Cellulose ether is a polymer compound with an ether structure made of cellulose. Each glucosyl ring in the cellulose macromolecule contains three hydroxyl groups, the primary hydroxyl group on the sixth carbon atom, the secondary hydroxyl group on the second and third carbon atoms, and the hydrogen in the hydroxyl group is replaced by a hydrocarbon group to generate cellulose ether derivatives things.
Application of Cellulose Ether
1. Building material grade cellulose ether
Cellulose ether is known as “industrial monosodium glutamate”. Thanks to its excellent thickening, water retention and retarding properties, it is widely used to improve and optimize ready-mixed mortar, PVC resin manufacturing, latex paint, putty powder and other building materials Product performance. Thanks to the improvement of my country’s urbanization level, the rapid development of the building materials industry, the continuous improvement of the level of construction mechanization, and the increasing environmental protection requirements of consumers for building materials have driven the demand for non-ionic cellulose ethers in the field of building materials.
2. Pharmaceutical grade cellulose ether
Cellulose ethers are widely used in film coatings, adhesives, pharmaceutical films, ointments, dispersants, vegetable capsules, sustained and controlled release preparations and other fields of pharmaceuticals. As a skeleton material, cellulose ether has the functions of prolonging the drug effect time and promoting drug dispersion and dissolution; as a capsule and coating, it can avoid degradation and cross-linking and curing reactions, and is an important raw material for the production of pharmaceutical excipients. The application technology of pharmaceutical grade cellulose ether is mature in developed countries.
3. Food grade cellulose ether
Food-grade cellulose ether is a recognized safe food additive. It can be used as a food thickener, stabilizer and moisturizer to thicken, retain water, and improve taste. It is widely used in developed countries, mainly for baking Foodstuffs, collagen casings, non-dairy cream, fruit juices, sauces, meat and other protein products, fried foods, etc.
Cellulose ether production process
1. Hydroxyethyl methylcellulose
A preparation method of hydroxyethyl methylcellulose, the method is to use refined cotton as a raw material and ethylene oxide as an etherification agent to prepare hydroxyethyl methylcellulose. The weight parts of raw materials for preparing hydroxyethyl methyl cellulose are as follows: 700-800 parts of toluene and isopropanol mixture as solvent, 30-40 parts of water, 70-80 parts of sodium hydroxide, 80-85 parts of refined cotton, ring 20-28 parts of oxy-ethane, 80-90 parts of methyl chloride, 16-19 parts of glacial acetic acid; the specific steps are:
The first step, in the reaction kettle, add toluene and isopropanol mixture, water, and sodium hydroxide, heat up to 60-80 ° C, keep warm for 20-40 minutes;
The second step, alkalization: cool the above materials to 30-50°C, add refined cotton, spray the toluene and isopropanol mixture solvent, vacuumize to 0.006Mpa, fill nitrogen for 3 replacements, and carry out alkali after replacement. Alkalinization, alkalization conditions are: alkalization time is 2 hours, alkalization temperature is 30 ℃ 50 ℃;
The third step, etherification: after the alkalization is completed, the reactor is evacuated to 0.05-0.07MPa, and ethylene oxide and methyl chloride are added for 30-50 minutes; the first stage of etherification: 40-60°C, 1.0-2.0 Hours, the pressure is controlled between 0.150.3Mpa; the second stage of etherification: 60～90℃, 2.0～2.5 hours, the pressure is controlled between 0.40.8Mpa;
The fourth step, neutralization: add measured glacial acetic acid in advance to the precipitation kettle, press into the etherified material for neutralization, raise the temperature to 75-80°C for precipitation, the temperature rises to 102°C, and the detected pH value is 68 When the desolventization is completed; the desolventization tank is filled with 90 ℃ ~ 100 ℃ tap water treated by the reverse osmosis device;
The fifth step, centrifugal washing: the material in the fourth step is centrifuged through a horizontal screw centrifuge, and the separated material is transferred to a washing tank filled with hot water in advance for washing of the material;
The sixth step, centrifugal drying: the washed material is conveyed into the dryer through a horizontal screw centrifuge, and the material is dried at 150-170°C, and the dried material is crushed and packaged.
Compared with the existing cellulose ether production technology, the present invention uses ethylene oxide as an etherification agent to prepare hydroxyethyl methyl cellulose, which has good mildew resistance because of containing hydroxyethyl groups. It has good viscosity stability and mildew resistance during long-term storage. It can be used instead of other cellulose ethers.
2. Hydroxypropyl methylcellulose
(1) Treat cotton linters or wood pulp fibers with caustic soda, then react with mono-chloromethane and propylene oxide successively, refine and pulverize;
(2) It is obtained by treating appropriate grade of methyl cellulose with sodium hydroxide, reacting with propylene oxide under high temperature and high pressure to the ideal level, and refining it. The molecular weight ranges from 10 000 to 1 500 000.
Post time: Apr-07-2023