Biphenyl benzyl derivative composite heat-conducting oil and preparation method thereof

Abstract

The invention belongs to the technical field of heat-conducting oil, and particularly relates to biphenyl benzyl derivative composite heat-conducting oil and a preparation method thereof. In order to solve the problem that the use temperature of heat-conducting oil in the prior art cannot meet the requirement, the biphenyl benzyl derivative composite heat-conducting oil and the preparation method thereof are provided, hydrogenated terphenyl and biphenyl benzyl derivatives are mixed, then carbon nanotubes, N, N '-(4, 4'-methylene diphenyl) bismaleimide and phenylmethyl silicone oil are added, and the heat-conducting oil is prepared. The high use temperature of the heat conduction oil is ensured, and the compatibility and stability of the whole system are also ensured.

Description

Technical Field

[0001] The present application belongs to the technical field of heat transfer oils, and in particular relates to a biphenyl benzyl derivative composite heat transfer oil and a preparation method thereof. Background Art

[0002] As a special liquid medium, thermal oil plays a vital role in the industrial heating and cooling process. Its main function is to transfer heat indirectly. The application range of thermal oil is very wide, covering a variety of industries from petrochemicals, chemical fibers, medicine, textile printing and dyeing to building materials. In these industries, thermal oil is used in various types of heating equipment, such as reactors, distillation towers, dryers, etc. Thermal oil can provide high temperature at relatively low pressure, and has good thermal and chemical stability, as well as a long service life, which makes it the preferred heat transfer medium in many industrial applications.

[0003] The development of heat transfer oil has gone through several stages. Early heat transfer oil was mainly based on mineral oil. Later, with the advancement of synthesis technology, synthetic heat transfer oil appeared. Mineral oil-based heat transfer oil has a low cost, but its maximum operating temperature is usually no more than 300 degrees Celsius, and long-term high-temperature operation will cause rapid aging of the oil and coke deposition. In contrast, synthetic heat transfer oils can provide a higher operating temperature range, and they also have better thermal stability and longer service life. In addition, synthetic heat transfer oils tend to have lower volatility, reduce losses caused by evaporation, and have less impact on the environment.

[0004] Thermal oil can be divided into different types according to its physical and chemical properties and uses, mainly including mineral oil type, synthetic aromatic hydrocarbon type, silicone oil type and other special purpose thermal oils. Mineral oil type thermal oil is obtained by refining petroleum. It is widely used because of its low price and wide source, but its thermal stability and antioxidant properties are relatively poor. Synthetic aromatic hydrocarbon type thermal oil is based on aromatic compounds and is made by chemical synthesis. This type of thermal oil is characterized by excellent stability at high temperatures and is suitable for occasions that require long-term high-temperature operation. Silicone oil type thermal oil is known for its excellent temperature resistance and low toxicity. It is suitable for industries such as food processing. However, its high cost limits its large-scale application.

[0005] An important problem faced by the existing technology is that the operating temperature of heat transfer oil is not high enough. Although synthetic heat transfer oil has pushed the upper limit of the operating temperature to a new height, in some special processes, such as certain chemical synthesis reactions or metal smelting processes, a higher temperature operating environment is still required. In this case, traditional heat transfer oil may not be able to meet the demand, because once its safe operating temperature is exceeded, the heat transfer oil will quickly decompose, resulting in a sharp decline in performance and may even cause safety accidents. Summary of the invention

[0006] In order to solve the problem that the operating temperature of heat transfer oil in the prior art cannot meet the demand, the present application provides a biphenyl benzyl derivative composite heat transfer oil and a preparation method thereof, by mixing hydrogenated terphenyl with a biphenyl benzyl derivative and then adding an auxiliary agent, which not only ensures that the heat transfer oil can be used at a higher temperature, but also ensures the compatibility and stability of the entire system.

[0007] The present application provides a biphenyl benzyl derivative composite heat-conducting oil, which comprises the following components by weight: 60-85 parts of base oil A, 15-20 parts of base oil B, 0.05-1 parts of carbon nanotubes, 1-3 parts of N,N'-(4,4'-methylenediphenyl)bismaleimide and 1-5 parts of benzyl silicone oil; wherein the base oil A is hydrogenated terphenyl, the base oil B is a biphenyl benzyl derivative, and the biphenyl benzyl derivative has the following structure: .

