A method of preparing hydroxyethylmethylcellulose by producing hydroxyethylmethyl cellulose.
The weight of hydroxyethyl methyl cellulose shall be 700~800 mixture of toluene and isopropanol as solvent, 30-40 water, 70-80 sodium hydroxide, 80 to 85 refined cotton, 20-28 ethylene oxide, 80~90 chloromethane, 16 to 19 ice glacial acetic acid;
specific steps are: In the first step, add toluene and isopropanol mixture, water, and sodium hydroxide, heat up to 60~80℃, heat preservation for 20~40 minutes.
The second step, alkalinization: cool the above materials to 30~50℃, add refined cotton, spray the solvent of toluene and isopropanol mixture, vacuum to 0.006Mpa, nitrogen filling gas for three times, after the alkalinization conditions are: alkalinization time is 2 hours, the alkalinization temperature is 30℃ 50℃;
Third step, etherification: alkalinization, reaction kettle vacuum to 0.05~0.07MPa, add ethylene oxide and chlorthane for 30~50 minutes; ether first phase: 40~60℃, 1.0~2.0 hours, pressure control between 0.150.3Mpa; etherification second phase: 60~ 90℃, 2.0~2.5 hours, pressure control between 0.40.8Mpa;
Step 4,neutralization: add the measured glacial acetic acid in the dedissolving kettle in advance, press into the etherified material for neutralization, heat up by 75~80℃ for dedissolving, the temperature rises to 102℃, detect the PH value of 68;
Complete the tap water treated with 90℃ ~100℃ in the dedissolving kettle;
The fifth step, centrifugal washing: the fourth step of the material through the horizontal spiral centrifuge centrifuge separation, separate the material to transfer to the washing kettle filled with hot water, material washing;
Step 6, centrifugal drying: the washed material is transported into the dryer through the horizontal spiral centrifuge, and the material is dried at 150~170℃, and the dried material is crushed and packaged.
Compared with the existing cellulose ether production technology.
The present invention uses ethylene oxide as an ether agent to produce hydroxyethyl methyl cellulose.