: Filter to obtain a colorless and transparent product.

[0078] The obtained product was characterized by gel permeation chromatography: number average molecular weight was 3848, weight average molecular weight was 4568, molecular weight distribution coefficient was 1.187; viscosity (25°C) = 53 mm 2 / s.

[0079] Figure 2 The infrared spectrum of the obtained product is 799 cm -1 The strong peak at 1021cm is the Si-C bond stretching vibration absorption peak. -1The strong peak at 1261 cm is the Si-O-Si stretching vibration absorption peak. -1 The peak at 2963cm is the stretching vibration absorption peak of Si-CH3; -1 The peaks appearing near are the stretching vibrations of -CH3, 2844 cm -1 There is a weak absorption peak at the stretching vibration absorption peak of Si-OCH3.

[0080] Example 3

[0081] According to the present invention, the target silicone oil product synthesized in Example 3 is described below with a specific case:

[0082]

[0083] The preparation method is carried out in sequence according to Example 1:

[0084] Step 1: Weigh 20 kg of hexamethylcyclotrisiloxane (D3) and 18 kg of toluene into a conventional reactor and heat to 40°C;

[0085] Step 2: Add 530mL of n-butyl lithium (2.5mol / L in hexane) into the kettle, wait for the reaction of the materials in the kettle for 20min, then add 0.13kg of trimethylsilyl chloride into the kettle, wait for the reaction of the materials in the kettle for 60min, then add 0.19kg of trimethylsilanol, 2.5kg of N,N-dimethylformamide, and 1kg of acetonitrile mixed solution into the kettle; keep N2 gas flowing into the kettle, set the oil temperature to 35°C, and time the reaction for 5h;

[0086] Step 3: Remove the solvent at 95-100°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0087] Step 4: Weigh 12 kg of methyl orthosilicate and 0.18 kg of anhydrous acetic acid, add them from the feeding port, and then perform end-capping reaction at 120° C. The reaction is completed after 6 hours;

[0088] Step 5: Remove the solvent at 150-155°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0089] Step 6: Filter to obtain a colorless and transparent product.

[0090] The obtained product was characterized by gel permeation chromatography: number average molecular weight was 6512, weight average molecular weight was 7769, molecular weight distribution coefficient was 1.193; viscosity (25°C) = 85 mm 2 / s.

[0091] Figure 3 The infrared spectrum of the obtained product is 799 cm -1The strong peak at 1021cm is the Si-C bond stretching vibration absorption peak. -1 The strong peak at 1260 cm is the Si-O-Si stretching vibration absorption peak. -1 The peak at 2963cm is the stretching vibration absorption peak of Si-CH3; -1 The peaks appearing near are the stretching vibrations of -CH3, 2845cm -1 There is a weak absorption peak at the stretching vibration absorption peak of Si-OCH3.

[0092] Example 4

[0093] According to the present invention, the target silicone oil product synthesized in Example 4 is described below with a specific case:

[0094]

[0095] The preparation method is carried out in sequence according to Example 1:

[0096] Step 1: Weigh 16 kg of hexamethylcyclotrisiloxane (D3) and 14 kg of toluene into a conventional reactor and heat to 40°C;

[0097] Step 2: Add 280mL of n-butyl lithium (2.5mol / L in hexane) into the kettle, wait for the reaction of the materials in the kettle for 20 minutes, then add 0.09kg of trimethylsilyl chloride into the kettle, wait for the reaction of the materials in the kettle for 60 minutes, then add 0.13kg of trimethylsilanol and 4kg of N,N-dimethylformamide mixed solution into the kettle; keep N2 gas flowing into the kettle, set the oil temperature to 35°C, and time the reaction for 5 hours; Step 3: Remove the solvent at 95-100°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0098] Step 4: Weigh 10 kg of methyl orthosilicate and 0.13 kg of anhydrous acetic acid, add them from the feeding port, and then carry out end-capping reaction at 125° C. The reaction is completed after 4 hours;

[0099] Step 5: Remove the solvent at 150-155°C using a negative pressure of -0.1Mpa, and stop when no solvent is removed;

[0100] Step 6: Filter to obtain a colorless and transparent product.

[0101] The obtained product was characterized by gel permeation chromatography: number average molecular weight was 8145, weight average molecular weight was 9896, molecular weight distribution coefficient was 1.215; viscosity (25°C) = 115 mm 2 / s.

[0102] Figure 4 is the infrared spectrum of the obtained product, 800cm -1The strong peak at 1023 cm is the Si-C bond stretching vibration absorption peak. -1 The strong peak at 1261 cm is the Si-O-Si stretching vibration absorption peak. -1 The peak at 2963cm is the stretching vibration absorption peak of Si-CH3; -1 The peaks appearing near are the stretching vibrations of -CH3, 2844 cm -1 There is a weak absorption peak at the stretching vibration absorption peak of Si-OCH3.

