Single-phase refrigerant medium and preparation method thereof

Abstract

The invention discloses a single-phase refrigerant medium and a preparation method thereof.The preparation method comprises the following preparation steps that S1, in an inert gas atmosphere, a dimethyl cyclosiloxane mixed ring body and 1, 1, 3, 3-tetramethyldisiloxane react under the action of a second catalyst, and after impurities are removed, a hydrogen-terminated polysiloxane intermediate is obtained; s2, in an inert gas atmosphere, adding the end hydrogen-containing polysiloxane intermediate and a first catalyst into a solvent, then adding isolated diene for reaction, adding alpha-olefin after the reaction is performed for a period of time, and performing low-temperature removal to obtain the single-phase refrigerant medium. The single-phase refrigerant medium has the advantages of being good in fluidity, resistant to high and low temperature, good in insulativity, good in thermal conductivity, high in safe usability and the like, does not contain fluorocarbon compounds, is environmentally friendly, is simple in preparation method and is suitable for industrial production.

Description

Technical Field

[0001] The present application relates to a refrigerant medium, and in particular to a single-phase refrigerant medium and a preparation method thereof. Background Art

[0002] Refrigerant is a medium used to transfer heat and is widely used in various cooling systems, such as liquid cooling systems in data centers and heat dissipation systems for electronic equipment. Its main function is to absorb and transfer heat to keep the equipment running within a suitable temperature range, thereby ensuring the stability and reliability of the equipment. For example, in the liquid cooling system of a data center, the refrigerant absorbs the heat of heat-generating components such as chips by flowing through a cold plate or being immersed in coolant, and transfers it to the heat exchanger for heat dissipation.

[0003] The single-phase refrigerant remains in liquid form throughout the cooling process without phase change. This characteristic gives single-phase refrigerants significant advantages in system design and operation. First, the system of single-phase refrigerants is relatively simple, usually consisting of a cooling liquid circulation pump, a heat exchanger, pipes, etc. It is relatively easy to maintain and manage, and the cost is relatively low. Secondly, single-phase refrigerants can distribute heat more evenly, making the temperature of the cooled equipment relatively uniform, and are suitable for heat dissipation of equipment with medium power density. In addition, single-phase refrigerants are relatively simple in terms of volatilization control, and when the sealing is good, the coolant loss is small, and there is no need to frequently replenish the coolant.

[0004] Although single-phase refrigerants have many advantages, they also have some problems. First, the heat dissipation efficiency of single-phase refrigerants is relatively lower than that of two-phase refrigerants, because during the entire heat dissipation process, heat transfer only relies on heat conduction and convection of the liquid, without the participation of latent heat of phase change. This makes single-phase refrigerants appear to be powerless when faced with extremely high power density heat dissipation requirements. Secondly, single-phase refrigerants may have local temperature differences in some equipment with complex structures, resulting in uneven heat dissipation. In addition, the selection range of single-phase refrigerants is relatively limited, and a balance needs to be found between high boiling point and low volatility to ensure the safety and reliability of the system. Summary of the invention

[0005] The purpose of this application is to improve the fluidity, insulation, thermal conductivity and safety of a single-phase refrigerant.

[0006] In order to achieve the above objectives, the technical solution adopted in the present application is: to provide a single-phase refrigerant medium containing a siloxane diene copolymer, wherein the structural formula of the siloxane diene copolymer is: , where R 1 It represents a double-terminal substituted alkane group, and the general molecular formula is C x H 2x , 4≤x≤8; R 2It represents a single-end substituted alkane group, and its molecular formula is C y H 2y+1 , 6≤y≤16.

[0007] As a preferred embodiment, the kinematic viscosity of the siloxane diene copolymer at 25°C is less than 30 mm 2 / s.

[0008] As a preferred embodiment, the siloxane diene copolymer is obtained by copolymerizing a terminal hydrogen-containing polysiloxane intermediate with an isolated diene under the action of a first catalyst, and then end-capping with an α-olefin.

[0009] As another preference, the isolated diene is any one of 1,5-hexadiene, 1,7-octadiene or 1,9-decadiene, or a combination of more thereof.

[0010] As another preference, the α-olefin is any one of 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene or 1-hexadecene, or a combination of more than one thereof.

