Synthesis method of low-total-chlorine epoxy resin

Abstract

The invention relates to a low-total-chlorine epoxy resin synthesis method, and belongs to the technical field of epoxy resin preparation. The invention provides a low-total-chlorine epoxy resin synthesis method. The low-total-chlorine epoxy resin synthesis method comprises the following steps: carrying out ring-opening reaction on a dihydric phenol compound and epoxy chloropropane in a mixed organic solvent under the action of alkali metal hydroxide; the mixed organic solvent is composed of a ketone solvent and an ether solvent, the ketone solvent is diisobutyl ketone, and the ether solvent is butyl ether and / or a branched ether compound; then carrying out mixed reaction on the system after the ring-opening reaction and an alkali metal hydroxide solution so as to carry out ring-closing reaction on a ring-opening reaction product; and finally, carrying out impurity removal and purification on the system after the ring-closure reaction to obtain the low-total-chlorine epoxy resin.

Description

Technical Field

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

[0002] Epoxy resin has excellent physical, mechanical, and electrical insulation properties, good adhesion to various materials, and flexibility in its application processes; therefore, it can be applied to industries such as coatings, composite materials, electronic packaging, casting materials, adhesives, molding materials, and injection molding materials, and is widely used in various sectors of the national economy.

[0003] In industries such as electronic and electrical packaging, excessive chlorine content in epoxy resin can affect the electrical properties, corrosion resistance, and heat resistance of the cured resin, leading to a decrease in the reliability of electronic components.

[0004] The total chlorine in epoxy resin includes inorganic chlorine and organic chlorine, with inorganic chlorine mainly composed of Cl. - Inorganic chlorine exists in the resin, and its content can be reduced by washing with water. Organic chlorine, however, exists as functional groups within organic molecules. Organic chlorine includes both active and inactive chlorine. Active chlorine content can be reduced by alkali purification, while inactive chlorine content cannot be reduced by alkali purification because it mainly exists in byproducts generated during the reaction. Therefore, reducing total chlorine content primarily involves reducing inactive chlorine content, which is only present in byproducts. Reducing byproducts during the reaction effectively controls the total chlorine content. Taking bisphenol A type epoxy resin as an example, the structure of the bisphenol A type epoxy resin monomer is as follows... Figure 1 As shown, the active and non-active chlorine produced in the synthesis of bisphenol A type epoxy resin are as follows: Figure 2 As shown.

[0005] However, the total chlorine content in currently prepared epoxy resins is relatively high, typically around 1600 ppm, requiring rigorous impurity removal and purification processes to prepare low-total-chlorine epoxy resins. Therefore, it is necessary to provide a method for synthesizing low-total-chlorine epoxy resins. Summary of the Invention

[0006] The purpose of this invention is to provide a method for synthesizing low-total-chlorine epoxy resin, in order to solve the problem that the currently prepared bisphenol A type epoxy resin has a high total chlorine content due to excessive by-products.

[0007] This invention provides a method for synthesizing low-total-chlorine epoxy resin, comprising the following steps: (1) the binary phenolic compound and the epichlorohydrin are subjected to ring-opening reaction in the presence of alkali metal hydroxide in a mixed organic solvent; the mixed organic solvent is composed of ketone solvent and ether solvent with a mass ratio of 0.5-1:0.5-1, the ketone solvent is diisobutyl ketone, and the ether solvent is butyl ether or is composed of butyl ether and branched ether compound with a mass ratio of 1:0.15-0.3, and the branched ether compound has the following chemical structure: ; (2) the ring-opening reaction product is subjected to ring-closing reaction by mixing the ring-opening reaction system with an alkali metal hydroxide solution; (3) the ring-closing reaction system is subjected to impurity removal and purification to obtain the low total chlorine type epoxy resin.

[0008] Preferably, the mass ratio of the diisobutyl ketone and the epichlorohydrin is 0.2-0.4:1.

[0009] Preferably, the molar ratio of the binary phenolic compound and the epichlorohydrin is 1:4-9.

