A method for synthesizing tetramethyl biphenol type epoxy resin

Abstract

The present application relates to a kind of synthesis method of tetramethyl biphenyl diphenol type epoxy resin, belong to epoxy resin preparation technical field.The yield of tetramethyl biphenyl diphenol type epoxy resin synthesized in the present application is greater than 94%, and total chlorine content is less than 240ppm.This is due to the process of two-step reaction in the present application, while adding mixed ether solvent consisting of diethylene glycol dibutyl ether, isobutoxy cyclohexane and triethyl glycerol ether in etherification reaction stage, diethylene glycol dibutyl ether and isobutoxy cyclohexane are slightly soluble in water, triethyl glycerol ether is insoluble in water, but the three solvents have good solubility for epoxy chloropropane and phenolic compounds, the use of three compounds can form transition phase, promote the migration of basic catalyst in aqueous phase to two-phase interface to participate in reaction, promote etherification reaction to proceed stably, avoid the occurrence of side reaction, and then improve product yield and purity, reduce total chlorine content.

Description

Technical Field

[0001] This invention relates to a method for synthesizing a tetramethylbiphenyl-type epoxy resin, belonging to the field of epoxy resin preparation technology. Background Technology

[0002] With the development of the electronics industry, electronic devices are evolving towards miniaturization, lightweighting, high performance, and high functionality, while electronic equipment is correspondingly developing towards high integration, thinness, and multilayering. To meet the requirements of the electronics industry, it is necessary to improve the heat resistance, dielectric properties, and toughness of epoxy resin encapsulation materials, while simultaneously reducing the resin's water absorption and internal stress. However, the performance of conventional bisphenol A type epoxy resin is no longer sufficient to meet these demands. To improve the performance of bisphenol A type epoxy resin, researchers have developed tetramethylbiphenyl epoxy resin. Compared to bisphenol A type epoxy resin, tetramethylbiphenyl epoxy resin incorporates highly rigid biphenyl groups and four symmetrical methyl groups into its molecular chain, resulting in advantages such as low melt viscosity, high tensile strength, good toughness, excellent chemical and solvent resistance, and good sealing properties. It is a special epoxy resin with superior overall performance.

[0003] Currently, the main methods for synthesizing tetramethylbiphenyl epoxy resin are the two-step method and the one-step method. The one-step method involves reacting tetramethylbiphenyl and epichlorohydrin under concentrated alkali conditions to synthesize tetramethylbiphenyl epoxy resin in one step, with ring-opening etherification and dehydrochlorination ring-closure occurring simultaneously. The two-step method involves first undergoing a ring-opening etherification reaction between tetramethylbiphenyl and epichlorohydrin, followed by the addition of alkali to allow the etherified product to undergo a ring-closure reaction. Compared to the one-step process, the two-step process has advantages such as easier molecular weight control, narrower molecular weight distribution, and higher epoxy value. However, the two-step process requires the use of excessive epichlorohydrin, increasing the epichlorohydrin recovery load and reducing production efficiency. Furthermore, the alkali metal hydroxide catalyst is often an aqueous solution, and the compatibility deviation between epichlorohydrin and water leads to uneven mixing of the alkali metal hydroxide catalyst with tetramethylbiphenyl and epichlorohydrin, resulting in more side reactions, higher total chlorine content in the product, and affecting product quality. Summary of the Invention

[0004] The purpose of this invention is to provide a method for synthesizing tetramethylbiphenyl epoxy resin, so as to solve the problem of high total chlorine content in the product when preparing tetramethylbiphenyl epoxy resin.

[0005] This invention provides a method for synthesizing tetramethylbiphenyl epoxy resin, comprising the following steps: first, tetramethylbiphenyl and epichlorohydrin undergo a ring-opening etherification reaction in an ether solvent under the catalysis of an alkali metal hydroxide solution; then, the water generated in the reaction is removed; and then an alkali metal hydroxide solution is added to perform a ring-closing reaction. After purification, tetramethylbiphenyl epoxy resin is obtained. The ether solvent is composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether, with a mass ratio of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether of 5~8:2~3:0.5~1; and the mass ratio of tetramethylbiphenyl, epichlorohydrin, and the ether solvent is 218:508~550:190~240.