[0011] As another preferred embodiment, the kinematic viscosity of the terminal hydrogen-containing polysiloxane intermediate at 25°C is less than 20 mm 2 / s.

[0012] As another preference, the first catalyst is one of chloroplatinic acid, platinum divinyltetramethyldisiloxane complex or platinum tetravinyltetramethylcyclotetrasiloxane complex.

[0013] Provided is a method for preparing a single-phase refrigerant, comprising the following preparation steps: S1: in an inert gas atmosphere, a dimethylcyclosiloxane mixed ring body and 1,1,3,3-tetramethyldisiloxane react under the action of a second catalyst, and a terminal hydrogen-containing polysiloxane intermediate is obtained after impurities are removed; S2: in an inert gas atmosphere, the terminal hydrogen-containing polysiloxane intermediate and a first catalyst are added to a solvent, and then isolated dienes are added for reaction, and after a period of reaction, α-olefins are added, and the single-phase refrigerant is obtained after deoxidation; the isolated dienes are any one or a combination of 1,5-hexadiene, 1,7-octadiene or 1,9-decadiene; the α-olefin is any one or a combination of 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene or 1-hexadecene; the structural formula of the siloxane diene copolymer is: , where R 1 It represents a double-terminal substituted alkane group, and the general molecular formula is C x H 2x , 4≤x≤8; R 2 It represents a single-end substituted alkane group, and its molecular formula is C y H 2y+1, 6≤y≤16.

[0014] As another preferred embodiment, the S1 step is specifically as follows, in parts by mass: in an inert gas atmosphere, 30 to 60 parts of the dimethylcyclosiloxane mixed ring body and 20 to 40 parts of the 1,1,3,3-tetramethyldisiloxane are stirred evenly at 25 to 40 °C, 1% to 5% of the total mass of the reactants of concentrated sulfuric acid are added to react for 2 to 6 hours, and after the reaction is completed, a corresponding amount of sodium carbonate is added to continue stirring for 2 to 6 hours and filtered, the filtrate is heated to 60 to 120 °C in an inert gas atmosphere to remove low molecular weight substances, and after removing for 2 to 6 hours, the system is cooled to 25 °C to obtain the terminal hydrogen-containing polysiloxane intermediate.

[0015] Further preferably, in parts by mass, the step S2 is specifically as follows: under an inert gas atmosphere, 5 to 20 parts of a solvent and the first catalyst are added to the hydrogen-terminated polysiloxane intermediate after dehydrogenation, wherein the amount of the first catalyst is 1×10 of the total mass of the reactants. -6 ~50×10 -6 , stirring and mixing at 50-120 °C, then dropping 10-25 parts of the isolated diene into the system, reacting at 50-120 °C for 1-8 h, adding 10-30 parts of the α-olefin and continuing the reaction for 1-8 h, heating to 100-150 °C after the reaction to remove low molecular weight substances, and cooling the system to 25 °C after 1-4 h to obtain the single-phase refrigerant.

[0016] The single-phase refrigerant of the present invention may be added with other components or functional additives as required.

[0017] As a preferred embodiment, the added component or functional additive can be any one or a combination of nano cerium oxide or rare earth isooctanoate, with a content of 0.05-2% of the total mass of the single-phase refrigerant, which can avoid decomposition, inactivation and ignition of the refrigerant under extreme conditions.

[0018] Compared with the prior art, the beneficial effects of this application are: (1) The single-phase refrigerant of the present application does not contain fluorocarbon compounds and is environmentally friendly; (2) The single-phase refrigerant medium of the present application has good fluidity and heat transfer performance, and is highly safe, and can serve temperature control systems such as energy storage equipment and large data centers; (3) The single-phase refrigerant medium of the present application has a low kinematic viscosity and achieves good fluidity and thermal conductivity. DETAILED DESCRIPTION

[0019] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0020] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0021] The present application provides a single-phase refrigerant medium containing a siloxane diene copolymer, the structural formula of which is as follows: , Where R 1 It represents a double-terminal substituted alkane group, and the general molecular formula is C x H 2x , 4≤x≤8; R 2 It represents a single-end substituted alkane group, and its molecular formula is C y H 2y+1 , 6≤y≤16.