[0010] Preferably, in step (1), the molar ratio of the binary phenolic compound and the alkali metal hydroxide is 1:0.005-0.10; the ring-opening reaction temperature is 40-80℃, and the reaction time is 1-6h.

[0011] Preferably, the molar ratio of the alkali metal hydroxide in the alkali metal hydroxide solution to the binary phenolic compound is 1-2.5:1.

[0012] Preferably, the mixing reaction of the ring-opening reaction system and the alkali metal hydroxide solution is carried out under a vacuum degree of 5-30kpa.

[0013] Preferably, the binary phenolic compound is bisphenol A, and the alkali metal hydroxide is sodium hydroxide.

[0014] Preferably, the method for removing impurities and purifying the ring-closing reaction system is as follows: the ring-closing reaction system is subjected to vacuum distillation to remove the epichlorohydrin and the mixed organic solvent, and then the crude product is obtained, and then the crude product is subjected to hydrolysis chlorine removal to obtain the low total chlorine type epoxy resin.

[0015] Compared with the prior art, the present application has the following advantages: The present application adds a mixed solvent composed of a ketone solvent and an ether solvent in the process of conventional epoxy resin synthesis. When a dihydric phenolic compound and epichlorohydrin are subjected to ring-opening reaction in the mixed solvent, the mixed solvent can effectively reduce the occurrence of side reactions and improve the reaction selectivity. When the ring-opening reaction product is subjected to ring-closing reaction in the mixed solvent, the mixed solvent is slightly soluble in water, which can play a transition role between the oil phase (ring-opening reaction product) and the aqueous phase (alkali hydroxide solution), thereby promoting the chemical reaction between the two phases, reducing the generation of by-products and lowering the total chlorine content. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a chemical structure diagram of a bisphenol A type epoxy resin monomer; Figure 2 is a chemical structure diagram of active chlorine and inactive chlorine generated in the synthesis of a bisphenol A type epoxy resin; Figure 3 is a nuclear magnetic hydrogen spectrum diagram of the branched ether compound prepared in the present application. DETAILED DESCRIPTION

[0017] The following examples are intended to further illustrate the present application, but not to limit the scope of protection of the present application.

[0018] The preparation method of the branched ether compound in Examples 3-6 of the present application is as follows: a toluene solution of sodium tert-pentoxide with a mass fraction of 45% is added to a reaction kettle, dry nitrogen is then introduced into the reaction kettle, 1-bromo-2-methylpropane (the molar ratio of 1-bromo-2-methylpropane to sodium tert-pentoxide is 1.1:1) is then added to the reaction kettle, heated to 85°C, stirred for 2h, cooled to room temperature, filtered, and the filtrate is rotary evaporated to remove toluene and unreacted 1-bromo-2-methylpropane to obtain a crude product, which is purified by column chromatography with a mixed solvent of n-hexane and dichloromethane in a volume ratio of 3:1 to obtain the branched ether compound, the nuclear magnetic hydrogen spectrum diagram of which is shown in Figure 3 , and the chemical structure is as follows: .

[0019] Example 1

[0020] The synthesis method of the low total chlorine type epoxy resin of the present example comprises the following steps: (1) 228g of bisphenol A, 462.5g of epichlorohydrin, 92.5g of diisobutyl ketone and 92.5g of butyl ether are added to a reaction kettle, the temperature is stirred to 50°C until the bisphenol A is fully dissolved, then 2g of sodium hydroxide is added to the reaction kettle, and the temperature of the material in the reaction kettle is raised to 60°C, and the reaction is stirred for 1.5h. In this step, the reaction is the etherification reaction stage, i.e. the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to form a chlorohydrin intermediate.

