Immersed organic silicon cooling liquid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of immersed cooling, and provides an immersed organic silicon cooling liquid as well as a preparation method and application thereof in order to solve the problem that the thermodynamic property of a dimethyl silicone oil cooling liquid needs to be further improved: at least one of (CH3) 3SiO (SiCH3RO) m (Si (CH3) 2O) nOSi (CH3) 3 and R (CH3) 2SiO (Si (CH3) 2O) n (CH3) 2SiOR; wherein R is C6-C18, m is 1 to 50, n is 0 to 100, and n / m is 0 to 0.8. The method comprises the following steps: carrying out hydrosilylation reaction by taking hydrogen-containing organic silicon and long-chain alpha-olefin as reactants; after the reaction is completed, free olefin is removed, and a long-chain alpha-olefin modified intermediate and a dimethyl ring body are used as reactants for ring-opening polymerization reaction. The thermodynamic property of the prepared organic silicon cooling liquid is obviously improved, and the balance among insulativity, compatibility and thermal conductivity is realized.

Description

Technical Field

[0001] This invention belongs to the field of immersion cooling technology, specifically relating to immersion organosilicon coolant, its preparation method, and its application. Background Technology

[0002] With the explosive growth in power density of AI, HPC, and high-performance GPUs, traditional air cooling is approaching its physical limits, and immersion cooling is a key technology to break through the "thermal wall." Coolant is the core of immersion cooling technology, and its performance is generally considered from the following five aspects: thermal performance (high thermal conductivity, suitable boiling point, low viscosity), safety (high insulation, non-flammable, non-toxic), compatibility (long-term stability with all materials), environmental friendliness (low GWP, biodegradable), and cost control (low price, long lifespan, easy to dispose of). Among these, thermodynamic properties directly determine the coolant's heat dissipation capacity. A higher thermal conductivity results in a faster heat transfer rate, playing a crucial role in initial heat dissipation efficiency; a higher specific heat capacity means the fluid can carry more heat per unit temperature rise, implying stronger sustained heat dissipation capacity at the same flow rate. Fluid flowability is another key parameter. At 25 ℃, a kinematic viscosity below 50 mm² / s indicates good fluidity in silicone oil. Low viscosity helps achieve better heat exchange in microchannels and is a common goal in coolant design. Regarding safety performance, flash point is an important basis for evaluating the fire safety of coolants. Ideally, a submersible coolant should have a high flash point (typically > 150°C). Simultaneously, electrochemical performance is the cornerstone of system insulation safety: high dielectric strength (typically > 30 kV / 2.5 mm) ensures the coolant is non-conductive under high voltage, preventing short circuits; high volume resistivity (typically > 10 kV / 2.5 mm) ensures the coolant is non-conductive under high voltage, preventing short circuits; high volume resistivity (typically > 10 kV / 2.5 mm) further enhances its performance. 9 A coolant temperature of Ω·cm (or even higher for high-quality products, exceeding 10¹² Ω·cm) reflects its excellent insulation properties, effectively suppressing leakage current. Finally, the coolant must also possess good chemical compatibility with various electronic components in the data center to ensure long-term stable operation.

[0003] Currently, the mainstream immersion coolants are dimethyl silicone oil, mineral oil, synthetic hydrocarbons, and fluorinated liquids. Among them, dimethyl silicone oil has an irreplaceable advantage in fields where equipment needs to operate for a long time in high-temperature or wide-temperature-range environments due to its excellent thermal stability. However, its specific heat capacity is relatively low, generally between 1.3 and 1.6 kJ / (kg·K), it heats up quickly, and its thermal conductivity is relatively low, generally not exceeding 0.15 W / (m·K). Therefore, its thermodynamic properties still need further improvement. For example, Chinese patent document CN120987994 A discloses an organosilicon coolant with a maximum specific heat capacity of 1.90 kJ / (kg·K) at 40℃. Chinese patent document CN120271827 A discloses an organosilicon coolant with a maximum thermal conductivity of 1.562 W / m·K (40℃).