[0022] The single-phase refrigerant medium of the present application has good fluidity, heat transfer performance, high and low temperature resistance and safety, improves the comprehensive performance of the single-phase refrigerant medium, and better obtains more efficient circulation efficiency within a given temperature range.

[0023] In some embodiments, the siloxane diene copolymer has a kinematic viscosity at 25° C. of less than 30 mm 2 / s, the siloxane diene copolymer within this range has smaller internal resistance, smaller friction between adjacent layers, and the fluid flows more easily, thereby improving the heat exchange efficiency.

[0024] The siloxane diene copolymer is obtained by copolymerizing a terminal hydrogen-containing polysiloxane intermediate with an isolated diene under the action of a first catalyst and then capping with an alpha-olefin.

[0025] Isolated dienes refer to dienes that contain two carbon-carbon double bonds in their molecules, and the two double bonds are separated by one or more single bonds. Their structural characteristics are that the double bonds are not directly connected to each other, but are "isolated" by single bonds.

[0026] In some embodiments, the isolated diene is any one or a combination of 1,5-hexadiene, 1,7-octadiene or 1,9-decadiene. In more preferred embodiments, the isolated diene is 1,5-hexadiene or 1,7-octadiene.

[0027] The use of isolated dienes for copolymerization can form siloxane diene copolymers, which effectively reduce their kinematic viscosity and make the single-phase refrigerant have better fluidity and thermal conductivity.

[0028] In some embodiments, the α-olefin is any one or a combination of 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene or 1-hexadecene. In a more preferred embodiment, the α-olefin is 1-hexene or 1-octene.

[0029] In some embodiments, the kinematic viscosity of the hydrogen-terminated polysiloxane intermediate at 25° C. is less than 20 mm 2 / s, in a more preferred embodiment, the kinematic viscosity of the hydrogen-terminated polysiloxane at 25°C is less than 10 mm 2 / s.

[0030] In some embodiments, the first catalyst is a platinum catalyst, which can be one of chloroplatinic acid, platinum divinyltetramethyldisiloxane complex or platinum tetravinyltetramethylcyclotetrasiloxane complex. In some more preferred embodiments, the mass fraction of platinum in the platinum catalyst is 0.5% to 3.0%.

[0031] The amount of the first catalyst used in the copolymerization reaction is 1×10 of the total mass of the reactants. -6 ~50×10 -6 The copolymerization temperature is 50~120 ℃, and the reaction time is 1~8 h.

[0032] In a more preferred embodiment, platinum tetravinyltetramethylcyclotetrasiloxane complex is selected as the first catalyst, wherein the mass fraction of platinum is 0.5% to 1.5%, and the amount of platinum catalyst is 2×10 of the total mass of the reactants. -6 ~10×10 -6 , the reaction temperature is 60~80 ℃, and the reaction time is 2~6 h.

[0033] In some embodiments, the copolymerization reaction is carried out in a solvent, the solvent is isopropanol or toluene, and the amount of the solvent used is 5% to 20% of the total mass of the reactants.

[0034] In some embodiments, after the copolymerization reaction, the product is heated at 100-150° C. to remove low molecular weight impurities.

[0035] The terminal hydrogen-containing polysiloxane intermediate is produced by the reaction of 1,1,3,3-tetramethyldisiloxane and a dimethylcyclosiloxane mixed ring body under the action of a second catalyst, wherein the amount of the catalyst is 0.5% to 10% of the total mass of the reactants, the reaction temperature is 25 to 40 °C, and the reaction time is 2 to 6 h.

[0036] In some embodiments, the second catalyst is concentrated sulfuric acid, the amount of concentrated sulfuric acid used is 1% to 5% of the total mass of the reactants, and after the reaction is completed, a corresponding amount of sodium carbonate is added to the system for neutralization.

[0037] The kinematic viscosity of the single-phase refrigerant medium of the present application at 25°C is less than 30 mm 2 / s, a flash point greater than 210 °C, a pour point less than -55 °C, a breakdown voltage higher than 60 kV, and good fluidity, thermal conductivity and safety. It can be used in temperature control systems such as energy storage equipment and big data centers.

[0038] The single-phase refrigerant of the present application can be added with other non-conflicting components or functional additives as needed to improve the performance of the single-phase refrigerant.