[0021] (2) After the etherification reaction stage is completed, the temperature of the material in the reaction kettle is raised to 65°C, and 155 g of a 50% by mass sodium hydroxide solution is added dropwise into the reaction kettle, the dropwise addition time being 3.5 h. After the dropwise addition is completed, the temperature of the material in the reaction kettle is raised to 70°C, and the vacuum degree in the reaction kettle is adjusted to 10 kPa. The reaction is stirred for 0.5 h under vacuum. In this step, the reaction is a ring closure reaction, i.e., an epoxidation stage. In the reaction process, the chlorohydrin intermediate is removed of HCl to form a new epoxy group under the catalysis of sodium hydroxide. HCl and sodium hydroxide react to form sodium chloride and water. Part of the generated water and part of the excess epichlorohydrin are removed under the action of vacuum.

[0022] (3) After the ring closure reaction is completed, the vacuum degree in the reaction kettle is continuously maintained at 10 kPa, and the temperature of the material in the reaction kettle is raised to 150°C. The remaining excess epichlorohydrin, diisobutyl ketone and butyl ether are removed, and a crude epoxy resin product is obtained.

[0023] (4) 200 g of toluene is added into the reaction kettle, and the crude epoxy resin product is fully dissolved. Then, 14.1 g of a 50% by mass sodium hydroxide solution is added into the reaction kettle. The reaction is heated to 65°C and stirred. At the same time, the hydrolytic chlorine content of the epoxy resin in the reaction kettle is measured every 0.5 h until the hydrolytic chlorine content reaches 50 ppm, and the reaction is completed. A 30% by mass phosphoric acid solution is added into the reaction kettle until the pH of the material in the reaction kettle is 7. Then, 250 g of deionized water is added into the reaction kettle, and the mixture is stirred for 10 min. After standing and separation, the organic phase obtained by separation is washed with deionized water for 2 times, and the mass of deionized water used for each washing is 80 g. Finally, the washed organic phase is heated to 150°C under a vacuum degree of 10 kPa to evaporate and recover toluene until the toluene content in the product reaches 100 ppm, and a low total chlorine type epoxy resin finished product is obtained.

[0024] Example 2

[0025] The low total chlorine type epoxy resin synthesis method of the present embodiment comprises the following steps: (1) 228 g of bisphenol A, 462.5 g of epichlorohydrin, 115.6 g of diisobutyl ketone and 115.6 g of butyl ether are added into a reaction kettle. The temperature is raised to 50°C to fully dissolve the bisphenol A, and then 2 g of sodium hydroxide is added into the reaction kettle. The temperature of the material in the reaction kettle is raised to 60°C, and the reaction is stirred for 1.5 h. In this step, the reaction is an etherification reaction stage, i.e., the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0026] (2) After the etherification reaction stage is completed, the temperature of the material in the reaction kettle is raised to 65°C, and 155 g of a 50% by mass sodium hydroxide solution is added dropwise into the reaction kettle, the dropwise addition time being 3.5 h. After the dropwise addition is completed, the temperature of the material in the reaction kettle is raised to 70°C, and the vacuum degree in the reaction kettle is adjusted to 10 kPa. The reaction is stirred for 0.5 h under vacuum. In this step, the reaction is a ring closure reaction, i.e., an epoxidation stage. In the reaction process, the chlorohydrin intermediate is removed of HCl to form a new epoxy group under the catalysis of sodium hydroxide. HCl and sodium hydroxide react to form sodium chloride and water. Part of the generated water and part of the excess epichlorohydrin are removed under the action of vacuum.

[0027] (3) After the ring closure reaction is completed, the vacuum degree in the reaction kettle is continuously maintained at 10 kPa, and the temperature of the material in the reaction kettle is raised to 150°C. The remaining excess epichlorohydrin, diisobutyl ketone and butyl ether are removed, and a crude epoxy resin product is obtained.

