Low-chlorine low-viscosity high-purity epoxy resin and preparation method thereof

Abstract

The invention relates to the technical field of low-chlorine low-viscosity high-purity epoxy resin and a preparation method thereof, and discloses low-chlorine low-viscosity high-purity epoxy resin and a preparation method thereof.The preparation method comprises the following steps that 1, bisphenol A (BPA) and epoxy chloropropane are subjected to an etherification reaction, and chlorohydrin ether is prepared; and 2, when the conversion rate of the chlorohydrin ether hydroxyl in the step 1 reaches 80-90%, adding a sodium hydroxide aqueous solution at one time to carry out ring-closure reaction. Step 3, filtering and washing after washing, adding methylbenzene and deionized water in batches, standing and separating, removing a water phase, and then adding acid to adjust the pH value to 6-8; and 4, evaporating the solvent, drying and crystallizing. The two-step method is short in reaction time, stable in operation, small in temperature fluctuation, easy to control, less in generated three wastes, stable in quality and high in yield, and can be used for producing a series of epoxy resins. And the product has the advantages of high epoxy value, narrow molecular mass distribution, low viscosity, mild conditions, low monomer loss and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of low-chlorine, low-viscosity, high-purity epoxy resins and their preparation methods, and in particular to a low-chlorine, low-viscosity, high-purity epoxy resin and its preparation method. Background Art

[0002] The one-step method is a process in which bisphenol A (BPA) and epichlorohydrin (ECH) are polycondensed under the action of sodium hydroxide, that is, the ring-opening and ring-closing reactions are carried out under the same reaction conditions. This method has a mature process, and most domestic E-44 resins are currently produced by this process. The disadvantages of this method are long reaction time, and a large excess of epichlorohydrin is required (n(ECH):n(BPA) = 6-12:1), resulting in more consumption of epichlorohydrin, increased reaction energy consumption, and more by-products.

[0003] Low-chlorine, high-purity bisphenol A epoxy resin mainly refers to bisphenol A epoxy resin with relatively high purity and chlorine content within a certain specified range. It is usually used in the encapsulation materials for manufacturing electronic components and semiconductor devices, the structural parts and composite materials for manufacturing aerospace aircraft, and the medical devices, artificial organs and biomedical materials in high-end application fields such as electronic appliances, aerospace, and medical equipment.

[0004] Compared with ordinary bisphenol A epoxy resin, low-chlorine, high-purity bisphenol A epoxy resin has higher purity and less chlorine content, so it has characteristics such as higher thermal stability, mechanical strength and corrosion resistance, and is more suitable for use in high-temperature, high-pressure and high-humidity environments. Therefore, it is more applied to relatively harsh application fields such as high-end electronics, electrical appliances, and aerospace.

[0005] In the process of synthesizing bisphenol A epoxy resin, bisphenol A and epichlorohydrin first undergo a condensation reaction in an aqueous NaOH solution to form a chloropropanol ether compound. Then, the chloropropanol ether compound undergoes a ring-closing reaction under the action of sodium hydroxide to obtain an epoxy resin. During this process, some side reactions occur, resulting in chlorine that is difficult to hydrolyze in the epoxy resin molecule, so that the total chlorine content of the obtained epoxy resin product is relatively high and the quality is low.

[0006] In the field of electronic sealants, strict requirements are often imposed on the total chlorine content of epoxy resins, and the epoxy resin products obtained by traditional processes are difficult to meet the industry requirements. Therefore, a variety of subsequent treatment methods for using existing epoxy resins with high total chlorine content have been derived. However, due to the relatively high total chlorine content of the products obtained by existing processes, the economic cost of subsequent treatment is relatively high, and it will cause certain environmental pollution and energy waste.