[0008] Furthermore, the benzyl silicone oil is a high-phenyl low-polymerization silicone oil, wherein the molar fraction of the phenyl substituent is 45%-55%.

[0009] Furthermore, the carbon nanotubes have a diameter of 7-15 nm and a length of 1-5 μm.

[0010] The present application also provides a method for preparing a biphenyl benzyl derivative composite heat-conducting oil, comprising the following steps: S1. Add palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate, 4-methoxyphenylboronic acid and ethanol in sequence, stir until all solids are dissolved, add 4-bromoacetate, heat and stir the mixture to react, filter and extract with hexane for multiple times after the reaction is completed, combine the organic layers, wash with deionized water, dry with anhydrous magnesium sulfate, and concentrate to obtain a crude product; S2, adding 4-trifluoromethylphenylboric acid, palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate and ethanol to the crude product obtained in S1, heating and stirring again to react, after the reaction is completed, filtering and extracting with hexane for multiple times, combining the organic layers, washing with deionized water, and then drying with anhydrous magnesium sulfate to obtain a biphenyl benzyl derivative; S3, adding N,N'-(4,4'-methylenediphenyl)bismaleimide to the biphenyl benzyl derivative obtained in step S2, heating to 60-80°C and stirring, then adding hydrogenated terphenyl, benzyl silicone oil and carbon nanotubes while maintaining the temperature and stirring, filtering and degassing to obtain the biphenyl benzyl derivative composite heat transfer oil.

[0011] Furthermore, in step S1, the molar ratio of palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate, 4-methoxyphenylboronic acid and 4-bromophenylacetate is 0.01-0.05: 0.01-0.05: 2-3: 1: 1-1.5.

[0012] Furthermore, in step S2, the molar ratio of palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate and 4-trifluoromethylphenylboric acid is 0.01-0.05:0.01-0.05:2-3:1.

[0013] Furthermore, the molar ratio of 4-trifluoromethylphenylboronic acid in step S2 to 4-bromoacetate in step S1 is 1:1.5.

[0014] Furthermore, the heating temperature of step S1 and step S2 is 75-95° C., the reaction time of step S1 is 3-5 h, and the reaction time of step S2 is 22-26 h.

[0015] In this application, hydrogenated terphenyl is used as base oil A, which provides excellent thermal stability and high flash point, and can maintain stable physical properties at high temperatures. Biphenyl benzyl derivatives are used as base oil B to further improve the thermal conductivity and chemical stability of the heat transfer oil. The addition of carbon nanotubes significantly improves the thermal conductivity efficiency of the heat transfer oil, and its nanoscale size helps to evenly disperse and enhance the thermal network. N,N'-(4,4'-methylenediphenyl) bismaleimide, as a high-performance additive, can improve the compatibility and mechanical strength of the heat transfer oil, while increasing its glass transition temperature. Benzyl silicone oil greatly improves the heat resistance and oxidation resistance of the heat transfer oil by introducing phenyl substituents, ensuring long-term stability in high temperature environments, so that the heat transfer oil can be used at 330°C and has good performance.