[0028] (4) 200 g of toluene is added into the reaction kettle, and the crude epoxy resin product is fully dissolved. Then, 14.1 g of a 50% by mass sodium hydroxide solution is added into the reaction kettle, and heated to 65°C for stirring reaction. At the same time, the hydrolytic chlorine content of the epoxy resin in the reaction kettle is determined every 0.5 h until the hydrolytic chlorine content reaches 50 ppm, and the reaction is completed. A 30% by mass phosphoric acid solution is added into the reaction kettle until the pH of the material in the reaction kettle is 7. Then, 250 g of deionized water is added into the reaction kettle, and stirred and mixed for 10 min. After standing and separation, the organic phase obtained by separation is washed with deionized water for 2 times, and the mass of deionized water used for each washing is 80 g. Finally, the washed organic phase is heated to 150°C under a vacuum degree of 10 kPa to evaporate and recover toluene until the toluene content in the product reaches 100 ppm, and a low total chlorine type epoxy resin finished product is obtained.

[0029] Example 3

[0030] The low total chlorine type epoxy resin synthesis method of the present embodiment comprises the following steps: (1) 228 g of bisphenol A, 462.5 g of epichlorohydrin, 92.5 g of diisobutyl ketone, 69.5 g of butyl ether and 23 g of a branched ether compound are added into a reaction kettle. The temperature is raised to 50°C for stirring until the bisphenol A is fully dissolved. Then, 2 g of sodium hydroxide is added into the reaction kettle. The temperature of the material in the reaction kettle is raised to 60°C, and stirred for 1.5 h. In this step, the reaction is an etherification reaction stage, i.e., the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0031] (2) After the etherification reaction stage is completed, the temperature of the material in the reaction kettle is raised to 65°C, and 155 g of a 50% by mass sodium hydroxide solution is added dropwise into the reaction kettle, the dropwise addition time being 3.5 h. After the dropwise addition is completed, the temperature of the material in the reaction kettle is raised to 70°C, and the vacuum degree in the reaction kettle is adjusted to 10 kPa. The reaction is stirred for 0.5 h under vacuum. In this step, the reaction is a ring closure reaction, i.e., an epoxidation stage. In the reaction process, the chlorohydrin intermediate is removed from HCl to form a new epoxy group under the catalysis of sodium hydroxide. HCl and sodium hydroxide react to form sodium chloride and water. Part of the generated water and part of the excess epichlorohydrin are removed under the action of vacuum.

[0032] (3) After the ring closure reaction is completed, the vacuum degree in the reaction kettle is continuously maintained at 10 kPa, and the temperature of the material in the reaction kettle is raised to 150°C. The remaining excess epichlorohydrin, diisobutyl ketone, butyl ether and branched ether compounds are removed, and a crude epoxy resin product is obtained.

[0033] (4) 200 g of toluene is added to the reaction kettle, and the crude epoxy resin product is fully dissolved. Then, 14.1 g of a 50% by mass sodium hydroxide solution is added to the reaction kettle, and heated to 65°C for stirring reaction. At the same time, the hydrolytic chlorine content of the epoxy resin in the reaction kettle is measured every 0.5 h until the hydrolytic chlorine content reaches 50 ppm, and the reaction is completed. A 30% by mass phosphoric acid solution is added to the reaction kettle until the pH of the material in the reaction kettle is 7. Then, 250 g of deionized water is added to the reaction kettle, and stirred and mixed for 10 min. After standing and separating, the organic phase obtained by separation is washed with deionized water for 2 times, and the mass of deionized water used for each washing is 80 g. Finally, the washed organic phase is heated to 150°C under a vacuum degree of 10 kPa to evaporate and recover toluene until the toluene content in the product reaches 100 ppm, and a low total chlorine type epoxy resin finished product is obtained.

[0034] Example 4

[0035] The low total chlorine type epoxy resin synthesis method of the present embodiment includes the following steps: (1) 228 g of bisphenol A, 462.5 g of epichlorohydrin, 92.5 g of diisobutyl ketone, 79.5 g of butyl ether and 13 g of branched ether compounds are added to the reaction kettle. The temperature is raised to 50°C to fully dissolve bisphenol A, and then 2 g of sodium hydroxide is added to the reaction kettle. The temperature of the material in the reaction kettle is raised to 60°C, and stirred for 1.5 h. In this step, the reaction is an etherification reaction stage, i.e., the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to form a chlorohydrin intermediate.