[0006] Preferably, the mass fraction of the alkali metal hydroxide solution used in the ring-opening etherification reaction is 50% to 55%.

[0007] Preferably, the amount of alkali metal hydroxide solution added during the ring-opening etherification reaction is 3 to 10% of the mass of tetramethylbiphenyl.

[0008] Preferably, the ring-opening etherification reaction is carried out at a temperature of 60-90°C for 2-5 hours.

[0009] Preferably, the removal of water generated after the ring-opening etherification reaction is carried out at a temperature of 60~90℃ and a pressure of 5~20kPa.

[0010] Preferably, the mass fraction of the alkali metal hydroxide solution used in the ring-closing reaction is 50% to 55%.

[0011] Preferably, the amount of alkali metal hydroxide solution added during the ring-closing reaction is 50% to 70% of the mass of tetramethylbiphenyl.

[0012] Preferably, the alkali metal hydroxide solution used in the closed-loop reaction is added dropwise at a rate of 0.8~1.2 g / min.

[0013] Preferably, the closed-loop reaction is carried out at a temperature of 50~80℃ for 0.5~1h.

[0014] Preferably, the purification method is as follows: the crude epoxy resin product obtained by the closed-ring reaction is extracted with an organic solvent and water, and then the extracted organic phase and sodium hydroxide solution are heated and mixed until the hydrolytic chlorine content of the crude epoxy resin product is not greater than 100 ppm. Water is then added for extraction, and the extracted organic phase is subjected to vacuum distillation and filtered to obtain tetramethylbiphenyl-type epoxy resin.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] The tetramethylbiphenyl epoxy resin synthesized in this invention has a yield greater than 94% and a total chlorine content less than 240 ppm, exhibiting higher yield and lower total chlorine content compared to conventional synthesis methods. This is because the invention employs a two-step reaction process, and a mixed ether solvent composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether is added during the etherification reaction stage. Diethylene glycol dibutyl ether and isobutoxycyclohexane are slightly soluble in water, while triethylglycerol ether is insoluble in water. However, all three solvents have good solubility for epichlorohydrin and phenolic compounds. The combined use of these three solvents can form a transition phase, promoting a more uniform migration of the alkaline catalyst in the aqueous phase to the interface between the two phases to participate in the reaction. This promotes the stable progress of the etherification and ring-closing reactions, avoids side reactions, and thus improves product yield and purity while reducing total chlorine content. Attached Figure Description

[0017] Figure 1 This is the 1H NMR spectrum of isobutoxycyclohexane prepared in this invention. Detailed Implementation

[0018] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0019] The preparation method of isobutoxycyclohexane used in the following embodiments and comparative examples of the present invention is as follows: Sodium cyclohexyloxide and anhydrous diethyl ether in a mass ratio of 1:5 are added to a reaction vessel, and then dry nitrogen gas is introduced into the reaction vessel. After stirring evenly, isoisobutane iodo (the molar ratio of isobutane bromoisobutane to sodium cyclohexyloxide is 1.2:1) is added, and the mixture is heated and stirred until reflux is reached. The reflux reaction is maintained for 20 hours. Then, the diethyl ether is distilled off, and the fraction with a boiling range of 85-88℃ at an absolute pressure of 3 kPa is collected to obtain isobutoxycyclohexane with a yield of 21%. The 1H NMR spectrum of isobutoxycyclohexane is shown below. Figure 1 As shown, the chemical structure is as follows: .

[0020] Example 1

[0021] The method for synthesizing tetramethylbiphenyl-type epoxy resin in this embodiment includes the following steps:

[0022] (1) Add tetramethylbiphenyl, epichlorohydrin and ether solvent in a mass ratio of 218:508:190 to the reactor, heat to 60°C, and then add 50% sodium hydroxide solution as an alkaline catalyst. The amount of sodium hydroxide solution added is 5% of the mass of tetramethylbiphenyl. Control the temperature of the material in the reactor to 60°C, stir the reaction for 5 hours to complete the etherification reaction.

