Method for preparing bisphenol-A liquid epoxy resin

Abstract

The invention relates to a method for preparing bisphenol-A liquid epoxy resin, and belongs to the field of high polymer preparation. The method comprises the following steps: 1) adding a quaternary ammonium salt phase-transfer catalyst, and performing etherification at a temperature of between 70 and 85 DEG C for 45 to 240 minutes; 2) at a constant temperature of between 60 and 70DEG C, droppingalkali by NaOH aqueous solution for 1.5 to 4 hours, keeping epoxy chloropropane refluxing in the alkali dropping period, and discharging water out of a reaction system; and 3) separating unreacted epoxy chloropropane by a rotary evaporator at a temperature of 135DEG C, dissolving a mixture of resin and salt, removing solid salt by a filter, washing the resin for 3 to 5 times by water, separating solvent, and obtaining the final product. The prepared epoxy resin has the epoxy value between 0.55 and 0.56 through titration by hydrochloric acid acetone solution, low viscosity (between 7,000 and 10,000mPas), and the epoxy index between 0.595 and 0.622 through infrared spectroscopic analysis, and comprises 91 to 92 percent of micro molecular epoxy resin.

Description

Technical field: [0001] The invention belongs to the field of polymer preparation, in particular to a method for preparing bisphenol A liquid epoxy resin. Background technique: [0002] Bisphenol A type epoxy resin, as the most common representative variety of epoxy resin, has many excellent characteristics, such as high bonding strength, wide bonding surface, low shrinkage, good stability and electrical insulation, etc. The epoxy group is the characteristic group of epoxy resin, and its content is the most important index of this resin. [0003] Patent No. CN1544502A pointed out that at a temperature of 40-50°C, bisphenol A, epichlorohydrin and a small amount of NaOH aqueous solution were pre-reacted for 150-240 minutes, and then the pre-reacted materials were fed into the reactor, At a temperature of ~70°C and a vacuum with an absolute pressure of 20-30KPa, NaOH aqueous solution is added at a certain flow rate to carry out the reaction. The water and epichlorohydrin steam...

AI Technical Summary

Problems solved by technology

[0008] The U.S. Patent No. 4582892 points out that with bisphenol A and epichlorohydrin (the molar ratio is 1: 9.85) in the presence of phase transfer catalyst to synthesize epoxy resin, the phase transfer catalyst is benzyltrimethylammonium chloride , the etherification reaction temperature is 55°C, the etherification reaction is stopped when the conversion rate of bisphenol A reaches 98.2%, and then alkali is added to carry out the second-stage ring-closure reaction, and finally the product resin is obtained. The conversion rate of phenol A is monitored, but the specific monitoring method is not given, and the influence of the etherification reaction conditions on the etherification result and the epoxy value of the resin are not discussed in depth.