[0036] (2) After the etherification reaction stage is completed, the temperature of the material in the reaction kettle is raised to 65°C, and 155 g of a 50% by mass sodium hydroxide solution is added dropwise into the reaction kettle, the dropwise addition time being 3.5 h. After the dropwise addition is completed, the temperature of the material in the reaction kettle is raised to 70°C, and the vacuum degree in the reaction kettle is adjusted to 10 kPa. The reaction is stirred for 0.5 h under vacuum. In this step, the reaction is a ring closure reaction, i.e., an epoxidation stage. In the reaction process, the chlorohydrin intermediate is removed of HCl to form a new epoxy group under the catalysis of sodium hydroxide. HCl and sodium hydroxide react to form sodium chloride and water. Part of the generated water and part of the excess epichlorohydrin are removed under the action of vacuum.

[0037] (3) After the ring closure reaction is completed, the vacuum degree in the reaction kettle is continuously maintained at 10 kPa, and the temperature of the material in the reaction kettle is raised to 150°C. The remaining excess epichlorohydrin, diisobutyl ketone, butyl ether and branched ether compounds are removed, to obtain a crude epoxy resin product.

[0038] (4) 200 g of toluene is added into the reaction kettle, and the crude epoxy resin product is fully dissolved. Then, 14.1 g of a 50% by mass sodium hydroxide solution is added into the reaction kettle. The reaction is heated to 65°C and stirred. At the same time, the hydrolytic chlorine content of the epoxy resin in the reaction kettle is measured every 0.5 h until the hydrolytic chlorine content reaches 50 ppm, and the reaction is completed. A 30% by mass phosphoric acid solution is added into the reaction kettle until the pH of the material in the reaction kettle is 7. Then, 250 g of deionized water is added into the reaction kettle, and the mixture is stirred for 10 min. After standing and separation, the organic phase obtained by separation is washed with deionized water for 2 times, and the mass of deionized water used for each washing is 80 g. Finally, the washed organic phase is heated to 150°C under a vacuum degree of 10 kPa to evaporate and recover toluene until the toluene content in the product reaches 100 ppm, to obtain a low total chlorine type epoxy resin finished product.

[0039] Example 5

[0040] The low total chlorine type epoxy resin synthesis method of the present embodiment comprises the following steps: (1) 228 g of bisphenol A, 462.5 g of epichlorohydrin, 115.6 g of diisobutyl ketone, 86.7 g of butyl ether and 28.9 g of branched ether compounds are added into a reaction kettle. The temperature is raised to 50°C to fully dissolve the bisphenol A, and then 2 g of sodium hydroxide is added into the reaction kettle. The temperature of the material in the reaction kettle is raised to 60°C, and the reaction is stirred for 1.5 h. In this step, the reaction is an etherification reaction stage, i.e., the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0041] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0042] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove excess epichlorohydrin, diisobutyl ketone, butyl ether and branched ether compounds to obtain crude epoxy resin.

[0043] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0044] Example 6

[0045] The method for synthesizing low-total-chlorine epoxy resin in this embodiment includes the following steps: (1) Add 228g of bisphenol A, 462.5g of epichlorohydrin, 115.6g of diisobutyl ketone, 99.1g of butyl ether and 16.5g of branched ether compounds to a reaction vessel, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reaction vessel, and then heat the material in the reaction vessel to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0046] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0047] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove excess epichlorohydrin, diisobutyl ketone, butyl ether and branched ether compounds to obtain crude epoxy resin.

[0048] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0049] Comparative Example 1 The method for synthesizing low-total-chlorine epoxy resin in this comparative example includes the following steps: (1) Add 228g of bisphenol A, 462.5g of epichlorohydrin, 23.1g of diisobutyl ketone and 23.1g of butyl ether to the reaction vessel, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reaction vessel, and then heat the material in the reaction vessel to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0050] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0051] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove the excess epichlorohydrin, diisobutyl ketone and butyl ether, and crude epoxy resin product is obtained.