[0023] Then, the temperature inside the reactor was controlled at 60℃, and the reactor was evacuated to 10kPa for vacuum dehydration of the material inside. After dehydration, the vacuum level inside the reactor was maintained, while the temperature of the material inside the reactor was controlled at 70℃. A 50% sodium hydroxide solution (the amount of sodium hydroxide solution added was 70% of the mass of tetramethylbiphenyl) was added dropwise to the reactor at a dropping rate of 1.2g / min. After the addition was completed, the reaction was stirred for 0.5h under the conditions of 10kPa pressure and 70℃. During the reaction... The generated water and a small amount of epichlorohydrin and ether solvents are distilled off under low pressure. The distilled water is separated, and the organic phase is refluxed back to the reactor. After the stirring reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature is raised to 150°C to remove excess epichlorohydrin and ether solvents from the reactor. After cooling to room temperature, crude epoxy resin product is obtained. The ether solvent is composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether, with a mass ratio of 5:2:0.5.

[0024] (2) Add toluene (the mass of toluene is twice the mass of the crude epoxy resin product) to the reactor, stir to fully dissolve the crude epoxy resin product, then add deionized water (the mass ratio of deionized water to crude epoxy resin product is 1:1), stir evenly and let stand to separate the layers, separate the organic phase, then add 20% sodium hydroxide solution (the mass ratio of sodium hydroxide solution to crude epoxy resin product is 0.03:1) to the organic phase, heat to 60°C, stir and mix until the hydrolyzed chlorine content of the crude epoxy resin product is 100ppm, control the temperature at 50°C, add deionized water (the mass ratio of deionized water to crude epoxy resin product is 0.25:1), stir evenly and let stand to separate the layers, separate the organic phase, heat the organic phase to 120°C, remove the solvent by vacuum until there is no distillate, filter at 130°C to remove solid impurities, and the filtrate is the tetramethylbiphenyl epoxy resin product.

[0025] Example 2

[0026] The method for synthesizing tetramethylbiphenyl-type epoxy resin in this embodiment includes the following steps:

[0027] (1) Add tetramethylbiphenyl, epichlorohydrin and ether solvent in a mass ratio of 218:520:210 to the reactor, heat to 60°C, and then add 50% sodium hydroxide solution as an alkaline catalyst. The amount of sodium hydroxide solution added is 5% of the mass of tetramethylbiphenyl. Control the temperature of the material in the reactor to 60°C, stir the reaction for 5 hours to complete the etherification reaction.

[0028] Then, the temperature inside the reactor was controlled at 60℃, and the reactor was evacuated to 10kPa for vacuum dehydration of the material inside. After dehydration, the vacuum inside the reactor was maintained, while the temperature of the material inside the reactor was controlled at 70℃. A 50% sodium hydroxide solution (the amount of sodium hydroxide solution added was 70% of the mass of tetramethylbiphenyl) was added dropwise to the reactor at a dropping rate of 1.2g / min. After the addition was completed, the reaction was stirred for 0.5h under the conditions of 10kPa pressure and 70℃. During the reaction, the product... The raw water and a small amount of epichlorohydrin and ether solvents are distilled off under low pressure. The distilled water is separated, and the organic phase is refluxed back to the reactor. After the stirring reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature is raised to 150°C to remove excess epichlorohydrin and ether solvents from the reactor. After cooling to room temperature, crude epoxy resin product is obtained. The ether solvent is composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether, with a mass ratio of 6:2.5:0.7.

[0029] (2) Add toluene (the mass of toluene is twice the mass of the crude epoxy resin product) to the reactor, stir to fully dissolve the crude epoxy resin product, then add deionized water (the mass ratio of deionized water to crude epoxy resin product is 1:1), stir evenly and let stand to separate the layers, separate the organic phase, then add 20% sodium hydroxide solution (the mass ratio of sodium hydroxide solution to crude epoxy resin product is 0.03:1) to the organic phase, heat to 60°C, stir and mix until the hydrolyzed chlorine content of the crude epoxy resin product is 100ppm, control the temperature at 50°C, add deionized water (the mass ratio of deionized water to crude epoxy resin product is 0.25:1), stir evenly and let stand to separate the layers, separate the organic phase, heat the organic phase to 120°C, remove the solvent by vacuum until there is no distillate, filter at 130°C to remove solid impurities, and the filtrate is the tetramethylbiphenyl epoxy resin product.

