Wax dispersion in alkylmethylsiloxane fluid

Abstract

C in the continuous phase of the alkylmethyl silicone fluid of Equation 1 16 ~C 28 A composition comprising a dispersion of hydrocarbon waxes is disclosed, wherein R, R 1 m and n are defined herein. The relative amounts of wax and alkylmethyl silicone fluid are such that the viscosity of the dispersion is in the range of 10 cSt to 100 cSt and the phase change energy absorbed by the dispersion is at least 12 J / g. This composition is useful as a two-phase immersion cooling fluid. [Formula 1] JPEG2026521504000008.jpg23170

Description

[Technical Field]

[0001] The present invention relates to a composition comprising a wax dispersion in an alkylmethylsiloxane fluid continuous phase. This composition is useful as an immersion cooling fluid for data centers.

[0002] Data centers consume enormous amounts of energy. Currently, most data centers are air-cooled, which is highly inefficient. In a typical data center, only 60% of the total energy is consumed for computing / information requests, data storage, and networking, while 40% is used to dissipate the heat generated by electronic components.

[0003] Immersion cooling, in which all components of a data center are immersed in a dielectric (non-conductive) fluid, is expected to replace air cooling in the coming years. Examples of dielectric fluids suitable as immersion coolants include fluorinated fluids such as hydrofluoroethers and fluoroketones. The dielectric and chemical inertness of fluorinated fluids, along with their wide boiling point range, low viscosity, low pour point, low surface tension, high thermal and chemical stability, and compatibility with metals, plastics, and elastomers, make them particularly attractive as heat transfer media. These fluids are further advantageous by being odorless, non-flammable, non-explosive, and substantially non-toxic. Furthermore, as two-phase immersion fluids that transition from liquid to gas phase below the operating temperature of heat-generating components (CPU and GPU) in servers, fluorinated fluids extract heat from the CPU and GPU using the latent heat of the phase transition.

[0004] Nevertheless, fluorinated fluids are hindered by their relatively high vapor pressure, long atmospheric lifetime, and relatively strong absorption of infrared radiation, all of which contribute to their serious potential for global warming. Losses due to evaporation or leakage due to low fluid surface tension also pose environmental hazards.

[0005] Silicone fluids are another class of dielectric fluids that are promising as immersion cooling fluids. Similar to fluorinated fluids, they exhibit low viscosity, low dielectric properties, thermal stability, low flammability, chemical inertness, and low toxicity. Silicone fluids have the additional advantage of not being environmentally permanent. However, as single-phase fluids, they extract heat with far lower efficiency than fluorinated fluids. Therefore, finding a medium that meets the requirements of properties and the environment would be advantageous in the field of immersion cooling fluids. [Background technology]

[0006] The present invention addresses the need by providing a composition comprising a dispersion of C16-C28 hydrocarbon wax in an alkylmethyl silicone fluid continuous phase of formula 1:

[0007] [ka] In the formula, R and R 1 Each is independently methyl or C6-C 18 -Alkyl, however, R and R 1 At least one of them is C6~C 18 -It is an alkyl group, where m is 1 to 20 and n is 0 to 10, except when n is 0, R 1 One or both of the elements are C6~C 18 -The wax is alkyl, and the relative amounts of the wax and alkylmethyl silicone fluid are such that the viscosity of the dispersion is in the range of 10 cSt to 100 cSt, and the phase change energy absorbed by the dispersion is at least 12 J / g. The composition of the present invention is useful as a two-phase immersion coolant. [Brief explanation of the drawing]

[0008] [Figure 1] This is a dynamic scanning calorimetry thermal analysis of a wax dispersion in a continuous phase of alkylmethyl silicone fluid. [Modes for carrying out the invention]

[0009] The present invention relates to a composition comprising a dispersion of C 16 ~C 28 hydrocarbon wax in an alkylmethyl silicone fluid continuous phase,

[0010]

Chemical formula

[0011] The wax may be a single wax or preferably a combination of C 16 ~C 28 hydrocarbon waxes having a melting point in the range of 18°C to 65°C. In one aspect, each R 1 is methyl, n is 1~10, m is 1 or 2~10 or 5, and each R is C6~C 18 alkyl, preferably C8~C 16 alkyl. In a second aspect, n is 0 and at least one of R 1 is C6~C 18 alkyl, preferably each of R 1 is C8~C 16 alkyl. In a third aspect, n is 1~10 and at least one of R 1 [[ID=5​​​​​It is an alkyl group, and each R is C6~C 18 It is alkyl, preferably C8-C 16 It is alkyl. R and R 1 C6~C 18 If it is a base, R and R 1 Preferably a linear C6-C 18 It is the basis.