[0039] The present application provides a method for preparing a single-phase refrigerant, comprising the following preparation steps: S1: In an inert gas atmosphere, a dimethylcyclosiloxane mixed ring body and 1,1,3,3-tetramethyldisiloxane react under the action of a second catalyst to obtain a terminal hydrogen-containing polysiloxane intermediate after impurities are removed; S2: Under an inert gas atmosphere, a terminal hydrogen-containing polysiloxane intermediate and a first catalyst are added to a solvent, and then isolated dienes are added for reaction. After a period of reaction, α-olefins are added, and a single-phase refrigerant medium of the present application is obtained after desulfurization.

[0040] In some embodiments, the specific preparation steps are as follows, based on parts by mass: S1: Under an inert gas atmosphere, 30-60 parts of a dimethylcyclosiloxane mixed ring body and 20-40 parts of 1,1,3,3-tetramethyldisiloxane are stirred evenly at 25-40 °C, and 1%-5% of the total mass of the reactants of concentrated sulfuric acid are added to react for 2-6 hours. After the reaction is completed, a corresponding amount of sodium carbonate is added and stirred for 2-6 hours and filtered. The filtrate is heated to 60-120 °C under an inert gas atmosphere to remove low molecular weight substances. After removing the low temperature for 2-6 hours, the system is cooled to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: In an inert gas atmosphere, 5 to 20 parts of solvent and a first catalyst are added to the hydrogen-terminated polysiloxane intermediate after dehydrogenation, wherein the amount of the first catalyst is 1×10 of the total mass of the reactants. -6 ~50×10 -6 , stir and mix evenly at 50~120 ℃, then add 10~25 parts of isolated diene into the system, react at 50~120 ℃ for 1~8 hours, add 10~30 parts of α-olefin and continue to react for 1~8 hours, after the reaction is completed, heat to 100~150 ℃ to remove low molecular weight substances, remove low molecular weight substances for 1~4 hours and then cool the system to 25 ℃.

[0041] The single-phase refrigerant prepared in the present application does not contain fluorocarbon compounds, is environmentally friendly, has a simple preparation method, and is suitable for industrial production.

[0042] Example 1 Prepare a single-phase refrigerant according to the following preparation steps: S1: Under nitrogen protection, add 50.0 g of dimethylcyclosiloxane mixed ring body and 25.0 g of 1,1,3,3-tetramethyldisiloxane to a 150 mL three-necked round-bottom flask, stir evenly at 25 °C, add 1.5 g of concentrated sulfuric acid to react for 2 h, add 2.2 g of sodium carbonate after the reaction, continue stirring for 2 h and filter, transfer the filtrate to a 250 mL three-necked round-bottom flask, heat to 80 °C under nitrogen atmosphere to remove low molecular weight substances, remove for 2 h and then cool the system to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: Under a nitrogen atmosphere, 11.0 g of isopropanol and 0.042 g of platinum tetravinyltetramethylcyclotetrasiloxane complex were added to the dehydrogenated terminal hydrogenated polysiloxane intermediate, and the mixture was stirred and mixed evenly at 80 °C, wherein the mass fraction of platinum in the platinum tetravinyltetramethylcyclotetrasiloxane complex was 0.5 wt%. Subsequently, 23.6 g of 1,7-octadiene was added dropwise to the system, and after the addition was completed, the mixture was reacted at 80 °C for 2 h. 17.2 g of 1-hexene was added and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 120 °C to remove low molecular weight substances. After 2 h of dehydrogenation reaction, the system was cooled to 25 °C.