[0004] Based on this, the present invention is proposed. Summary of the Invention

[0005] To address the aforementioned issue of the need for further improvement in the thermodynamic properties of dimethyl silicone oil coolant, this invention provides an immersion-type organosilicon coolant, its preparation method, and its application. By synthesizing high-purity, long-chain alkyl-modified polysiloxanes with specific molecular structures, the thermodynamic properties of the organosilicon coolant are significantly improved, achieving an effective balance between insulation, compatibility, and thermal conductivity.

[0006] This invention is achieved through the following technical solution: The first aspect of this invention provides an immersion-type silicone coolant, the molecular structure of which is: (CH3)3SiO(SiCH3RO) m (Si(CH3)2O) n OSi(CH3)3 and R(CH3)2SiO(Si(CH3)2O) n At least one of (CH3)2SiOR; Wherein, R is a long-chain alkyl group selected from C6~C6. 18 The range of m is 1~50, the range of n is 0~100, and the ratio of n / m is between 0 and 0.8. In the same molecular structure, R can be two different structures.

[0007] Furthermore, R (alkane) can be -C6H 14 —C8H 18 —C 10 H 22 —C 12 H 26 —C 14 H 30 —C 16 H 34 —C 18 H 38 One or more of them, with the ratio of n / m between 0.1 and 0.6.

[0008] A second aspect of the present invention provides a method for preparing the immersion-type organosilicon coolant, comprising the following steps: (1) Hydrosilylation reaction was carried out using hydrogen-containing organosilicon and long-chain α-olefin as reactants under the action of a catalyst; after the reaction was complete, the free olefin was removed to obtain a pure long-chain α-olefin modified intermediate. (2) Using the long-chain α-olefin modified intermediate and dimethyl cyclopropion obtained in step (1) as reactants, a ring-opening polymerization reaction is carried out under the action of a catalyst to obtain a long-chain alkyl modified polysiloxane coolant.

[0009] Furthermore, the hydrogen-containing organosilicon in step (1) is preferably tetramethylhydrocyclotetrasiloxane, tetramethyldihydrodisiloxane, methyldimethoxysilane, or hydrogen-containing silicone oil with a hydrogen content of 0.015%~1.67%; the long-chain α-olefin is preferably 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, or 1-octadecene; the catalyst is preferably manganese pentacarbonyl bromide (MnBr(CO)5).

[0010] Furthermore, in step (1), when the temperature is raised to 40~80 ℃, the mixture of long-chain α-olefin and catalyst is added dropwise for about 15~30 min. After the addition is completed, the temperature is kept at 60~120 ℃ for 5 h.

[0011] In step (1), the mixture of long-chain α-olefin and catalyst is dispersed in a solvent, the concentration of the mixture in the solvent being 0.5~1 g / mL, and the solvent being any one or more of tetrahydrofuran, cyclohexanone, toluene, n-hexane, and isopropanol.

[0012] Furthermore, step (1) involves removing free olefins by washing with petroleum ether or by vacuum distillation.

[0013] Furthermore, the dimethyl cyclic compound in step (2) is preferably octamethylcyclotetrasiloxane; the catalyst is preferably tert-butylphosphazene base (t-Bu-P4).

[0014] Furthermore, the reaction temperature in step (2) is 60~100 ℃ and the reaction time is 3~8 hours; preferably 80 ℃ and the reaction time is 5 hours.

[0015] A third aspect of the present invention provides the application of the immersion silicone coolant as an immersion coolant.

[0016] Furthermore, the immersion-type silicone coolant of this invention can be applied to single-phase immersion cooling systems in big data centers. Through molecular structure design, this coolant combines the thermal stability of polysiloxane-based compounds with the excellent material affinity of long-chain alkyl groups, effectively preventing swelling and corrosion of internal plastic and rubber materials in servers. It possesses a high flash point, is non-flammable, has high operational safety, and is chemically stable, enabling ultra-long-term use. In application, this coolant directly immerses the server's heat-generating components, efficiently removing heat through optimized convection, and then transferring the heat to the secondary cooling circuit via an external heat exchanger, significantly improving heat dissipation efficiency.