[0012] The compound of formula 1 can be prepared by catalytic hydrosilylation of a 1-alkene with an organohydrogenpolysiloxane containing an internal Si-H group.

[0013] [ka]

[0014] Other compounds of Formula 1 can be prepared by hydrosilylation of alkenes with organohydrogenpolysiloxanes containing terminal Si-H groups or terminal and internal Si-H groups.

[0015] The viscosity of the dispersion and the absorbed phase change energy can be easily adjusted to desired levels by adjusting the wax-to-alkylmethyl silicone fluid ratio. Generally, the weight-to-weight ratio of wax to alkylmethyl silicone fluid ranges from 3:97, or 5:95, or 7:93, up to 25:75, or up to 20:80, or up to 15:85. The wax and alkylmethyl silicone fluid preferably constitute at least 90, 95, 99, or 100 percent of the composition. The composition may optionally further contain low dielectric and low viscosity fluids such as hydrocarbon and fluorocarbon fluids.

[0016] The dispersion exhibits an absorbed phase transition energy greater than 12 J / g, preferably in the range of 12 J / g to 150 J / g, or ~120 J / g or ~110 J / g, as determined by dynamic scanning calorimetry (DSC). The dispersion has a maximum phase transition temperature, preferably in the range of 5°C to 60°C, for both heating and cooling cycles, as determined by DSC. Figure 1 shows 77 parts by weight (pbw) of compound of formula 1 (wherein R is n-hexadecyl, m is 3, and n is 6), 18 pbw of C 18 Hydrocarbon wax, and 5pbw C 22 This is a DSC of a dispersion containing hydrocarbon wax. The peak temperature during cold scanning (10.3°C), the peak temperature during heated scanning (19.9°C), and the absorbed phase change energy (105.9 J / g) all exceeded the physical property requirements of the composition.

[0017] The present invention addresses the needs in the art by providing a composition that has all the advantages of the properties of fluorinated fluids without the environmental drawbacks. [Examples]

[0018] The cooling fluids for the examples and comparative examples were prepared by mixing alkylmethyl silicone fluid with one or more waxes using a magnetic stirrer for 30 minutes. The sample viscosity at 25°C, the maximum phase change temperature during the cooling and heating cycles, and the absorbed phase change energy were measured by the following method.

[0019] Viscosity measurement Viscosity was measured using a DHR-III viscometer with 25 mm parallel plates. Flow temperature was measured at a rate of 3°C / min and 200 s. -1 The temperature was increased from 25°C to 150°C at a shear rate.

[0020] Phase change measurement The maximum phase transition temperature and the absorbed phase transition energy were measured using the DSC-Q2000 instrument as follows.

[0021] The sample was equilibrated at -80.00°C. Data storage was initiated, and the temperature was increased at a rate of 10°C / min to 70.00°C to complete the first cycle. Next, the temperature was decreased at a rate of 10°C / min to 80.00°C and maintained at this temperature for 3.00 minutes to complete the second cycle. Finally, the temperature was increased at a rate of 10°C / min to 70.00°C to complete the third cycle.

[0022] Heat removal from devices using the two-phase immersion coolant of the present invention is achieved in two ways. First, the alkylmethyl silicone fluid continuous phase removes heat from high-temperature devices by having a lower temperature than the device. Second, the phase change energy absorbed by the melting of the wax dispersion phase during heating provides a second mechanism for heat removal. The higher the absorbed phase change energy, the more efficient the heat removal from the device becomes.

[0023] The absorbed phase change energy is calculated by integrating the area under the heat-absorbing flow as a function of temperature (enthalpy, see Figure 1), and then dividing the enthalpy by the mass of the specimen.

[0024] Table 1 shows the properties of the immersion fluid. Silicone oil (silicone) is a silicone fluid with a viscosity of 20 cSt at 25°C. AMS-C8 refers to the alkylmethyl silicone of formula 1, where R is n-octyl, and each R 1 is methyl, m is 3, n is 6, AMS-C16 refers to the alkylmethyl silicone of formula 1, where R is n-hexadecyl, and each R 1 is methyl, m is 3, and n is 6.