[0030] Example 3

[0031] The method for synthesizing tetramethylbiphenyl-type epoxy resin in this embodiment includes the following steps:

[0032] (1) Add tetramethylbiphenyl, epichlorohydrin and ether solvent in a mass ratio of 218:550:240 to the reactor, heat to 60°C, and then add 50% sodium hydroxide solution as an alkaline catalyst. The amount of sodium hydroxide solution added is 5% of the mass of tetramethylbiphenyl. Control the temperature of the material in the reactor to 60°C, stir the reaction for 5 hours to complete the etherification reaction.

[0033] Then, the temperature inside the reactor was controlled at 60℃, and the reactor was evacuated to 10kPa for vacuum dehydration of the material inside. After dehydration, the vacuum level inside the reactor was maintained, while the temperature of the material inside the reactor was controlled at 70℃. A 50% sodium hydroxide solution (the amount of sodium hydroxide solution added was 70% of the mass of tetramethylbiphenyl) was added dropwise to the reactor at a dropping rate of 1.2g / min. After the addition was completed, the reaction was stirred for 0.5h under the conditions of 10kPa pressure and 70℃. The water and a small amount of epichlorohydrin and ether solvents generated in the reaction are distilled off under low pressure. The distilled water is separated, and the organic phase is refluxed back to the reactor. After the stirring reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature is raised to 150°C to remove excess epichlorohydrin and ether solvents in the reactor. After cooling to room temperature, crude epoxy resin product is obtained. The ether solvent is composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether, and the mass ratio of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether is 8:3:1.

[0034] (2) Add toluene (the mass of toluene is twice the mass of the crude epoxy resin product) to the reactor, stir to fully dissolve the crude epoxy resin product, then add deionized water (the mass ratio of deionized water to crude epoxy resin product is 1:1), stir evenly and let stand to separate the layers, separate the organic phase, then add 20% sodium hydroxide solution (the mass ratio of sodium hydroxide solution to crude epoxy resin product is 0.03:1) to the organic phase, heat to 60°C, stir and mix until the hydrolyzed chlorine content of the crude epoxy resin product is 100ppm, control the temperature at 50°C, add deionized water (the mass ratio of deionized water to crude epoxy resin product is 0.25:1), stir evenly and let stand to separate the layers, separate the organic phase, heat the organic phase to 120°C, remove the solvent by vacuum until there is no distillate, filter at 130°C to remove solid impurities, and the filtrate is the tetramethylbiphenyl epoxy resin product.

[0035] Comparative Example 1

[0036] The difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example, diethylene glycol dibutyl ether in the ether solvent is replaced with ethylene glycol diethyl ether.

[0037] Comparative Example 2

[0038] The difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example, diethylene glycol dibutyl ether in the ether solvent is replaced with diethylene glycol methyl ethyl ether.

[0039] Comparative Example 3

[0040] The difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example, diethylene glycol dibutyl ether in the ether solvent is replaced with dipropylene glycol dimethyl ether.

[0041] Comparative Example 4

[0042] The difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example, isobutoxycyclohexane in the ether solvent is replaced with butyl ether.

[0043] Comparative Example 5

[0044] The difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example, isobutoxycyclohexane in the ether solvent is replaced with octyl ether.

[0045] Comparative Example 6

[0046] The difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example, isobutoxycyclohexane in the ether solvent is replaced with cyclohexyl methyl ether.

[0047] Comparative Example 7

[0048] The only difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that the ether solvent in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example is composed of diethylene glycol dibutyl ether and isobutoxycyclohexane, and the mass ratio of diethylene glycol dibutyl ether to isobutoxycyclohexane is 5.36:2.14.

[0049] Comparative Example 8

[0050] The only difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that the ether solvent in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example is composed of diethylene glycol dibutyl ether and triethylglycerol ether, and the mass ratio of diethylene glycol dibutyl ether to triethylglycerol ether is 6.8:0.7.