[0016] In the initial reaction of synthesizing biphenyl benzyl derivatives, palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate, 4-methoxyphenylboronic acid and ethanol are added in sequence. In this step, 4-bromoacetate phenyl ester is coupled with 4-methoxyphenylboronic acid by palladium catalysis cross-coupling reaction to generate an intermediate. Palladium chloride is used as a catalyst, 1,5-bis(diphenylphosphino)pentane is used as a ligand, sodium bicarbonate provides an alkaline environment, and ethanol is used as a solvent. Then step S2 further modifies the biphenyl benzyl derivative, adding 4-trifluoromethylphenylboronic acid, palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate and ethanol, and heating to 75-95°C again and stirring the reaction for 22-26 hours. In this step, the intermediate is coupled with 4-trifluoromethylphenylboronic acid by palladium catalysis cross-coupling reaction to generate the target biphenyl benzyl derivative. The process is as follows: The phenyl substituents in phenylmethyl silicone oil have high thermal stability and antioxidant properties. At high temperatures, the benzene ring structure can effectively absorb and disperse heat, preventing polymer chain breakage and cross-linking reactions. In addition, the presence of phenyl increases the π-π interaction between molecules, enhancing the rigidity and stability of the molecular chain. The phenyl substituent has a high antioxidant capacity and can effectively inhibit the generation and propagation of free radicals at high temperatures, slowing down the rate of oxidation reactions. In addition, the benzene ring structure itself has a high chemical inertness and is not easy to react with other substances. The aromatic ring structure in biphenyl benzyl derivatives and N,N'-(4,4'-methylenediphenyl) bismaleimide gives the heat transfer oil excellent chemical resistance, enabling it to resist the erosion of various acids, alkalis and organic solvents.

[0017] N,N'-(4,4'-methylenediphenyl) bismaleimide is a high-performance aromatic polyimide prepolymer, which contains multiple conjugated double bonds and aromatic rings in its molecules. These structures can form a stable network structure at high temperatures, which helps the heat transfer oil to maintain good thermal stability and oxidation resistance in high temperature environments, avoiding decomposition and aging caused by high temperatures. As a compatibilizer in the system of this application, it can promote good compatibility between different components through interaction and reduce phase separation between components. The molecular chains of biphenyl benzyl derivatives and phenylmethyl silicone oil are long and flexible, and a certain degree of entanglement will occur during the heating process, forming a stable three-dimensional network structure. This structure improves its shear stability and anti-sedimentation properties.

[0018] Carbon nanotubes have extremely high thermal conductivity, and their one-dimensional nanostructure allows heat to be quickly transferred along the axial direction. In addition, the high aspect ratio of carbon nanotubes enables them to form an effective heat conduction network in the heat transfer oil, significantly improving the overall heat conduction efficiency. There are strong van der Waals forces and π-π interactions between carbon nanotubes and biphenyl benzyl derivatives, which not only contribute to the uniform dispersion of carbon nanotubes, but also enhance the continuity of the heat conduction path, and can provide interfacial bonding force, which can build bridges between different phases, not only improving the mechanical strength, but also promoting the interaction between molecules, helping to form a more uniform mixture.

[0019] There is a synergistic effect between carbon nanotubes, N,N'-(4,4'-methylenediphenyl)bismaleimide and phenylmethyl silicone oil, which further enhances the stability of the entire system. The addition of carbon nanotubes not only improves the thermal conductivity, but also improves the rheological properties of the heat transfer oil; N,N'-(4,4'-methylenediphenyl)bismaleimide enhances the cross-linking between molecules and prevents stratification during long-term use. Each component maintains good compatibility and stability in a high temperature environment, avoiding the occurrence of stratification and precipitation. During long-term use, the performance of the heat transfer oil remains consistent, ensuring the reliability and consistency of the system. DETAILED DESCRIPTION

[0020] The technical scheme of the present invention and its effects are further described below by specific examples. The following examples are only used to illustrate the content of the present invention and are not used to limit the protection scope of the present invention. Simple changes made to the present invention by applying the concept of the present invention are all within the scope of the protection claimed by the present invention.

[0021] The equipment used in the preparation method of the present invention can be the well-known equipment in the art. The raw materials used in the present invention are commercially available unless otherwise specified.

[0022] Example 1 A biphenyl benzyl derivative composite heat-conducting oil comprises the following components by weight: 60 parts of base oil A, 20 parts of base oil B, 0.05 parts of carbon nanotubes, 3 parts of N,N'-(4,4'-methylenediphenyl)bismaleimide and 1 part of benzyl silicone oil; wherein the base oil A is hydrogenated terphenyl, the base oil B is a biphenyl benzyl derivative, and the biphenyl benzyl derivative has the following structure: The benzyl silicone oil is a high phenyl and low polymerization degree silicone oil, wherein the molar fraction of the phenyl substituent is 45%-55%. The carbon nanotube has a diameter of 7-15 nm and a length of 1-5 μm.