[0025] C 16 Hydrocarbon wax (C 16 The melting point of the wax was 18.2°C. 18 Hydrocarbon wax (C 18 The melting point of the wax was 28.18°C. 22 Hydrocarbon wax (C 22 Wax has a melting point of 42°C to 45°C, C24~28 Hydrocarbon wax (C 24~28 The wax had a melting point of 49°C to 64°C.

[0026] η refers to viscosity in cSt units at 25°C, T cmax This refers to the maximum phase change temperature in the cooling cycle. hmax This refers to the maximum phase change temperature of the heating cycle, E a This refers to the phase change energy absorbed in J / g. The target characteristics of the immersion coolant were a viscosity in the range of 10 cSt to 100 cSt, a maximum phase change temperature in the range of 5°C to 60°C, and a phase change energy absorption value of >12 J / g. All amounts are weight percentages based on the weight of the composition.

[0027] [Table 1]

[0028] The data demonstrate that viscosity, maximum phase transition temperature, and absorbed phase transition energy can be adjusted to desired targets by adjusting the relative amounts and types of wax and alkylmethylsiloxane. In contrast, the silicone oil and wax blend resulted in unacceptably low maximum phase transition cooling and heating temperatures, as well as unacceptably low phase transition absorbed energy.

Claims

1. C in the continuous phase of the alkylmethyl silicone fluid of Equation 1 １６ ~C ２８ A composition comprising a dispersion of hydrocarbon waxes, 【Chemistry 1】 In the formula, R and R １ are each independently methyl or C ６ to C １８ -alkyl, provided that at least one of R and R １ is C ６ to C １８ -alkyl, where m is from 1 to 20, n is from 0 to 10, provided that when n is 0, one or both of the R １ groups are C ６ to C １８ -alkyl, and the relative amounts of the wax and the alkylmethyl silicone fluid are such that the viscosity of the dispersion is in the range of 10 cSt to 100 cSt and the absorbed phase change energy of the dispersion is at least 12 J / g, a composition.

2. The composition according to claim 1, wherein the phase change energy absorbed by the dispersion is in the range of 12 J / g to 150 J / g, and the weight-to-weight ratio of the wax to the alkylmethyl silicone fluid is in the range of 3:97 to 25:

75.

3. n is 1 to 10, m is 2 to 10, and each R １ The composition according to claim 2, wherein is a methyl group, the weight-to-weight ratio of the wax to the alkylmethyl silicone fluid is in the range of 5:95 to 25:75, the phase change energy absorbed by the dispersion is in the range of 12 J / g to 120 J / g, and at least 90% by weight of the composition comprises the wax and the alkylmethyl silicone fluid.

4. n is 0, m is 2 to 10, and each R １ C ８ ~C １６ - The composition according to claim 2, wherein the alkyl group is an alkyl group, and at least 95% by weight of the composition comprises the wax and the alkylmethyl silicone fluid.

5. n is 1 to 10, m is 2 to 10, and each R １ C ８ ~C １６ The composition according to claim 2, wherein the alkyl group is such that the phase change energy absorbed by the dispersion is in the range of 12 J / g to 110 J / g.

6. The composition according to claim 1, wherein the dispersion has a maximum phase change temperature in the range of 5°C to 60°C for both the heating cycle and the cooling cycle in dynamic scanning calorimetry thermal analysis.

7. C in the continuous phase of the alkylmethyl silicone fluid of Equation 1 １６ ~C ２８ A composition comprising a dispersion of hydrocarbon waxes, 【Chemistry 2】 In the formula, R and R １ These are, independently, methyl or C ６ ~C １８ - Alkyl, where R and R １ At least one of them is C ６ ~C １８ - It is an alkyl group, where m is 1 to 20 and n is 0 to 10, except when n is 0, R １ One or both of the elements are C ６ ~C １８ A composition in which the wax is alkyl and the relative amount of the alkylmethyl silicone fluid is such that the viscosity of the dispersion is in the range of 10 cSt to 100 cSt and the phase change energy absorbed by the dispersion is at least 12 J / g.

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