A method for synthesizing p-aminophenol type epoxy resin

Abstract

This invention relates to a method for synthesizing p-aminophenol type epoxy resin, belonging to the field of epoxy resin preparation technology. By adding n-butanol and / or cyclopentyl methyl ether to the reaction system, this invention can effectively reduce the total chlorine content of the p-aminophenol type epoxy resin product and improve its purity. The total chlorine content of the p-aminophenol type epoxy resin synthesized by this invention is less than 500 ppm. In this invention, n-butanol and cyclopentyl methyl ether are slightly soluble in water. During the cyclization reaction stage, when sodium hydroxide solution is used as a catalyst, n-butanol and cyclopentyl methyl ether can form a transition phase, promoting the uniform migration of sodium hydroxide from the aqueous phase to the interface between the two phases to participate in the reaction. This promotes the stable progress of the cyclization reaction, reduces the occurrence of side reactions, thereby reducing the total chlorine content of the p-aminophenol type epoxy resin and improving the synthesis yield of the p-aminophenol type epoxy resin.

Description

Technical Field

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

[0002] In the electromechanical and electronics industries, epoxy resin has been widely used as a basic insulating material. With increasingly stringent requirements for environmental resistance, reliability, and lifespan, the performance of conventional bisphenol A type epoxy resins can no longer meet these demands. Therefore, new types of epoxy resins have emerged, such as p-aminophenol type epoxy resins. Initially named AFG-90 epoxy resin, p-aminophenol type epoxy resin is synthesized by reacting p-aminophenol with epichlorohydrin and is a reddish-brown liquid resin. It possesses three epoxy functional groups. Due to the large number of epoxy functional groups, this epoxy resin exhibits high reactivity, rapid and exothermic reaction during curing, and also features excellent heat resistance and low viscosity. Furthermore, the presence of tertiary amines improves the resin's flexibility and adhesion, making it primarily used in electronic adhesives, composite materials, and copper-clad laminates.

[0003] Currently, p-aminophenol-type epoxy resins are synthesized using p-aminophenol and excess epichlorohydrin as raw materials. The synthesis process includes etherification and cyclization reactions. During the synthesis, excess epichlorohydrin serves as both a solvent and a reactant. The cyclization reaction is usually carried out under alkaline catalysis. Under alkaline conditions, epichlorohydrin is prone to hydrolysis side reactions, generating impurities such as glycerol. Moreover, the alkali metal hydroxides in the alkaline solution have poor solubility in the epichlorohydrin solvent, resulting in slow and unstable migration of alkali metal hydroxides from the aqueous phase to the epichlorohydrin. This leads to numerous side reactions during the cyclization reaction, resulting in a high total chlorine content in the product, which in turn affects the final performance of the product. Summary of the Invention

[0004] The purpose of this invention is to provide a method for synthesizing p-aminophenol type epoxy resin, so as to solve the problem of high total chlorine content in the product when using p-aminophenol and excess epichlorohydrin as raw materials to synthesize p-aminophenol type epoxy resin.

[0005] This invention provides a method for synthesizing p-aminophenol type epoxy resin, comprising the following steps: firstly, p-aminophenol and epichlorohydrin are subjected to an etherification reaction in the presence of an organic solvent; then, an alkali metal hydroxide solution is added to the etherified system to carry out a cyclization reaction to obtain p-aminophenol type epoxy resin; wherein the organic solvent is n-butanol and / or cyclopentyl methyl ether; and the mass of the organic solvent is 1-5% of the mass of epichlorohydrin.

[0006] Preferably, the mass of the organic solvent is 4-5% of the mass of epichlorohydrin.

[0007] Preferably, the organic solvent is composed of n-butanol and cyclopentyl methyl ether, and the mass ratio of n-butanol to cyclopentyl methyl ether is 1~5:1.

[0008] Preferably, the mass of the p-aminophenol is 10-20% of the mass of epichlorohydrin.

[0009] Preferably, the etherification reaction is carried out at a temperature of 40~80°C.

[0010] Preferably, the method for etherification reaction of p-aminophenol and epichlorohydrin in the presence of an organic solvent is as follows: epichlorohydrin and organic solvent are mixed and heated to 40-80°C, then p-aminophenol is added and the mixture is reacted; the p-aminophenol is added in batches and the reaction time is 1-3 hours.