[0051] Comparative Example 9

[0052] The only difference between the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example and the synthesis method of the tetramethylbiphenyl epoxy resin in Example 1 is that the ether solvent in step (1) of the synthesis method of the tetramethylbiphenyl epoxy resin in this comparative example is composed of isobutoxycyclohexane and triethylglycerol ether, and the mass ratio of isobutoxycyclohexane to triethylglycerol ether is 6:1.5.

[0053] Comparative Example 10

[0054] The method for synthesizing the tetramethylbiphenyl-type epoxy resin of this comparative example includes the following steps:

[0055] (1) Add tetramethylbiphenyl and epichlorohydrin in a mass ratio of 218:508 to the reactor, heat to 60°C, and then add sodium hydroxide solution with a mass fraction of 50% as an alkaline catalyst. The amount of sodium hydroxide solution added is 5% of the mass of tetramethylbiphenyl. Control the temperature of the material in the reactor to 60°C, stir the reaction for 5 hours, and complete the etherification reaction.

[0056] Then, the temperature inside the reactor was controlled at 60℃, and the reactor was evacuated to 10kPa to perform vacuum dehydration on the material inside the reactor. After dehydration, the vacuum inside the reactor was maintained, and the temperature of the material inside the reactor was controlled at 70℃. A 50% sodium hydroxide solution (the amount of sodium hydroxide solution added was 70% of the mass of tetramethylbiphenyl) was added dropwise to the reactor at a dropping rate of 1.2g / min. After the addition was completed, the reaction was stirred for 0.5h under the conditions of 10kPa pressure and 70℃. The water and a small amount of epichlorohydrin and ether solvents generated during the reaction were distilled off under low pressure. The distilled water was separated, and the organic phase was refluxed back to the reactor. After the stirring reaction was completed, the vacuum inside the reactor was maintained at 10kPa, and the temperature was raised to 150℃ to remove excess epichlorohydrin and ether solvents from the reactor. After cooling to room temperature, the crude epoxy resin product was obtained.

[0057] (2) This step is the same as step (2) in Example 1.

[0058] Experimental Example

[0059] To evaluate the quality of the tetramethylbiphenyl epoxy resins prepared by the synthesis methods of the various embodiments and comparative examples, the yield of the tetramethylbiphenyl epoxy resins was calculated based on the mass of tetramethylbiphenyl and the mass of the finished tetramethylbiphenyl epoxy resin. The total chlorine content of the finished tetramethylbiphenyl epoxy resin was tested according to the standard GB / T 12007.3-1989 "Determination of Total Chlorine Content in Epoxy Resins". Finally, the epoxy equivalent and melting point of the finished tetramethylbiphenyl epoxy resin were tested, and the results are shown in Table 1.

[0060] Table 1. Total chlorine content of epoxy resins synthesized in each example and comparative example.

[0061] Synthesis method Yield (%) Total chlorine content (ppm) Epoxy equivalent (g / mol) Melting point (°C) Example 1 94.7 215 188.2 101.5 Example 2 94.6 231 187.7 101.3 Example 3 94.9 224 186.5 100.8 Comparative Example 1 79.4 1108 190.2 102.7 Comparative Example 2 81.7 1051 189.7 102.1 Comparative Example 3 92.4 1027 189.2 101.8 Comparative Example 4 83.5 1014 192.1 103.6 Comparative Example 5 89.2 996 191.4 103.3 Comparative Example 6 92.5 985 190.2 102.5 Comparative Example 7 90.2 1102 191.6 103.4 Comparative Example 8 91.6 1083 190.8 102.9 Comparative Example 9 88.7 1077 191.1 103.1 Comparative Example 10 90.8 1850 203.4 107.6

[0062] According to the test results in Table 1, the tetramethylbiphenyl epoxy resin synthesized in Examples 1-3 of this invention has a yield greater than 94% and a total chlorine content less than 240 ppm, showing higher yield and lower total chlorine content compared to the synthesis methods of Comparative Examples 1-10. This is because this invention employs a two-step reaction process, and a mixed ether solvent composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether is added during the etherification reaction stage. While diethylene glycol dibutyl ether and isobutoxycyclohexane are slightly soluble in water, and triethylglycerol ether is insoluble in water, all three solvents have good solubility for epichlorohydrin and phenolic compounds. The combined use of these three solvents forms a transition phase, promoting a more uniform migration of the alkaline catalyst in the aqueous phase to the two-phase interface to participate in the reaction. This promotes the stable progress of the etherification and ring-closing reactions, avoids side reactions, and thus improves product yield and purity while reducing total chlorine content.