[0017] This invention has found that when long-chain alkyl silicone oil is used as an immersion coolant, if the residual amount of silicon-hydrogen bonds (Si–H) is too high, it is easy to hydrolyze to generate silanols under the action of moisture. This not only changes the chemical structure of the silicone oil and affects its thermal stability, but also releases hydrogen gas, posing a safety hazard. At the same time, the hydrolysis products may further transform into silicic acid compounds, reducing the overall performance of the silicone oil.

[0018] The present invention has the following beneficial effects: (1) The long-chain alkyl-modified silicone oil synthesized in this invention has the advantage of high purity, specifically manifested in low Si-H and free olefin residues, with Si-H residues as low as 0~5 ppm and free olefin residues as low as 0~5 wt%. Its thermodynamic properties are characterized by low kinematic viscosity (< 20 mm at 25 ℃). 2 It exhibits high flash point (> 200 ℃), high thermal conductivity (1.52 ~ 1.74 W / (m·K)), and high specific heat capacity (1.9 ~ 2.1 kJ / (kg·K)). It also displays safe electrochemical properties, specifically high dielectric strength (> 40 kV) and high volume resistivity (8.12 ~ 9.78) × 10^ 12 Ω·cm. The long-chain alkyl-modified silicone oil synthesized in this invention has good compatibility with data center materials (organic silicone rubber, EPDM rubber), specifically manifested as (< 10% change in length and weight).

[0019] (2) The specific heat capacity is significantly improved, achieving an effective balance between insulation, compatibility and thermal conductivity.

[0020] (3) It has the combined advantages of higher safety, better environmental protection and lower cost.

[0021] (4) This invention addresses the issues of cost, process, and purity through catalytic synergy: Manganese pentacarbonyl bromide is selected as the catalyst for the first step of the hydrosilylation reaction. As a non-precious metal catalyst, it significantly reduces the raw material cost compared to platinum-based catalysts while maintaining high activity and air stability. Tert-butylphosphazene base is selected as the catalyst for the second step of the ring-opening polymerization reaction. Its extremely high catalytic activity ensures that the polymerization reaction can proceed rapidly at low temperatures. More importantly, its self-decomposition upon heating eliminates the need for traditional post-treatment steps such as neutralization and filtration after the reaction, allowing for the direct acquisition of high-purity silicone oil, thus fundamentally guaranteeing the high purity of the final coolant product. Attached Figure Description

[0022] Figure 1 : 1H NMR spectrum of long-chain alkyl-modified silicone oil; Figure 2 Infrared spectra of long-chain alkyl-modified silicone oils; Figure 3Summary table of performance tests for long-chain alkyl-modified silicone oils. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. Example

[0025] Tetramethylhydrocyclotetrasiloxane was added to a three-necked flask, and the reaction was carried out under an inert gas atmosphere at a temperature of 75 °C. At this temperature, 1-octene and manganese pentacarbonyl bromide were added dropwise, with a carbon-carbon double bond to silicon-hydrogen bond ratio of 1.2:1. The addition time was controlled at 15–30 min, and the temperature was maintained at 80 °C during the addition. After the addition was complete, the mixture was kept at 120 °C for 5 h. After the reaction was complete, excess 1-hexene was removed by vacuum distillation, yielding a long-chain α-olefin-modified intermediate. In a separate three-necked flask, the obtained long-chain α-olefin-modified intermediate and octamethylcyclotetrasiloxane were added, and tert-butylphosphazene base was added as a catalyst to initiate a ring-opening polymerization reaction at 80 °C for 5 h, synthesizing a long-chain alkyl-modified polysiloxane.