[0023] The preparation method of the above-mentioned biphenyl benzyl derivative composite heat-conducting oil comprises the following steps: S1. Add 0.3 mmol palladium chloride, 0.3 mmol 1,5-bis(diphenylphosphino)pentane, 0.2 mol sodium bicarbonate, 0.1 mol 4-methoxyphenylboric acid and 80 ml ethanol in sequence, stir until all solids are dissolved, add 0.1 mol 4-bromoacetate, heat the mixture to 75°C and stir to react, react for 3 hours, filter and extract with hexane for 3 times, combine the organic layers, wash with deionized water, dry with anhydrous magnesium sulfate, and concentrate to obtain a crude product; S2, add 0.1 mol 4-trifluoromethylphenylboric acid, 0.3 mmol palladium chloride and 0.3 mmol 1,5-bis(diphenylphosphino)pentane, 0.2 mol sodium bicarbonate and 80 ml ethanol to the crude product obtained in S1, heat to 75°C again with stirring to react, react for 22 hours, filter and extract with hexane three times, combine the organic layers, wash with deionized water, and then dry with anhydrous magnesium sulfate to obtain a biphenyl benzyl derivative; S3. Add 3 parts of N,N'-(4,4'-methylenediphenyl)bismaleimide to 20 parts of the biphenyl benzyl derivative obtained in step S2, raise the temperature to 60°C and stir, then add 60 parts of hydrogenated terphenyl, 1 part of benzyl silicone oil and 0.05 parts of carbon nanotubes while maintaining the temperature and stirring, and obtain the biphenyl benzyl derivative composite heat transfer oil after filtering and degassing.

[0024] Example 2 A biphenyl benzyl derivative composite heat-conducting oil comprises the following components by weight: 85 parts of base oil A, 15 parts of base oil B, 1 part of carbon nanotubes, 1 part of N,N'-(4,4'-methylenediphenyl)bismaleimide and 5 parts of benzyl silicone oil; wherein the base oil A is hydrogenated terphenyl, the base oil B is a biphenyl benzyl derivative, and the biphenyl benzyl derivative has the following structure: The benzyl silicone oil is a high phenyl and low polymerization degree silicone oil, wherein the molar fraction of the phenyl substituent is 45%-55%. The carbon nanotube has a diameter of 7-15 nm and a length of 1-5 μm.

[0025] The preparation method of the above-mentioned biphenyl benzyl derivative composite heat-conducting oil comprises the following steps: S1. 1.6 mmol palladium chloride, 1.6 mmol 1,5-bis(diphenylphosphino)pentane, 0.3 mol sodium bicarbonate, 0.15 mol 4-methoxyphenylboric acid and 80 ml ethanol were added in sequence, and stirred until all solids were dissolved. Then, 0.1 mol 4-bromoacetate was added, and the mixture was heated to 95° C. and stirred for reaction. After reacting for 5 h, the mixture was filtered and extracted with hexane for 3 times. The organic layers were combined, washed with deionized water, dried over anhydrous magnesium sulfate, and concentrated to obtain a crude product. S2, add 0.06 mol 4-trifluoromethylphenylboric acid, 1 mmol palladium chloride and 1 mmol 1,5-bis(diphenylphosphino)pentane, 0.18 mol sodium bicarbonate and 80 ml ethanol to the crude product obtained in S1, heat to 95°C again with stirring to react, react for 26 hours, filter and extract with hexane three times, combine the organic layers, wash with deionized water, and then dry with anhydrous magnesium sulfate to obtain a biphenyl benzyl derivative; S3. Add 1 part of N,N'-(4,4'-methylenediphenyl)bismaleimide to 15 parts of the biphenyl benzyl derivative obtained in step S2, raise the temperature to 60°C and stir, then add 85 parts of hydrogenated terphenyl, 5 parts of benzyl silicone oil and 1 part of carbon nanotube while maintaining the temperature and stirring, and obtain the biphenyl benzyl derivative composite heat transfer oil after filtering and degassing.