[0063] As shown in Example 1 and Comparative Examples 1-6, when diethylene glycol dibutyl ether in the ether solvent is replaced with diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, or dipropylene glycol dimethyl ether, or when isobutoxycyclohexane is replaced with butyl ether, octyl ether, or cyclohexyl methyl ether, the yield of the synthesized tetramethylbiphenyl epoxy resin decreases and the total chlorine content increases. This proves that the combination of diethylene glycol dibutyl ether and isobutoxycyclohexane has the best effect. When the two are used together, the resulting mixed solvent can better promote the catalytic effect of the alkaline catalyst on tetramethylbiphenyl and epichlorohydrin, reduce side reactions, and improve product quality.

[0064] As can be seen from Example 1 and Comparative Examples 7-9, only by using a mixed ether solvent composed of diethylene glycol dibutyl ether (slightly soluble in water), isobutoxycyclohexane, and triethylglycerol ether (insoluble in water) can the high yield and low total chlorine content of tetramethylbiphenyl epoxy resin be achieved. This proves that the three ether solvents each play different roles, and the best results can be achieved by using the three ether solvents simultaneously.

Claims

1. A method for synthesizing a tetramethylbiphenyl-type epoxy resin, characterized in that, Includes the following steps: First, tetramethylbiphenyl and epichlorohydrin undergo a ring-opening etherification reaction in an ether solvent under the catalysis of an alkali metal hydroxide solution. Then, the water generated in the reaction is removed, and a ring-closing reaction is carried out after adding an alkali metal hydroxide solution. After purification, a tetramethylbiphenyl-type epoxy resin is obtained. The ether solvent is composed of diethylene glycol dibutyl ether, isobutoxycyclohexane, and triethylglycerol ether, with a mass ratio of 5~8:2~3:0.5~1. The mass ratio of tetramethylbiphenyl, epichlorohydrin, and the ether solvent is 218:508~550:190~240.

2. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 1, characterized in that, The mass fraction of the alkali metal hydroxide solution used in the ring-opening etherification reaction is 50%~55%.

3. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 2, characterized in that, The amount of alkali metal hydroxide solution added during the ring-opening etherification reaction is 3-10% of the mass of tetramethylbiphenyl.

4. The method for synthesizing the tetramethylbiphenyl-type epoxy resin according to any one of claims 1-3, characterized in that, The ring-opening etherification reaction is carried out at a temperature of 60-90℃ for 2-5 hours.

5. The method for synthesizing the tetramethylbiphenyl-type epoxy resin according to any one of claims 1-3, characterized in that, The removal of water generated after the ring-opening etherification reaction is carried out at a temperature of 60~90℃ and a pressure of 5~20kPa.

6. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 1, characterized in that, The mass fraction of the alkali metal hydroxide solution used in the closed-loop reaction is 50%~55%.

7. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 6, characterized in that, The amount of alkali metal hydroxide solution added during the ring-closing reaction is 50% to 70% of the mass of tetramethylbiphenyl.

8. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 1, characterized in that, The alkali metal hydroxide solution used in the closed-loop reaction was added dropwise at a rate of 0.8~1.2 g / min.

9. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 1, characterized in that, The closed-loop reaction is carried out at a temperature of 50~80℃ for 0.5~1h.

10. The method for synthesizing tetramethylbiphenyl-type epoxy resin as described in claim 1, characterized in that, The purification method is as follows: The crude epoxy resin product obtained by the closed-ring reaction is extracted with organic solvent and water. Then, the extracted organic phase and sodium hydroxide solution are heated and mixed until the hydrolytic chlorine content of the crude epoxy resin product is no more than 100 ppm. Water is then added for extraction. The extracted organic phase is then distilled under reduced pressure and filtered to obtain tetramethylbiphenyl-type epoxy resin.

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