[0011] Preferably, the p-aminophenol is added in 8 to 10 batches over 3 to 5 hours, with each batch containing the same amount and the same time interval between adjacent batches.

[0012] Preferably, the alkali metal hydroxide solution is a sodium hydroxide solution, the mass fraction of the sodium hydroxide solution is 50-55%, the mass of the sodium hydroxide solution is 1.8-2.4 times the mass of p-aminophenol, and the dropping rate of the sodium hydroxide solution is 1-3 g / min.

[0013] Preferably, the cyclization reaction is carried out at a temperature of 40~70℃ for 1~2 hours and at a pressure of 10~12 kPa.

[0014] Preferably, the method for synthesizing p-aminophenol type epoxy resin further includes the following steps: after the cyclization reaction is completed, the reaction system is subjected to vacuum distillation to remove the water, excess epichlorohydrin and organic solvent generated in the reaction, to obtain a crude product of p-aminophenol type epoxy resin, and then the crude product of p-aminophenol type epoxy resin is purified to obtain a finished product of p-aminophenol type epoxy resin.

[0015] Preferably, the refining method is as follows: the crude product of p-aminophenol type epoxy resin is dissolved in an organic solvent, and then sodium hydroxide solution is added and heated and mixed until the hydrolyzed chlorine content of the crude product of p-aminophenol type epoxy resin is not greater than 1000 ppm. Then water is added for extraction, and the organic phase obtained by extraction is subjected to vacuum distillation. After filtration at 80~100℃, the finished product of p-aminophenol type epoxy resin is obtained.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention effectively reduces the total chlorine content and improves the purity of p-aminophenol-type epoxy resin products by adding n-butanol and / or cyclopentyl methyl ether to the reaction system. The epoxy equivalent of the p-aminophenol-type epoxy resin synthesized by this invention is 108~118 g / mol, and the total chlorine content is less than 500 ppm. In this invention, n-butanol and cyclopentyl methyl ether are slightly soluble in water. During the cyclization reaction stage, when sodium hydroxide solution is used as a catalyst, n-butanol and cyclopentyl methyl ether can form a transition phase, promoting the uniform migration of sodium hydroxide in the aqueous phase to the interface between the two phases to participate in the reaction, promoting the stable progress of the cyclization reaction, reducing the occurrence of side reactions, thereby reducing the total chlorine content of the p-aminophenol-type epoxy resin and improving the synthesis yield of the p-aminophenol-type epoxy resin. 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] Example 1

[0020] The method for synthesizing p-aminophenol type epoxy resin in this embodiment includes the following steps:

[0021] (1) Add 1 kg of epichlorohydrin to the reactor, heat to 60°C, then add an organic solvent (n-butanol), the amount added is 4% of the mass of epichlorohydrin, stir evenly, adjust the temperature of the material in the reactor to 70°C, then add p-aminophenol to the reactor in batches (the total amount of p-aminophenol added is 20% of the mass of epichlorohydrin, p-aminophenol is added in 10 batches within 3 hours, each batch is equal in amount, and the time interval between adjacent batches is the same), while controlling the temperature of the material in the reactor to 70°C, after the p-aminophenol is added, continue stirring and react for 3 hours to complete the etherification reaction; after the etherification reaction is completed, adjust the temperature of the material in the reactor to 5°C. At 5℃, a 50% sodium hydroxide solution (1.8 times the mass of p-aminophenol) was added dropwise to the reactor. The dropwise rate of the sodium hydroxide solution was 3 g / min. After the addition was completed, the reactor was evacuated, and the material in the reactor was stirred and reacted at a constant temperature for 1 hour under a vacuum of 10 kPa to complete the cyclization reaction. The water produced during the cyclization reaction was removed under vacuum conditions, and the epichlorohydrin was refluxed back to the reactor. After the cyclization reaction was completed, the system was heated to 80℃ to continue removing the water produced during the reaction. Finally, the temperature was raised to 110℃ to remove the remaining epichlorohydrin and organic solvent, yielding the crude product of p-aminophenol type epoxy resin.

[0022] (2) Add toluene (the mass of toluene is 1.5 times the mass of p-aminophenol) to the reactor and stir until the crude p-aminophenol epoxy resin is fully dissolved. Then add 20% sodium hydroxide solution to the reactor, the amount of which is 3% of the mass of p-aminophenol. Heat to 70°C and stir until the hydrolyzed chlorine content of the crude p-aminophenol epoxy resin is 90 ppm. Cool to room temperature and add deionized water (the mass ratio of deionized water to p-aminophenol is 2:1). Stir evenly and let stand to separate the layers. Separate the organic phase. Heat the organic phase to 100°C and remove the solvent by vacuum until there is no distillate. Filter at 90°C to remove solid impurities. The filtrate is the finished p-aminophenol epoxy resin.