[0043] Example 2 Prepare a single-phase refrigerant according to the following preparation steps: S1: Under nitrogen protection, add 50.0 g of dimethylcyclosiloxane mixed ring body and 20.0 g of 1,1,3,3-tetramethyldisiloxane to a 150 mL three-necked round-bottom flask, stir evenly at 25 °C, add 1.4 g of concentrated sulfuric acid to react for 2 h, add 2.1 g of sodium carbonate after the reaction, continue stirring for 2 h and filter, transfer the filtrate to a 250 mL three-necked round-bottom flask, heat to 80 °C under nitrogen atmosphere to remove low molecular weight substances, remove for 2 h and then cool the system to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: Under a nitrogen atmosphere, 9.0 g of isopropanol and 0.056 g of platinum tetravinyltetramethylcyclotetrasiloxane complex were added to the dehydrogenated terminal hydrogenated polysiloxane intermediate, and the mixture was stirred and mixed evenly at 80 °C, wherein the mass fraction of platinum in the platinum tetravinyltetramethylcyclotetrasiloxane complex was 0.5 wt%. Subsequently, 18.4 g of 1,7-octadiene was added dropwise to the system, and after the addition was completed, the mixture was reacted at 80 °C for 2 h. 13.4 g of 1-hexene was added and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 120 °C to remove low molecular weight substances. After 2 h of dehydrogenation reaction, the system was cooled to 25 °C.

[0044] Example 3 Prepare a single-phase refrigerant according to the following preparation steps: S1: Under nitrogen protection, add 60.0 g of dimethylcyclosiloxane mixed ring body and 20.0 g of 1,1,3,3-tetramethyldisiloxane to a 150 mL three-necked round-bottom flask, stir evenly at 25 °C, add 1.6 g of concentrated sulfuric acid to react for 2 h, add 2.4 g of sodium carbonate after the reaction, continue stirring for 2 h and filter, transfer the filtrate to a 250 mL three-necked round-bottom flask, heat to 80 °C under nitrogen atmosphere to remove low molecular weight substances, remove for 2 h and then cool the system to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: Under a nitrogen atmosphere, 10.0 g of isopropanol and 0.060 g of platinum tetravinyltetramethylcyclotetrasiloxane complex were added to the dehydrogenated terminal hydrogenated polysiloxane intermediate, and the mixture was stirred and mixed evenly at 80 °C, wherein the mass fraction of platinum in the platinum tetravinyltetramethylcyclotetrasiloxane complex was 0.5 wt%. Subsequently, 11.3 g of 1,5-hexadiene was added dropwise to the system, and after the addition was completed, the mixture was reacted at 80 °C for 2 h. 13.0 g of 1-hexene was added and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 120 °C to remove low molecular weight substances. After 2 h of dehydrogenation reaction, the system was cooled to 25 °C.

[0045] Example 4 Prepare a single-phase refrigerant according to the following preparation steps: S1: Under nitrogen protection, add 60.0 g of dimethylcyclosiloxane mixed ring body and 15.0 g of 1,1,3,3-tetramethyldisiloxane to a 150 mL three-necked round-bottom flask, stir evenly at 25 °C, add 1.5 g of concentrated sulfuric acid to react for 2 h, add 2.2 g of sodium carbonate after the reaction, continue stirring for 2 h and filter, transfer the filtrate to a 250 mL three-necked round-bottom flask, heat to 80 °C under nitrogen atmosphere to remove low molecular weight substances, remove for 2 h and then cool the system to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: Under a nitrogen atmosphere, 9.0 g of isopropanol and 0.054 g of platinum tetravinyltetramethylcyclotetrasiloxane complex were added to the dehydrogenated terminal hydrogenated polysiloxane intermediate, and the mixture was stirred and mixed evenly at 80 °C, wherein the mass fraction of platinum in the platinum tetravinyltetramethylcyclotetrasiloxane complex was 0.5 wt%. Subsequently, 8.7 g of 1,5-hexadiene was added dropwise to the system, and after the addition was completed, the mixture was reacted at 80 °C for 2 h. 10.7 g of 1-hexene was added and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 120 °C to remove low molecular weight substances. After the dehydrogenation reaction for 2 h, the system was cooled to 25 °C.

[0046] Example 5 Prepare a single-phase refrigerant according to the following preparation steps: S1: Under nitrogen protection, add 50.0 g of dimethylcyclosiloxane mixed ring body and 25.0 g of 1,1,3,3-tetramethyldisiloxane to a 150 mL three-necked round-bottom flask, stir evenly at 25 °C, add 1.5 g of concentrated sulfuric acid to react for 2 h, add 2.2 g of sodium carbonate after the reaction, continue stirring for 2 h and filter, transfer the filtrate to a 250 mL three-necked round-bottom flask, heat to 80 °C under nitrogen atmosphere to remove low molecular weight substances, remove for 2 h and then cool the system to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: Under a nitrogen atmosphere, 12.0 g of isopropanol and 0.066 g of platinum tetravinyltetramethylcyclotetrasiloxane complex were added to the dehydrogenated terminal hydrogenated polysiloxane intermediate, and the mixture was stirred and mixed evenly at 80 °C, wherein the mass fraction of platinum in the platinum tetravinyltetramethylcyclotetrasiloxane complex was 0.5 wt%. Subsequently, 18.4 g of 1,7-octadiene was added dropwise to the system, and after the addition was completed, the mixture was reacted at 80 °C for 2 h, 22.9 g of 1-octene was added and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 150 °C to remove low molecular weight substances, and the system was cooled to 25 °C after the dehydrogenation reaction for 3 h.