[0026] Example 3 A biphenyl benzyl derivative composite heat-conducting oil comprises the following components by weight: 70 parts of base oil A, 18 parts of base oil B, 0.08 parts of carbon nanotubes, 2 parts of N,N'-(4,4'-methylenediphenyl)bismaleimide and 3 parts of benzyl silicone oil; wherein the base oil A is hydrogenated terphenyl, the base oil B is a biphenyl benzyl derivative, and the biphenyl benzyl derivative has the following structure: The benzyl silicone oil is a high phenyl and low polymerization degree silicone oil, wherein the molar fraction of the phenyl substituent is 45%-55%. The carbon nanotube has a diameter of 7-15 nm and a length of 1-5 μm.

[0027] The preparation method of the above-mentioned biphenyl benzyl derivative composite heat-conducting oil comprises the following steps: S1. Add 1 mmol palladium chloride, 1 mmol 1,5-bis(diphenylphosphino)pentane, 0.25 mol sodium bicarbonate, 0.13 mol 4-methoxyphenylboric acid and 80 ml ethanol in sequence, stir until all solids are dissolved, add 0.1 mol 4-bromoacetate, heat the mixture to 80°C, stir and react, react for 4 hours, filter and extract with hexane 3 times, combine the organic layers, wash with deionized water, dry with anhydrous magnesium sulfate, and concentrate to obtain a crude product; S2, to the crude product obtained in S1, add 0.13 mol 4-trifluoromethylphenylboric acid, 1 mmol palladium chloride and 1 mmol 1,5-bis(diphenylphosphino)pentane, 0.25 mol sodium bicarbonate and 80 ml ethanol, heat to 80°C again and stir to react, react for 24 hours, filter and extract with hexane three times, combine the organic layers, wash with deionized water, and then dry with anhydrous magnesium sulfate to obtain a biphenyl benzyl derivative; S3. Add 2 parts of N,N'-(4,4'-methylenediphenyl)bismaleimide to 18 parts of the biphenyl benzyl derivative obtained in step S2, heat to 60°C and stir, then add 70 parts of hydrogenated terphenyl, 3 parts of benzyl silicone oil and 0.08 parts of carbon nanotubes while maintaining the temperature and stirring, and obtain the biphenyl benzyl derivative composite heat transfer oil after filtering and degassing.

[0028] Comparative Example 1 is the biphenyl benzyl derivative obtained in Example 3.

[0029] In Comparative Example 2, N,N′-(4,4′-methylenediphenyl)bismaleimide, carbon nanotubes and phenylmethyl silicone oil were not added, and the rest was the same as in Example 3.

[0030] Comparative Example 3 does not add carbon nanotubes and phenylmethyl silicone oil, and the rest is the same as Example 3.

[0031] In Comparative Example 4, no carbon nanotubes and N,N'-(4,4'-methylenediphenyl)bismaleimide were added, and the rest was the same as in Example 3.

[0032] In Comparative Example 5, N,N'-(4,4'-methylenediphenyl)bismaleimide and benzyl silicone oil were not added, and the rest was the same as in Example 3.

[0033] Comparative Example 6 does not add carbon nanotubes, and the rest is the same as Example 3.

[0034] The test results of the heat transfer oil are shown in Tables 1 and 2.

[0035] Table 1 is a table of physical and chemical parameters of the heat transfer oil obtained in the examples.

[0036] Table 2 is a test table of thermal stability of heat transfer oil of Examples 1-3 and Comparative Examples 1-4.

[0037] It can be seen that Comparative Example 1 is the biphenyl benzyl derivative obtained in the present application, which will deteriorate and become turbid when used at 330°C, which shows that 330°C has exceeded its applicable range. Comparative Example 2 only mixes two base oils, and obvious stratification occurs, and the stability is very poor. Comparative Example 3 does not add carbon nanotubes and benzyl silicone oil, Comparative Example 4 does not add carbon nanotubes and N,N'-(4,4'-methylenediphenyl)bismaleimide, and Comparative Example 5 does not add N,N'-(4,4'-methylenediphenyl)bismaleimide and benzyl silicone oil. The stability of these three heat transfer oils at 330°C is still poor, and the deterioration rate does not meet the requirements. Comparative Example 6 does not add carbon nanotubes, and it can be seen that there is not much obvious stratification, and the deterioration rate is also the best among the comparative examples, but it still does not meet the use requirements.