[0052] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0053] Comparative Example 2 The method for synthesizing low-total-chlorine epoxy resin in this comparative example includes the following steps: (1) Add 228g of bisphenol A, 462.5g of epichlorohydrin, 69.4g of diisobutyl ketone and 69.4g of butyl ether to the reaction vessel, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reaction vessel, and then heat the material in the reaction vessel to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0054] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0055] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove the excess epichlorohydrin, diisobutyl ketone and butyl ether, and crude epoxy resin product is obtained.

[0056] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0057] Comparative Example 3 The method for synthesizing low-total-chlorine epoxy resin in this comparative example includes the following steps: (1) Add 228g of bisphenol A, 462.5g of epichlorohydrin, 231.3g of diisobutyl ketone and 231.3g of butyl ether to the reaction vessel, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reaction vessel, and then heat the material in the reaction vessel to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0058] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0059] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove the excess epichlorohydrin, diisobutyl ketone and butyl ether, and crude epoxy resin product is obtained.

[0060] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0061] Comparative Example 4 The difference between the low total chlorine epoxy resin synthesis method of this comparative example and the low total chlorine epoxy resin synthesis method of Example 3 is that in step (1) of the low total chlorine epoxy resin synthesis method of this comparative example, diisobutyl ketone is replaced with methyl isobutyl ketone.

[0062] Comparative Example 5 The difference between the low total chlorine epoxy resin synthesis method of this comparative example and the low total chlorine epoxy resin synthesis method of Example 3 is that in step (1) of the low total chlorine epoxy resin synthesis method of this comparative example, diisobutyl ketone is replaced with diisopropyl ketone.

[0063] Comparative Example 6 The difference between the low total chlorine epoxy resin synthesis method of this comparative example and the low total chlorine epoxy resin synthesis method of Example 3 is that in step (1) of the low total chlorine epoxy resin synthesis method of this comparative example, diisobutyl ketone is replaced with dipentyl ketone.

[0064] Comparative Example 7 The difference between the low total chlorine epoxy resin synthesis method of this comparative example and the low total chlorine epoxy resin synthesis method of Example 3 is that butyl ether is replaced with propyl ether in step (1) of the low total chlorine epoxy resin synthesis method of this comparative example.

[0065] Comparative Example 8 The difference between the low total chlorine epoxy resin synthesis method of this comparative example and the low total chlorine epoxy resin synthesis method of Example 3 is that in step (1) of the low total chlorine epoxy resin synthesis method of this comparative example, butyl ether is replaced with pentyl ether.

[0066] Comparative Example 9 The difference between the low-total-chlorine epoxy resin synthesis method of this comparative example and the low-total-chlorine epoxy resin synthesis method of Example 3 is only that the branched ether compound in step (1) of the low-total-chlorine epoxy resin synthesis method of this comparative example is isobutyl tert-butyl ether, and the chemical structure of isobutyl tert-butyl ether is as follows: .

[0067] Comparative Example 10 The method for synthesizing low-total-chlorine epoxy resin in this comparative example includes the following steps: (1) Add 228g of bisphenol A, 462.5g of epichlorohydrin and 185g of diisobutyl ketone to the reactor, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reactor, and then heat the material in the reactor to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0068] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0069] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove the excess epichlorohydrin and diisobutyl ketone, and crude epoxy resin product is obtained.

[0070] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0071] Comparative Example 11 The method for synthesizing low-total-chlorine epoxy resin in this comparative example includes the following steps: (1) Add 228g of bisphenol A, 462.5g of epichlorohydrin and 185g of butyl ether to the reactor, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reactor, and then heat the material in the reactor to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0072] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0073] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove the excess epichlorohydrin and butyl ether, and crude epoxy resin product is obtained.