[0047] Example 6 Under a nitrogen atmosphere, 0.05 g of rare earth isooctanoate was added to 50.0 g of the single-phase refrigerant of Example 1, and the mixture was fully stirred at 25° C. to obtain the single-phase refrigerant of Example 6.

[0048] Comparative Example 1 A comparative cold medium was prepared as follows: under nitrogen protection, 50.0 g of dimethylcyclosiloxane mixed ring body and 15.0 g of hexamethyldisiloxane were added to a 150 mL three-necked round-bottom flask, and the mixture was stirred evenly at 25 °C. Subsequently, 1.3 g of concentrated sulfuric acid was added and the mixture was reacted at 25 °C for 2 h. After the reaction was completed, 2.0 g of sodium carbonate was added and the mixture was stirred for 2 h and filtered. Subsequently, the filtrate was transferred to a 250 mL three-necked round-bottom flask, and the temperature was raised to 120 °C under nitrogen protection and low molecular weight substances were removed at this temperature for 2 h. After the low molecular weight substances were removed, the system temperature was cooled to 25 °C.

[0049] Comparative Example 2 Prepare another comparative refrigerant as follows: under nitrogen protection, add 50.0 g of hydrogenated silicone oil with a kinematic viscosity of 5-10 mm into a 150 mL three-necked round-bottom flask. 2 / s, hydrogen mass fraction is 0.22%, and then 16.0g 1-octene is added and stirred evenly at 25℃, followed by adding 0.070g platinum divinyltetramethyldisiloxane complex and heating to 80℃ for reaction for 2h. The mass fraction of platinum in the platinum divinyltetramethyldisiloxane complex is 0.5wt%. After the reaction is completed, the temperature is raised to 120℃ and low molecular weight substances are removed at this temperature for 2h. After the low molecular weight substances are removed, the temperature is cooled to 25℃.

[0050] Comparative Example 3 The third comparative refrigerant was prepared as follows: 50.0 g of hydrogenated silicone oil with a kinematic viscosity of 10-20 mm was added to a 150 mL three-necked round-bottom flask under nitrogen protection. 2 / s, hydrogen mass fraction is 0.36%, and then 24.0g 1-octene is added and stirred evenly at 25 ℃, followed by adding 0.074g platinum divinyltetramethyldisiloxane complex and heating to 80 ℃ for reaction for 2 h. The mass fraction of platinum in the platinum divinyltetramethyldisiloxane complex is 0.5 wt%. After the reaction is completed, the temperature is raised to 120 ℃ and low molecular weight substances are removed at this temperature for 2 h. After the low molecular weight substances are removed, the temperature is cooled to 25 ℃.

[0051] Comparative Example 4 The fourth comparative refrigerant was prepared as follows: under nitrogen protection, 50.0 g of 1,1,1,3,5,7,7,7-octamethyltetrasiloxane and 79.0 g of 1-hexadecene were added to a 150 mL three-necked round-bottom flask, and the mixture was stirred evenly at 25 °C. Subsequently, 0.078 g of platinum divinyltetramethyldisiloxane complex was added and the temperature was raised to 80 °C for reaction for 2 h. The mass fraction of platinum in the platinum divinyltetramethyldisiloxane complex was 0.5 wt%. After the reaction was completed, the temperature was raised to 120 °C and low molecular weight substances were removed at this temperature for 2 h. After the low molecular weight substances were removed, the temperature was cooled to 25 °C.