[0023] Example 2

[0024] The method for synthesizing p-aminophenol type epoxy resin in this embodiment includes the following steps:

[0025] (1) Add 1 kg of epichlorohydrin to the reactor and heat it to 60°C. Then add an organic solvent (cyclopentyl methyl ether) at a rate of 4% of the mass of epichlorohydrin. After stirring evenly, adjust the temperature of the material in the reactor to 70°C. Then add p-aminophenol to the reactor in batches (the total amount of p-aminophenol added is 20% of the mass of epichlorohydrin. The p-aminophenol is added in 10 batches within 3 hours, with each batch having an equal amount and the same time interval between adjacent batches). At the same time, control the temperature of the material in the reactor to 70°C. After the p-aminophenol is added, continue stirring for 3 hours to complete the etherification reaction. After the etherification reaction is completed, adjust the temperature of the material in the reactor to 70°C. At 55℃, a 50% sodium hydroxide solution (1.8 times the mass of p-aminophenol) was added dropwise to the reactor. The dropwise rate of the sodium hydroxide solution was 3 g / min. After the addition was completed, the reactor was evacuated, and the material in the reactor was stirred and reacted at a constant temperature for 1 hour under a vacuum of 10 kPa to complete the cyclization reaction. The water produced during the cyclization reaction was removed under vacuum conditions, and the epichlorohydrin was refluxed back to the reactor. After the cyclization reaction was completed, the system was heated to 80℃ to continue removing the water produced during the reaction. Finally, the temperature was raised to 110℃ to remove the remaining epichlorohydrin and organic solvent, yielding the crude product of p-aminophenol type epoxy resin.

[0026] (2) Add toluene (the mass of toluene is 1.5 times the mass of p-aminophenol) to the reactor and stir until the crude p-aminophenol epoxy resin is fully dissolved. Then add 20% sodium hydroxide solution to the reactor, the amount of which is 3% of the mass of p-aminophenol. Heat to 70°C and stir until the hydrolyzed chlorine content of the crude p-aminophenol epoxy resin is 90 ppm. Cool to room temperature and add deionized water (the mass ratio of deionized water to p-aminophenol is 2:1). Stir evenly and let stand to separate the layers. Separate the organic phase. Heat the organic phase to 100°C and remove the solvent by vacuum until there is no distillate. Filter at 90°C to remove solid impurities. The filtrate is the finished p-aminophenol epoxy resin.

[0027] Example 3

[0028] The method for synthesizing p-aminophenol type epoxy resin in this embodiment includes the following steps:

[0029] (1) Add 1 kg of epichlorohydrin to the reactor and heat it to 60°C. Then add an organic solvent (composed of n-butanol and cyclopentyl methyl ether in a mass ratio of 3:1), the amount added being 4% of the mass of epichlorohydrin. After stirring evenly, adjust the temperature of the material in the reactor to 70°C. Then add p-aminophenol to the reactor in batches (the total amount of p-aminophenol added is 20% of the mass of epichlorohydrin, and p-aminophenol is added in 10 batches within 3 hours, with each batch having an equal amount and the same time interval between adjacent batches). At the same time, control the temperature of the material in the reactor to 70°C. After the p-aminophenol is added, continue stirring for 3 hours to complete the etherification reaction. After the etherification reaction is completed, remove the contents of the reactor. The temperature of the material was adjusted to 55℃, and then a 50% sodium hydroxide solution was added dropwise to the reactor (the amount of sodium hydroxide solution added was 1.8 times the mass of p-aminophenol, and the dropping rate of the sodium hydroxide solution was 3 g / min). After the addition was completed, the reactor was evacuated, and the material in the reactor was stirred and reacted at a constant temperature for 1 hour under a vacuum of 10 kPa to complete the cyclization reaction. The water produced during the cyclization reaction was removed under vacuum conditions, and the epichlorohydrin was refluxed back to the reactor. After the cyclization reaction was completed, the temperature of the reaction system was raised to 80℃ to continue removing the water produced during the reaction. Finally, the temperature was raised to 110℃ to remove the remaining epichlorohydrin and organic solvent, and the crude product of p-aminophenol type epoxy resin was obtained.