[0074] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0075] Comparative Example 12 The method for synthesizing low-total-chlorine epoxy resin in this comparative example includes the following steps: (1) Add 228g of bisphenol A and 462.5g of epichlorohydrin to the reactor, stir and heat to 50°C until bisphenol A is fully dissolved, then add 2g of sodium hydroxide to the reactor, and then heat the material in the reactor to 60°C and stir for 1.5h. The reaction in this step is the etherification reaction stage, that is, the phenolic hydroxyl group of bisphenol A reacts with the epoxy group of epichlorohydrin to generate a chlorohydrin intermediate.

[0076] (2) After the etherification reaction stage is completed, the temperature of the material in the reactor is raised to 65°C, and 155g of 50% sodium hydroxide solution is added dropwise to the reactor for 3.5h. After the addition is completed, the temperature of the material in the reactor is raised to 70°C, and the vacuum degree in the reactor is adjusted to 10kPa. The reaction is stirred under vacuum for 0.5h. The reaction in this step is a closed-loop reaction, i.e. the epoxidation stage. During the reaction, the chlorohydrin intermediate is dehydrated under the catalysis of sodium hydroxide to form a new epoxy group. HCl and sodium hydroxide react to generate sodium chloride and water. Part of the water and part of the excess epichlorohydrin generated in the reaction are removed under vacuum.

[0077] (3) After the closed-loop reaction is completed, the vacuum degree in the reactor is maintained at 10 kPa, and the temperature of the material in the reactor is raised to 150°C to remove the excess epichlorohydrin and obtain the crude epoxy resin product.

[0078] (4) Add 200g of toluene to the reactor to fully dissolve the crude epoxy resin product. Then add 14.1g of 50% sodium hydroxide solution to the reactor and heat to 65°C for stirring reaction. At the same time, measure the hydrolytic chlorine content of the epoxy resin in the reactor every 0.5h until the hydrolytic chlorine content reaches 50ppm. After the reaction is completed, add 30% phosphoric acid solution to the reactor until the pH of the material in the reactor is 7. Then add 250g of deionized water to the reactor and stir for 10min. Let stand and separate the liquid. Wash the organic phase obtained by separation with deionized water twice. The mass of deionized water used for each wash is 80g. Finally, heat the washed organic phase to 150°C under a vacuum of 10kpa to evaporate and recover toluene until the toluene content in the product reaches 100ppm to obtain the low total chlorine epoxy resin product.

[0079] Experimental Example To evaluate the differences in total chlorine content of epoxy resins synthesized by the low-total-chlorine epoxy resin synthesis methods of the various examples and comparative examples, the total chlorine content of the epoxy resins was tested according to the method in standard GB / T 12007.3-1989 "Determination of Total Chlorine Content in Epoxy Resins", and the results are shown in Table 1.

[0080] Table 1. Total chlorine content of epoxy resins synthesized in each example and comparative example. Synthesis method Total chlorine content (ppm) Synthesis method Total chlorine content (ppm) Example 1 887 Comparative Example 4 1028 Example 2 742 Comparative Example 5 1107 Example 3 116 Comparative Example 6 1011 Example 4 109 Comparative Example 7 1056 Example 5 113 Comparative Example 8 1130 Example 6 118 Comparative Example 9 995 Comparative Example 1 1353 Comparative Example 10 1253 Comparative Example 2 1124 Comparative Example 11 1186 Comparative Example 3 1064 Comparative Example 12 1572 As shown in Table 1, the total chlorine content of the epoxy resins prepared in Examples 1-6 of this invention is less than 1000 ppm, indicating that the epoxy resin synthesis method of this invention can effectively reduce by-products in the reaction process and improve the purity and quality of the epoxy resin.

[0081] As shown in Examples 1-2 and Comparative Examples 1-3, the total chlorine content of the epoxy resin initially decreased and then increased with increasing amounts of diisobutyl ketone (DIK) and butyl ether (BTE). This indicates that when the mass ratio of DK to epichlorohydrin in the system is greater than or equal to 0.2:1 and less than 0.5:1, the total chlorine content of the synthesized epoxy resin is low. Conversely, when the mass ratio is less than 0.2:1 or greater than 0.5:1, the total chlorine content of the synthesized epoxy resin increases. This may be because both insufficient and excessive amounts of DK and BTE affect their transitional role between the aqueous and oil phases, thus hindering their effective promotion of the chemical reaction between the two phases during the reaction process, leading to the generation of byproducts and an increase in the total chlorine content.