[0026] The obtained long-chain alkyl-modified polysiloxane has the structure (CH3)3SiO(SiCH3RO). m (Si(CH3)2O) n OSi(CH3)3, Where R is —C6H 14 n=0, m=30, n / m=0. Example

[0027] The difference from Example 1 is that the long-chain α-olefin is 1-octene.

[0028] The obtained long-chain alkyl-modified polysiloxane has the structure (CH3)3SiO(SiCH3RO). m (Si(CH3)2O) n OSi(CH3)3, Where R is —C8H 18 n=5, m=25, n / m=0.2.

[0029] Example 3: The difference from Example 1 is that the long-chain α-olefin is 1-decene.

[0030] The obtained long-chain alkyl-modified polysiloxane has the structure (CH3)3SiO(SiCH3RO).m (Si(CH3)2O) n OSi(CH3)3, Where R is —C 10 H 22 n=5, m=25, n / m=0.2. Example

[0031] Tetramethyldihydrodisiloxane was added to a three-necked flask, and the reaction was carried out under an inert gas atmosphere at a temperature of 65 °C. At this temperature, 1-dodecene and a catalyst were added dropwise, with the carbon-carbon double bond to silicon-hydrogen bond ratio controlled between 1.2 and 1.1:1, and the addition time controlled between 15 and 30 min. The temperature was maintained below 70 °C during the addition process. After the addition was complete, the mixture was kept at 90 °C for 5 h. After the reaction was complete, the solution was washed three times with a small amount of petroleum ether to remove residual 1-dodecene. Then, residual petroleum ether was removed by vacuum distillation to obtain a long-chain α-olefin-modified intermediate. In another three-necked flask, the obtained long-chain α-olefin-modified intermediate and octamethylcyclotetrasiloxane were added, and tert-butylphosphazene base was added as a catalyst to carry out a ring-opening polymerization reaction at 80 °C for 5 h to synthesize a long-chain alkyl-modified polysiloxane.

[0032] The obtained long-chain alkyl-modified polysiloxane has the structure R(CH3)2SiO(Si(CH3)2O). n (CH3)2SiOR.

[0033] Where R is —C 12 H 26 n=30. Example

[0034] The difference from Example 3 is that the long-chain α-olefin is 1-tetradecene.

[0035] The obtained long-chain alkyl-modified polysiloxane has the structure R(CH3)2SiO(Si(CH3)2O). n (CH3)2SiOR.

[0036] Where R is —C 14 H 30 n=30. Example

[0037] Methyldimethoxysilane was added to a three-necked flask, and the reaction was carried out under an inert gas atmosphere at a temperature of 40 °C. At this temperature, 1-hexadecene and a catalyst were added dropwise, with the carbon-carbon double bond to silicon-hydrogen bond ratio controlled between 1.2 and 1.1:1, and the addition time controlled between 15 and 30 min. The temperature was maintained below 50 °C during the addition process. After the addition was complete, the mixture was kept at 80 °C for 5 h. After the reaction was complete, the solution was washed three times with a small amount of petroleum ether to remove residual 1-hexadecene. Then, residual petroleum ether was removed by vacuum distillation to obtain a long-chain α-olefin-modified intermediate. In another three-necked flask, the obtained long-chain α-olefin-modified intermediate and octamethylcyclotetrasiloxane were added, and tert-butylphosphazene base was added as a catalyst to carry out a ring-opening polymerization reaction at 80 °C for 5 h to synthesize a long-chain alkyl-modified polysiloxane.

[0038] The obtained long-chain alkyl-modified polysiloxane has the structure (CH3)3SiO(SiCH3RO). m (Si(CH3)2O) n OSi(CH3)3, Where R is —C 16 H 34 n=16, m=20, n / m=0.8.

[0039] Example 7: The difference from Example 6 is that the long-chain α-olefin is 1-octadecene.