Claims

1. A biphenyl benzyl derivative composite heat transfer oil, characterized in that: The composition comprises the following components by weight: 60-85 parts of base oil A, 15-20 parts of base oil B, 0.05-1 parts of carbon nanotubes, 1-3 parts of N,N'-(4,4'-methylenediphenyl)bismaleimide and 1-5 parts of benzyl silicone oil; wherein the base oil A is hydrogenated terphenyl, the base oil B is a biphenyl benzyl derivative, and the biphenyl benzyl derivative has the following structure: 。 2. The biphenyl benzyl derivative composite heat transfer oil according to claim 1, characterized in that: The benzyl silicone oil is a high-phenyl and low-polymerization silicone oil, wherein the molar fraction of the phenyl substituent is 45%-55%.

3. The biphenyl benzyl derivative composite heat transfer oil according to claim 1, characterized in that: The carbon nanotubes have a diameter of 7-15 nm and a length of 1-5 μm.

4. A method for preparing a biphenyl benzyl derivative composite heat-conducting oil according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Add palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate, 4-methoxyphenylboronic acid and ethanol in sequence, stir until all solids are dissolved, add 4-bromoacetate, heat and stir the mixture to react, filter and extract with hexane for multiple times after the reaction is completed, combine the organic layers, wash with deionized water, dry with anhydrous magnesium sulfate, and concentrate to obtain a crude product; S2, adding 4-trifluoromethylphenylboric acid, palladium chloride, 1,5-bis(diphenylphosphino)pentane, sodium bicarbonate and ethanol to the crude product obtained in S1, heating and stirring again to react, after the reaction is completed, filtering and extracting with hexane for multiple times, combining the organic layers, washing with deionized water, and then drying with anhydrous magnesium sulfate to obtain a biphenyl benzyl derivative; S3, adding N,N'-(4,4'-methylenediphenyl)bismaleimide to the biphenyl benzyl derivative obtained in step S2, heating to 60-80°C and stirring, then adding hydrogenated terphenyl, benzyl silicone oil and carbon nanotubes while maintaining the temperature and stirring, filtering and degassing to obtain the biphenyl benzyl derivative composite heat transfer oil.

5. The method for preparing a biphenyl benzyl derivative composite heat-conducting oil according to claim 4, characterized in that: In step S1, the molar ratio of sodium bicarbonate, 4-methoxyphenylboronic acid and 4-bromophenylacetate is 2-3:1-1.5:1, the molar ratio of palladium chloride to 4-methoxyphenylboronic acid is 0.01-0.05:3, and the molar ratio of 1,5-bis(diphenylphosphino)pentane to 4-methoxyphenylboronic acid is 0.01-0.05:

3.

6. The method for preparing a biphenyl benzyl derivative composite heat-conducting oil according to claim 5, characterized in that: In step S2, the molar ratio of sodium bicarbonate to 4-trifluoromethylphenylboric acid is 2-3:1, the molar ratio of palladium chloride to 4-trifluoromethylphenylboric acid is 0.01-0.05:3, and the molar ratio of 1,5-bis(diphenylphosphino)pentane to 4-trifluoromethylphenylboric acid is 0.01-0.05:

3.

7. The method for preparing a biphenyl benzyl derivative composite heat transfer oil according to claim 6, characterized in that: The molar ratio of the 4-trifluoromethylphenylboronic acid in step S2 to the 4-bromoacetate in step S1 is 1:1-1.

5.

8. The method for preparing a biphenyl benzyl derivative composite heat-conducting oil according to claim 4, characterized in that: The heating temperature of step S1 and step S2 is 75-95° C., the reaction time of step S1 is 3-5 h, and the reaction time of step S2 is 22-26 h.

Images