[0052] Comparative Example 5 S1: Under nitrogen protection, add 50.0 g of dimethylcyclosiloxane mixed ring body and 25.0 g of 1,1,3,3-tetramethyldisiloxane to a 150 mL three-necked round-bottom flask, stir evenly at 25 °C, add 1.5 g of concentrated sulfuric acid to react for 2 h, add 2.2 g of sodium carbonate after the reaction, continue stirring for 2 h and filter, transfer the filtrate to a 250 mL three-necked round-bottom flask, heat to 80 °C under nitrogen atmosphere to remove low molecular weight substances, remove for 2 h and then cool the system to 25 °C to obtain a terminal hydrogen-containing polysiloxane intermediate; S2: Under a nitrogen atmosphere, 11.0 g of isopropanol and 0.069 g of platinum tetravinyltetramethylcyclotetrasiloxane complex were added to the dehydrogenated terminal hydrogenated polysiloxane intermediate, and the mixture was stirred and mixed evenly at 80 °C, wherein the mass fraction of platinum in the platinum tetravinyltetramethylcyclotetrasiloxane complex was 0.5 wt%. Subsequently, 45.8 g of 1-octene was added dropwise into the system and the reaction was continued for 3 h. After the reaction was completed, the temperature was raised to 150 °C to remove low molecular weight substances. After 3 h of dehydrogenation reaction, the system was cooled to 25 °C.

[0053] Performance Testing The kinematic viscosity at 25 ℃ and 40 ℃ is tested according to GB / T 265-1988 standard; the flash point is tested according to GB / T 261-2008 standard; the pour point is tested according to GB / T 3535-2006 standard; the dielectric constant is tested according to GB / T 5654-2007 standard; the breakdown voltage is tested according to GB / T 507-2022 standard; the specific heat capacity is tested according to ASTM E1269-2011 method; and the thermal conductivity is tested according to GB / T32064-2015 standard method.

[0054] The performance test results of each embodiment and each comparative example are recorded in the following Table 1.

[0055] Table 1 Performance test results of various embodiments and comparative examples

[0056] Analyzing the performance test results in Table 1, the flash point of the single-phase refrigerant prepared in the embodiment is significantly improved compared with the refrigerant in Comparative Example 1 and Comparative Example 2, which indicates that the single-phase refrigerant prepared in the present application is more difficult to catch fire and has a higher safety factor for use. At the same time, the pour point of the single-phase refrigerant prepared in each embodiment of the present application is reduced to varying degrees compared with that of Comparative Example 4, which indicates that the single-phase refrigerant of the present application is more suitable for flowing at low temperatures and can be better stored and used in low-temperature environments.

[0057] The single-phase refrigerant prepared in each embodiment of the present application has a lower dielectric constant and a higher breakdown voltage compared with Comparative Example 1 and Comparative Example 2, which indicates that the single-phase refrigerant of the present application has excellent insulation performance and is safer to use.

[0058] The test data in Table 1 also show that the single-phase refrigerant prepared in each embodiment of the present application has a certain degree of specific heat capacity and thermal conductivity compared with Comparative Example 1 and Comparative Example 2, indicating that it has excellent thermal conductivity, can perform better heat transfer during use, and maintain the stability of the working interface ambient temperature.

[0059] By analyzing the performance test results of Example 5 and Comparative Example 5, the present application selects isolated dienes and other substances to prepare siloxane diene copolymers, so that the prepared single-phase refrigerant medium has better high and low temperature resistance, thermal conductivity and safety.

[0060] The single-phase refrigerant of Example 1 and Example 6 was subjected to a thermal weight loss test, and the test results are recorded in Table 2 below.

[0061] Table 2 Thermogravimetric test results of Example 1 and Example 6

[0062] According to the test results of Example 6, it is shown that the addition of heat-resistant additives can effectively improve the stability of a single refrigerant under extreme conditions.

[0063] Compared with the comparative example, the single-phase refrigerant medium prepared in the embodiment of the present application has lower kinematic viscosity, higher flash point, lower pour point and higher breakdown voltage, and has better comprehensive properties such as dielectric constant, specific heat capacity and thermal conductivity. It can be used as a coolant to provide stable and reliable heat dissipation for working devices.

[0064] In summary, the present application provides a single-phase refrigerant medium with excellent comprehensive performance, simple preparation method and environmental friendliness, which has certain practicality.