[0082] As can be seen from Examples 1 and 3-6, when branched ether compounds are added to the system, the total chlorine content of the synthesized epoxy resin is further reduced. This indicates that branched ether compounds can further promote the transitional role of the mixed solvent in the aqueous and oil phases, thereby promoting the chemical reaction between the two phases, reducing the generation of by-products and lowering the total chlorine content.

[0083] As shown in Example 3 and Comparative Examples 4-9, when the structure of the ketone solvent, the structure of the ether solvent, or the structure of the branched ether compound in the mixed solvent is changed, the total chlorine content of the synthesized epoxy resin increases. This indicates that the structure of the ketone solvent, the ether solvent, and the branched ether compound in the mixed solvent has an important influence on the reduction of by-products during the epoxy resin synthesis process. This may be due to factors such as the polarity, oleophilicity, hydrophilicity, density, and steric hindrance of the solvent.

[0084] As can be seen from Example 1 and Comparative Examples 10-11, when only diisobutyl ketone or butyl ether is used, the total chlorine content of the synthesized epoxy resin increases, indicating that both diisobutyl ketone and butyl ether play a role in reducing byproducts during epoxy resin synthesis, and neither can be omitted.

[0085] As shown in Example 1 and Comparative Example 12, when no mixed solvent of diisobutyl ketone and butyl ether is added to the system, the total chlorine content of the synthesized epoxy resin reaches 1572 ppm, which again proves that the mixed solvent can reduce the by-products in the epoxy resin synthesis process, thereby reducing the total chlorine content.

Claims

1. A method for synthesizing a low-total-chlorine epoxy resin, characterized in that, Includes the following steps: (1) A ring-opening reaction is carried out between a diphenolic compound and epichlorohydrin in a mixed organic solvent under the action of an alkali metal hydroxide; the mixed organic solvent is composed of a ketone solvent and an ether solvent in a mass ratio of 0.5~1:0.5~1, wherein the ketone solvent is diisobutyl ketone, and the ether solvent is butyl ether or is composed of butyl ether and a branched ether compound in a mass ratio of 1:0.15~0.3, wherein the chemical structure of the branched ether compound is as follows: ； (2) Mix the system after the ring-opening reaction with the alkali metal hydroxide solution to make the ring-opening reaction product undergo a ring-closing reaction; (3) The system after the closed-ring reaction is purified to obtain a low total chlorine epoxy resin.

2. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1, characterized in that, The mass ratio of diisobutyl ketone to epichlorohydrin is 0.2~0.4:

1.

3. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1 or 2, characterized in that, The molar ratio of the diphenolic compound to epichlorohydrin is 1:4~9.

4. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1 or 2, characterized in that, In step (1), the molar ratio of the diphenolic compound to the alkali metal hydroxide is 1:0.005~0.10; the ring-opening reaction temperature is 40~80℃ and the time is 1~6h.

5. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1 or 2, characterized in that, The molar ratio of alkali metal hydroxide to diphenol compound in alkali metal hydroxide solution is 1~2.5:

1.

6. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1 or 2, characterized in that, The system after the ring-opening reaction was mixed with an alkali metal hydroxide solution and the reaction was carried out under a vacuum of 5-30 kPa.

7. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1 or 2, characterized in that, The diphenolic compound is bisphenol A, and the alkali metal hydroxide is sodium hydroxide.

8. The method for synthesizing low-total-chlorine epoxy resin as described in claim 1 or 2, characterized in that, The method for purifying the system after the ring-closing reaction is as follows: the system after the ring-closing reaction is distilled under reduced pressure to remove epichlorohydrin and mixed organic solvents to obtain a crude product. Then, the crude product is dehydrochlorinated to obtain a low-total-chlorine epoxy resin.

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