[0030] (2) Add toluene (the mass of toluene is 1.5 times the mass of p-aminophenol) to the reactor and stir until the crude p-aminophenol epoxy resin is fully dissolved. Then add 20% sodium hydroxide solution to the reactor, the amount of which is 3% of the mass of p-aminophenol. Heat to 70°C and stir until the hydrolyzed chlorine content of the crude p-aminophenol epoxy resin is 90 ppm. Cool to room temperature and add deionized water (the mass ratio of deionized water to p-aminophenol is 2:1). Stir evenly and let stand to separate the layers. Separate the organic phase. Heat the organic phase to 100°C and remove the solvent by vacuum until there is no distillate. Filter at 90°C to remove solid impurities. The filtrate is the finished p-aminophenol epoxy resin.

[0031] Example 4

[0032] The method for synthesizing p-aminophenol type epoxy resin in this embodiment includes the following steps:

[0033] (1) Add 1 kg of epichlorohydrin to the reactor and heat it to 60°C. Then add an organic solvent (composed of n-butanol and cyclopentyl methyl ether in a mass ratio of 1:1), the amount added being 4% of the mass of epichlorohydrin. After stirring evenly, adjust the temperature of the material in the reactor to 70°C. Then add p-aminophenol to the reactor in batches (the total amount of p-aminophenol added is 20% of the mass of epichlorohydrin. The p-aminophenol is added in 10 batches within 3 hours, with each batch having an equal amount and the same time interval between adjacent batches). At the same time, control the temperature of the material in the reactor to 70°C. After the p-aminophenol is added, continue stirring for 3 hours to complete the etherification reaction. After the etherification reaction is completed, remove the contents of the reactor. The temperature of the material was adjusted to 55℃, and then a 50% sodium hydroxide solution was added dropwise to the reactor (the amount of sodium hydroxide solution added was 1.8 times the mass of p-aminophenol, and the dropping rate of the sodium hydroxide solution was 3 g / min). After the addition was completed, the reactor was evacuated, and the material in the reactor was stirred and reacted at a constant temperature for 1 hour under a vacuum of 10 kPa to complete the cyclization reaction. The water produced during the cyclization reaction was removed under vacuum conditions, and the epichlorohydrin was refluxed back to the reactor. After the cyclization reaction was completed, the temperature of the reaction system was raised to 80℃ to continue removing the water produced during the reaction. Finally, the temperature was raised to 110℃ to remove the remaining epichlorohydrin and organic solvent, and the crude product of p-aminophenol type epoxy resin was obtained.

[0034] (2) Add toluene (the mass of toluene is 1.5 times the mass of p-aminophenol) to the reactor and stir until the crude p-aminophenol epoxy resin is fully dissolved. Then add 20% sodium hydroxide solution to the reactor, the amount of which is 3% of the mass of p-aminophenol. Heat to 70°C and stir until the hydrolyzed chlorine content of the crude p-aminophenol epoxy resin is 90 ppm. Cool to room temperature and add deionized water (the mass ratio of deionized water to p-aminophenol is 2:1). Stir evenly and let stand to separate the layers. Separate the organic phase. Heat the organic phase to 100°C and remove the solvent by vacuum until there is no distillate. Filter at 90°C to remove solid impurities. The filtrate is the finished p-aminophenol epoxy resin.

[0035] Example 5

[0036] The method for synthesizing p-aminophenol type epoxy resin in this embodiment includes the following steps:

[0037] (1) Add 1 kg of epichlorohydrin to the reactor and heat it to 60°C. Then add an organic solvent (composed of n-butanol and cyclopentyl methyl ether in a mass ratio of 5:1), the amount added being 4% of the mass of epichlorohydrin. After stirring evenly, adjust the temperature of the material in the reactor to 70°C. Then add p-aminophenol to the reactor in batches (the total amount of p-aminophenol added is 20% of the mass of epichlorohydrin. The p-aminophenol is added in 10 batches within 3 hours, with each batch having an equal amount and the same time interval between adjacent batches). At the same time, control the temperature of the material in the reactor to 70°C. After the p-aminophenol is added, continue stirring for 3 hours to complete the etherification reaction. After the etherification reaction is completed, remove the contents of the reactor. The temperature of the material was adjusted to 55℃, and then a 50% sodium hydroxide solution was added dropwise to the reactor (the amount of sodium hydroxide solution added was 1.8 times the mass of p-aminophenol, and the dropping rate of the sodium hydroxide solution was 3 g / min). After the addition was completed, the reactor was evacuated, and the material in the reactor was stirred and reacted at a constant temperature for 1 hour under a vacuum of 10 kPa to complete the cyclization reaction. The water produced during the cyclization reaction was removed under vacuum conditions, and the epichlorohydrin was refluxed back to the reactor. After the cyclization reaction was completed, the temperature of the reaction system was raised to 80℃ to continue removing the water produced during the reaction. Finally, the temperature was raised to 110℃ to remove the remaining epichlorohydrin and organic solvent, and the crude product of p-aminophenol type epoxy resin was obtained.

[0038] (2) Add toluene (the mass of toluene is 1.5 times the mass of p-aminophenol) to the reactor and stir until the crude p-aminophenol epoxy resin is fully dissolved. Then add 20% sodium hydroxide solution to the reactor, the amount of which is 3% of the mass of p-aminophenol. Heat to 70°C and stir until the hydrolyzed chlorine content of the crude p-aminophenol epoxy resin is 90 ppm. Cool to room temperature and add deionized water (the mass ratio of deionized water to p-aminophenol is 2:1). Stir evenly and let stand to separate the layers. Separate the organic phase. Heat the organic phase to 100°C and remove the solvent by vacuum until there is no distillate. Filter at 90°C to remove solid impurities. The filtrate is the finished p-aminophenol epoxy resin.

[0039] Comparative Example 1

[0040] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the amount of organic solvent added in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is 0.

[0041] Comparative Example 2

[0042] The difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the amount of organic solvent added in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is 0.5% of the mass of epichlorohydrin.

[0043] Comparative Example 3

[0044] The difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the amount of organic solvent added in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is 10% of the mass of epichlorohydrin.

[0045] Comparative Example 4

[0046] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the organic solvent in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is n-propanol.

[0047] Comparative Example 5

[0048] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the organic solvent in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is n-pentanol.

[0049] Comparative Example 6

[0050] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the organic solvent in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is isobutanol.

[0051] Comparative Example 7

[0052] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 1 is that the organic solvent in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is sec-butanol.

[0053] Comparative Example 8

[0054] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 2 is that the organic solvent in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is cyclohexyl methyl ether.

[0055] Comparative Example 9

[0056] The only difference between the synthesis method of the p-aminophenol type epoxy resin in this comparative example and the synthesis method of the p-aminophenol type epoxy resin in Example 2 is that the organic solvent in step (1) of the synthesis method of the p-aminophenol type epoxy resin in this comparative example is n-pentyl methyl ether.

[0057] Experimental Example

[0058] To examine the efficiency of the synthesis methods for p-aminophenol-type epoxy resins in each embodiment and comparative example, as well as the basic properties of the prepared p-aminophenol-type epoxy resins, the yield of the synthesis methods was calculated based on the mass of p-aminophenol used in the synthesis and the mass of the finished p-aminophenol-type epoxy resin. The epoxy equivalent and total chlorine content of the synthesized p-aminophenol-type epoxy resins were also tested, and the results are shown in Table 1. The total chlorine content was tested according to the specifications in standard GB / T 12007.3-1989, "Determination of Total Chlorine Content in Epoxy Resins".

[0059] Table 1. Epoxy equivalent and total chlorine content of p-aminophenol type epoxy resin

[0060] Synthesis method Yield (%) Epoxy equivalent (g / mol) Total chlorine content (ppm) Example 1 89.3 116.3 447 Example 2 89.6 117.7 496 Example 3 94.2 108.2 182 Example 4 93.1 109.1 271 Example 5 93.7 110.3 215 Comparative Example 1 80.2 129.8 2164 Comparative Example 2 82.3 123.4 1408 Comparative Example 3 91.2 119.6 1150 Comparative Example 4 84.6 124.2 837 Comparative Example 5 85.7 125.0 1092 Comparative Example 6 86.2 122.4 795 Comparative Example 7 87.1 123.5 926 Comparative Example 8 85.9 125.7 1196 Comparative Example 9 84.8 124.4 1084