[0040] The obtained long-chain alkyl-modified polysiloxane has the structure (CH3)3SiO(SiCH3RO). m (Si(CH3)2O) n OSi(CH3)3, Where R is —C 18 H 38 n=16, m=20, n / m=0.8. Example

[0041] Hydrogen-containing silicone oil with a hydrogen content of 0.8% was added to a three-necked flask. The reaction was carried out under an inert gas atmosphere at a temperature of 60 °C. At this temperature, 1-octene and a catalyst were added dropwise, and the temperature was maintained at 80 °C during the addition. Stirring was continued for 2 h, followed by the dropwise addition of 1-octadecene, with the carbon-carbon double bond to silicon-hydrogen bond ratio controlled between 1.2 and 1.1:1. After the addition was complete, the mixture was kept at 100 °C for 5 h. After the reaction was complete, excess 1-octene was removed by vacuum distillation to obtain a long-chain α-olefin-modified intermediate. In a separate three-necked flask, the obtained long-chain α-olefin-modified intermediate and octamethylcyclotetrasiloxane were added, and tert-butylphosphazene base was added as a catalyst to initiate a ring-opening polymerization reaction at 80 °C for 5 h, synthesizing a long-chain alkyl-modified polysiloxane.

[0042] The obtained long-chain alkyl-modified polysiloxane has the structure (CH3)3SiO(SiCH3R1O). m1 (SiCH3R2O) m2 (Si(CH3)2O) n OSi(CH3)3, Where R1 is —C8H 18 R2 is —C 18 H 38 , n=16, m1+m2=20, n / (m1+m2)=0.8.

[0043] (1) Using FT-IR (Thermo Fisher Scientific, Nicolet iS 10), 1 The obtained sample was characterized by H-NMR (BrukerAVANCE NEO 400). No Si-H (2100 cm⁻¹) was observed in the FT-IR spectrum. -1 ) and C=C (1650cm) -1 Characteristic peaks of ) 1 H-NMR spectrum Figure 3 No characteristic peaks were observed in the 0.0 ~ 6.0 ppm range, indicating the absence of Si-H and free olefin residues in the sample. See the attached instruction manual for details. Figure 1 and attached Figure 2 .

[0044] (2) The kinematic viscosity of the sample was determined by using a glass capillary Canon-Fensk viscometer at 25 °C according to ASTM-D 445. Specific data for the example can be found in the appendix of the instruction manual. Figure 3 .

[0045] (3) The flash point of the sample was determined using a Cleveland open cup. The COC was measured using approximately 50 mL of sample. For specific examples, the flash point data are attached. Figure 3 .

[0046] (4) Thermal conductivity test: The sample was tested at 40°C according to the standard test method for thermal conductivity of liquids in ASTM D 2717-2009.

[0047] (5) Specific heat capacity: The sample was tested using DSC at 40 °C.

[0048] (6) Breakdown voltage (dielectric strength): The sample is tested according to the disk electrode method of ASTM D 877.

[0049] (7) Volume resistivity, the sample was tested at 25 °C according to the method of ASTM D 257.

[0050] (8) Compatibility test: Cut EPDM rubber and silicone rubber test samples, each 3 cm long, 1 cm wide, and 0.2 cm thick. Record the initial weight and initial length of each test sample. Completely immerse the test sample in the fluid in a container. Seal the container and store it at 50 °C for 4 months. Then remove the test sample, blot dry both sides with absorbent paper, and record the sample weight and length. Determine the changes in weight and length relative to before immersion. A length increase greater than 15% constitutes "significant swelling," and a weight increase greater than 50% constitutes "significant absorption." Specific test results for each example can be found in the appendix. Figure 3 .

[0051] The long-chain alkyl-modified polysiloxane coolant obtained by this invention is colorless, transparent, and odorless. It possesses the advantage of high purity, specifically low Si-H and free olefin residues, with Si-H residues as low as 0-5 ppm and free olefin residues as low as 0-5 wt%. Its thermodynamic properties include low kinematic viscosity (< 20 mm at 25 °C). 2 It exhibits high flash point (> 200℃), high thermal conductivity (1.52 ~ 1.74 W / (m·K)), and high specific heat capacity (1.9 ~ 2.1 kJ / (kg·K)). It also displays safe electrochemical properties, specifically high dielectric strength (> 40 kV) and high volume resistivity (8.12 ~ 9.78) × 10^ 12 Ω·cm. The long-chain alkyl-modified silicone oil synthesized in this invention exhibits good compatibility with data center materials (silicone rubber, EPDM rubber), specifically with (<10% length and weight change). It significantly improves the thermodynamic properties of silicone coolants, achieving an effective balance between insulation, compatibility, and thermal conductivity.