[0007] For example, CN115093542A discloses a method for treating high total chlorine epoxy resin using an electrochemical method. The epoxy resin is mixed uniformly with water, and the resulting mixture is electrolyzed. The following reactions occur during the electrolysis of the mixture under the condition of energization: the inorganic chlorine in the epoxy resin enters the aqueous phase and undergoes an electrolysis reaction to form hydroxides, chlorine gas is generated at the anode, and hydrogen gas is generated at the cathode (the chlorine gas and hydrogen gas escape from the anode and cathode respectively); the organic chlorine in the epoxy resin reacts with the generated hydroxides to form hydroxy compounds and product inorganic chlorine; the product inorganic chlorine is hydrolyzed to form hydroxides, chlorine gas, and hydrogen gas, and this cycle continues until the total chlorine content of the epoxy resin is reduced to the lowest level. This method can reduce the resin with an original total chlorine content of 1800 ppm to below 500 ppm, and the resin with an original total chlorine content of 1000 ppm to below 300 ppm. Moreover, for resins with a lower original total chlorine content, both the treatment difficulty, treatment time, and treatment effect are better than those of resins with a higher original total chlorine content.

[0008] Again, CN115073712B discloses a post-treatment method for ultra-low total chlorine epoxy resin. Under the first preset reaction conditions, bisphenol A epoxy resin containing chlorine impurities undergoes an aldol condensation reaction with perfluoroalkyl aldehyde to obtain a reaction product; a perfluoroalkane solution is added to the reaction product for extraction, and after standing, the extraction phase and the raffinate phase are separated respectively. The extraction phase includes the fluorochlorinated product, and the raffinate phase includes low-chlorine bisphenol A epoxy resin; separating the extraction phase and the raffinate phase achieves the purpose of separating the chlorine-containing bisphenol A epoxy resin from the chlorine-free bisphenol A epoxy resin, and low-chlorine bisphenol A epoxy resin is obtained. The chlorine content of the low-chlorine bisphenol A epoxy resin is lower than that of the bisphenol A epoxy resin before the reaction. This method requires the total chlorine content of the original epoxy resin to be within 1000 ppm to obtain a better treatment effect. However, the total chlorine content of epoxy resins produced by existing ordinary processes often exceeds 1800 ppm, making it difficult to meet the raw material requirements of this method.

[0009] This case is proposed to solve or improve the shortcomings or deficiencies of the existing technology. Summary of the Invention

[0010] The present invention is achieved by adopting the following technical solutions:

[0011] A low-chlorine, low-viscosity, high-purity epoxy resin and a preparation method thereof, comprising the following steps

[0012] Step 1: Esterify bisphenol A (BPA) and epichlorohydrin to obtain chlorohydrin ether;

[0013] Step 2: When the hydroxy conversion rate of the chlorohydrin ether in Step 1 reaches 80%-90%, add an aqueous sodium hydroxide solution all at once for a ring-closure reaction.

[0014] Step 3: Filter after water washing and then wash again with water. Add toluene and deionized water in batches, let it stand for separation, remove the aqueous phase, and then add acid to adjust its pH to 6 - 8;

[0015] Step 4: Obtained after evaporating the solvent and then drying and crystallizing.

[0016] In a preferred embodiment, a catalyst is added during the etherification reaction in Step 1 and the reaction is carried out at a working temperature between 55 - 75 degrees Celsius.

[0017] In a preferred embodiment, the catalyst is an ammonium salt or choline.

[0018] In a preferred embodiment, the molar ratio of bisphenol A to epichlorohydrin in Step 1 is 1:3 - 10; the weight ratio of the solvent to epichlorohydrin is 1:3 - 5.

[0019] In a preferred embodiment, the concentration of the NaOH aqueous solution is 15 - 25% by weight, and the NaOH aqueous solution is added in one batch.

[0020] In a preferred embodiment, the low - chlorine high - purity bisphenol A - type epoxy resin in Step 1 contains 0.005 - 0.01% chlorine by weight, 99.8% - 99.9% bisphenol A - type epoxy resin, and other compounds below 0.13%.

[0021] In a preferred embodiment, the molar ratio of sodium hydroxide to bisphenol A in Step 2 is 0.7 - 1.0:1.0.