[0061] According to the test results in Table 1, the epoxy equivalent of the p-aminophenol type epoxy resin synthesized in Examples 1-5 of this invention is 108~118 g / mol, and the total chlorine content is less than 500 ppm. This result demonstrates that adding n-butanol and / or cyclopentyl methyl ether to the reaction system can effectively reduce the total chlorine content of the product. This is because n-butanol and cyclopentyl methyl ether are slightly soluble in water. During the cyclization reaction stage, when sodium hydroxide solution is used as a catalyst, a transition phase can be formed, promoting the uniform migration of sodium hydroxide from the aqueous phase to the interface between the two phases to participate in the reaction. This promotes the stable progress of the cyclization reaction, reduces the occurrence of side reactions, thereby reducing the total chlorine content of the p-aminophenol type epoxy resin and increasing the product yield.

[0062] As can be seen from Example 1 and Comparative Examples 1-3, when n-butanol and / or cyclopentyl methyl ether are not added to the reaction system, the total chlorine content of the product increases significantly, and the total chlorine content of the p-aminophenol type epoxy resin shows a trend of first decreasing and then increasing with the increase of n-butanol dosage.

[0063] As can be seen from Example 1 and Comparative Examples 4-7, when n-butanol is replaced with n-propanol, n-pentanol, isobutanol or sec-butanol, the boiling point or water solubility of the alcohol solvent may change, which may lead to a decrease in reaction stability and the stability of sodium hydroxide migration to the two-phase interface, resulting in an increase in side reactions and a higher total chlorine content in the product.

[0064] As can be seen from Example 2 and Comparative Examples 8-9, when cyclopentyl methyl ether is replaced with cyclohexyl methyl ether or n-pentyl methyl ether, the reaction stability and the stability of sodium hydroxide migration to the two-phase interface decrease due to the change in the boiling point or water solubility of the ether solvent, resulting in a higher total chlorine content in the product.

Claims

1. A method for synthesizing a p-aminophenol-type epoxy resin, characterized by, Includes the following steps: First, p-aminophenol and epichlorohydrin are etherified in the presence of an organic solvent. Then, an alkali metal hydroxide solution is added to the etherified system to induce a cyclization reaction, yielding a p-aminophenol-type epoxy resin. The organic solvent is cyclopentyl methyl ether or a mixture of n-butanol and cyclopentyl methyl ether, with a mass ratio of 1-5:

1. The mass of the organic solvent is 4-5% of the mass of epichlorohydrin. The method for etherifying p-aminophenol and epichlorohydrin in the presence of an organic solvent is as follows: epichlorohydrin and the organic solvent are mixed and heated to 40-80°C, then p-aminophenol is added, followed by a mixing reaction. The p-aminophenol is added in batches, and the mixing reaction takes 1-3 hours. The alkali metal hydroxide solution is a sodium hydroxide solution with a mass fraction of 50-55%, and the mass of the sodium hydroxide solution is 1.8-2.4 times the mass of p-aminophenol. The dropping rate of the sodium hydroxide solution is 1-3 g / min.

2. The method for synthesizing p-aminophenol type epoxy resin according to claim 1, characterized in that, The mass of the p-aminophenol is 10-20% of the mass of epichlorohydrin.

3. The method for synthesizing p-aminophenol type epoxy resin according to claim 1, characterized in that, The cyclization reaction is carried out at a temperature of 40~70℃ for 1~2 hours and at a pressure of 10~12 kPa.

4. The method for synthesizing p-aminophenol type epoxy resin according to claim 1, characterized in that, The method for synthesizing p-aminophenol type epoxy resin further includes the following steps: after the cyclization reaction is completed, the reaction system is subjected to vacuum distillation to remove the water, excess epichlorohydrin and organic solvent produced in the reaction, to obtain a crude product of p-aminophenol type epoxy resin, and then the crude product of p-aminophenol type epoxy resin is purified to obtain a finished product of p-aminophenol type epoxy resin.

5. The method for synthesizing p-aminophenol type epoxy resin according to claim 4, characterized in that, The refining method is as follows: the crude product of p-aminophenol type epoxy resin is dissolved in an organic solvent, and then sodium hydroxide solution is added and heated and mixed until the hydrolyzed chlorine content of the crude product of p-aminophenol type epoxy resin is not greater than 1000 ppm. Then water is added for extraction. The organic phase obtained by extraction is then subjected to vacuum distillation and filtered at 80~100℃ to obtain the finished p-aminophenol type epoxy resin.