[0065] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. A single-phase refrigerant, characterized in that: Contains a siloxane diene copolymer, the structural formula of the siloxane diene copolymer is: , where R 1 It represents a double-terminal substituted alkane group, and the general molecular formula is C x H 2x , 4≤x≤8; R 2 It represents a single-end substituted alkane group, and its molecular formula is C y H 2y+1 , 6≤y≤16.

2. The single-phase refrigerant according to claim 1, characterized in that: The kinematic viscosity of the siloxane diene copolymer at 25°C is less than 30 mm 2 / s.

3. The single-phase refrigerant according to claim 1, characterized in that: The siloxane diene copolymer is obtained by copolymerizing a terminal hydrogen-containing polysiloxane intermediate with an isolated diene under the action of a first catalyst and then capping with an alpha-olefin.

4. The single-phase refrigerant according to claim 3, characterized in that: The isolated diene is any one of 1,5-hexadiene, 1,7-octadiene or 1,9-decadiene, or a combination of more than one thereof.

5. The single-phase refrigerant according to claim 3, characterized in that: The α-olefin is any one of 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene or 1-hexadecene, or a combination of more than one of them.

6. The single-phase refrigerant according to claim 3, characterized in that: The kinematic viscosity of the hydrogen-terminated polysiloxane intermediate at 25° C. is less than 20 mm 2 / s.

7. The single-phase refrigerant according to claim 3, characterized in that: The first catalyst is one of chloroplatinic acid, platinum divinyltetramethyldisiloxane complex or platinum tetravinyltetramethylcyclotetrasiloxane complex.

8. A method for preparing a single-phase refrigerant, characterized in that: The method comprises the following preparation steps: S1: In an inert gas atmosphere, a dimethylcyclosiloxane mixed ring body and 1,1,3,3-tetramethyldisiloxane react under the action of a second catalyst to obtain a terminal hydrogen-containing polysiloxane intermediate after impurities are removed; S2: In an inert gas atmosphere, the terminal hydrogen-containing polysiloxane intermediate and the first catalyst are added to a solvent, and then isolated dienes are added to react. After a period of reaction, α-olefins are added to obtain the single-phase refrigerant after desulfurization; The isolated diene is any one or a combination of 1,5-hexadiene, 1,7-octadiene or 1,9-decadiene; the α-olefin is any one or a combination of 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene or 1-hexadecene; The structural formula of the siloxane diene copolymer is: , where R 1 It represents a double-terminal substituted alkane group, and the general molecular formula is C x H 2x , 4≤x≤8; R 2 It represents a single-end substituted alkane group, and its molecular formula is C y H 2y+1 , 6≤y≤16.

9. The preparation method according to claim 8, characterized in that: In parts by mass, the S1 step is specifically as follows: in an inert gas atmosphere, 30 to 60 parts of the dimethylcyclosiloxane mixed ring body and 20 to 40 parts of the 1,1,3,3-tetramethyldisiloxane are stirred evenly at 25 to 40 ° C, 1% to 5% of the total mass of the reactants of concentrated sulfuric acid are added to react for 2 to 6 hours, and after the reaction is completed, a corresponding amount of sodium carbonate is added to continue stirring for 2 to 6 hours and filtered, and the filtrate is heated to 60 to 120 ° C in an inert gas atmosphere to remove low molecular weight substances, and after removing for 2 to 6 hours, the system is cooled to 25 ° C to obtain the terminal hydrogen-containing polysiloxane intermediate.

10. The preparation method according to claim 8, characterized in that: In parts by mass, the step S2 is specifically as follows: under an inert gas atmosphere, 5 to 20 parts of a solvent and the first catalyst are added to the hydrogen-terminated polysiloxane intermediate after dehydrogenation, wherein the amount of the first catalyst is 1×10 of the total mass of the reactants. -6 ~50×10 -6 , stirring and mixing at 50-120 °C, then dropping 10-25 parts of the isolated diene into the system, reacting at 50-120 °C for 1-8 hours, adding 10-30 parts of the α-olefin and continuing the reaction for 1-8 hours, heating to 100-150 °C after the reaction to remove low molecular weight substances, and cooling the system to 25 °C after 1-4 hours to obtain the single-phase refrigerant.

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