[0022] The advantages and positive effects of the present invention are:

[0023] 1. The two - step method has a short reaction time, stable operation, small temperature fluctuation, is easy to control, produces less three - wastes, has stable quality, high yield, and can produce a series of epoxy resins. It also has the advantages of high epoxy value of the product, narrow molecular mass distribution, low viscosity, mild conditions, and low monomer loss. Detailed implementation mode

[0024] A low - chlorine low - viscosity high - purity epoxy resin and its preparation method according to the present invention include the following steps

[0025] Step 1: Carry out an etherification reaction on bisphenol A (BPA) and epichlorohydrin to obtain chlorohydrin ether;

[0026] Step 2: When the hydroxyl conversion rate of the chlorohydrin ether in Step 1 reaches 80% - 90%, add the sodium hydroxide aqueous solution in one batch for a ring - closing reaction.

[0027] Step 3: Filter after water washing and then wash again with water. Add toluene and deionized water in batches, let it stand for separation, remove the aqueous phase, and then add acid to adjust its pH to 6 - 8;

[0028] Step 4: After evaporating the solvent, the product is dried and crystallized.

[0029] In a preferred embodiment, a catalyst is added during the etherification reaction in step 1 and the reaction is carried out at a working temperature between 55 and 75 degrees Celsius.

[0030] In a preferred embodiment, the catalyst is an ammonium salt or choline.

[0031] In a preferred embodiment, the molar ratio of bisphenol A to epichlorohydrin in step 1 is 1:3-10; the weight ratio of solvent to epichlorohydrin is 1:3-5.

[0032] In a preferred embodiment, the concentration of the NaOH aqueous solution is 15-25% by weight, and the NaOH aqueous solution is added in batches at one time.

[0033] In a preferred embodiment, the low-chlorine high-purity bisphenol A epoxy resin in step 1 contains 0.005-0.01% chlorine, 99.8%-99.9% bisphenol A epoxy resin and less than 0.13% other compounds by weight.

[0034] In a preferred embodiment, in step 2, the molar ratio of sodium hydroxide to bisphenol A is 0.7-1.0:1.0.

[0035] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, and therefore the present invention is not limited to the embodiments described in the specific implementation manners. Any other implementation manners derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A low-chlorine, low-viscosity, high-purity epoxy resin and a preparation method thereof, characterized in that: The following steps are included Step 1: etherifying bisphenol A (BPA) and epichlorohydrin to obtain chlorohydrin ether; Step 2: When the conversion rate of chlorohydrin ether hydroxyl in step 1 reaches 80%-90%, sodium hydroxide aqueous solution is added at one time to carry out ring-closing reaction. Step 3: After washing with water, filter and wash again with water, add toluene and deionized water in batches, stand and separate, remove the aqueous phase, and then add acid to adjust the pH to 6-8; Step 4: After evaporating the solvent, the product is dried and crystallized.

2. A low-chlorine, low-viscosity, high-purity epoxy resin and preparation method according to claim 1, characterized in that: During the etherification reaction in step 1, a catalyst is added and the reaction is carried out at a working temperature between 55 and 75 degrees Celsius.

3. A low-chlorine, low-viscosity, high-purity epoxy resin and preparation method according to claim 1, characterized in that: The catalyst is an ammonium salt or choline.

4. A low-chlorine, low-viscosity, high-purity epoxy resin and preparation method according to claim 1, characterized in that: The molar ratio of bisphenol A to epichlorohydrin in step 1 is 1:3-10; the weight ratio of solvent to epichlorohydrin is 1:3-5.

5. A low-chlorine, low-viscosity, high-purity epoxy resin and preparation method according to claim 1, characterized in that: The concentration of the NaOH aqueous solution is 15-25% by weight, and the NaOH aqueous solution is added in batches at one time.

6. A low-chlorine, low-viscosity, high-purity epoxy resin and preparation method according to claim 1, characterized in that: The low-chlorine high-purity bisphenol A epoxy resin in step 1 contains 0.005-0.01% chlorine, 99.8%-99.9% bisphenol A epoxy resin and less than 0.13% other compounds by weight.

7. A low-chlorine, low-viscosity, high-purity epoxy resin and preparation method according to claim 1, characterized in that: In step 2, the molar ratio of sodium hydroxide to bisphenol A is 0.7-1.0:1.0.