[0052] Compared with the performance of the organosilicon coolant disclosed in the patent, the thermodynamic performance of the present invention is significantly improved, specifically manifested in high thermal conductivity (1.52 ~ 1.74 W / (m·K)) and high specific heat capacity (1.9 ~ 2.1 kJ / (kg·K)).

[0053] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An immersion-type silicone coolant, characterized in that, Its molecular structure is: (CH3)3SiO(SiCH3RO) m (Si(CH3)2O) n OSi(CH3)3 and R(CH3)2SiO(Si(CH3)2O) n At least one of (CH3)2SiOR; wherein R is C6~C 18 Alkanes, m ranges from 1 to 50, n ranges from 0 to 100, and the ratio of n to m is between 0 and 0.

8.

2. The immersion-type silicone coolant according to claim 1, characterized in that, The R is -C6H 14 —C8H 18 —C 10 H 22 —C 12 H 26 —C 14 H 30 —C 16 H 34 —C 18 H 38 At least one of them.

3. The immersion-type silicone coolant according to claim 1, characterized in that, The value of m is 5~40, the value of n is 20~80, and the ratio of n / m is between 0.1 and 0.

6.

4. A method for preparing the immersion-type organosilicon coolant according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Hydrosilylation reaction was carried out using hydrogen-containing organosilicon and long-chain α-olefin as reactants under the action of a catalyst; after the reaction was complete, the free olefin was removed to obtain a pure long-chain α-olefin modified intermediate. (2) Using the long-chain α-olefin modified intermediate and dimethyl cyclopropion obtained in step (1) as reactants, a ring-opening polymerization reaction is carried out under the action of a catalyst to obtain a long-chain alkyl modified polysiloxane coolant.

5. The method according to claim 4, characterized in that, The preferred hydrogen-containing organosilicon in step (1) is at least one of tetramethylhydrocyclotetrasiloxane, tetramethyldihydrodisiloxane, methyldimethoxysilane, or hydrogen-containing silicone oil with a hydrogen content of 0.015% to 1.67%, and the long-chain α-olefin is selected from at least one of 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, or 1-octadecene; the dimethyl cyclic compound in step (2) is octamethylcyclotetrasiloxane.

6. The method according to claim 4, characterized in that, In step (1), when the temperature is raised to 40~80 ℃, the mixture of long-chain α-olefin and catalyst is added dropwise for about 15~30 min. After the addition is completed, the temperature is kept at 60~120 ℃ for 5 h. In step (2), the reaction temperature is 60~100 ℃ and the reaction time is 3~8 hours.

7. The method according to claim 4, characterized in that, The catalyst in step (1) is manganese pentacarbonyl bromide, and the catalyst in step (2) is tert-butylphosphonic acid base.

8. The method according to claim 4, characterized in that, In step (1), the mixture of long-chain α-olefin and catalyst is dispersed in a solvent, the concentration of the mixture in the solvent being 0.5~1 g / mL, and the solvent being any one or more of tetrahydrofuran, cyclohexanone, toluene, n-hexane, and isopropanol.

9. The method according to claim 4, characterized in that, In step (1), free olefins are removed by washing with petroleum ether or by vacuum distillation.

10. The application of the immersion-type silicone coolant according to any one of claims 1-3 and 5-9 in an immersion cooling system, characterized in that, As a single-phase, non-volatile, and liquid heat transfer and electrical insulating medium, the components immersed in it include silicone rubber or EPDM rubber.

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