[0103] Application Example 5-11

[0104] Component 1: Vinyl silicone oil (model RH-Vi321D, viscosity 100mPa·s, Ningbo Runhe High-tech Materials Technology Co., Ltd.)

[0105] Component 2: Alumina (Model: TM-LA-T, Particle size: ≤2.8μm; Specific surface area: 4-7m 2 g -1 ).

[0106] Component 3: single-end-capped silicone oil 3-1: Example 1;

[0107] Single-terminated silicone oil 3-2: Example 2;

[0108] Single-end-capped silicone oil 3-3: Example 3;

[0109] Single-terminated silicone oil 3-4: Example 4.

[0110] Component 4: Coupling agent 4-1: n-octyltrimethoxysilane (GC content ≥ 99%, Jiangxi Chenguang New Materials Co., Ltd.);

[0111] Coupling agent 4-2: γ-glycidyloxypropyltrimethoxysilane (GC content ≥ 99%, Jiangxi Chenguang New Materials Co., Ltd.).

[0112] First, vinyl silicone oil, alumina and single-end silicone oil or coupling agent are added into a 200 ml stainless steel cup and stirred in a disperser for 10 minutes. Then, the viscosity of the mixture is tested and the thixotropic value is calculated.

[0113] Viscosity test

[0114] Test instrument: Use Bolifei viscometer to test the viscosity of the material system;

[0115] Test conditions: temperature is 25±0.1℃, the viscometer rotor used is No. 29, and the speed is 10r / min and 100r / min.

[0116] The calculation formula of thixotropic value is as follows:

[0117]

[0118] Table 1 Dispersion effects of different powder treatment agents in application examples

[0119]

[0120]

[0121] From the above table examples 5 to 11, it can be seen that the single-end silicone oil of the present invention can give the thermal conductive filler excellent dispersibility compared with coupling agent 4-1 and coupling agent 4-2, and give the thermal conductive material a higher filler addition amount without increasing the thixotropic value of the thermal conductive material. In addition, it can be seen that the single-end silicone oil treatment agent with a smaller molecular weight can make the thermal conductive material have a lower viscosity and a lower thixotropic value, which is manifested in good fluidity even at a high filler addition ratio of the thermal conductive material.

[0122] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A single-end-capped silicone oil for thermal conductive filler treatment, the chemical structure of which is shown below; in, X is an alkane group, R is an alkoxy group, and n is a natural number.

2. The single-end-capped silicone oil for treating thermal conductive fillers according to claim 1, characterized in that: X is a substituted or unsubstituted C1-C4 hydrocarbon group; R is a methoxy group, an ethoxy group or other alkoxy group; 10≤n≤300.

3. The method for preparing the single-end-capped silicone oil for treating thermally conductive fillers according to claim 1, comprising the following steps: mixing hexamethylcyclotrisiloxane with organic lithium, silane, a molecular weight regulator, and an initiator and reacting them, then adding an end-capping agent and a catalyst to carry out an end-capping reaction, and then removing the solvent to obtain the single-end-capped silicone oil for treating thermally conductive fillers.

4. The preparation method according to claim 3, characterized in that: The molecular weight regulator is trimethylsilanol; the initiator is any one or more of tetrahydrofuran, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, and trimethyl urea; the end-capping agent is methyl orthosilicate; and the catalyst is one of formic acid, acetic acid, propionic acid, and citric acid.

5. The preparation method according to claim 3, characterized in that: When hexamethylcyclotrisiloxane is mixed with organic lithium, the temperature is 30-40°C and the reaction time is 10-20 minutes. Then a molecular weight regulator is added and the mixture is reacted at 10-80°C for 3-8 hours.

6. The preparation method according to claim 3, characterized in that: The organic lithium is one of methyl lithium, n-butyl lithium and sec-butyl lithium; and the silane is trimethylchlorosilane.

7. A method for surface treatment of filler, characterized in that: The filler is surface treated using the single-end-capped silicone oil for treating the thermally conductive filler as claimed in claim 1.

8. Use of the single-terminated silicone oil for treating thermal conductive fillers according to claim 1 as a surface treatment agent.

9. Use of the single-end-capped silicone oil for treating thermal conductive fillers according to claim 1 in treating the surface of fillers.

10. A thermally conductive silicone material, comprising a silicone raw material and a surface-treated thermally conductive filler, characterized in that: The surface-treated thermally conductive filler is the thermally conductive filler surface-treated with the single-terminated silicone oil for thermally conductive filler treatment as claimed in claim 1.

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