Application and preparation of hydroxyethyl methylcellulose

Hydroxyethylmethyl cellulose HEMC can serve as a colloidal protective agent. Emulsifier and dispersant due to the surface active function of aqueous solution. Application examples are as follows: hydroxyethyl methyl cellulose influence on cement properties. Hydroxyethylmethylcellulose is a nonodorless, tasteless, and non-toxic white powder that dissolves in cold water to form a transparent, viscous solution. It has the characteristics of thickening, adhesion, dispersion, emulsification, film formation, suspension, adsorption, cemelling, surface activity, etc. Because the aqueous solution has a surface-active function, it can act as a colloidal protective agent, emulsifier and dispersant. Hydroxyethylmethyl cellulose solution is a high efficiency water retaining agent.

lining-up:

A method of preparing hydroxyethylmethylcellulose by producing hydroxyethylmethylcellulose. The weight of hydroxyethyl methyl cellulose shall be 700~800 parts of toluene and isopropanol mixture, 30 to 40 parts of water, 70-80 sodium hydroxide, 80 to 85 refined cotton, 20 to 28 ethylene oxide, 80 to 90 chloromethane, and 16 to 19 glacial acetic acid.

The specific steps are:
  • In the first step, at first add toluene and isopropanol mixture, water, and sodium hydroxide. Heat up to 60~80℃, heat preservation for 20~40 minutes;
  • The second step, alkalinization: at first 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 3 times. After the replacement, the alkalinization conditions are: the alkalinization time is 2 hours, the alkalinization temperature is 30℃ 50℃;
  • The third step, etherification: at first after alkalization. Reaction kettle vacuum to 0.05~0.07MPa, add ethylene oxide and chloromethane for 30~50 minutes. The first phase: 40~60℃, 1.0~2.0 hours, pressure control between 0.150.3Mpa.the second phase: 60~ 90℃, 2.0~2.5 hours, pressure control between 0.40.8Mpa;
  • Step 4, neutralization: at first in the dedissolution kettle adds the measured glacial acetic acid in advance, press into the etherified material for neutralization, heat up 75~80℃ for dedissolution, the temperature rises to 102℃, detect the PH value of 68; add the tap water treated with 90℃ ~100℃ in the dissociation kettle;
  • The fifth step, centrifugal washing: at first the fourth step of the material through the horizontal spiral centrifuge centrifugation separation, separation material transfer to the pre-filled with hot water washing kettle, 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 ethification agent to produce hydroxyethyl methyl cellulose, because it contains hydroxxyethyl group, has good mildew resistance, long-term viscosity stability and mildew resistance in long-term storage.It can replace other cellulose ether for use.

HEMC

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